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Cardiovascular responses to a psychological stressor in high versus low reactive women Frankish, Charles James 1985

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CARDIOVASCULAR RESPONSES TO A PSYCHOLOGICAL  STRESSOR  I N HIGH VERSUS LOW R E A C T I V E WOMEN by CHARLES JAMES B.A.,  FRANKISH  The U n i v e r s i t y o f B r i t i s h C o l u m b i a ,  A T H E S I S SUBMITTED I N P A R T I A L FULFILLMENT THE REQUIREMENTS  FOR THE DEGREE OF  MASTER OF ARTS  in THE FACULTY OF GRADUATE Department of  We a c c e p t  this  Psychology  t h e s i s as  to the required  THE U N I V E R S I T Y  STUDIES  conforming  standard  OF B R I T I S H  July,  COLUMBIA  1985  ©Charles Frankish,  1985  7 8  1981  OF  In  presenting  requirements of  British  it  freely  agree for  this  thesis  i np a r t i a l  f o r an advanced  degree  Columbia, I agree that available  that  f o r reference  permission  fulfilment of the a t the University  the Library  shall  and study.  I  f o r extensive  s c h o l a r l y p u r p o s e s may b e g r a n t e d b y t h e h e a d o r by h i s o r h e rrepresentatives.  understood  that  for  financial  copying o r publication  gain  shall  Department o f  PSYCHOLOGY  The U n i v e r s i t y o f B r i t i s h 1956 Main M a l l Vancouver, Canada V6T 1Y3  /si ^  November 15,  1985.  of this  Columbia  thesis  o f my  I t i s thesis  n o t b e a l l o w e d w i t h o u t my  permission.  Date  further  copying o f this  department  make  written  ABSTRACT Recent stressor  s t u d i e s have i m p l i c a t e d a c u t e r e a c t i v i t y t o a  as a p o t e n t i a l marker i n  disorders.  However,  the pathogenesis  o n l y v e r y few w e l l c o n t r o l l e d  of  psychological  cardiovascular  prospective  n e c e s s a r y t o c o n f i r m t h i s h y p o t h e s i s have been c o n d u c t e d .  Such s t u d i e s  need t o demonstrate t h a t c a r d i o v a s c u l a r h y p e r r e a c t i v i t y i s a individual-specific  p r e d i s p o s i t i o n which i s  between degree of  h a b i t u a t i o n as a f u n c t i o n interstressor  cardiovascular  o f number o f  stable,  In the present  r e s p o n s i v e n e s s and  across t r i a l s  response  s t r e s s o r r e p e t i t i o n s and l e n g t h  white noise interference rest period followed  three,  two e x p e r i m e n t a l  each t a s k p e r i o d .  laboratory session.  conditions:  identical  was  A three  Subjects in Condition 2  fifteen-minute  recovery period.  s u b j e c t s completed a s e r i e s of  t o t h o s e c o m p l e t e d i n C o n d i t i o n 1,  experimental sessions heart rate  by a  single  During  three mental a r i t h m e t i c  visit  (HR), s y s t o l i c  minute  (single  exposure) completed the twenty-minute adaptation period followed  second v i s i t a l l  the  3 m i n u t e m e n t a l a r i t h m e t i c t a s k s w i t h a 90 db  during the f i r s t  t a s k and a subsequent  (2  (mean a g e 2 4 . 6 y e a r s ) p a r t i c i p a t e d i n  i n C o n d i t i o n 1 (repeated exposure) a twenty minute a d a p t a t i o n p e r i o d by a s e r i e s o f  (3  i n h i g h v e r s u s l o w c a r d i o - r e a c t i v e women.  S u b j e c t s w e r e r a n d o m l y a s s i g n e d t o one o f  3-minute  of  ( 3 per s e s s i o n ) , and a c r o s s e x p e r i m e n t a l s e s s i o n s  Ninety female, normotensive subjects  followed  the  i n t e r v a l was a s s e s s e d .  s e s s i o n s w i t h a 4-week i n t e r v a l )  study.  by  study  Responses t o a m e n t a l a r i t h m e t i c t a s k were compared w i t h i n t r i a l s minutes),  would  not s i g n i f i c a n t l y a f f e c t e d  response h a b i t u a t i o n to repeated s t r e s s o r exposures. relationship  studies  1.  (SBP),  Throughout  the  diastolic  (DBP),  their tasks  and  -  mean a r t e r i a l p r e s s u r e  i i i  -  (MAP) w e r e m o n i t o r e d a t one m i n u t e i n t e r v a l s u s i n g  a u t o m a t e d , d i g i t a l Dinamap 845 V i t a l S i g n s M o n i t o r . i n t o h e a r t r a t e a n d SBP r e a c t i v i t y t e r c i l e s the f i r s t into  s t r e s s t a s k i n the i n i t i a l  t h e l o w e s t and h i g h e s t  S u b j e c t s were  on t h e b a s i s o f  session.  classified  their  response  O n l y t h o s e s u b j e c t s who  r e a c t i v i t y t e r c i l e s were i n c l u d e d  an  in  to  fell  subsequent  analyses. Given t h at not a l l  subjects received a l l  c o v a r i a n c e were n e c e s s a r y t o f u l l y  trials  three s e t s of a n a l y s e s  examine t h e 2 (low v e r s u s h i g h  reactivity)  X 2 ( c o n d i t i o n s ) X 2 ( v i s i t s ) X 3 ( t r i a l s ) X 3 (minutes per t r i a l ) measures f a c t o r i a l covariates.  design.  the r e a c t i v i t y groups, dependent measures.  visits,  trials,  These f i n d i n g s  i n d i c a t e d main e f f e c t s and m i n u t e s f a c t o r s  tests identified  decreases i n response l e v e l s w i t h i n t r i a l s ,  greater  on e a c h o f  across t r i a l s ,  r e s p o n s e s showed a d e l a y e d o n s e t o f experimental t r i a l s .  All  subsequent  and a c r o s s t h e each t r i a l  each t r i a l .  For  reactivity  groups i n the repeated s t r e s s o r  the  The  d i s c r i m i n a t e d from those of  the low r e a c t o r s .  and t h e use o f a c u t e c a r d i o v a s c u l a r  same  of  response  showed  experimental  could not  The n o t i o n o f  were  within  s t r e s s t a s k t h e HR, DBP a n d MAP r e s p o n s e s o f condition  two  pressure  High reactors  than low r e a c t o r s a c r o s s  sessions.  response s p e c i f i c i t y  Blood  b l o o d p r e s s u r e m e a s u r e s showed e v i d e n c e  i n responses  the f i n a l  factor.  decreases i n response magnitude  d e c r e a s e s from minute 2 t o minute 3 of greater decreases  the t r i a l s  four  significant  Decreases from minute 1 to minute 2 of  d e c r e a s e s was o b s e r v e d f o r  for  the  t h a n t h o s e f r o m m i n u t e 2 t o m i n u t e 3 on h e a r t r a t e m e a s u r e s .  p a t t e r n of  as  (_p_ < . 0 0 1 )  together w i t h the r e s u l t s of  t r e n d a n a l y s e s and Newman-Keuls p o s t - h o c  experimental sessions.  repeated  Age a n d r e s p e c t i v e b a s e l i n e s w e r e e m p l o y e d  The r e s u l t s c o n s i s t e n t l y  of  the  high  be  within-individual  r e a c t i v i t y as both  c l a s s i f i c a t i o n a n d a n o u t c o m e m e a s u r e may t h e r e f o r e n e e d t o be r e - e v a l u a t e d .  a  - iv -  TABLE OF CONTENTS Page ii  ABSTRACT L i s t of Tables L i s t of Figures L i s t of Appendices Acknowledgement  v  i  l  vxxx  ix x  INTRODUCTION  x  LITERATURE REVIEW  5  Basic Cardiophysiology Stress and Cardiovascular  Disease  Cardiovascular Reactivity and Coronary Heart Disease  ^ Q  Animal models Q  Prospective human studies Retrospective studies Type-A studies Individual Differences Response stereotypy Psychological mediators Physiological mediators Task Influences Stimulus s p e c i f i c i t y C l a s s i f i c a t i o n of stressors Sensory intake versus sensory rejection Active versus passive coping Engagement-involvement Mental arithmetic as a stressor Summary: Stimulus s p e c i f i c i t y versus response stereotypy  ^ ^ ^ 12 12 13 ^ ^ 16 16 17 19 20 24  Task-Person Interactions  25  S t a b i l i t y of Individual Differences i n Cardiovascular Reactivity  28  Habituation of Cardiovascular Responses  30  Characteristics of cardiovascular habituation  31  -  V  -  Page Methodological  Issues Regarding R e a c t i v i t y  Subject c h a r a c t e r i s t i c s A d a p t a t i o n and b a s e l i n e measures Instruction effects Task c h a r a c t e r i s t i c s S t i m u l u s r e p e t i t i o n and i n t e r - s t r e s s o r Summary S e l e c t i o n of response measures Purpose of  and H a b i t u a t i o n  interval  t h e S t u d y and E x p e r i m e n t a l H y p o t h e s e s  32 33 36 38 39 40 42 43 45  Method S y n o p s i s  47  Method  49  Subject c h a r a c t e r i s t i c s Experimental setting A p p a r a t u s and Equipment C a r d i o v a s c u l a r dependent S e l f - r e p o r t measures Stress task  49 49 49 50 50  measures  5 0  Procedure Pre-experimental preparations Pre-stress adaptation Experimental condition Debriefing E x p e r i m e n t a l d e s i g n and s t a t i s t i c a l  51  analyses  Results D e s c r i p t i v e c h a r a c t e r i s t i c s of c a r d i o v a s c u l a r dependent measures D e s c r i p t i v e c h a r a c t e r i s t i c s of s e l f - r e p o r t dependent measures D e s c r i p t i v e c h a r a c t e r i s t i c s of c a r d i o v a s c u l a r r e a c t i v i t y groups C o r r e l a t i o n a l Analyses Within session cardiovascular correlations Across session cardiovascular correlations I n t e r c o r r e l a t i o n s of s e l f - r e p o r t measures I n t e r c o r r e l a t i o n s of s e l f - r e p o r t and c a r d i o v a s c u l a r measures A n a l y s e s of c o v a r i a n c e H e a r t r a t e ANCOVAs C o n d i t i o n 1 ANCOVA T a s k 1 ANCOVA V i s i t 2 ANCOVA S y s t o l i c b l o o d p r e s s u r e ANCOVAS C o n d i t i o n 1 ANCOVA T a s k 1 ANCOVA V i s i t 2 ANCOVA  51 51 52 53 55 55 55 56 56 69 72 74 75 75 77 78 79 84 86 90 90 94 95  -  vi  Page  D i a s t o l i c b l o o d p r e s s u r e ANCOVAs C o n d i t i o n 1 ANCOVA T a s k 1 ANCOVA V i s i t 2 ANCOVA Mean a r t e r i a l p r e s s u r e ANCOVAS C o n d i t i o n 1 ANCOVA T a s k 1 ANCOVA V i s i t 2 ANCOVA Summary o f ANCOVA E f f e c t s Discussion S u b j e c t c h a r a c t e r i s t i c s and r e a c t i v i t y g r o u p s C a r d i o v a s c u l a r Dependent measures S e l f - r e p o r t measures C o n d i t i o n 1 ANCOVAS T a s k 1 ANCOVAS V i s i t 2 ANCOVAs M a j o r c o n c l u s i o n s and recommendations  97 97 103 104 106 106 109 110 112 114 115 120 122 123 124 125 126  References  131  Appendices  155  -  vii  -  L I S T OF TABLES Page Table 1  C o r r e l a t i o n s Among C a r d i o v a s c u l a r Change S c o r e s by a V a r i e t y o f T a s k s  Table 2  C a r d i o v a s c u l a r Changes A s s o c i a t e d w i t h a Arithmetic Stressor  Table 3  Experimental  Table 4  B l o o d P r e s s u r e Norms f o r Women A g e d 1 8 - 6 7  Table 5  Means a n d S t a n d a r d D e v i a t i o n s o f C a r d i o v a s c u l a r Measures  Elicited 11  Mental  21 49  Design  55  Years  58  Table 6  Means a n d S t a n d a r d D e v i a t i o n s o f  Table 7  Frequency D i s t r i b u t i o n of Rate R e a c t i v i t y Groups  Table 8  C o m p a r i s o n o f H e a r t R a t e and S y s t o l i c R e a c t i v i t y Experimental Sessions  across  Table 9  C l a s s i f i c a t i o n o f S u b j e c t s by H e a r t R a t e v e r s u s Blood Pressure R e a c t i v i t y  Systolic  T a b l e 10  Cross t a b u l a t i o n of B i r t h C o n t r o l , Menstruation Reactivity Variables  and  T a b l e 11  Intercorrelations  T a b l e 12  C o r r e l a t i o n s o f S u b j e c t Age w i t h B a s e l i n e B l o o d and S t r e s s Response Measures  Pressure  T a b l e 13  C o r r e l a t i o n s o f S e l f - R e p o r t e d F i t n e s s L e v e l and of P h y s i c a l A c t i v i t y w i t h C a r d i o v a s c u l a r S t r e s s and R e c o v e r y P e r i o d V a l u e s  Frequency Response  T a b l e 14  Intercorrelations  T a b l e 15  - Summary o f ANCOVA  Self-Report  Dependent  S y s t o l i c B l o o d P r e s s u r e and  of C a r d i o v a s c u l a r Dependent  of  Measures  Self-Report  63 Heart  65  66  68  69 71  Measures  72  74 77  Measures  114  Effects  V  -  viii  -  L I S T OF FIGURES Page Figure  1  C o n d i t i o n 1: H e a r t R a t e D a t a  58  Figure  2  T a s k 1: H e a r t R a t e D a t a  80  Figure  3  Visit  81  Figure  4  Condition  2: H e a r t Rate Data 1: S y s t o l i c B l o o d P r e s s u r e D a t a  59  Figure 5  T a s k 1: S y s t o l i c B l o o d P r e s s u r e D a t a  91  Figure  6  Visit  92  Figure  7  C o n d i t i o n 1: D i a s t o l i c B l o o d P r e s s u r e D a t a  60  Figure  8  T a s k 1: D i a s t o l i c B l o o d P r e s s u r e D a t a  89  2: S y s t o l i c B l o o d P r e s s u r e Data  Figure 9  Visit  2: D i a s t o l i c B l o o d P r e s s u r e Data  100  Figure  10  C o n d i t i o n 1: Mean A r t e r i a l P r e s s u r e D a t a  Figure  11  T a s k 1: Mean A r t e r i a l P r e s s u r e D a t a  107  Figure  12  Visit  108  Figure  13  Task 1 Heart R a t e : V i s i t s X C o n d i t i o n s X Groups I n t e r a c t i o n  87  Figure  14  Visit  2 Heaert Rate: T r i a l s  89  Figure  15  Visit  2 S y s t o l i c Blood Pressure: Conditions X T r i a l s  61  2 : Mean A r t e r i a l P r e s s u r e D a t a  X Minutes X Groups I n t e r a c t i o n X  Groups I n t e r a c t i o n Figure  Figure  Figure  Figure  16  17  18  19  98  Condition 1 D i a s t o l i c Blood Pressure: T r i a l s Groups I n t e r a c t i o n  X Minutes  X 102  V i s i t 2 D i a s t o l i c Blood Pressure: Conditions X Minutes X Groups I n t e r a c t i o n  105  T a s k 1 Mean A r t e r i a l P r e s s u r e : C o n d i t i o n s X M i n u t e s X Groups I n t e r a c t i o n  111  Condition 1 Heart Rate: V i s i t s X T r i a l s  X Groups I n t e r a c t i o n  83  L I S T OF  APPENDICES Page  Appendix 1  Subject Consent  Form  155  Appendix 2  Par-Q Screening  Questionnaire  156  Appendix  Stress Perception  3  158  Appendix 4  Experimental  Appendix 5  C o n d i t i o n 1 Heart Rate  Appendix 6  Task 1 Heart Rate  Appendix  7  Visit  157  Questionnaire  Script  160  ANCOVA  161  ANCOVA  162  2 H e a r t R a t e ANCOVA  163  Appendix 8  Newman K u e l s T e s t s  of Heart Rate  Appendix 9  Scheffe's Tests  Heart Rate  A p p e n d i x 10  Condition 1 S y s t o l i c Blood Pressure  A p p e n d i x 11  Task 1 S y s t o l i c Blood P r e s s u r e  A p p e n d i x 12  Visit  A p p e n d i x 13  Newman-Keuls T e s t s  of S y s t o l i c Blood Pressure  A p p e n d i x 14  Scheffe's Tests  S y s t o l i c Blood Pressure  A p p e n d i x 15  Condition 1 D i a s t o l i c Blood Pressure  A p p e n d i x 16  Task 1 D i a s t o l i c Blood P r e s s u r e  A p p e n d i x 17  Visit  A p p e n d i x 18  Newman-Keuls T e s t s  A p p e n d i x 19  Scheffe's Tests  A p p e n d i x 20  C o n d i t i o n 1 Mean A r t e r i a l P r e s s u r e  Appendix  21  of  164  Data  165  ANCOVA  166  ANCOVA  2 S y s t o l i c Blood Pressure  of  Data  167  ANCOVA Data  170  ANCOVA  171 172  ANCOVA  of D i a s t o l i c Blood Pressure  of D i a s t o l i c Blood Pressure  T a s k 1 Mean A r t e r i a l P r e s s u r e  Data  Data  A p p e n d i x 23  Neuman-Keuls T e s t s  A p p e n d i x 24  S c h e f f e ' s T e s t s o f Mean A r t e r i a l P r e s s u r e  174  176  ANCOVA  Visit  173  175  ANCOVA  A p p e n d i x 22  2 Mean A r t e r i a l P r e s s u r e  169  Data  ANCOVA  2 D i a s t o l i c Blood Pressure  168  177  ANCOVA  o f Mean A r t e r i a l P r e s s u r e  Data  Data  178 179  -  X  -  ACKNOWLEDGEMENTS  I would l i k e  t o t h a n k my f r i e n d a n d s u p e r v i s o r ,  s u p p o r t and a d v i c e n e v e r Second, G.J.  D r . W. L i n d e n ,  whose  wavered.  I w i s h t o e x p r e s s my g r a t i t u d e t o my t h e s i s c o m m i t t e e m e m b e r s : D r .  Johnson,  D r . W. I a c o n o ,  a n d D r . D. C r o c k e t t f o r  their  high  quality  guidance. Third, centre  my t h a n k s a r e e x t e n d e d t o t h e r e s e a r c h a s s i s t a n t s a n d  staff  Finally,  for  their  computing  assistance.  I am i n d e b t e d t o my f a m i l y ,  friends,  s u p p o r t a n d c a r i n g a r e i n e x t r i c a b l y woven i n t o  and f e l l o w  students  the substance of  this  whose thesis.  -  1  -  INTRODUCTION  Over t h e p a s t t h r e e decades numerous r e s e a r c h e r s Dembroski,  1982; Frankenhaeuser,  provided evidence  the i n f l u e n c e in fact,  of  b e h a v i o r a l and p s y c h o s o c i a l f a c t o r s  influences  or her c h r o n i c Recent  on h e a l t h .  a c u t e e n d o c r i n e and c a r d i o v a s c u l a r  pathology.  C a r d i o v a s c u l a r p a t h o l o g y has  e s s e n t i a l h y p e r t e n s i o n and o t h e r  For example, i t  has been s u g g e s t e d t h a t  Singer,  regarding  (see E l i o t ,  1983; K r a n t z & Manuck,  psychosomatic disorders S t u d i e s of  of  Bickford,  1961; Manuck,  behaviorally-induced, stress with  physiologic pathogenic  coronary heart disease  1984 f o r  extensive reviews).  In  that  and  general,  potentially  through exposure to b e h a v i o r a l s t i m u l i Kaplan, & Clarkson, 1983).  b o t h n a t u r a l i s t i c and l a b o r a t o r y s t r e s s o r s .  D u r i n g such a t a s k the s u b j e c t  an  cardiovascular  incidence  (Dembroski, 1978; S t e p t o e , Ross, & M e l v i l l e ,  o f t e n induced i n the l a b o r a t o r y  and  B u e l l , & D e m b r o s k i , 1 9 8 2 ; K r a n t z , Baum, &  b o t h a n i m a l s a n d humans i n d i c a t e  s t a t e s c a n be p r o d u c e d  of  been  p h y s i o l o g i c a l h y p e r r e s p o n s e s have been a s s o c i a t e d w i t h an i n c r e a s e d of  has  time.  s t r e s s may be a m a r k e r o f  and i n c r e a s e d r i s k i n t h e e t i o l o g y  essential hypertension  of  i n i t i a l or acute response to s t r e s s  responses to psychological  hyperresponsiveness to psychological processes  Research  coping response to a given s t r e s s o r over  of  have  on c o r o n a r y d i s e a s e  b i o m e d i c a l and b e h a v i o r a l r e s e a r c h h a s l i n k e d  increased incidence  1981)  t h e most e x t e n s i v e l y d e v e l o p e d a r e a s i n t h e s t u d y  a s s o c i a t e d w i t h b o t h an i n d i v i d u a l ' s his  Buell, &  between the development  and m a l a d a p t i v e r e s p o n s e s t o s t r e s s .  become one o f  psychological  1975; G l a s s , 1977; O b r i s t ,  of a p o s i t i v e r e l a t i o n s h i p  coronary pathology  (Eliot,  (Engel &  stress is  through the use of mental s t r e s s performs a c o g n i t i v e  pathogenic  Such s t u d i e s have  Psychological  task while  1984).  employed most  tasks.  multiple  -  subjective,  2  -  b e h a v i o r a l , and p h y s i o l o g i c a l  dependent v a r i a b l e s are  assessed.  S t r e s s t a s k r e s p o n s e l e v e l s a r e t h e n compared t o p r e - s t r e s s o r b a s e l i n e (Linden & McEachern,  1985).  Perhaps  t h e most f r e q u e n t l y e m p l o y e d  stressor  i s a mental a r i t h m e t i c t a s k .  Typically,  serially  s u b t r a c t a g i v e n number f r o m t h e number 1 , 0 0 0 .  cognitive  subjects are required  al.,  stressor  (Vossel & Laux,  1977; S c h u l t e & Neus,  1981; S c h u l t e F r i e d r i c h , R u d d e l , S c h i r m e r , & von E i f f ,  Frankish,  & McEachern,  The s t u d y o f  acute cardiovascular  reliable  1 9 7 9 ; Neus  (Obrist,  mental  1981; K r a n t z & Manuck,  Responses to c o g n i t i v e  stressors  h a v e b e e n v a r i o u s l y c h a r a c t e r i z e d a s b e i n g due t o i n d i v i d u a l - s p e c i f i c stimulus-specific factors,  psychological control  et  1981; L i n d e n ,  responses to s t r e s s o r s such as  1984; L i n d e n et a l . , 1 9 8 5 ) .  Individual-specific  or  some i n t e r a c t i o n o f  t h e s e two  characteristics  such as n e u r o t i c i s m (Eysenck,  factors,  dimensions.  r e s p o n s e s t o s t r e s s have been a t t r i b u t e d t o  both  1967), locus  ( H a r r e l , 1980) and r e p r e s s i o n - s e n s i t i z a t i o n ( L i n d e n , 1 9 8 4 ) , and  p r e v i o u s l y noted p h y s i o l o g i c a l hyperresponsiveness. relatively & Lacey,  stable,  characteristics  Evidence e x i s t s that  such as  individuals  McKinney, Ruddel, B u e l l , E l i o t ,  tend to d i s p l a y  & Grant,  a r i t h m e t i c have been c h a r a c t e r i z e d as i n v o l v i n g s e n s o r y r e j e c t i o n  Grignolo,  Light,  1962) and a c t i v e c o p i n g & McCubbin,  1978; L i n d e n ,  r e j e c t i o n t a s k s t y p i c a l l y produce blood pressure.  (Obrist, 1984).  significant  the  Gabelein, Teller, Active coping,  e l e v a t i o n s of  a (Lacey  1984).  From a s t i m u l u s - s p e c i f i c p e r s p e c t i v e r e s p o n s e s t o t a s k s s u c h a s  Lacey, & Lacey,  of  sympathetic  i d i o s y n c r a t i c a l l y determined s t r e s s response pattern  1962; M i n e r ,  have  1985).  a r i t h m e t i c h a s b e e n u n d e r t a k e n by many a u t h o r s 1984; L i n d e n ,  to  Some r e s e a r c h e r s  added an a d d i t i o n a l w h i t e n o i s e component i n an a t t e m p t t o d e v e l o p a psychological  values  mental  (Libby, Langer, sensory  heart rate  and  Such hemodynamic changes a r e presumed i n s t r u m e n t a l i n  the  - 3  development of Bonter,  essential hypertension  1984) t h u s  j u s t i f y i n g the recent  on s t r e s s a n d c o p i n g . evidence  that  (Obrist, focus  1981; H i j z e n , van der G u g t e r , & of  cardiovascular  L a z a r u s and F o l k m a n ( 1 9 8 4 ) h a v e p r e s e n t e d  the e f f e c t i v e n e s s  of  psychosocial  factors  in  p o t e n t i a l l y pathogenic  s y m p a t h e t i c a r o u s a l d e p e n d s on t h e  c o g n i t i v e a p p r a i s a l of  his  or her a b i l i t y  individual's  t o cope i n a g i v e n  r e s e a r c h e r s are concerned w i t h the r o l e  i n the t r a n s d u c t i o n of Obrist  acute hyperresponses i n t o  e t a l . (1978) have s u g g e s t e d f o r  to psychological  of  situation.  chronic  cognitive  rate responses f o l l o w i n g  s t r e s s o r has been r e p o r t e d  coronary  (Lane,  stressor  metabolic  q u e s t i o n of  1 9 8 4 ; Manuck & S c h a e f f e r ,  a n d mean a r t e r i a l p r e s s u r e Through the use of s t u d i e s of associate  inter-stressor  stimulus repetition effects  intervals  on s y s t o l i c  Although there  (MAP) h a s n o t b e e n a d e q u a t e l y  1984),  diastolic  the  (DBP),  addressed.  e x p e r i m e n t a l paradigms s i m i l a r t o those employed  i n d i v i d u a l - s p e c i f i c and s t i m u l u s - s p e c i f i c c h a r a c t e r i s t i c s pathogenic  p a t t e r n s of  physiologic  habituation.  The  r e s p o n s e r e p r e s e n t s t h e most e x t e n s i v e l y r e s e a r c h e d p h y s i o l o g i c system (O'Gorman, 1977).  Much l e s s e v i d e n c e e x i s t s a s t o t h e  between c o r o n a r y d i s e a s e and c a r d i o v a s c u l a r  is  arithmetic  (Lane,  (SBP),  a  1978;  a c u t e c a r d i o v a s c u l a r r e a c t i v i t y , r e s e a r c h e r s have attempted  potentially  s t u d i e s of  need.  repeated p r e s e n t a t i o n of  s y s t o l i c blood pressure h a b i t u a t i o n to a mental  across r e l a t i v e l y short  response  maintained  Manuck & G a r l a n d , 1 9 8 0 ; S c h u l t e e t a l . , 1 9 8 1 ; Z w a g a , 1 9 7 3 ) . some e v i d e n c e o f  stress  disease.  example, that a maladaptive  c a r d i o v a s c u l a r a r o u s a l i s not a s s o c i a t e d with a s p e c i f i c heart  psychological  repeated exposure to  s t r e s s may be one i n w h i c h i n c r e a s e d o r  H a b i t u a t i o n of  further  producing  In a d d i t i o n to assessing acute c a r d i o v a s c u l a r r e a c t i v i t y to stress,  researchers  to  with  electrodermal response  relationship  response h a b i t u a t i o n .  p e r s o n a l i t y and c a r d i o v a s c u l a r h a b i t u a t i o n have  in  yielded  Generally,  _  4  -  i n c o n c l u s i v e r e s u l t s ( c f . O'Gorman, 1977).  Age and a e r o b i c f i t n e s s l e v e l have  been a s s o c i a t e d w i t h p o s t - s t r e s s p h y s i o l o g i c r e c o v e r y f a c t o r has been r e l a t e d t o w i t h i n t a s k h a b i t u a t i o n .  r a t e s , however n e i t h e r With r e g a r d  t o gender  d i f f e r e n c e s i n c a r d i o v a s c u l a r h a b i t u a t i o n , measures o f h e a r t r a t e and b l o o d pressure  h a b i t u a t i o n have not been r e p o r t e d .  I n an e x t e n s i v e  r e v i e w O'Gorman  (1977) c o n c l u d e d t h a t s u b j e c t s t r e s s t a s k m e n t a t i o n d i d n o t e x e r t a s t r o n g i n f l u e n c e on e l e c t r o d e r m a l  habituation.  Similar studies involving  c a r d i o v a s c u l a r response measures were n o t r e p o r t e d . The r o l e o f t a s k c h a r a c t e r i s t i c s i n c a r d i o v a s c u l a r h a b i t u a t i o n has been only p a r t i a l l y assessed.  F a c t o r s such as s t i m u l u s c o m p l e x i t y ,  inter-stimulus  i n t e r v a l , and s t i m u l u s d u r a t i o n have been i m p l i c a t e d as p r o b a b l e m e d i a t o r s o f response h a b i t u a t i o n .  The s i g n a l - v a l u e and s u b j e c t i v e i m p o r t a n c e o f t h e  s t r e s s t a s k has been r e l a t e d t o d e l a y e d response h a b i t u a t i o n (Iacono & L y k k e n , 1984).  H a b i t u a t i o n o f h e a r t r a t e r e s p o n s e s has been demonstrated  i n t e r - s t i m u l u s i n t e r v a l s ranging ranging  across  from a few minutes t o f o u r weeks.  Intervals  from two months t o f o u r y e a r s have been shown t o produce l i t t l e o r no  r e t e n t i o n o f h a b i t u a t i o n e f f e c t s (Manuck & G a r l a n d , 1980).  Little  evidence  e x i s t s however as t o t h e s p e c i f i c e f f e c t o f c o g n i t i v e s t r e s s o r c h a r a c t e r i s t i c s on h a b i t u a t i o n o f b l o o d p r e s s u r e  responses.  Acute c a r d i o v a s c u l a r r e a c t i v i t y and r e p e a t e d exposure t o s t r e s s have each been s e p a r a t e l y i m p l i c a t e d as p r o b a b l e e x a c e r b a t o r s coronary heart disease.  of the pathogenesis of  The r e l a t i o n s h i p between a c u t e p h y s i o l o g i c  h y p e r r e s p o n s i v e n e s s and h a b i t u a t i o n o f responses t o a r e p e a t e d c o g n i t i v e s t r e s s o r has n o t been t h o r o u g h l y r e a c t i v e versus hyperreactive  examined.  The p r e s e n t s t u d y examines low  female s u b j e c t s f o r p o t e n t i a l l y m a l a d a p t i v e  p a t t e r n s o f c a r d i o v a s c u l a r response h a b i t u a t i o n a c r o s s v a r y i n g i n t e r - s t r e s s o r intervals.  -  5  -  LITERATURE REVIEW  Basic  Cardiophysiology  The s t u d y o f  single  r e s p o n s e s such as b l o o d p r e s s u r e or h e a r t  rate  r e s p o n s e s t o a g i v e n s t i m u l u s can a t b e s t p r o v i d e o n l y an i n c o m p l e t e of  basic cardiovascular  psychophysiology  A person's adjustment to h i s  functioning  or her environment i n v o l v e s s h i f t i n g  i n t e g r a t e d somatomotor, p h y s i o l o g i c a l , appropriate  i n an i n t a c t  and n e u r o e n d o c r i n e  to a given person-environment i n t e r a c t i o n .  approach to c a r d i o v a s c u l a r  psychophysiology  B a s i c aspects of  person-environment  individual. patterns  behaviors that  Thus,  a  occur  in  i s a necessary precursor  section.  An u n d e r s t a n d i n g o f  t o a r e v i e w and d i s c u s s i o n of  cardiovascular and o r g a n s .  and s i m p l e s t , system i s  t h i s system i s  briefly  these basic the  principles  cardiovascular  the maintenance of  a r a t e of  stressor.  the primary f u n c t i o n of v a r i o u s body  the  tissues  nutrients,  v i t a m i n s , and t h e r e m o v a l of waste m a t e r i a l s .  system f u n c t i o n s  The k e y a s p e c t  blood flow to t i s s u e s  The means by w h i c h t h e  that  is  is  complex.  and a c o r t i c a l  the i n t e g r a t i n g centre  o u t p u t a n d d i s t r i b u t i o n a r e r e g u l a t e d on b o t h level. for  a  The h y p o t h a l a m u s a n d b r a i n s t e m f u n c t i o n  neurogenic  cardiovascular control.  of  cardiovascular  i n a n i n t e g r a t e d manner t o meet t h e s e m e t a b o l i c n e e d s  Changes i n c a r d i a c cellular  that  i n v o l v e s the d e l i v e r y of oxygen,  c o n s i s t e n t w i t h t h e i r metabolic needs.  extremely  is  t o meet t h e m e t a b o l i c n e e d s o f  This function  electrolytes,  principle  of  interaction.  responses associated with a given i n d i v i d u a l i n response to a given The f i r s t ,  are  association  c a r d i o v a s c u l a r mechanisms and p h y s i o l o g y a r e  reviewed i n the f o l l o w i n g  of  comprehensive  i n v o l v e s the determination  which p a t t e r n s of m u l t i p l e response measures r e l i a b l y w i t h a given type of  picture  The  as  efferent  -  l i m b of  neural control  6  -  i n v o l v e s changes i n s y m p a t h e t i c and  nervous system m e d i a t i o n .  There i s  a l s o an a f f e r e n t  p r o v i d e s i n f o r m a t i o n about the s t a t u s of mechano-pressor.and chemoreceptors  parasympathetic  feedback mechanism w h i c h  the c a r d i o v a s c u l a r system v i a  throughout the  B l o o d p r e s s u r e i s d e t e r m i n e d by t h e p r o d u c t o f  body. the c a r d i a c output  and  t o t a l p e r i p h e r a l r e s i s t a n c e w h i c h a r e i n t u r n c o m p l e x l y d e t e r m i n e d by  the  v a r i o u s aforementioned mechanisms. qualitatively  different  It  s h o u l d be n o t e d t h a t  there  m e c h a n i s m s by w h i c h b e h a v i o r a l i n f l u e n c e s  are can a c t  i n c r e a s e or decrease blood p r e s s u r e .  I n c r e a s e s i n b l o o d p r e s s u r e may be  p r i m a r i l y due t o i n c r e a s e s i n c a r d i a c  o u t p u t o r a l t e r n a t i v e l y t o an  in total peripheral resistance. independent  of  C h a n g e s i n b l o o d f l o w may h o w e v e r  changes i n c a r d i a c o u t p u t .  b l o o d f l o w a r e a c h i e v e d by means o f alpha receptors  blood pressure.  results  Withdrawal of  be  Active  blood  increases  in  increased sympathetic nerve s t i m u l a t i o n  of  i n a r t e r i a l smooth m u s c l e .  c i r c u l a t i n g epinephrine,  increase  Increases or decreases i n  f l o w a r e g e n e r a t e d by b o t h a c t i v e a n d p a s s i v e m e c h a n i s m s .  to  Beta-adrenergic  stimulation,  i n a c t i v e v a s o d i l a t i o n and a d e c r e a s e  the i n f l u e n c e  of  either  of  in  these sources  a c t i v e v a s o d i l a t i o n or v a s o c o n s t r i c t i o n r e s u l t s i n a c o r r e s p o n d i n g  by  of  counter  response. S t r e s s and C a r d i o v a s c u l a r  Disease  Over t h e p a s t s e v e r a l decades numerous a u t h o r s have p r e s e n t e d e v i d e n c e a p o s i t i v e r e l a t i o n s h i p between m a l a d a p t i v e r e s p o n s e s t o s t r e s s and development of  coronary heart disease  (Glass, 1976).  has been a s s o c i a t e d w i t h b o t h an i n d i v i d u a l ' s s t r e s s and h i s time.  the  Cardiovascular  initial  pathology  or acute response  or her c h r o n i c or coping response to a g i v e n s t r e s s o r  pathogenic e f f e c t s .  The n o t i o n t h a t  to  over  Cannon (1932) a r g u e d t h a t r e p e a t e d o r p r o l o n g e d e l i c i t a t i o n of  responses produced p o t e n t i a l l y  of  stress  one's  -  7  -  r e s p o n s e t o s t r e s s may p l a y a f u n d a m e n t a l r o l e of  a v a r i e t y of  further  disorders,  and  b o t h p s y c h o l o g i c a l and p h y s i o l o g i c a l  d e v e l o p e d by S e l y e ( 1 9 7 6 ) .  More r e c e n t l y ,  (1979) suggested t h a t acute p s y c h o l o g i c a l pathogenic  i n the e t i o l o g y  Gliner,  development  in nature,  B e d i and H o r v a t h  s t r e s s o r s may e v o k e  potentially  c a r d i o v a s c u l a r r e a c t i o n s o f a m a g n i t u d e and d u r a t i o n g r e a t e r  t h a t r e q u i r e d t o meet e x i s t i n g m e t a b o l i c r e q u i r e m e n t s .  The e v i d e n c e  than  for  a  p o s i t i v e r e l a t i o n s h i p between a c u t e h y p e r r e a c t i v i t y and t h e p a t h o g e n e s i s cardiovascular  disease i s  reviewed i n the f o l l o w i n g  C a r d i o v a s c u l a r R e a c t i v i t y and C o r o n a r y H e a r t  Disease  1961; Keys, T a y l o r ,  physiological  p s y c h o p h y s i o l o g i c a l responses seen i n  to environmental s t i m u l i (Brod, F e n c l ,  of  section.  T h e r e h a s b e e n much r e s e a r c h on c a r d i o v a s c u l a r d i s o r d e r s , r e a c t i v i t y and t h e p a t t e r n s of  was  response  H e j l , & J i r k a , 1959; Engel & B i c k f o r d ,  B l a c k b u r n , Brozek, Anderson, & Simonsen, 1971).  It  has  been s u g g e s t e d t h a t p h y s i o l o g i c h y p e r r e a c t i v i t y t o e m o t i o n a l or  psychological  s t r e s s may be a m a r k e r f o r  i n c r e a s e d r i s k of  (Eliot,  & Dembroski, 1982; O b r i s t ,  1981).  coronary pathology  In general,  physiological  a p p e a r t o be a s s o c i a t e d w i t h a n i n c r e a s e d i n c i d e n c e (Dembroski, & Ross,  1978; Manuck, H a r v e y , L e c h l e i t e r ,  1984).  pathogenic  S t u d i e s of  been produced  & Neal,  disorders  1978; S t e p t o e ,  Melville,  that  c a n be p r o d u c e d by s p e c i f i c  L a r g e c a r d i o v a s c u l a r and n e u r o e n d o c r i n e  (Cannon, 1936; F r a n k e n h a e u s e r ,  It  types  of  responses  have  short-term  stressors.  s h o u l d be r e c o g n i z e d t h a t  from a complex i n t e r a c t i o n of press).  potentially  1975; Frankenhaeuser & Johansson,  1976) i n r e s p o n s e t o b o t h n a t u r a l i s t i c and l a b o r a t o r y - i n d u c e d psychological  hyperresponses  psychosomatic  b o t h a n i m a l s a n d humans s u g g e s t  physiological conditions  environmental s t i m u l i .  of  Buell,  physiological  r e a c t i v i t y to s t r e s s  biobehavioral factors  (Watkins & Rose,  results in  Numerous a u t h o r s have a l s o r e c o g n i z e d t h a t p h y s i o l o g i c r e a c t i o n s  to  8  chronic  s t r e s s a r e more v a r i a b l e a n d c o m p l e x t h a n a c u t e r e s p o n s e s  Gatchel,  & Schaeffer,  Given the present  1 9 8 3 ; Manuck & K r a n t z , 1 9 8 4 ; M a s o n , 1 9 6 8 ; S e l y e ,  body o f  evidence,  it  is  plausible  r e s p o n s e s t o a c u t e s t i m u l i may h a v e s i g n i f i c a n t underlying chronic  cardiovascular disorders.  (1984) f o u r primary l i n e s of data from animal models, case-control  The f i r s t  type of  that  i n a study of  of  hypothesis.  processes  evidence  Krantz  These  retrospective  Type A b e h a v i o r  provide i n i t i a l  include  or  i n humans.  Each  l i n k i n g acute r e a c t i v i t y Manuck,  to  Kaplan  and  behaviorally-induced heart rate r e a c t i v i t y  support  for  stress is  the hypothesis that  a precursor  corroborated this  finding  (Manuck & K r a n t z ,  P r o s p e c t i v e human s t u d i e s .  In a recent  (1981) found t h a t the r e l a t i v e r i s k of  times greater  greater  as a p r e d i c t o r  prospective study, Wilson  coronary pathology,  Keys et a l .  t h a t magnitude of  diastolic  blood pressure response to a cold subsequent coronary heart d i s e a s e .  w e r e s u p p o r t e d by Wood, S h e p s , E l v e b a c k , to a c o l d pressor  and S c h i n g e r  t e s t was p r e d i c t i v e o f  reactivity  (1971)  found  p r e s s o r t a s k was These  findings  ( 1 9 8 4 ) who f o u n d  subsequent  2.28  hyperresponse  I n a p r o s p e c t i v e study which examined of  of  yet  and  d e v e l o p i n g h y p e r t e n s i o n was  incidence  predictor  of  1984).  of  a significant  These  Human s t u d i e s h a v e n o t  i n those i n d i v i d u a l s e x h i b i t i n g a blood pressure  to exercise induced s t r e s s .  in  cardiovascular  to the development  fatality.  of  sections.  from animal r e s e a r c h .  a t h e r o s c l e r o s i s and subsequent c o r o n a r y  reactivity  that  c o r o n a r y a t h e r o s c l e r o s i s t h a n d i d low h e a r t r a t e r e a c t o r s .  h y p e r r e s p o n s i v i t y under  Meyer  on t h e  found t h a t high heart r a t e r e a c t o r s d i s p l a y e d s i g n i f i c a n t l y  incidence findings  this  reviewed i n the f o l l o w i n g  chronic coronary disease i s  monkeys,  effects  A s n o t e d by Manuck a n d  support  and s t u d i e s of  these areas of evidence i s  Clarkson (1983),  evidence  1976).  to suggest however,  p r o s p e c t i v e human s t u d i e s ,  human s t u d i e s ,  Animal models.  (Baum,  that  hypertension.  -  9  Retrospective, case-control studies.  ~  Several r e t r o s p e c t i v e or  case-control studies comparing the psychophysiological responses of persons with and without coronary heart disease have been reported (Corse, Manuck, Cantwell, Giordani, & Matthews, 1982; Dembroski, MacDougall, & Lushene, 1979; Krantz, Schaeffer, Davia, Dembroski, MacDougall, & Schaeffer, 1981; N e s t e l , Verghese, & L o v e l l , 1967; Sime, B u e l l , & E l i o t , 1980; S h i f f e r , H a r t l e y , Schulman, & Abelman, 1976).  Most of these studies found a greater r e a c t i v i t y  i n terms of blood pressure responses to laboratory s t r e s s o r s i n patients with previous h i s t o r i e s of angina or myocardial i n f a r c t i o n .  Disconfirmatory  r e s u l t s have however also been reported (Krantz et a l . , 1981).  While  case-control studies have revealed some suggestive evidence, a consistent a s s o c i a t i o n between a given measure of physiologic r e a c t i v i t y and a s p e c i f i c c l i n i c a l endpoint has not yet been e s t a b l i s h e d .  Light (1981) found that  parents of high heart reactors showed a greater incidence of e s s e n t i a l hypertension.  This f i n d i n g supports the notion of a possible genetic or  f a m i l i a l f a c t o r i n the process l i n k i n g acute r e a c t i v i t y t o chronic coronary pathology. Type A s t u d i e s .  Research on the Type A or coronary-prone behavior  pattern  has stimulated much of the current i n t e r e s t i n the measurement of cardiovascular r e a c t i v i t y to s t r e s s . Type A persons are characterized as impatient, h a r d - d r i v i n g , and ambitious (Matthews, Glass, Rosenman, & Bortner, 1977).  The hypothesis has been suggested that the types of behaviors which  are t y p i c a l of Type A i n d i v i d u a l s are r e l a t e d to pathogenic neuroendocrine and cardiovascular responses.  These pathogenic responses are thought t o l i n k  psychosocial s t r e s s o r s to coronary heart disease. d i s p l a y heightened p h y s i o l o g i c a l responsiveness  For example, Type A persons  (Dembroski, 1978), greater  catecholamine s e c r e t i o n ( L e v i , 1974), and v a s o c o n s t r i c t i o n responses to  -  10  -  psychological  stress  recent  (Manuck & K r a n t z , 1984) t h e a u t h o r s s u r v e y e d t h e r e s u l t s o f  review  ( W i l l i a m s , B i t t k e r , B u c h s b a u m , & Wynne,  s t u d i e s of Type A and r e a c t i v i t y .  Twenty-six  reactivity  t o s t r e s s among t y p e A s u b j e c t s .  difference  or g r e a t e r  conclude that  studies reported  pattern i s  physiological hyperreactivity in specific  In  a 37  greater  Eleven studies reported  r e a c t i v i t y by T y p e B s u b j e c t s .  t h e Type A b e h a v i o r  1975).  no  Manuck a n d K r a n t z  (1984)  only moderately c o r r e l a t e d  laboratory paradigms.  with  Systolic  b l o o d p r e s s u r e r e a c t i v i t y a p p e a r s t o be t h e m o s t c o n s i s t e n t c o r r e l a t e o f A behavior  (Wright,  Contrada, & Glass,  Individual Differences  in  in Cardiovascular  T h e r e a p p e a r s t o be a v a r i e t y o f  Type  press). Reactivity  individual-specific  characteristics  that  a r e r e l a t e d t o t h e d e g r e e of h y p e r r e a c t i v i t y w h i c h an i n d i v i d u a l d i s p l a y s  in  response to a given s t r e s s o r  in  press).  Manuck, M o r r i s o n , B e l l a c k ,  Schulte, F r i e d r i c h , Ruddel,  the l a r g e s t p r o p o r t i o n of across  (cf.  & Polefrone,  S c h i r m e r , and von E i f f  the variance  (1981) argue  that  in psychophysiological reactivity  seen  i n d i v i d u a l s c a n be a t t r i b u t e d t o i n d i v i d u a l - s p e c i f i c  E n g e l and B i c k f o r d  (1961), for  characteristics.  example, found wide i n d i v i d u a l d i f f e r e n c e s  autonomic nervous system responses to emotional s t r e s s .  The t e n d e n c y f o r  persons to d i s p l a y a c h a r a c t e r i s t i c cardiovascular h y p e r r e a c t i v i t y e m o t i o n a l s t r e s s has a l s o been e s t a b l i s h e d ( F a l k n e r , Fernandes,  & Langmann, 1979; E l i o t  Manuck ( 1 9 8 4 ) r e v i e w e d f i v e  studies  Onesti,  et a l . , 1982; O b r i s t , i n an a n a l y s i s o f  stress  tasks.  found t h a t most o f that  Angelakos,  1981).  Krantz  the c o r r e l a t i o n  These d a t a a r e p r e s e n t e d i n T a b l e 1.  t h e i n t e r - t a s k c o r r e l a t i o n s were s i g n i f i c a n t  t h e r e was a s h a r e d v a r i a n c e i n r e a c t i v i t y a s a  individual-specific  characteristic across tasks.  some  to  h e a r t r a t e and b l o o d p r e s s u r e change s c o r e s w i t h i n i n d i v i d u a l s a c r o s s v a r i e t y of  in  The  and  between a  authors  indicating  stable,  However,  the authors  note  - 11 -  TABLE 1* C o r r e l a t i o n s Among Change Scores on C a r d i o v a s c u l a r Measures (Task Mean Minus B a s e l i n e )  Study/subject Dembroski ( p e r s o n a l communication, 1983) College students Manuck & G a r l a n d (1979) College students H i l l & K r a n t z (1983) Medical students  Dembroski ( p e r s o n a l communication, 1983) Executives  G l a s s e t a l . (1983) B l u e - c o l l a r working  males  Stressor/procedure  SBP  DBP  HR  Mental a r i t h m e t i c / structured interview  .57  .62  .44  Cognitive test/mental  .50  .23 ( n s )  .86  Reaction time/structured interview Reaction time/medical quiz Medical quiz/structured interview  .54  .60  .57  .54 .74  .66 .60  .53 .81  Video game/1 minute c o l d pressor Video game/reaction time R e a c t i o n time/1 minute c o l d pressor  .79  .62  .49  .73 .70  .74 .53  .67 .43  Stroop color-word /mental arithmetic  .69  .47  .45  a  Note. C o r r e l a t i o n s a r e s t a t i s t i c a l l y r e l i a b l e u n l e s s i n d i c a t e d ( n s ) . SBP = s y s t o l i c b l o o d p r e s s u r e ; DBP = d i a s t o l i c b l o o d p r e s s u r e ; HR = h e a r t r a t e . a  S t r o o p t a s k was a d m i n i s t e r e d a t second s e s s i o n 2 months l a t e r .  *Taken from K r a n t z & Manuck, 1984.  -  t h a t the s t r e n g t h of c h a r a c t e r i z e d as  relations  12  -  b e t w e e n t h e a s s e s s e d c h a n g e s c o r e s c a n be  moderate.  T h i s d i s p o s i t i o n towards h y p e r r e a c t i v i t y conceivably h e r e d i t a r y or p s y c h o s o c i a l for  forces  o r some i n t e r a c t i o n o f  example, reported that neonates d i s p l a y d i f f e r e n t  vulnerability basis of  to stress.  these.  Kagan ( 1 9 8 4 ) ,  thresholds  of  their  h e a r t r a t e and s y m p a t h e t i c n e r v o u s  the  system  stress.  Response s t e r e o t y p y .  The v a r i a b i l i t y i n m a g n i t u d e a n d p a t t e r n  a u t o n o m i c r e s p o n s e s t o s t r e s s a c r o s s i n d i v i d u a l s has been termed response stereotypy or  i n d i v i d u a l response s p e c i f i c i t y .  e x h i b i t a s i m i l a r response p a t t e r n to v a r i o u s s t i m u l i or Schneider, & Walschburger,  s t u d i e d through the comparison of  1983).  I t has a l s o  comparing the p s y c h o p h y s i o l o g i c a l c h a r a c t e r i s t i c s of a d a p t i v e p a t t e r n s of maladaptive patterns.  response  an i n d i v i d u a l  to  situations" been  i n response to  been s t u d i e d  individuals  response s p e c i f i c i t y with those d i s p l a y i n g In the f o l l o w i n g  individual  Response s t e r e o t y p y has  individual differences  under c o n t r o l l e d e x p e r i m e n t a l c o n d i t i o n s .  of  Individual  s t e r e o t y p y has been d e f i n e d as " t h e h a b i t u a l d i s p o s i t i o n of  (Foerster,  either  Some n e o n a t e s may be c l a s s e d a s h i g h r e a c t o r s on  the magnitude of  responses to  a r i s e s from  two s e c t i o n s e v i d e n c e  stress  by  displaying potentially  regarding  i n d i v i d u a l - s p e c i f i c p s y c h o l o g i c a l and p h y s i o l o g i c a l m e d i a t o r s of  reactivity  is  Numerous a u t h o r s h a v e a t t e m p t e d  to  reviewed. P s y c h o l o g i c a l m e d i a t o r s of  reactivity.  c h a r a c t e r i z e and d i s t i n g u i s h v a r i o u s g r o u p s of their  i n d i v i d u a l s on t h e b a s i s  members e x h i b i t i n g common p s y c h o p h y s i o l o g i c a l r e s p o n s e s t o  ( G r o v e s e t a l . , 1 9 8 2 ; Manuck & G a r l a n d , 1 9 8 0 ) .  stress  Certain physiological  p a t t e r n s have been v a r i o u s l y c h a r a c t e r i z e d as b e i n g t y p i c a l  of  response  of  i n t r o v e r s i o n - e x t r o v e r s i o n ( H i n t o n & C r a s k e , 1 9 7 7 ) , Type A b e h a v i o r  (Dembroski  -  et a l . , 1978), l e v e l l i n g - s h a r p e n i n g 1967), locus  field of  independence  control  associated with higher  l e v e l s of  and Type A b e h a v i o r .  differences Leventhal, Erlanger,  such as degree of  1983) a l s o r e l a t e  i n d i v i d u a l s on t h e b a s i s o f  of  psychological  physiological b a s i s of Patton  introversion, neuroticism, levelling field  dependence,  Other recent  reports  self-involvement  suggest  that  or  of  individual  ( G l a s s , Lake, C o n t r a d a , Kehoe, & reactivity.  Attempts to i d e n t i f y  common b i o l o g i c a l  characteristics  subgroups  such as  response pattern  s t r e s s h a v e a l s o b e e n made.  of  gender  under  In terms of  their the  b l o o d p r e s s u r e , h e a r t r a t e , and a u t o n o m i c n e r v o u s s y s t e m r e a c t i v i t y . example, c l a s s i f i e d s u b j e c t s as e i t h e r  o r p a r a s y m p a t h e t i c r e a c t o r s on t h e b a s i s o f  increases  conditions.  sympathetic  the r e l a t i v e degree of  or parasympathetic a r o u s a l d i s p l a y e d at r e s t .  Bickford,  showed  i n b l o o d p r e s s u r e and h e a r t r a t e under a v a r i e t y o f  A s y s t o l i c hyperresponse to a p s y c h o l o g i c a l s t r e s s o r has  1961; Linden & F e u e r s t e i n ,  however,  controls either  was n o t s i g n i f i c a n t l y at rest,  1983; Ohlsson & Henningsen, different  M o s t d a t a on r e a c t i v i t y h a v e b e e n c o l l e c t e d u s u a l l y composed o f w h i t e m a l e , c o l l e g e p a t i e n t and n o n - p a t i e n t  also  1982).  Heart  versus  tasks.  f r o m homogeneous  samples,  s t u d e n t v o l u n t e e r s or matched  samples ( K r a n t z & Manuck,  stressor  (Engel &  in mild hypertensives  or d u r i n g v a r i o u s s t r e s s  reactors  sympathetic  Sympathetic reactors  been found t o d i s t i n g u i s h m i l d h y p e r t e n s i v e s from n o r m a l c o n t r o l s  rate,  is  (Scherwitz, Berton, &  to l e v e l of heart r a t e Reactivity.  external locus  and  r e s p o n s e p a t t e r n g r o u p s have been v a r i o u s l y d i s c r i m i n a t e d on  (1969), for  greater  (Groves et a l . , 1982),  o r on t h e b a s i s o f a common p h y s i o l o g i c a l  conditions  (Eysenck,  high heart rate r e a c t i v i t y  1 9 7 8 ) , and o r s e l f - r e p o r t e d anger  P h y s i o l o g i c a l M e d i a t o r s of  .or a g e ,  dependence  Generally,  ignoring certain stimulus aspects, control,  -  ( I s r a e l , 1969), neuroticism  versus f i e l d  (Harrel, 1980).  13  1984).  coronary  Only r e c e n t l y  have  _  14  _  r e s e a r c h e r s begun t o a s s e s s t h e c o m p a r a t i v e c a r d i o v a s c u l a r persons d i f f e r i n g respect  i n gender,  to gender,  l e v e l s are lower  it  age,  socioeconomic  i n women t h a n i n men u n t i l a b o u t of  In psychophysiologic  coronary heart  higher  levels  of  heart rate  blood pressure r e a c t i v i t y among f e m a l e s u b j e c t s .  1983).  Other a u t h o r s ,  however,  (Forsman & L i n b l a d ,  Hastrup, Light,  cardiovascular  and O b r i s t  systolic  (1980) argue t h a t  r e a c t i v i t y may be a c c o u n t e d f o r  phase.  This finding  phases of  of m e n s t r u a l p h a s e - s p e c i f i c  S c h u l t h e i s s , & Cohen, 1983).  Carroll,  r e a c t i v i t y across menstrual c y c l e s . cardiovascular 1984).  Turner,  by menstrual  stability  Finally,  of  the  responsivity in  (Asso,  Lee,  task  this  the  variations  r e a c t i v i t y as a f u n c t i o n of m e n s t r u a l phase  (1984) have r e p o r t e d i n d i v i d u a l - s p e c i f i c  and  1978; Stephenson  cardiovascular  s i m i l a r i t i e s i n magnitude  r e a c t i v i t y among t w i n s h a v e a l s o b e e n r e p o r t e d  of  (Rose, Grim, &  D a t a d i s t i n g u i s h i n g same g e n d e r v e r s u s c r o s s g e n d e r  twins  were  reported. Some a u t h o r s h a v e s u g g e s t e d t h a t  t h a n young a d u l t s is  1978) and  reported  1983) to a c o g n i t i v e s t r e s s  h a s b e e n r e f u t e d by o t h e r s who h a v e f o u n d no r e l i a b l e  not  have  less  stimuli  These a u t h o r s found decreased c a r d i o v a s c u l a r r e a c t i v i t y d u r i n g  pre-ovulatory  Miller,  essential  responsivity to behavioral  v a r i a t i o n s i n hormone l e v e l s c o i n c i d i n g w i t h s p e c i f i c  Strauss,  d i s e a s e and  after  Nichaman, & T a l b e r t ,  ( C o l l i n s & Frankenhaeuser,  variance i n female c a r d i o v a s c u l a r  cycle.  pressure  s t u d i e s , women h a v e b e e n r e p o r t e d t o d i s p l a y  pronounced c a t e c h o l a m i n e and c a r d i o v a s c u l a r t h a n do men ( F r a n k e n h a e u s e r ,  r e s t i n g blood  With  50-60 y e a r s of age,  h y p e r t e n s i o n r i s e s m a r k e d l y i n women ( B o y l e , G r i f f e y , 1976).  of  s t a t u s , and e t h n i c i t y .  h a s b e e n commonly o b s e r v e d t h a t  w h i c h b l o o d p r e s s u r e and t h e i n c i d e n c e  reactivity  elderly  i n d i v i d u a l s appear l e s s  on h e a r t r a t e r e s p o n s e m e a s u r e s .  This decreased  p o s t u l a t e d t o be due t o a d e c r e a s e d s e n s i t i v i t y t o  reactive  reactivity  beta-adrenergic  - 15 "  stimulation.  The n o t i o n o f d e c r e a s e d b e t a - a d r e n e r g i c  b e e n s u b s t a n t i a t e d by t h e f a c t beta-adrenergic Kioski, Task  that  s e n s i t i v i t y to  s e n s i t i v i t y has i n  drug-induced  s t i m u l a t i o n a p p e a r s t o d e c l i n e w i t h a d v a n c i n g age  v a n B r u m m e l e n , Amann, B e r t e l ,  turn,  (Buhler,  Landmann, L u t o l d , & B o l l i ,  1980).  Influences Stimulus s p e c i f i c i t y .  and p a t t e r n of  cardiovascular  c h a r a c t e r i s t i c of Muller,  In s p i t e of  an i n d i v i d u a l  1 9 7 9 ) a number o f  that only  tends to  (Fahrenberg, Walschburger,  t h e v a r i a n c e s e e n i n an  responses to s t r e s s .  23% - 29% o f  under s t r e s s t h a t  a  Foerster  et a l .  Foerster,  Myrtek, & accounts  individual's (1983),  for  example,  the response v a r i a n c e i n p h y s i o l o g i c a l measures  be a t t r i b u t e d t o i n d i v i d u a l - s p e c i f i c  factors  level  be  s t u d i e s have found t h a t response s t e r e o t y p y  f o r o n l y a modest p o r t i o n o f physiological  function  strong evidence that there i s  across different  found  could  stressor  conditions. Four s t u d i e s used a measure of  response concordance across  attempting to estimate the percentage of specific  response  1983; F o e r s t e r  et a l . , 1983b).  i n t h e amount o f  response.  However,  These s t u d i e s  found a high degree  v a r i a n c e a s s o c i a t e d w i t h an  they a l s o r e v e a l e d the e x i s t e n c e of  unexplained v a r i a b i l i t y .  This additional  has been termed s i t u a t i o n a l s t e r e o t y p y  et  individual-specific considerable  v a r i a n c e has been a t t r i b u t e d t o  (Lacey,  (Lacey,  u n i f o r m and c o n s i s t e n t  1967; F o e r s t e r  et a l . , 1983).  r e s e a r c h e r s have a t t e m p t e d t o i d e n t i f y c h a r a c t e r i s t i c s and s p e c i f i c  al.,  of  1967).  The  response patterns across  For  the past s e v e r a l  what  stimulus-specific  s i t u a t i o n - s t e r e o t y p e r e s p o n s e has been d e f i n e d as a tendency f o r  s t i m u l i to e l i c i t  in  s u b j e c t s s h o w i n g an i n d i v i d u a l -  ( E n g e l , 1960; Knobloch & K n o b l o c h , 1979; F o e r s t e r  similarity  or  situations  specific  individuals  decades  the r e l a t i o n s h i p between  c a r d i o v a s c u l a r response patterns  stimulus  (Lacey & Lacey,  -  1966; O b r i s t ,  1981; Linden et a l . , i n  C l a s s i f i c a t i o n of  stressors.  16 -  press).  The r e s e a r c h l i t e r a t u r e on m e t h o d s  classifying stimuli associated with cardiovascular experimental stress research i s  (Lacey, Kagan, Lacey, Gabelein,  Teller,  & Moss,  Langer,  engagement-involvement  response measures  reviewed i n the f o l l o w i n g  major t h e o r e t i c a l c o n c e p t u a l i z a t i o n s :  section.  Light,  & McCubbin,  (Williams, Frankel, G i l l i n ,  Sensory i n t a k e versus sensory r e j e c t i o n . what has been termed t h e L a c e y s '  1978),  & Weiss,  The e a r l i e s t  attentional hypothesis  in Three  sensory intake versus sensory  1963), a c t i v e versus passive coping  Grignolo,  for  rejection  (Obrist,  and  1973) a r e  presentation  Lacey,  1966; L i b b y ,  In s e v e r a l subsequent experiments Lacey, & Lacey,  (Lacey,  1973) t h e L a c e y s and t h e i r  termed " s e n s o r y i n t a k e " s t i m u l i .  or v i s u a l s t i m u l i .  1963) and  1967; Lacey & colleagues  c o n f i r m e d t h a t h e a r t r a t e d e c e l e r a t e d i n s i t u a t i o n s where t h e s u b j e c t r e q u i r e d to a t t e n d to simple a u d i t o r y  of  (Lacey et a l . ,  d e s c r i b e d an a s s o c i a t i o n between c a r d i a c a c c e l e r a t i o n o r d e c e l e r a t i o n focus of a t t e n t i o n .  reviewed.  was  These s t i m u l i  I n s i t u a t i o n s w h e r e t h e s u b j e c t was  were  required  t o e n g a g e i n more e l a b o r a t e c o g n i t i v e a c t i v i t i e s a n a c c e l e r a t i o n i n h e a r t was o b s e r v e d .  The s t i m u l i a s s o c i a t e d w i t h t h i s p a t t e r n o f  termed " s e n s o r y r e j e c t i o n " s t i m u l i .  T h i s group of  s t i m u l i and t h o s e i n v o l v i n g r e t r i e v a l of c o n c e n t r a t i o n and p r o b l e m s o l v i n g . produce  stimuli include  stored information,  In general,  (Lacey,  sensory r e j e c t i o n  (1967) c h a l l e n g e d the concept  a function  of  the type of  noxious  stimuli  heightened  1967).  The a f o r e m e n t i o n e d f i n d i n g s a r e i m p o r t a n t f o r  suggesting that a subject's  were  mental  b l o o d p r e s s u r e and h e a r t r a t e i n c r e a s e s i n d i c a t i v e o f  sympathetic arousal  Lacey  response  rate  of  a number o f  non-specific  arousal  reasons.  ( S e l y e , 1976)  p h y s i o l o g i c a l r e s p o n s e p a t t e r n was i n l a r g e  stimulus involved.  Proponents  of  First,  traditional  by  part,  -  arousal theory task,  (Duffy,  the greater  r a t e should be. all-or-none Lacey's  1962) would p r e d i c t  Lacey  viewpoint  found the c a r d i a c  example t h a t the h a r d e r  is  the higher  ( 1 9 6 7 ) a r g u e d t h a t a r o u s a l may n o t be a solely  responsive to stimulus  s u p p o r t e d by a s t u d y by C o l e s  deceleratory  d u r i n g an easy s e n s o r y i n t a k e  r e s p o n s e t o be g r e a t e r  response measures.  Lacey  the  heart  unitary, intensity.  during a hard  author  than  task.  response measures.  to the e x i s t e n c e of  the  (1972) i n which the  r e s u l t s are a l s o c o n s i s t e n t w i t h the concept  f r a c t i o n a t i o n " of refers  for  t h e p h y s i o l o g i c a l a r o u s a l , and h e n c e ,  phenomenon w h i c h i s  The L a c e y s '  17 _  Simply put,  low c o r r e l a t i o n s (1967) found f o r  of  directional  "directional fractionation  between v a r i o u s body example, t h a t  sensory  system intake  s t i m u l i p r o d u c e d h e a r t r a t e a n d b l o o d p r e s s u r e d e c r e a s e s a c c o m p a n i e d by a n increase  i n s k i n c o n d u c t a n c e and p u p i l  On t h e b a s i s o f Williams  this  e a r l i e r w o r k by t h e L a c e y s  ( i n p r e s s ) proposed that  a c c o m p a n i e d by d i s t i n c t According to W i l l i a m s '  diameter. (Lacey & Lacey,  1970),  s e n s o r y i n t a k e and s e n s o r y r e j e c t i o n  and c o n s i s t e n t  physiologic  response  patterns.  v i e w p o i n t when a s t i m u l u s s u c h a s a m e n t a l  arithmetic  task r e q u i r e s sensory r e j e c t i o n the defense r e a c t i o n i s a c t i v a t e d . reaction is p a t t e r n of  environment i s pattern,  output.  required a different  t y p i c a l of  response pattern i s  1969) i s  elicited.  d e c r e a s e d h e a r t r a t e and c a r d i a c  output,  the  This  (Lacey & Lacey,  c h a r a c t e r i z e d by d e c r e a s e d  i n c r e a s e d s k e l e t a l muscle v a s o c o n s t r i c t i o n Wynne,  response  When s e n s o r y i n t a k e o r a t t e n t i o n t o  responses to r e a c t i o n time tasks  N o w l i n , Thompson, & E i s d o r f e r , arousal,  This  c h a r a c t e r i z e d by e m o t i o n a l a r o u s a l , a n d a c a r d i o v a s c u l a r increased cardiac  are  1974;  emotional  d e c r e a s e d motor a c t i v i t y  and  ( W i l l i a m s , B i t t k e r , Buchsbaum, &  1975).  Active versus passive coping.  O b r i s t and h i s c o l l e a g u e s  define a  stimulus  -  i n terms of individual  the type of  -  "coping s t y l e " which i t  (Obrist et a l . , 1978).  q u a l i t a t i v e f e a t u r e of  18  elicits  from a  Obrist hypothesized that a  Passive coping i s  f i l m which subjects  are associated with s i g n i f i c a n t  tolerate increases  passively.  t e s t or  in diastolic  during passive coping conditions  On t h e o t h e r h a n d , O b r i s t  of  t a s k s w e r e more l i k e l y t o e l i c i t  stressful  pattern indicative influences  of  strong beta-adrenergic  are r e f l e c t e d i n s i g n i f i c a n t  and h e a r t r a t e  (Light & Obrist,  "active coping" task.  1980).  O b r i s t et  a cardiovascular  response.  goal-directed,  of  T h i s type of  the s t r e s s o r .  specific,  Further evidence  for  pressure  physiological  influences  Obrist  response Linden  (1984)  arithmetic  significant  characterize  the  stress  relationship  d e r i v e s f r o m two  studies,  t o c o p e w i t h i n t h e same t a s k  1 9 8 0 ) , and a s e c o n d , w h i c h f o u n d t h a t effects  subject  T a s k s c h a r a c t e r i z e d by  the a s s e r t i o n of a p o s i t i v e  one w h i c h m a n i p u l a t e d t h e s u b j e c t ' s a b i l i t y  beta-adrenergic  These  t a s k was t e r m e d a n  o v e r t b e h a v i o r s and t h a t  between a c t i v e c o p i n g and b e t a - a d r e n e r g i c  kinds  response  increases i n s y s t o l i c blood  s y s t o l i c b l o o d p r e s s u r e and h e a r t r a t e  (Light & Obrist,  rapidly  i n f l u e n c e s on t h e h e a r t .  e x a m p l e , n o t e d t h a t an a c t i v e c o p i n g t a s k s u c h a s m e n t a l  e l e v a t i o n s of  i.e.,  (1978) found t h a t c e r t a i n  (1978) as r e q u i r i n g a c t i v e coping produce  requires  al.  beta-adrenergic,  p a t t e r n s s i m i l a r t o t h o s e p r o d u c e d by s e n s o r y r e j e c t i o n t a s k s . for  and  A c t i v e coping s i t u a t i o n s are those wherein the  can seek to modify the e f f e c t et a l .  et a l .  these  blood pressure  a c c e l e r a t i v e i n f l u e n c e s on h e a r t r a t e w e r e e i t h e r m i n i m a l o r w e r e dissipated.  of  a  S t i m u l i such as  changes i n h e a r t r a t e and s y s t o l i c b l o o d p r e s s u r e .  (1978) found t h a t  or  e x e m p l i f i e d by t h e p a t t e r n  r e s p o n s e s p r o d u c e d by s t r e s s o r s s u c h a s t h e c o l d p r e s s o r  lesser  crucial  s t r e s s f u l t a s k s i s whether s u b j e c t s a c t i v e l y  p a s s i v e l y cope w i t h s t r e s s .  pornographic  given  drugs which  blocked  e l i m i n a t e d the t y p i c a l a c t i v e coping p a t t e r n  of  -  response  (Obrist et a l . ,  19 -  1978).  A c t i v e c o p i n g appears t o be a s s o c i a t e d w i t h the type o f hemodynamic changes presumed t o be i n s t r u m e n t a l i n the development o f e s s e n t i a l hypertension (Obrist et a l . ,  1978).  G l a s s (1977) argued t h a t an i n d i v i d u a l ' s  h a b i t u a l p h y s i o l o g i c a l c o p i n g s t y l e may p r e d i s p o s e one t o produce  fluctuations  i n sympathetic a r o u s a l which a r e s u f f i c i e n t l y dramatic so as t o i n f l u e n c e the p a t h o g e n e s i s o f coronary h e a r t d i s e a s e . several studies.  T h i s h y p o t h e s i s i s supported by  Sherwood, A l l e n , O b r i s t , and Langer  found t h a t a c t i v e c o p i n g t a s k s produced  (1984) f o r example,  an i n c r e a s e i n h e a r t r a t e g r e a t e r than  t h a t r e q u i r e d t o meet m e t a b o l i c demands i n a g i v e n s i t u a t i o n . Gugter  and Bouter  (1984) a l s o found i n c r e a s e s i n c i r c u l a t i n g  during a c t i v e coping.  catecholamines  Both i n c r e a s e d sympathetic a c t i v i t y and i n c r e a s e d  e n d o c r i n e s e c r e t i o n s a r e o f i n t e r e s t because approaches  H i j z e n , Van der  a number o f t h e o r e t i c a l  have i m p l i c a t e d these f a c t o r s i n the development o f c o r o n a r y  pathology ( K r a n t z & Manuck, Engagement-involvement.  1984). A t h i r d l i n e o f i n v e s t i g a t i o n r e l e v a n t t o the  i s s u e o f s t i m u l u s s p e c i f i c i t y i n c a r d i o v a s c u l a r responses t o s t r e s s has been conducted 1973;  by W i l l i a m s and c o l l e a g u e s ( W i l l i a m s , F r a n k e l , G i l l i n , & Weiss,  W i l l i a m s , B i t t k e r , Buchsbaum & Wynne, 1975; W i l l i a m s , 1981).  Williams  e t a l . (1973) found a d i a s t o l i c p r e s s u r e i n c r e a s e i n response t o a s t r e s s f u l i n t e r v i e w , a sensory r e j e c t i o n s i t u a t i o n .  In a subsequent  study  (Bittker,  Buchsbaum, W i l l i a m s , & Wynne, 1975) the n a t u r a l i s t i c i n t e r v i e w was compared t o a sensory i n t a k e (word i d e n t i f i c a t i o n ) , and a sensory r e j e c t i o n arithmetic) task.  (mental  The r e s u l t s i n d i c a t e d t h a t the l e v e l o f sympathetic  cardiac  a c t i v i t y was d i r e c t l y r e l a t e d t o the a s s o c i a t e d l e v e l o f "engagementi n v o l v e m e n t " w i t h the c u r r e n t environment. r e j e c t i o n produced  Decreased  involvement or sensory  s i g n i f i c a n t e l e v a t i o n s i n h e a r t r a t e and s y s t o l i c b l o o d  -  20  -  p r e s s u r e w i t h o n l y minimal changes i n d i a s t o l i c L i n d e n and F e u e r s t e i n  (1983) demonstrated t h a t  pressure.  I n t h e same  in hypertensive  i n c r e a s e d i n v o l v e m e n t o r s e n s o r y i n t a k e was a s s o c i a t e d w i t h a nonsignificant  diastolic  a r i t h m e t i c t a s k a s an e x e m p l a r y example o f is  The c h o i c e  t h e l i t e r a t u r e on  the  The m o s t common f o r m o f  a r i t h m e t i c task i n v o l v e s asking the subject  to s e r i a l l y  e x a m p l e , s e v e n f r o m t h e number one t h o u s a n d the l i t e r a t u r e r e v e a l e d t h i r t y - o n e  mental a r i t h m e t i c alone,  subtract a  mental given  studies,  1979). using  and e i g h t u s i n g m e n t a l a r i t h m e t i c p l u s n o i s e i n  which  13 b e a t s p e r m i n u t e f o r  mm Hg a n d 5 mm Hg f o r  s y s t o l i c and d i a s t o l i c  Nineteen studies c i t e  significant  mental a r i t h m e t i c s t r e s s o r  (Brod,  heart rate,  increases in heart rate  alone  and i n c r e a s e s o f  blood pressure,  10  respectively.  i n response to  1979; Dembroski, McDougall & Lushene,  1980; Frankenhaeuser & Johansson,  1982; H e s l e g r a v e & Furedy,  stressor.  On a v e r a g e , m e n t a l a r i t h m e t i c  produced i n c r e a s e s of  a 1979;  1976; F r e d r i k s e n et  al.,  1979; H i n t o n & C r a s k e , 1977; Jorgensen & Houston,  1981; Lake et a l . , 1985; Lane, et a l . , 1985; Ludbrook,  a  twenty-three  are presented i n Table 2.  Diamond & C a r v e r ,  stressor.  ( S c h u l t e & Neus,  r e s e a r c h e r s employed the aforementioned type of mental a r i t h m e t i c These f i n d i n g s  reliable  a mental a r i t h m e t i c alone or  mental a r i t h m e t i c plus noise s t r e s s task.  A review of  of a mental  a s s o c i a t e d w i t h t h i s type of  r e s e a r c h e r s have employed e i t h e r  number, f o r  flat,  an a c t i v e c o p i n g t a s k and  b a s e d on a r e v i e w o f  task-specific cardiovascular effects Typically  patients  response.  M e n t a l a r i t h m e t i c as an e x p e r i m e n t a l s t r e s s o r .  experimental stressor  vein,  1984; L a w l e r ,  Vincent,  1980; L i n d e n et a l . , 1984;  Linden  & W a l s h , 1 9 7 6 ; Neus e t a l . , 1 9 8 1 ; S c h e r w i t z e r  e t a l . , 1978; Ruddel e t a l . , 1983; V o s s e l & L a u x , 1977; Zwaga, 1 9 7 3 ) , fifteen  s t u d i e s found s i g n i f i c a n t  increases i n blood pressure  Glaros,  1980; Dembroski & M a c D o u g a l l ,  while  (Benthem &  1 9 7 9 , 1 9 7 9 ; Diamond & C a r v e r ,  1980;  -  21 -  TABLE 2 Cardiovascular  Changes A s s o c i a t e d w i t h a M e n t a l A r i t h m e t i c  AUTHOR  HEART RATE  E n g e l & B i c k f o r d , 1961 Zwaga, 1973 L u d b r o o k & W a l s h , 1976 W i l l i a m s e t a l . , 1976 Manuck & S c h a e f e r , 1 9 7 8 B r o d e t a l . , 1979 H e s l e g r a v e & F u r e d y , 1979 L a w l e r , 1980 Manuck & G a r l a n d , 1 9 8 0 K u s h n e r & F a l k n e r , 1981 B e n t h e m & G l a r o s , 1982 Drummond, 1 9 8 3 F o e r s t e r e t a l . , 1983 Linden, i n press F r e d r i k s e n e t a l . , 1982 Diamond & C a r v e r , 1980 Dembroski & MacDougall Lake et a l . , i n p r e s s L i n d e n e t a l . , 1985 J o r g e n s o n & H o u s t o n , 1981 L a n e , 1984 S c h e r w i t z e r e t a l . , 1978 R u d d e l e t a l . , 1983 Mean C h a n g e : Cardiovascular  +10 +10 +20% +15% +8 +16 +12 +25 +13 +17 +14 +15 +8 +12 +4 +10 +13 +10 +15 +10 +17 +17 13.45  Changes A s s o c i a t e d  V o s s e l & L a u x , 1977 Neus e t a l . , 1 9 8 1 S c h u l t e & Neus, 1979 S c h u l t e e t a l . , 1981 F r a n k e n h a e u s e r e t a l . , 1983 F r a n k e n h a e u s e r & J o h a n s s o n , 1976 F r a n k e n h a e u s e r & L u n d b e r g , 1974 Linden et a l . , i n press Mean C h a n g e :  Note: Heart r a t e i s expressed MAP = mean a r t e r i a l p r e s s u r e . * % change were r e p o r t e d  SYSTOLIC  DIASTOLIC  +10% +12  +12% +19  +5 +17 +6  +2  +10  +6  +9 +15 +8.3 +21 +14 +10 +18 +11 +7 +16 9.83  +9 +9 +5.2 +11 +13 +11  +4  +10 +14 +12 5.25  Arithmetic  Noise  +14 +16  +11 +10  +13 15.0  +12 10.5  +14  +17% Stressor  +9  +14 8.5  i n beats per minute,  by o r i g i n a l  MAP  +15%  with a Mental +3 +11 +11  Stressor  blood pressure  a u t h o r s % change  scores.  n.a.  i n mm H g ,  -  22  -  F r e d r i k s e n et a l . , 1982; Lake e t a l . , 1985; Lane,  1984; Lawler  Linden i n press; Linden et a l . , i n press; Ludbrook,  et a l . , 1980;  e t a l . , 1 9 7 6 ; Neus e t  1981; Ruddel et a l . , 1983; S c h e r w i t z e r et a l . , 1978; S c h u l t e & Neus, Schulte et a l . ,  Shipman, G o l d s t e i n , G r i n k e r & F i s h ,  laboratory  stressor.  The d e c i s i o n o f  to a task already r e q u i r i n g e f f o r t  The a r o u s a l e f f e c t s 1973; Broadbent,  of  1981).  to mental a r i t h m e t i c as  was b a s e d on t h e o b s e r v a t i o n t h a t  1981) and s i g n i f i c a n t  (Frankenhaeuser & Lundberg,  i n task performance  increases in  subjective  Physiological  (cf.  s e c o n d s ) a n d when p r o l o n g e d i s Louder n o i s e  for  If  Graham,  changes a s s o c i a t e d w i t h exposure  t h r e s h o l d b u t b e l o w 8 5 db t e n d s t o e l i c i t  increases  noise  arousal  n o i s e have been e x t e n s i v e l y s t u d i e d  a s s o c i a t e d w i t h low v e r s u s h i g h n o i s e l e v e l s .  noise produces  noise  1974).  there are opposing d i r e c t i o n s  a s n o x i o u s and a v e r s i v e .  a  (Broadbent,  n o i s e a p p e a r t o be m u l t i p h a s i c a n d v a r y w i t h s t i m u l u s i n t e n s i t y .  (Graham, 1 9 7 3 ) .  1974;  p r e v i o u s a u t h o r s t o add background  i n t e r f e r e n c e was a s s o c i a t e d w i t h d e c r e a s e s 1981; T e r a s a k i ,  (Oken, Heath,  1966; Frankenhaeuser & Lundberg,  1981) s e v e r a l r e s e a r c h e r s have added n o i s e  of white noise  1979;  1981).  S i n c e n o i s e a l o n e i s known t o p r o d u c e a r o u s a l e f f e c t s  Terasaki,  al.,  of  cardiovascular  startle  a c c o m p a n i e d by s l i g h t  i n t h e 9 0 - 1 1 0 db r a n g e i s  in heart rate  reflex  cardiac  case  above  (lasting  2-4  deceleration  generally  experienced  a number o f m i n u t e s t h i s  (Graham, 1 9 7 3 ) .  the  change  White n o i s e c l e a r l y  a brief  presented for  For  to  level  Oken e t a l .  of  (1966),  e x a m p l e m e a s u r e d b l o o d p r e s s u r e a n d h e a r t r a t e r e s p o n s e s t o a one m i n u t e  exposure to a high l e v e l white n o i s e .  The a u t h o r s  p r e s s u r e c h a n g e s o f +8 mm H g , h e a r t r a t e c h a n g e s o f diastolic  p r e s s u r e c h a n g e s o f - 5 mm H g .  noise alone i f  found s y s t o l i c  blood  +6 b e a t s p e r m i n u t e ,  O v e r a l l , these f i n d i n g s  h i g h i n v o l u m e (>85 d b ) p r o v o k e s s i g n i f i c a n t  confirm  and that  cardiac arousal  in  -23  -  healthy a d u l t s .  T h i s a r o u s a l however tends to be l e s s than the c a r d i o v a s c u l a r  changes observed  i n t y p i c a l a c t i v e oping c o n d i t i o n s ( c f . O b r i s t , 1981;  Linden,  et a l . , i n p r e s s ) . E i g h t s t u d i e s which employed mental a r i t h m e t i c p l u s n o i s e (90 db) as a s t r e s s o r were reviewed.  Mental a r i t h m e t i c p l u s n o i s e was  average i n c r e a s e s of 15 mm heart r a t e .  Hg,  11 mm  Hg d i a s t o l i c , and  found  9 beats per minute i n  F i v e s t u d i e s (Frankenhaeuser & Johansson, 1976;  p r e s s ; S c h u l t e & Neus, 1979;  S c h u l t e e t a l . , 1981;  to produce  Linden  et a l . , i n  V o s s e l & Laux, 1977)  cite  s i g n i f i c a n t i n c r e a s e s i n heart r a t e , while three (Linden et a l . , i n press; S c h u l t e & Neus, 1979;  S c h u l t e e t a l . , 1981)  c i t e i n c r e a s e s i n blood  In a d d i t i o n to i n c r e a s e s i n r e a c t i v i t y , L i n d e n  pressure.  et a l . ( i n press) reported  less  v a r i a b i l i t y of responses w i t h i n h i g h v e r s u s low h e a r t r a t e r e a c t o r groups under a mental a r i t h m e t i c p l u s 90 db white n o i s e i n t e r f e r e n c e c o n d i t i o n . In summary, a mental a r i t h m e t i c p l u s n o i s e s t r e s s o r appears to produce r e l i a b l e and  s i g n i f i c a n t i n c r e a s e s i n h e a r t r a t e and  p a t t e r n of h e a r t r a t e and  s y s t o l i c p r e s s u r e responses e l i c i t e d  w i t h t h a t d e s c r i b e d by O b r i s t ( O b r i s t e t a l . , 1978) response.  The  blood p r e s s u r e .  The  i s consistent  as an a c t i v e c o p i n g  d i a s t o l i c b l o o d p r e s s u r e response to mental a r i t h m e t i c p l u s  n o i s e r e q u i r e s f u r t h e r examination.  As p r e v i o u s l y noted,  diastolic  responses  t o mental a r i t h m e t i c p l u s white n o i s e a r e o f t e n s i m i l a r i n magnitude to the aforementioned  s y s t o l i c blood p r e s s u r e  increases.  This finding i s  i n c o n s i s t e n t w i t h O b r i s t ' s f o r m u l a t i o n of an a c t i v e coping t a s k . p r e d i c t very l i t t l e may  be due  change i n d i a s t o l i c p r e s s u r e .  O b r i s t would  This discrepancy  in results  i n p a r t to d i f f e r e n c e s i n the c h a r a c t e r i s t i c s of the t a s k s i n v o l v e d  i n O b r i s t ' s t y p i c a l a c t i v e c o p i n g paradigm v e r s u s the t y p i c a l mental arithmetic plus noise condition. t a s k as an a c t i v e c o p i n g t a s k .  O b r i s t t y p i c a l l y employs a shock avoidance  C l e a r l y the aforementioned  differences in  - 24  diastolic  _  r e s p o n s e p a t t e r n may a r i s e f r o m d i f f e r e n c e s  s u b j e c t i v e e x p e r i e n c e of shock avoidance  individual's  t h e demands i m p o s e d by m e n t a l a r i t h m e t i c v e r s u s  versus response stereotypy.  the c a r d i o v a s c u l a r system i s  I n summary,  c h a r a c t e r i z e d by b o t h  influence  of  these dimensions v a r i e s both a c r o s s groups,  v e r s u s low h e a r t r a t e r e a c t o r s ; and w i t h i n i n d i v i d u a l s a c r o s s These a p p a r e n t l y c o n f l i c t i n g  positions,  s i t u a t i o n a l r e a c t i v i t y r e m i n d one t h a t t o a g i v e n s t r e s s o r one i s consider  both f a c t o r s .  individual-specific  Foerster  The  i.e.,  versus  i n d i s s e c t i n g an i n d i v i d u a l ' s by t h e n e e d t o  et a l . (1983) suggest t h a t  high  situations.  temporal s t a b i l i t y  constantly confronted  response  simultaneously  the  r e s p o n s e and t h e s t i m u l u s - s p e c i f i c r e s p o n s e i n t e r a c t  p r o d u c e w h a t may be c a l l e d  it  individual  r e s p o n s e s t e r e o t y p y and a s e n s i t i v i t y t o s t i m u l u s - s p e c i f i c v a r i a b l e s . degree of  a  task.  Summary: S t i m u l u s s p e c i f i c i t y c a n be s e e n t h a t  i n the  the " i n d i v i d u a l - s i t u a t i o n - s p e c i f i c "  to  response  w h e r e b y i n d i v i d u a l r e s p o n s e s a r e i n f l u e n c e d by a s t i m u l u s t o t h e d e g r e e  that  the r e s u l t i n g p a t t e r n of  seen  under a g i v e n s t i m u l u s It  response conforms to t h a t of  situation.  s h o u l d a l s o be n o t e d t h a t  the d e l i n e a t i o n of  stimulus properties in a given stressor s i t u a t i o n i s complex u n d e r t a k i n g .  (Pervin, 1968).  aforementioned factors influence  of  specific  An a c c e p t a n c e o f is  influences  and involved  t h e o t h e r on a n  the i n t e r a c t i v e nature of  c r u c i a l t o an u n d e r s t a n d i n g of  K o r n e r and Simon ( 1 9 7 5 ) s u g g e s t e d t h a t  or  a very d i f f i c u l t  t h e v a r i a b l e s i n v o l v e d i n an i n d i v i d u a l ' s  up t o i n t e g r a t e  subject  The i n d i v i d u a l a n d h i s o r h e r e n v i r o n m e n t a r e  i n a t r a n s a c t i o n i n which each r e c i p r o c a l l y basis  t y p i c a l responses  the  ongoing  the  relative  response to  stress.  the c e n t r a l nervous system i s  " n o t o n l y a u t o n o m i c but a l s o s o m a t i c and b e h a v i o r a l  by w h i c h t h e o r g a n i s m m e e t s b o t h p h y s i o l o g i c a l a n d p s y c h o l o g i c a l  set  responses  demands".  -  -25  They argue t h a t t h e b r a i n i s cardiovascular  o r g a n i z e d t o produce somatomotor  " b e h a v i o r s " as components of a s i n g l e  and  integrated  pattern,  d e p e n d i n g upon t h e a d j u s t m e n t s r e q u i r e d by e n v i r o n m e n t a l e v e n t s . such i n t e g r a t e d p a t t e r n s of  r e s p o n s e h a v e now b e e n i d e n t i f i e d  associated w i t h organism-environment i n t e r a c t i o n s flight,  f e e d i n g , or d i v i n g behaviors  f o r a review of  these  being  involving exercise,  (see Aboud, H e i s t a d , Mark,  response  fight  & Schmid,  ( H i l t o n , 1975) t h a t have  t h e b e s t known a n d m o s t e x t e n s i v e l y s t u d i e d i s  defense r e a c t i o n .  as  The d e f e n s e r e a c t i o n i s  h e i g h t e n e d somatomotor a c t i v i t y ,  the  c h a r a c t e r i z e d by i n t e n s e  increased cardiac  system (Abrahams, H i l t o n , & Z b r o z y n a , 1960).  of  1971; Henry, E l y ,  ouput,  affect,  and a s h u n t i n g  Several investigators  the defense r e a c t i o n  reaction is  o n l y one o f  (1976) n o t e d , " i t  (Aboud, that  upon  seems l i k e l y t h a t t h e  s e v e r a l emotionally induced behavioral  p a t t e r n s w h e r e i n n e u r o h o r m o n a l a d j u s t m e n t s may p r o d u c e c o n c e r n i n g b o t h o r g a n f u n c t i o n and m e n t a l s t a t e " . surprising, p a t t e r n of stressor  that recent  cardiovascular  is  pathogenic  s e t of  1984; L i n d e n et a l . , i n  too  i n v e s t i g a t i o n s have suggested t h a t  cardiovascular responses  The f o r m a l a p p r o a c h e s  the  psychological different,  ( G l a s s , 1977; H i j z e n  press).  Task X person i n t e r a c t i o n s .  defense  disturbances  perhaps not  responses seen i n r e a c t i o n to a  of  response  s u c h a s m e n t a l a r i t h m e t i c may r e p r e s e n t a q u a l i t a t i v e l y  yet equally al.,  therefore,  It  serious  of  brain  b a r o r e c e p t o r a n d v a s c u l a r f u n c t i o n may be i m p o r t a n t i n t h e p a t h o g e n e s i s As H a l l b a c k  of  All  & S t e p h e n s , 1972) have proposed  the repeated a c t i v a t i o n s of  coronary disease.  1976  been  t h e s e c o o r d i n a t e d r e s p o n s e s h a v e b e e n shown t o be m e d i a t e d by a common  the e f f e c t s  or  aforementioned  b l o o d f r o m t h e s k i n and v i s c e r a t o t h e s k e l e t a l m u s c l e v a s c u l a t u r e .  1976; Folkow & N e i l ,  of  patterns).  Among t h e i n t e g r a t e d p a t t e r n s o f studied,  A number  for  classifying  et  - 26  stressor  tasks previously described,  -  i.e.,  sensory r e j e c t i o n versus  i n t a k e and p a s s i v e v e r s u s a c t i v e c o p i n g c o m p r i s e o n l y dimensions of  probable  genetic,  psychosocial,  two p o s s i b l e  importance i n the d e t e r m i n a t i o n of  responses to a given s t r e s s o r .  Numerous a u t h o r s h a v e ,  for  example,  attempts to analyze the s t r e s s response from a t r a n s a c t i o n a l  suggested that nature of  ( G r i n k e r , 1953; L e v i ,  the emotional q u a l i t y of  the subsequent  There are however,  physiological Manuck  f e a r and a n g e r ,  inconsistencies  of  p a t t e r n s of  the p r e c i s e  experience  in  different  physiologic  physiological  their  has a l s o  been  respectively,  the  supported  i n terms  by  of  responses" (Ax, 1953; S c h a c t e r , t h e l i t e r a t u r e on  emotion (Glass & Contrada, 1984).  (1984) concluded t h a t w h i l e  by d i f f e r e n t 1983),  correlates  in  or  This hypothesis i s  "epinephrine-like" versus "norepinephrine-like 1957).  It  implicated  the task i n v o l v e d i n f l u e n c e s  stress response.  research which d i f f e r e n t i a t e d  1974).  stimulus  physiologic  p h y s i o l o g i c a l , and e n v i r o n m e n t a l f a c t o r s  diathesis-stress viewpoint  sensory  the Krantz  e m o t i o n s a p p e a r t o be  and  accompanied  r e s p o n d i n g (Ekman, L e v e n s o n , & F r i e s e n ,  p a t t e r n a s s o c i a t e d w i t h each  subjective  o r e m o t i o n r e m a i n s t o be d e t e r m i n e d .  A l a r g e body o f (Frankenhaeuser,  p s y c h o e n d o c r i n e a n d p s y c h o l o g i c a l r e s e a r c h on  1983; G l a s s & S i n g e r ,  1972; L a z a r u s ,  1966; L a z a r u s ,  L a z a r u s & Folkman, 1984; Mason, 1975) s u p p o r t s the h y p o t h e s i s effectiveness  of  psychosocial factors  situation.  1974;  the  pathogenic  c o g n i t i v e a p p r a i s a l of  Lazarus (1966) proposed t h a t p s y c h o l o g i c a l s t r e s s r e q u i r e s  judgement t h a t individual's  that  i n producing p o t e n t i a l l y  s y m p a t h e t i c a r o u s a l d e p e n d s on t h e i n d i v i d u a l ' s  stress  t h e demands i n h e r e n t  self-perceived ability  & F o l k m a n , 1984) p o s t u l a t e d t h a t and c o p i n g a r e i n v o l v e d .  the a  i n a given s i t u a t i o n tax or exceed  the  to d e a l w i t h them.  Lazarus  Lazarus  (1966;  two i n t e r a c t i n g p r o c e s s e s t e r m e d  appraisal  A p p r a i s a l i n v o l v e s a judgement t h a t an e v e n t  is  -  either  27  i r r e l e v a n t or s t r e s s f u l i n i t s  Breznitz,  1982).  -  possible  consequences  (Goldberger &  B o t h p o s i t i v e a n d n e g a t i v e e v e n t s may be a p p r a i s e d  as  stressful. Depue, Monroe,  a n d Shackman ( 1 9 7 9 ) o f f e r e d a c o g e n t a n a l y s i s o f  a p p r a i s a l p r o c e s s e s may m e d i a t e t h e i m p a c t o f pathogenesis  of  cardiovascular  psychosocial  factors  t h e way on  the  disorders:  " A t a s p e c i f i c l e v e l , c e r t a i n p s y c h o l o g i c a l c h a r a c t e r i s t i c s may o p e r a t e d i r e c t l y o n t h e a p p r a i s a l p r o c e s s a n d may p r e d i s p o s e t h e i n d i v i d u a l t o p e r c e i v e a p a r t i c u l a r c l a s s of e v e n t s as t h r e a t e n i n g . A t a more g e n e r a l l e v e l , p s y c h o l o g i c a l c h a r a c t e r i s t i c s may l e a d t o t h e d e v e l o p m e n t o f schema p r e d i s p o s i n g the i n d i v i d u a l to p e r c e i v e a wider range of events as threatening. By i n c r e a s i n g t h e p o t e n t i a l i m p a c t o f p s y c h o s o c i a l s t i m u l i , p s y c h o l o g i c a l p r e d i s p o s i n g v a r i a b l e s may p l a y a k e y r o l e i n e x a c e r b a t i n g the e m o t i o n a l - b i o l o g i c a l mediators that serve to a c t i v a t e b i o l o g i c a l predisposing biases leading to disease". A p p r a i s a l s which r e s u l t  i n h o s t i l i t y and anger  for  example, have  l i n k e d t o a c u t e m a l a d a p t i v e b l o o d p r e s s u r e and h e a r t r a t e r e s p o n s e s Melville,  & Ross,  heart disease  1 9 8 4 ) , and have been f o u n d t o p r e d i c t  (Shekelle, Gale, O s t f e l d , & Oglesby,  As p r e v i o u s l y n o t e d , dependent them.  physiological  I n t u r n e a c h i n d i v i d u a l makes a j u d g e m e n t o f  w i t h a g i v e n s t r e s s o r b a s e d upon h i s Judgements of  Greenfield,  1980).  Bandura (1982) a l s o  perceived s e l f - e f f i c a c y psychological  to  h i s or her a b i l i t y  cope  the  stress.  to  situation. s t r e s s have  various psychosomatic  1968; M u l l e n & S u l s , 1981; G l a s s ,  critically  the s t i m u l i presented  or her a p p r a i s a l of  of  of  1983).  p e r c e i v e d i n a b i l i t y t o cope w i t h p s y c h o l o g i c a l  l i n k e d to the subsequent development (Engel,  interpret  (Steptoe,  the development  responses to s t r e s s are  on t h e manner i n w h i c h s u b j e c t s  been  been  disorders  1976; L l o y d , A l e x a n d e r , R i c e , &  f o u n d t h a t s u b j e c t s who w e r e l o w  on  displayed great p h y s i o l o g i c a l arousal i n response Recent evidence d e r i v e d from s t u d i e s of  p a t i e n t s under g e n e r a l a n e s t h e s i a  (Kahn, K o r n f i e l d , Frank,  1980; K r a n t z , A r a b i a n , D a v i a , & P a r k e r ,  1982) f u r t h e r  to  cardiac  Heller,  suggests that  & Hoar, conscious  -  -28  m e d i a t i o n may n o t be a n e c e s s a r y c o n d i t i o n pathogenic  s y s t o l i c blood pressure  Physiological challenges  r e a c t i v i t y a p p e a r s t o be m o s t p r o n o u n c e d t o  t a s k s such as the c o l d  pressor  Manuck e t a l . , i n p r e s s ) . a r i t h m e t i c the s u b j e c t ' s  subject's 1984). stress  test  In the case of p e r c e p t i o n of  the  mental and  stressor's  Perceptions  of  task  (Krantz, 1983).  Estimates of  high heart rate r e a c t i v i t y The e x i s t e n c e o f  Fowles  an  difficulty, of  the  individual's  example, found  self-reported  i n c r e a s e d t a s k d u r a t i o n have a l s o (Manuck, C o r s e , & Winkelman,  level  that  of  been l i n k e d  to  1979).  the aforementioned evidence r e g a r d i n g the  the s t r e s s response should a l e r t  significant  a p p r a i s a l a n d c o p i n g on t h e n a t u r e  r e s e a r c h e r s t o the danger of a d o p t i n g  a p p r o a c h t o the measurement of stress.  (1983) f o r  the s u b j e c t s '  the p s y c h o l o g i c a l processes of  task  s t a t u s ( K r a n t z & Manuck,  have a l s o been found t o e f f e c t  h e a r t r a t e v a r i e d as a f u n c t i o n of  psychological  t a s k s such as  the s t r e s s f u l n e s s , d i f f i c u l t y ,  e d u c a t i o n , and s o c i o e c o n o m i c  task behavior  reductionistic  & D a v i a , 1982;  F o r e x a m p l e , n o i s e h a s b e e n shown t o i n c r e a s e p e r c e i v e d  Coping cognitions  impact of  cognitive  physical  p e r f o r m a n c e , a n d i m p o r t a n c e may a l s o v a r y a s a f u n c t i o n  gender,  motivation.  than  (Krantz, Glass, Schaeffer,  (Lovallo & P i s h k i n , 1980).  stressfulness,  potentially  psychological  task involvement rather  t h e t a s k may v a r y a s a f u n c t i o n o f  characteristics. difficulty  the e l i c i t a t i o n of  responses.  i n v o l v i n g a h i g h degree of  importance of  for  a  cardiovascular reactivity  R e s e a r c h e r s must c o n t i n u e  to include  c o g n i t i v e and p h y s i o l o g i c a l measures i n t h e i r e f f o r t s  of  to  multi-dimensional  to a n a l y z e Person X Task  interactions. S t a b i l i t y of body o f  individual differences  evidence e x i s t s which supports  stereotypy  in cardiovascular reactivity. the n o t i o n of  individual  A  large  response  ( F o e r s t e r e t a l . , 1983) i n c a r d i o v a s c u l a r r e s p o n s e s to  cognitive  -  stressors. factors  In seeking to further  29  -  a n a l y z e the impact of  on t h e s t r e s s r e s p o n s e n u m e r o u s a u t h o r s  1 9 6 9 ; Manuck & S c h a e f f e r ,  (Lacey & Lacey,  responses to a given s t r e s s o r over time.  l e v e l of  physiological  I n an e a r l y p a p e r ,  Lacey and  Lacey  s u b j e c t s d i s p l a y e d an i d i o s y n c r a t i c a l l y d e t e r m i n e d , maximal  response to a s t r e s s o r administered over a four-year  m a x i m a l l e v e l was i n d e p e n d e n t response  1962; P a t t o n ,  1 9 7 8 ; Manuck & G a r l a n d , 1 9 8 0 ; S c h u l t e e t a l . , 1 9 8 1 ;  C a r r o l l e t a l . , 1984) have i n v e s t i g a t e d the s t a b i l i t y of  (1962) noted t h a t  individual-specific  levels.  Miner,  of w i d e l y v a r y i n g i n i t i a l  McKinney, Ruddel, B u e l l , E l i o t ,  period.  This  within-subject and G r a n t  (1984)  also  found good t e s t - r e t e s t r e l i a b i l i t y f o r a m e n t a l a r i t h m e t i c s t r e s s o r i n  terms  of  that  individual-specific  reactivity.  s u b j e c t s responded c o n s i s t e n t l y cold pressor t e s t ,  P a t t o n (1969) concurred i n f i n d i n g  to a v a r i e t y of  exposure to heat,  and e x p o s u r e t o a f i l m o f  Subjects displayed i n d i v i d u a l - s p e c i f i c r e s p o n s e change and a b s o l u t e and s y s t o l i c b l o o d p r e s s u r e  stressors including  l e v e l of  responses i n terms of  anagrams,  surgery.  both magnitude  c a r d i o v a s c u l a r a c t i v i t y on h e a r t  s t u d i e s Manuck a n d h i s  colleagues  r e p r o d u c i b i l i t y of  individual differences  i n b l o o d p r e s s u r e and h e a r t  to a d i f f i c u l t  intervals.  heart rate after  their  initial  formation task across varying  responses to the s t r e s s t a s k .  r e a c t o r s were found t o d i f f e r  a t each of  1 week a n d 13 m o n t h i n t e r v a l s , r e s p e c t i v e l y  Manuck & G a r l a n d , 1 9 8 0 ) . reactivity. week,  concept  the  t h i r t e e n months.  rate  inter-stressor  on t h e b a s i s H i g h and  two f o l l o w - u p  (Manuck & S c h a e f f e r ,  study of heart r a t e r e s p o n s i v i t y i n c h i l d r e n a l s o  found  low  1978;  systolic  r e a c t o r s were d i s t i n g u i s h a b l e a f t e r G i o r d a n i , Manuck a n d F a r m e r  of  evaluations  S i m i l a r r e s u l t s were found f o r measures o f  H i g h and low d i a s t o l i c  but not a f t e r  subsequent  have examined  S u b j e c t s were c l a s s i f i e d as h i g h or low r e a c t o r s  the magnitude of  rate  measures.  In a s e r i e s of  reactions  of  one  (1981) i n  a  -  30  -  reproducible  individual differences  correlations  between change s c o r e s c a l c u l a t e d  ranged from Similar Lane,  .60 t o  .80 f o r  o v e r a one week i n t e r v a l . for  each of  t h e two  As n o t e d by L a n e ( 1 9 8 4 ) , t h e m a g n i t u d e o f  c o r r e l a t i o n s means h o w e v e r t h a t a p p r o x i m a t e l y h a l f second response i s  not accounted f o r  measures d e s i g n t h i s u n a c c o u n t e d - f o r variance.  The r e s u l t  of  this  by t h e f i r s t  r e p o r t e d by s e v e r a l r e s e a r c h e r s .  s t a b i l i t y of  It  In a review of  periods  1 t o 4 weeks a t t e n u a t i o n o f  Schaeffer,  the variance i n  response.  In a  1978).  the  repeated  to the o v e r a l l  error power  individual-specific  time i n t e r v a l s has  s t r e s s response over repeated exposures are not  e x p o s u r e was r e p o r t e d  1981;  aforementioned  been  s h o u l d be n o t e d h o w e v e r , t h a t  constant. of  (Obrist,  effect.  to a given s t r e s s o r over s i g n i f i c a n t  in  rate.  l o w r e l i a b i l i t y may be a r e d u c t i o n i n t h e  I n summary, a m o d e r a t e d e g r e e o f  differences  of  the  variance contributes  of a given experiment to d e t e c t a treatment  reactivity  visits  b o t h s y s t o l i c b l o o d p r e s s u r e and h e a r t  i n t e r - t a s k c o r r e l a t i o n s have been r e p o r t e d e l s e w h e r e  1984).  Pearson  research involving r e l a t i v e l y short  individual  entirely test-retest  r e a c t i v i t y to the second  stressor  ( H i l l & K r a n t z , 1 9 8 3 ; Manuck e t a l . , 1 9 8 1 ; Manuck &  With longer  t e s t - r e t e s t i n t e r v a l s of  1 year, attenuation  of  r e a c t i v i t y was n o t o b s e r v e d ( M a n u c k & G a r l a n d , 1 9 8 0 ) . H a b i t u a t i o n of Cardiovascular  Responses  I n a d d i t i o n to a s s e s s i n g the r e l a t i v e s t a b i l i t y of also  consider  the dimension of  cardiovascular a decrease of  an e l i c i t i n g  of  fatigue  r e s p o n s e h a b i t u a t i o n when  changes over t i m e .  i n magnitude of  responses,  The t e r m , h a b i t u a t i o n ,  one m u s t  considering i s used to r e f e r  a response w i t h repeated or extended  presentation  s t i m u l u s when t h a t d e c r e a s e c a n n o t be a c c o u n t e d f o r  or receptor  adaptation  (Thompson & S p e n c e r ,  to  in  terms  1966; Graham, 1 9 7 3 ) .  -  I n man, h a b i t u a t i o n i s  31 -  t y p i c a l l y s t u d i e d i n terms of  c o r t i c a l or  autonomic  responses to simple sensory s t i m u l a t i o n recorded v i a non-invasive H a b i t u a t i o n h a s b e e n l e s s commonly m e a s u r e d i n t e r m s o f m o t o r (Scholander,  1 9 6 1 ) , and s e l f - r e p o r t  measures ( G l a s e r ,  techniques.  responses  1966).  As p r e v i o u s l y n o t e d , a d j u s t m e n t t o s t r e s s by a n i n d i v i d u a l r e q u i r e s c o g n i t i v e a p p r a i s a l of  the s i g n i f i c a n c e  of  a given event  (Lazarus,  1966).  I a c o n o and L y k k e n ( 1 9 8 3 ) have s u g g e s t e d t h a t h a b i t u a t i o n i n v o l v e s s u c h appraisal.  Habituation i s  seen as i n v o l v i n g the a b i l i t y  The i d e n t i f i c a t i o n  of  profound i m p l i c a t i o n s the t r a n s d u c t i o n of chronic  specific for  p a t t e r n s of  coronary pathology.  Obrist  et a l .  its  of  possible  continue  significance.  i.e.,  pathways i n v o l v e d  hyperreactivity,  not a s s o c i a t e d w i t h a metabolic need.  • cardiovascular  cardiovascular  Maladaptive  patterns of  habituation.  r e s p o n s e s may  h e a r t r a t e i n c r e a s e s as a dependent measure of Several other  researchers  (Jones & Johnson,  stimulus.  on  s t r e s s focused  habituation  (Engel,  1978;  1984; Zwaga, 1973)  heart rate responses f o l l o w i n g  c o g n i t i v e s t r e s s o r such as mental a r i t h m e t i c .  on  1960).  1 9 7 5 ; Manuck & S c h a e f f e r ,  Manuck & G a r l a n d , 1 9 8 0 ; S c h u l t e e t a l . , 1 9 8 1 ; L a n e , r e p o r t e d h a b i t u a t i o n of  E a r l y work  habituation to psychological  example,  maintained  t o o c c u r d e s p i t e t h e c e s s a t i o n or absence of an e l i c i t i n g  C h a r a c t e r i s t i c s of  have  repeated exposure to  Lacey and o t h e r s  (Lacey,  The h e a r t r a t e r e s p o n s e i n v o l v e s b o t h a c c e l e r a t i v e a n d  components.  in  decelerative  I n g e n e r a l , d e c e l e r a t i v e components have been found t o  r a p i d l y w h i l e a c c e l e r a t i v e c o m p o n e n t s show f a r  a  1963;  Lacey e t a l . , 1967) have argued t h a t h e a r t r a t e r e s p o n s e s a r e m u l t i - p h a s i c nature.  in  into  (1978) have suggested f o r  t h a t a m a l a d a p t i v e r e s p o n s e may be one i n w h i c h i n c r e a s e d o r arousal i s  stop  c a r d i o v a s c u l a r h a b i t u a t i o n may h a v e  the i d e n t i f i c a t i o n  acute stress responses,  an  to tune out or  r e a c t i n g t o a s t i m u l u s t h a t h a s no s i g n a l v a l u e o r h a s l o s t  a  greater v a r i a b i l i t y  habituate depending  -  on t h e s t i m u l u s c o n d i t i o n s recent  evidence of  inter-stressor effects  32  -  (Lang & Hnatiow,  1962).  Although there i s  some  s y s t o l i c blood pressure habituation across r e l a t i v e l y  intervals  (Lane,  1984) the q u e s t i o n of  on b l o o d p r e s s u r e h a s n o t b e e n t h o r o u g h l y  stimulus  short  repetition  explored.  I n r e v i e w i n g t h e r e s e a r c h l i t e r a t u r e , B o h l i n ( 1 9 7 3 ) r e a c h e d a number general conclusions  r e g a r d i n g the c h a r a c t e r i s t i c s of  habituation.  First,  both l e v e l of  a r o u s a l and r a t e of  cardiovascular  there i s a s t r o n g dimension of  on b o t h a p h y s i o l o g i c a l  (Obrist,  habituation. Lawler,  Froberg, Hagdahl, R i s s l e r ,  a psychological  (Lazarus, 1966).  produces a concurrent  individual differences  These d i f f e r e n c e s  Borkvall, & Wolff,  Second, the process of  decrease i n a r o u s a l .  Scholander  suggests that criteria concluded  (1966) however,  the discrepancy  i n t h e measurement o f that  independent  of  f o u n d no s u c h r e l a t i o n s h i p .  in results is  In order  Third,  i n c r e a s e d a r o u s a l b r i n g s about a delay  a l s o s u p p o r t e d by M a t t h e w s a n d L a d e r Methodological  due t o t h e u s e o f  response h a b i t u a t i o n .  the c h a r a c t e r i s t i c s of  the s t r e s s o r  1967)  and  habituation an  habituation. Bohlin  (1973)  different Bohlin  (1973)  i n habituation which  involved.  This  finding  is is  (1965).  I s s u e s R e g a r d i n g R e a c t i v i t y and  to study the r e l a t i o n s h i p  response h a b i t u a t i o n i t  mediated  (1960) h e l d t h a t  i n v e r s e r e l a t i o n s h i p e x i s t s between a r o u s a l l e v e l and r a t e of B o h l i n and T i z a r d  are  for  Howard, S m i t h s o n , M a r t i n , & Manning,  1974; Frankenhaeuser, level  of  Habituation  between c a r d i o v a s c u l a r r e a c t i v i t y  i s n e c e s s a r y t o o b t a i n v a l i d and r e l i a b l e  and  measurements  across time.  I n t h i s r e g a r d , s e v e r a l m e t h o d o l o g i c a l and m e a s u r e m e n t - r e l a t e d  i s s u e s are of  concern.  situational influences, effects,  These i s s u e s which i n c l u d e  p r e - s t r e s s a d a p t a t i o n and b a s e l i n e ,  task c h a r a c t e r i s t i c s ,  and t h e d e f i n i t i o n  subject  stimulus repetition,  and s e l e c t i o n of  characteristics, instruction  inter-stressor  a p p r o p r i a t e response measures  interval, are  33  discussed i n the f o l l o w i n g  sections.  Subject c h a r a c t e r i s t i c s .  A number o f m e t h o d o l o g i c a l p r o b l e m s a r i s e  attempts to i n v e s t i g a t e the r e l a t i o n s h i p individual differences specific  to the e f f e c t s  elsewhere & Todd,  dimensions of  I n a more r e c e n t  habituation.  about  A n x i e t y as d e f i n e d  individual  A difficulty  for  differences  by t h e M a n i f e s t  was p o s i t i v e l y c o r r e l a t e d w i t h c a r d i a c  clear,  arousal i s  response systems.  S t u d i e s of  As L a c e y ' s  of  is  i s s u e by r e s t r i c t i n g  their  (O'Gorman,  (Barratt,  1969; K o r i a t  in discussions  C h a r a c t e r i s t i c s of  of  the s u b j e c t ,  habituation independent  have been s u g g e s t e d as p o t e n t i a l c o n f o u n d i n g response h a b i t u a t i o n are gender, fitness  level,  (1973) r e p o r t e d t h a t  of of  1977). non-clinical  1 9 6 8 ; Dykman e t  et a l . , 1973).  cardiovascular  The  al, overall  i n t h e measurement  recruitment for  and s u b j e c t m e n t a t i o n d u r i n g t h e t a s k .  females took longer  the  to  which of  study,  McGuiness  than males to h a b i t u a t e  range  responses.  personality variables  factors  a g e , method of  on  personality  t h a t h y p o t h e s e s i n v o l v i n g p e r s o n a l i t y measures have a l i m i t e d  applicability  aerobic  evidence  ( 1 9 6 7 ) r e s e a r c h h a s made  the e l e c t r o d e r m a l  et a l . , 1965; I s r a e l ,  1983)  in  Most h y p o t h e s e s about  have y i e l d e d i n c o n c l u s i v e r e s u l t s  1959; G a l b r e c h t result  Anxiety Scale (Taylor,  p e r s o n a l i t y and c a r d i o v a s c u l a r h a b i t u a t i o n i n v o l v i n g  populations  be  response  the p r e v i o u s l y c i t e d  n o t a u n i t a r y phenomenon.  t o one r e s p o n s e s y s t e m ,  the  found to  hypotheses regarding i n d i v i d u a l d i f f e r e n c e s  and r e s p o n s e h a b i t u a t i o n have a v o i d e d t h i s predictions  in  Christie  output.  h a b i t u a t i o n b a s e d on m e a s u r e s o f a r o u s a l i s the d i s s o c i a t i o n of  1972;  (1977) found t h a t  a n x i e t y and e x t r a v e r s i o n were most f r e q u e n t l y  implicated in predictions  reviewed  1971; Johnson & L u b i n ,  r e v i e w O'Gorman  and  Problems  p e r s o n a l i t y on h a b i t u a t i o n h a v e b e e n  ( A v e r i l l & Opton, 1968; F i s k e ,  1975).  between s u b j e c t c h a r a c t e r i s t i c s  i n r e a c t i v i t y and r e s p o n s e h a b i t u a t i o n . of  in  an  -  auditory  s t i m u l u s on a m e a s u r e o f  differences reported.  The e f f e c t s  conductance  forearm blood volume.  of  Cross-gender  conductance  (0'Gorman, 1977). S t e r n (1968) r e p o r t e d t h a t the  undergraduates.  and t h e r e i s  pressure  l i n k e d t o age as i s  heart  rate reactivity  Blood pressure  i s known t o i n c r e a s e w i t h  t h a t h y p e r t e n s i v e s show s l o w e r  Godicke, Hartrodt,  Naumann, & L a u t e r ,  1973),  and  1 9 6 0 ) t h a n do  n o r m o t e n s i v e s . _ G i v e n t h e s e two p i e c e s  future  i n e s t a b l i s h i n g a more d e f i n i t i v e  Kotses,  slower  r e s e a r c h may  succeed  t h e r e l a t i o n s h i p between age  (1974) s t u d i e d the e f f e c t  r e c r u i t m e n t p r o c e d u r e s on c a r d i a c between groups v o l u n t e e r i n g ,  of  different  responsiveness to noise.  conscripted,  habituation  recruitment procedures  of  age,  and  habituation.  G l a u s and F i s h e r  observed i n terms of  picture  evidence  have  habituation  recovery f o l l o w i n g a mental a r i t h e m t i c task (Brod, of  and  (Glass  o f a g e on b l o o d p r e s s u r e h a b i t u a t i o n h o w e v e r  examined.  cardiovascular response  skin  Some e v i d e n c e e x i s t s t h a t s y s t o l i c b l o o d  also evidence  (Baumann, Z i p r i a n ,  in  children  The e f f e c t s  n o t y e t been c l o s e l y  rapidly  i n a comparison of  not as s t r o n g l y  et a l . , 1983).  s t i m u l u s i n a d u l t s h a b i t u a t e d more  rate habituation  been  skin  More r e c e n t l y G r e e n ( 1 9 7 6 ) o b s e r v e d no d i f f e r e n c e s  response or heart  is  been  a g e on h a b i t u a t i o n a n d r e a c t i v i t y h a v e a l s o n o t  responses to a cool a i r  than i n c h i l d r e n .  reactivity  -  i n b l o o d p r e s s u r e or h e a r t r a t e h a b i t u a t i o n have not  studied in detail  college  34  of  or being paid f o r  heart rate.  on r e s p o n s e s t o c o g n i t i v e  The e f f e c t  No  subject  differences  the study of  were  different  s t r e s s o r s has not  been  reported. An i n d i v i d u a l ' s a b i l i t y by h i s  or her l e v e l of  Physiological  t o cope w i t h p s y c h o l o g i c a l  aerobic  correlates  of  fitness  aerobic  ( F o l k i n s & Sime,  stress is also 1981; Morgan,  f i t n e s s may m e d i a t e o n e ' s  mediated 1982).  subjective  e x p e r i e n c e o f a g i v e n s t r e s s o r and o n e ' s s u b s e q u e n t r e a c t i v i t y l e v e l and  rate  -  of  habituation.  35  -  The r e l a t i o n s h i p b e t w e e n a e r o b i c  fitness  level  and  c a r d i o v a s c u l a r h a b i t u a t i o n t o a r e p e a t e d s t r e s s o r has n o t been a d d r e s s e d . S e v e r a l s t u d i e s have however examined p o s t s t r e s s r e c o v e r y r a t e s and relationship  to aerobic  fitness  level.  Hollander  and S e r a g a n i a n  s t u d i e d the r e l a t i o n s h i p between i n d i v i d u a l - s p e c i f i c and a e r o b i c  fitness  level.  d u r i n g and f o l l o w i n g aerobic Evans,  fitness  their  (1984)  cardiovascular  The a u t h o r s m e a s u r e d p h y s i o l o g i c a l  responses  reactivity  e x p o s u r e t o a m e n t a l a r i t h m e t i c t a s k and found  that  l e v e l was u n r e l a t e d t o h e a r t r a t e d u r i n g t h e t a s k .  Cox,  and J a m i e s o n ( 1 9 7 9 ) a l s o r e p o r t e d t h a t h e a r t r a t e r e a c t i v i t y d i d  vary as a f u n c t i o n of  the s u b j e c t ' s a e r o b i c  mental a r i t h m e t i c task Hollander aerobic  fitness  fitness  Seraganian (1983) a l s o  and S e r a g a n i a n (1984) found however,  Sinyor, Schwartz, Perronet,  found t h a t a e r o b i c a l l y  fit  r a t e recovery from a mental a r i t h m e t i c plus noise the r e l a t i o n between p h y s i o l o g i c a l  c e n t r e s n o t upon i n i t i a l m a g n i t u d e of for which a r o u s a l p r e v a i l s . aerobic  fitness  Following  l e v e l was p o s i t i v e l y c o r r e l a t e d w i t h s p e e d o f  rate recovery to baseline.  suggest  level.  post  Brisson,  the that  task  s u b j e c t s showed f a s t e r stressor.  These  r e a c t i v i t y and a e r o b i c  i n m e d i a t i n g p h y s i o l o g i c a l h a b i t u a t i o n and i t s c h r o n i c exposure to  heart  findings fitness  r e s p o n s e b u t upon t h e d u r a t i o n o f  of  heart  and  F u t u r e r e s e a r c h s h o u l d f o c u s on t h e r o l e  importance i n a m e l i o r a t i n g the e f f e c t s  not  time  of  possible stress.  S u b j e c t m e n t a t i o n d u r i n g t h e s t r e s s t a s k h a s a l s o b e e n s u g g e s t e d by some a u t h o r s as a p o s s i b l e  source of  (Barratt,  1973; Luborsky,  1972; G a l e ,  e r r o r v a r i a n c e i n s t u d i e s of 1967).  Dykman, R e e s e , G a l b r e c h t ,  Thomasson ( 1 9 5 9 ) a t t e m p t e d t o a s s e s s t h e s u b j e c t i v e s t a t e o f during habituation  habituation  the  through the use of a post s t r e s s o r i n t e r v i e w .  More r e c e n t l y ,  Neary and Zuckerman (1976) r e p o r t e d a  subject Only  s e l f - r a t e d a n x i e t y showed a p o s i t i v e c o r r e l a t i o n t o p h y s i o l o g i c a l arousal.  and  indices  significant  of  -  36  -  r e l a t i o n s h i p between s e l f - r a t e d a n x i e t y and h a b i t u a t i o n o f r e s p o n s e s t o an a u d i t o r y  stimulus.  O'Gorman  m e n t a l e x p e r i e n c e and h a b i t u a t i o n . measures were c i t e d .  skin  (1977) reviewed the l i t e r a t u r e  No s t u d i e s i n v o l v i n g  O'Gorman c o n c l u d e d t h a t i n terms o f  Future s t u d i e s of  the e f f e c t s  of  cognition  electrodermal  cardiovascular  function  on  response  and i m a g i n a t i o n  b o t h c a r d i o v a s c u l a r r e a c t i v i t y a n d h a b i t u a t i o n s h o u l d be A d a p t a t i o n and B a s e l i n e .  is  or b a s e l i n e ,  R e a c t i v i t y or h a b i t u a t i o n measures  of  d e r i v e t h e i r meaning through comparison of  conditions.  Because the attachment of  l i k e l y t o produce an a r o u s i n g e f f e c t  p r e c e d e measurement of  it  b a s e l i n e values w i t h a p e r i o d of  d u r i n g w h i c h t h e s u b j e c t may a d a p t however,  on t h e s u b j e c t  these  devices  i s necessary  to  i n a c t i v i t y and  to the experimental s e t t i n g .  blood pressure or heart r a t e measures.  under  recording  quiet  There  some c o n t r o v e r s y r e g a r d i n g t h e o p t i m a l p e r i o d n e e d e d t o  s t a b i l i z a t i o n of  on  conducted.  m e a s u r e s w i t h c o r r e s p o n d i n g m e a s u r e s made o n t h e same i n d i v i d u a l b u t resting,  is  achieve  In a recent  review  t h e l i t e r a t u r e on p h y s i o l o i g c a l p r e - s t r e s s a d a p t a t i o n  (Linden & McEachern,  1985) the a u t h o r s examined the q u e s t i o n of e f f e c t s  the duration  a d a p t a t i o n p e r i o d s on s t a b i l i z a t i o n o f parameters.  of  various physiological  l e n g t h from 5 m i n u t e s (Benthem & G l a r o s , 1983).  O n l y two o f  of  (1985) concluded t h a t t h e r e i s  some e v i d e n c e  L i n d e n and  McEachern  that heart rate tends to  be  s t a b l e whereas blood p r e s s u r e tends to decrease c o n t i n u o u s l y over  20-minute adaptation p e r i o d .  It  in  (Drummond,  35 s t u d i e s r e p o r t e d e m p i r i c a l d a t a on o b s e r v e d c h a n g e s  physiological a c t i v i t y during prestress adaptation.  fairly  response  These p e r i o d s ranged  1 9 7 8 ) t o 60 m i n u t e s  of  of  The a u t h o r s n o t e d s u b s t a n t i a l v a r i a b i l i t y i n t h e l e n g t h  a d a p t a t i o n p e r i o d s b e i n g employed i n v a r i o u s s t u d i e s .  on  cardiovascular  measures s u b j e c t m e n t a t i o n does not e x e r t a s t r o n g i n f l u e n c e habituation.  conductance  r e m a i n s u n c e r t a i n a s t o how l o n g  full  a  in  -  -37  s t a b i l i z a t i o n of  b l o o d p r e s s u r e may r e q u i r e .  l e n g t h of a d a p t a t i o n p e r i o d remains u n c l e a r , the e n t i r e  time spent  Zwaga's  baseline  Obrist  (1981),  that  of  for  appropriate  example had argued  that  b a s a l h e m o d y n a m i c l e v e l s c a n n o t be made d u r i n g  same r e c o r d i n g s e s s i o n a t w h i c h a s t r e s s o r i s Obrist  optimal  (1973) s u g g e s t i o n  (1985) a l s o addressed the q u e s t i o n of  values.  accurate d e t e r m i n a t i o n of  arousal.  of an  warranted.  L i n d e n and McEachern of  the choice  i n t h e l a b o r a t o r y s h o u l d be v i e w e d a s a s o u r c e  valuable data appears  definition  While  presented evidence that  p r e s e n t e d , due t o  the magnitude of  the  anticipatory  heart rate  and  p r e s s o r c h a n g e s s c o r e s i n r e s p o n s e t o a g i v e n s t r e s s o r a r e u n d e r e s t i m a t e d when c a l c u l a t e d a s c h a n g e s f r o m b a s e l i n e m e a s u r e s made i m m e d i a t e l y p r i o r p r e s e n t a t i o n of  the s t r e s s o r .  to  the  M e y e r s and C r a i g h e a d ( 1 9 7 8 ) on t h e o t h e r  hand  argued t h a t the use of minute 6 of a 20-minute a d a p t a t i o n p e r i o d as a  baseline  v a l u e would a l l o w f o r  same  adequate p h y s i o l o g i c a l  s t a b i l i z a t i o n and a t  time a v o i d the problem of a n t i c i p a t o r y a r o u s a l . (Elliott, Levita, onset i t  1975; Monat,  Averill,  & Lazarus,  possible  d a t a by t h e f a c t  that t h i s  baseline  1972; Monat,  appears a r b i t r a r y given the f a c t response systems i s lowest  In their  problem i s  choice  studies  1976; Rakover &  exaggerated i n  that h i s subjects expected aversive shocks.  M e y e r s and C r a i g h e a d ( 1 9 7 8 ) t h e i r  their  W h i l e numerous o t h e r  1973) c o n f i r m the e x i s t e n c e of a n t i c i p a t o r y a r o u s a l p r i o r is  the  stimulus  Obrist's  In the case  o f m i n u t e 6 a s an o p t i m a l  t h a t change a c r o s s v a r i o u s  to  of  baseline  physioloigcal  a s y n c h r o n o u s and v a r i o u s measures a r e n o t c o n s i s t e n t l y  l e v e l s a t minute review of  6.  t h e l i t e r a t u r e , L i n d e n and McEachern  (1985) found  that  t h e m o s t f r e q u e n t l y u s e d b a s e l i n e v a l u e was t h e a v e r a g e o f m i n u t e s t o 1 t o of  the adaptation p e r i o d .  at  Clearly,  this  choice  of  b a s e l i n e s a l s o does  adequately address the aforementioned problems regarding s t a b i l i z a t i o n  not of  5  -  38  -  p h y s i o l o g i c a l p a r a m e t e r s and a n t i c i p a t o r y a r o u s a l .  The a u t h o r s n o t e t h a t  r e s e a r c h w i t h informed s u b j e c t s experimenters can expect a r e v e r s e d a r o u s a l curve during p r e s t r e s s a d a p t a t i o n from the f i r s t to the immediate p r e s t r e s s p e r i o d . s e r i e s of  readings  They s u g g e s t  taken during a l a t e r  minute of  taken at  this  p o i n t would represent  reversed J arousal curve.  In defining  observation  segment o f  p e r i o d may be c o n s i d e r e d t h e b e s t a p p r o x i m a t i o n o f a " t r u e " Readings  J-shape  s t a b l e responses over  but not the f i n a l  a  prestress  baseline.  t h e presumed bottom of  such a b a s e l i n e  in  the  individual-specific  or  g r o u p mean s c o r e s c o u l d be e m p l o y e d . Instruction effects.  I a c o n o and L y k k e n ( 1 9 8 3 ) f o u n d t h a t s k i n  r e s p o n s e s c a n be a f f e c t e d Instructions  subjects'  pre-task instructions  to attend to a s t i m u l u s or n e u t r a l i n s t r u c t i o n s  h a b i t u a t i o n of facilitate  by t h e t y p e o f  responses; while  habituation. attention also  pre-task instructions.  instructions  i n c r e a s e d h a b i t u a t i o n of  Drummond ( 1 9 8 3 ) f o u n d t h e g r e a t e s t  No d i f f e r e n c e s  l e v e l of  subjects'  provided.  To a v o i d t h e p o t e n t i a l c o n f o u n d i n g e f f e c t s  during  p e r i o d should separate the p r o v i s i o n of  of  type of  the experimental s t r e s s o r .  from the  The i n c l u s i o n o f  w a i t i n g p e r i o d would serve to minimize the e f f e c t s s t r e s s response  of  The and  instructions the  A post-instruction,  instructions  neutral  instructions  task instructions only after  the p r e s t r e s s adaptation p e r i o d .  a n t i c i p a t o r y a r o u s a l on i n i t i a l  neutral  focus of a t t e n t i o n  r e a c t i v i t y may be s e n s i t i v e t o t h e t y p e o f  specific  the  i n b l o o d p r e s s u r e were s e e n . that  waiting  first such a  brief  instruction-related  levels.  to  between-group  in heart rate  subsequent  researchers should provide  for  responses during  t h e s e two s t u d i e s i n d i c a t e  p r e s e n t a t i o n of  decreased  The p r o v i s i o n o f a n a l t e r n a t i v e f o c u s  r e s u l t s of  completion of  provided.  to ignore the stimulus served  (hypertensives versus normotensives) differences pre-task instructions.  conductance  -  Task C h a r a c t e r i s t i c s . cardiovascular  In a s s e s s i n g the r e l a t i o n s h i p  reactivity  s t r e s s o r a number o f  and s u b s e q u e n t  individual  Third, response  stereotypy.  A review of  1981; Lane,  satisfied  or the e f f e c t s  r e a c t i v i t y are a l s o of  attentional  and Laux  interest.  the hypothesis task,  when t h e s u b j e c t prior  of  relative  experience  In order  Task c h a r a c t e r i s t i c s  a c r o s s each t r i a l . habituation  in  and  task-specific  stressor  reveals  that  (Schulte et  al.,  the s u b j e c t ' s  appraisal  (1979), for  variability  the t e s t  stressor  for  of  The  i n each of  in a  only effects Vossel  two  prior  s  researchers  participated  s h o u l d employ o n l y  in stress  response  to the assessment  t h e t a s k m u s t be c o n s i s t e n t l y  Since habituation  to t r i a l is  showed  subsequent  the p o s s i b l e e f f e c t s o f  are also relevant  an  exposed t o a g i v e n s t r e s s o r  to c o n t r o l  1977).  during  situation.  to a novel stressor  First,  example,  have a l s o been i n v e s t i g a t e d .  to a d i f f e r e n t  responsivity,  on  p e r i o d , was s u p p o r t e d  S t i m u l i which vary from t r i a l  (O'Gorman,  to the s t r e s s o r  reactivity  on p h y s i o l o g i c a l  habituation.  in  stressor  s u b j e c t s who h a v e n o t p r e v i o u s l y  response  exposure  Subjects previously  i n heart rate  t e s t i n g phase.  prior  to a r e s t i n g b a s e l i n e  (1978) exposed s u b j e c t s  experience  on  criteria  O ' N e i l l and H i n t o n  to a d i f f e r e n t  experimental sessions.  of  decreased heart rate  had p r e v i o u s  exposure  a decrease  the aforementioned  differences  reliability  plus noise  task  responses.  individual  the l i t e r a t u r e  the  1984).  Novelty effects  found t h a t  each of  repeated  First,  cardiovascular  t h e t a s k m u s t show g o o d t e s t - r e t e s t  acute  to a  importance.  range of  associated with a mental a r i t h m e t i c  such a s t r e s s o r  of  evokes s i g n i f i c a n t  between  habituation  are of  t h e t a s k must y i e l d a s i g n i f i c a n t  reactivity.  effects  response  task characteristics  m u s t be o n e w h i c h r e l i a b l y Second,  \  -  3 9  of  research. cardiovascular  administered result  considered  the s t i m u l u s c h a r a c t e r i s t i c s  naive  (Iacono  in  slower  t o depend & Lykken,  on  - 40  -  1983) u n v a r y i n g s t i m u l i s h o u l d f a c i l i t a t e h a b i t u a t i o n . h y p o t h e s i s comes f r o m t h e r e s e a r c h o f (1963),  and S p i n k s and S i d d l e  Support f o r  B e r l y n e , Craw, S a l a p a t e k and  (1976).  More r e c e n t l y ,  1 9 8 3 ) , and h i g h t a s k - r e l e v a n c e  Lewis  physiological  h a b i t u a t i o n h a s b e e n f o u n d t o be d e l a y e d u n d e r c o n d i t i o n s (Hulstjin,  this  of  response  high signal  value  (Woestenburg, Verbaten, & Slangen,  1983). Stressor  c o m p l e x i t y may a l s o  be i n c r e a s e d t h r o u g h t h e  p r e s e n t a t i o n of m u l t i p l e s t i m u l i , i . e , p r e s e n t a t i o n of m u l t i p l e confusing effects  of  picture  mental a r i t h m e t i c plus n o i s e .  emerges however f r o m a r e v i e w of  c o m p e t i n g s t i m u l i on h a b i t u a t i o n .  other  s t u d i e s h a v e f o u n d no e f f e c t  s h o u l d be n o t e d t h a t t h e s e s t u d i e s d i d n o t e m p l o y  revealed that the e f f e c t s  interference  Kortenaar, cognitive  the  relevant  sufficient  d u r a t i o n so as t o a l l o w f o r  Finally,  the  noise  s t r e s s t a s k s r e q u i r i n g fewer  A l t h o u g h e x p e r i m e n t a l t a s k s have  1984).  t h a n 15 m i n u t e s t o a d m i n i s t e r  I n c i r c u m s t a n c e s where a c r o s s t a s k h a b i t u a t i o n  stimulus repetition i s  is  has  stressor  an a c c u r a t e a s s e s s m e n t  i n d u r a t i o n f r o m 1 h o u r t o a few m i n u t e s , r e s e a r c h e r s have g e n e r a l l y  Manuck,  while  simultaneous s t r e s s o r s such as  examined ( L i n d e n et a l . , i n p r e s s ) .  the presence of h a b i t u a t i o n e f f e c t s .  single  to  a n d m e n t a l a r i t h m e t i c on c a r d i o v a s c u l a r r e s p o n s e h a b i t u a t i o n  not been t h o r o u g h l y m u s t be o f  of  A review of  A  the  1983) h a b i t u a t i o n ;  (van 0 1 s t , Heemstra, & ten  s t r e s s o r s or c a r d i o v a s c u l a r response measures. literature  t h e l i t e r a t u r e on  Such t a s k s have been found  ( B o h l i n , 1 9 7 6 ) , and t o speed ( F r i t h & a l i e n ,  It  The  s t r e s s o r s may s e r v e t o d e l a y r e s p o n s e h a b i t u a t i o n .  delay  1979).  simultaneous  of  varied  used  (Krantz & of  interest  necessary.  S t i m u l u s r e p e t i t i o n and i n t e r - s t r e s s o r i n t e r v a l . s t i m u l u s r e p e t i t i o n s and l e n g t h o f  The c h o i c e o f  i n t e r - s t r e s s o r i n t e r v a l are of  i m p o r t a n c e i n any a t t e m p t t o a s s e s s r e s p o n s e h a b i t u a t i o n .  As  number  paramount  previously  of  -  noted,  41  -  e a c h s t i m u l u s p r e s e n t a t i o n m u s t be o f  allow within stressor habituation to occur. repeatedly  sufficient  d u r a t i o n so as  In a d d i t i o n ,  presented w i t h i n a given session.  A review of  t h e s t r e s s o r must the l i t e r a t u r e  w i t h i n - s e s s i o n responses to a mental a r i t h m e t i c s t r e s s o r revealed consistent  results.  cardiovascular  First,  e t a l . , 1984; Miner  their  (Lacey & Lacey,  et a l . , 1984).  initial  two  reactivity  Second, w i t h i n experimental  s t u d i e s have demonstrated c a r d i o v a s c u l a r  & Siddle,  also reported significant  response h a b i t u a t i o n to  s t i m u l i across  five,  time (Steptoe,  h a b i t u a t i o n of  1-minute t r i a l s .  display greater heart rate habituation a c r o s s 3, twenty-minute t a s k p e r i o d s ,  1977).  there i s  a  (Turpin  (1983) noise  some e v i d e n c e  that  t h a n men t o a S t r o o p p e r c e p t i o n gender d i f f e r e n c e s  1967)  (Zwaga,  Sosnowski  heart rate responses to a  While  Glass  (Frankenaeuser et a l . ,  1 9 7 5 ; Neus e t a l . , 1 9 8 1 ) , b l o o d p u l s e a m p l i t u d e  1 9 8 3 ) , and p u l s e t r a n s i t  to  sessions  m e n t a l a r i t h m e t i c t a s k on a v a r i e t y o f measures s u c h a s h e a r t r a t e 1973; Jones & J o h n s o n ,  of  1 9 6 2 ; Manuck & G a r l a n d , 1 9 8 0 ;  r a n g i n g f r o m 2 m i n u t e s (Drummond, 1 9 8 3 ) t o 1 h o u r other  l e v e l of  be  on  i n d i v i d u a l s d i s p l a y an i d i o s y n c r a t i c p a t t e r n  r e s p o n s i v i t y i n terms of  each s t r e s s o r p r e s e n t a t i o n  to  i n response  women  task  to  h a b i t u a t i o n t o a m e n t a l a r i t h m e t i c p l u s n o i s e t a s k have n o t been r e p o r t e d . Taken t o g e t h e r  these r e s u l t s suggest  an a c c u r a t e a s s e s s m e n t o f through the use of intervals. least  t a s k - s p e c i f i c h a b i t u a t i o n c a n be a c h i e v e d  a reliable  s t r e s s o r repeated at  E a c h s t r e s s t a s k s h o u l d be f o l l o w e d  equal duration.  the l e n g t h of  and B r i t t a i n (1971)  the between t r i a l r e c o v e r y significance  (Cannon, 1932; Frankenhaeuser,  of  only  discrete  parameters across s t r e s s o r t r i a l s  Given the p o t e n t i a l c l i n i c a l stress  specific  session  time  by a r e c o v e r y p e r i o d o f  H o k a n s o n , DeGood, F o r r e s t ,  t h a t changes i n p h y s i o l o g i c a l f u n c t i o n of  that within a given experimental  at  noted  v a r i e d as  a  period.  chronic,  1980), the impact of  repeated exposure longer  to  - 42  inter-stressor  intervals is  a l s o of  l i t e r a t u r e r e v e a l s the use of (Manuck & S c h a e f f e r , Sedlacek,  interest.  The e v i d e n c e  suggests  i n t e r v a l s r a n g i n g f r o m one d a y t o s e v e r a l w e e k s habituation effects,  r e a c t i v i t y and an i n c r e a s e d r a t e o f  i.e.,  f o u r weeks a p p e a r t o p r o d u c e l i t t l e  Inter-visit  o r no r e t e n t i o n o f  habituation,  In a review of  their  f a c t o r s which i n f l u e n c e  influence:  s t i m u l u s c o m p l e x i t y and i n t e n s i t y ,  intervals in  subject  for  habituation  the f o l l o w i n g  gender,  of  such f a c t o r s  1982;  effects Ludbrook  factors  inter-stimulus  s u b j e c t ' s e x p e c t a t i o n s , and one m o n t h .  s t u d i e s reviewed i n v o l v e d electrodermal measures.  the i n f l u e n c e  excess  physiological  h a b i t u a t i o n t o t h e same s t i m u l u s w i t h i n a p e r i o d o f of  1 9 6 6 ; Neus  1980).  O'Gorman ( 1 9 7 7 ) c o n c l u d e d t h a t  s t r o n g evidence of  cardiovascular  (Glaser,  and s u b s t a n t i a l l y l e s s r e s p o n s e v a r i a b i l i t y (Cohen & S e d l a c e k , & W a l s h , 1 9 8 2 ; Manuck & G a r l a n d ,  that  produce  decreased  response h a b i t u a t i o n  et a l . , 1981; Frankenhaeuser et a l . , 1967).  Summary.  the  1 9 7 8 ; Neus e t a l . , 1 9 8 1 ) t o s e v e r a l m o n t h s ( C o h e n &  s u b s t a n t i a l r e t e n t i o n of  of  A thorough review of  i n t e r - v i s i t i n t e r v a l s r a n g i n g f r o m one week  1 9 8 2 ; Manuck & G a r l a n d , 1 9 8 0 ) .  inter-visit  -  there  interval,  previous The  The e v i d e n c e  majority regarding  on c a r d i o v a s c u l a r r e s p o n s e s i s n o t a s  extensive  or as c o n c l u s i v e .  I n a more r e c e n t r e v i e w a n d m e t h o d o l o g i c a l c r i t i q u e  & Manuck,  acute cardiovascular  1984) o f  coronary disease the authors i d e n t i f i e d situation-specific  factors  (Krantz  r e a c t i v i t y and i t s r e l a t i o n s h i p similar individual-specific  as i m p o r t a n t i n f l u e n c e s  on  is  to  and  cardiovascular  reactivity. S e l e c t i o n of  response measures.  A thorough e v a l u a t i o n of  r e a c t i v i t y a n d h a b i t u a t i o n b a s e d on t e c h n i q u e s psychophysiologic  s t u d i e s would i n c l u d e  cardiovascular  commonly e m p l o y e d  in  simultaneous assessment of  a n d d i a s t o l i c b l o o d p r e s s u r e , mean a r t e r i a l p r e s s u r e ,  systolic  s t r o k e volume,  systolic  -  t i m e i n t e r v a l s , and h e a r t r a t e  of  -  ( K r a n t z & Manuck,  b o t h t i m e - c o n s u m i n g and e x p e n s i v e . presented e a r l i e r  43  S e v e r a l of  1984).  Such an a p p r o a c h  the methodological  do h o w e v e r s u g g e s t some g e n e r a l g u i d e l i n e s  response measures.  First,  a s n o t e d by S t e p t o e  (1980),  p h y s i o l o g i c a l v a r i a b l e s t o be r e c o r d e d i s  best  questions  for  the  Second, the  Where h e m o d y n a m i c r e s p o n s e c h a r a c t e r i s t i c s a r e o f  measures of  t a s k - r e l a t e d changes i n h e a r t r a t e and b l o o d p r e s s u r e a r e  appropriate  the v a r i a b l e s of  Third,  i n a d d i t i o n to  be made d u r i n g a l a b o r a t o r y s e s s i o n .  some v a r i a b l e s ,  e.g.,  heart  rate,  is  most  choosing physiological  Continuous  readily achieved, while  measurement other  v a r i a b l e s s u c h a s b l o o d p r e s s u r e c a n be s a m p l e d o n l y a t d i s c r e t e  time  intervals.  collect  To e n s u r e m e a s u r e m e n t r e l i a b i l i t y  multiple recordings  for  repeated e x p e r i m e n t a l s t r e s s o r s are used i t or recovery periods  i n v e s t i g a t o r s must  each autonomic parameter of is  interest.  r e s p o n s i v i t y to each task w i l l  then r e f l e c t  -Finally,  necessary to interpose  between each s t r e s s o r p r e s e n t a t i o n .  to  interest,  r e s p o n s e m e a s u r e s , e x p e r i m e n t e r s m u s t d e c i d e when  recordings w i l l of  choice.  choice  g u i d e d by t h e h y p o t h e s e s  be t e s t e d .  frequently  selection  physiological  m e a s u r e s s h o u l d be u n o b t r u s i v e , a u t o m a t i c , a n d f r e q u e n t . of  is  if  baseline  Subjects'  changes from r e s t i n g v a l u e s  than changes from response l e v e l s a c h i e v e d d u r i n g immediately p r e c e d i n g  rather task  periods. Two i s s u e s s p e c i f i c a l l y  r e l a t e d t o t h e measurement of  reactivity  are a l s o r e l e v a n t to the appropriate  measures.  First,  that  there i s  a n d Manuck  a review of  s e l e c t i o n of  of  cardiovascular  response  ( K r a n t z & Manuck,  no c o n s e n s u s a s t o t h e b e s t d e f i n i t i o n  1984)  reactivity.  (1984) n o t e d t h a t r e a c t i v i t y has been v a r i o u s l y d e f i n e d as  changes from b a s e l i n e , response l e v e l . of  the l i t e r a t u r e  acute  reactivity.  changes a d j u s t e d f o r  b a s e l i n e , and a v e r a g e  reveals Krantz absolute  stress  A b s o l u t e changes s c o r e s a r e t h e most f r e q u e n t l y used measure R e c e n t l y however,  some a u t h o r s h a v e recommended t h e u s e  of  - 44  covariance techniques basal levels  -  to d e f i n e measures of  change w h i c h a r e independent  ( G l a s s et a l . , 1984; L i n d e n e t a l . , i n p r e s s ) .  of  Second, there  is  a l s o no c o n s e n s u s a s t o w h i c h r e s p o n s e m e a s u r e p r o v i d e s t h e m o s t r e l i a b l e v a l i d measure of  reactivity.  It  i s w e l l known t h a t v a r i o u s  r e s p o n s e s a r e m o d e s t l y c o r r e l a t e d and r e f l e c t  the i n f l u e n c e  u n d e r l y i n g mechanisms.  for  Obrist  et a l .  (1978),  and  physiological of  different  example, found t h a t  mental  a r i t h e m t i c p r o d u c e d i n c r e a s e s i n h e a r t r a t e a n d s y s t o l i c b l o o d p r e s s u r e due common s y m p a t h e t i c a l l y m e d i a t e d , b e t a - a d r e n e r g i c diastolic  p r e s s u r e changes were s a i d t o r e f l e c t  dimension under the i n f l u e n c e f r a c t i o n a t i o n of different  Task-related  an i n d e p e n d e n t  response  peripheral vascular resistance.  Given  r e s p o n s e measures v a r i o u s a u t h o r s have chosen t o  c a r d i o v a s c u l a r v a r i a b l e s as i n d i c e s of  ( O b r i s t et a l . , 1978; L i g h t , of  of  influences.  reactivity.  this  employ  O b r i s t and  1981) argue t h a t h e a r t r a t e i s a s u p e r i o r  r e a c t i v i t y due t o t h e f a c t  Light  measure  t h a t h e a r t r a t e changes a r e most s e n s i t i v e  to  the b e t a - a d r e n e r g i c mechanisms i m p l i c a t e d i n the p a t h o g e n e s i s o f  coronary  disease.  pressure  Glass et a l .  reactivity is  (1984) argue however,  i s a superior  independent  measures of  classification  of a g e - r e l a t e d changes.  questionable. advantages of  The a d e q u a c y o f  v a r i a b l e in* t h a t s y s t o l i c  reactivity  The d e g r e e o f  between  any s i n g l e measure o f  concordance  sampling m u l t i p l e response dimensions.  their  seems  (1983) p o i n t s out These a u t h o r s  the  found  The f i r s t  ouput and d e c r e a s e d s y s t e m i c r e s i s t a n c e ;  i n b l o o d p r e s s u r e due t o i n c r e a s e d c a r d i a c  on  pattern the  second  showed d e c r e a s e d c a r d i a c o u p u t a n d i n c r e a s e d p e r i p h e r a l r e s i s t a n c e ; w h i l e third involved increases  that  three c a r d i o v a s c u l a r response patterns  responses to a mental a r i t h m e t i c t a s k .  involved increased cardiac  been  reactivity  R e c e n t w o r k by D e m b r o s k i a n d M c D o u g a l l  i n d i v i d u a l s c o u l d be c l a s s i f i e d i n t o the b a s i s of  that s y s t o l i c blood  b l o o d p r e s s u r e and h e a r t r a t e r e a c t i v i t y has n o t  established.  to  the  output,  - 45  -  w i t h s m a l l changes i n p e r i p h e r a l r e s i s t a n c e . fact  that different  different  patterns of  mechanisms o f  The a s s e s s m e n t o f  These r e s u l t s u n d e r s c o r e  r e s p o n d i n g may r e f l e c t  cardiovascular  response h a b i t u a t i o n  i n a g i v e n s t u d y a l s o depends  d a t a a n a l y s i s , and p a r t i c u l a r l y t h e i n d e x o f  Differences trials  have been t h e most w i d e l y used i n d e x f o r i n response h a b i t u a t i o n  a n a l y s i s of  v a r i a n c e on a m p l i t u d e o f  groups of s u b j e c t s . as evidence of  A significant  a significant  and l a s t  trials  for  the l i t e r a t u r e  research questions 1.  to  the use  the  of  recommended  differences  (Linden et a l . , i n  in press).  evidence  between a c u t e c a r d i o v a s c u l a r r e a c t i v i t y  The p u r p o s e s o f  and  s t r e s s o r s such as  The p r e s e n t s t u d y was d e s i g n e d t o a d d r e s s the present  mental several  study  were:  b l o o d p r e s s u r e and  r a t e changes seen i n response t o a mental a r i t h m e t i c p l u s stressor.  that  Hypotheses  t o a n a l y z e t h e t i m e c o u r s e and p a t t e r n s o f  experimental  As  s c o r e s between  of  an  interpeted  equivalent  r e v e a l s a r e l a t i v e s c a r c i t y of  in this area.  group  contrasting  c o v a r i a n c e a p p r o a c h has been  response h a b i t u a t i o n to p s y c h o l o g i c a l  arithmetic plus noise.  for  Recently,  removing the p o s s i b l e confounding e f f e c t s  regarding the r e l a t i o n s h i p subsequent  i n t e r a c t i o n term i s  response h a b i t u a t i o n  of  T h i s method i n v o l v e s  v a r i a n c e on d i f f e r e n c e s  the S t u d y and E x p e r i m e n t a l  A review of  between  in habituation across groups.  the experimental groups.  b a s e l i n e l e v e l s on m e a s u r e s o f  method  in a series  groups-by-trials interaction is  b a s e l i n e c o v a r i a t e s i n an a n a l y s i s o f a s a method of  the  on  t o be u s e d .  comparison of  response over t r i a l s  difference  o b t a i n e d i n a one-way a n a l y s i s of  Purpose of  habituation  (O'Gorman, 1977).  n o t e d by Huck a n d M c L e a n ( 1 9 7 5 ) t h i s  first  recording,  i n r e s p o n s e a m p l i t u d e b e t w e e n two o r more p o i n t s  differences  of  control.  t h e p h y s i o l o g i c a l s y s t e m t o be e x a m i n e d , t h e m e t h o d o f of  the i n f l u e n c e s  the  heart  noise,  - 46  2.  -  to i d e n t i f y and compare patterns of blood pressure response i n high versus low heart rate r e a c t i v i t y groups.  3.  to i d e n t i f y and compare patterns of heart rate response i n high versus low s y s t o l i c blood pressure r e a c t i v i t y groups.  4.  to compare s y s t o l i c r e a c t i v i t y versus heart rate r e a c t i v i t y as subject c l a s s i f i c a t i o n variables.  5.  to i d e n t i f y and compare the s t a b i l i t y of patterns of heart rate versus s y s t o l i c r e a c t i v i t y across a four-week i n t e r v a l .  6.  to i d e n t i f y and compare the e f f e c t of single versus repeated exposure to the stressor on cardiovascular responses i n high versus low reactor groups.  7.  to i d e n t i f y and compare the effects of short, i . e . , 3 minutes versus long, i . e . , 4 weeks, inter-stressor i n t e r v a l s on cardiovascular responses i n high versus low reactor groups.  8.  to analyze the relationship between subject's perception of task d i f f i c u l t y , task importance, stressfulness of task, and perceived performance, acute cardiovascular r e a c t i v i t y and habituation of cardiovascular  responses.  With regard to the aforementioned  purposes the following experimental  hypotheses were tested: 1.  heart rate and blood pressure responses to the stressor w i l l  decrease  within t r i a l s (3 minutes duration) and experimental sessions (3 t r i a l s per session), and across two sessions scheduled four weeks apart. 2.  high heart rate reactors w i l l show greater decreases i n blood pressure than low heart rate reactors.  3.  high s y s t o l i c blood pressure reactors w i l l show greater decreases i n heart rate than low s y s t o l i c reactors.  -  4.  47  -  s u b j e c t s c l a s s i f i e d as high heart r a t e r e a c t o r s w i l l systolic  reactors.  reactivity 5.  Similar  overlap w i l l  i n response i n a l l  significant  subjects.  have g r e a t e r e f f e c t  the magnitude of  on h i g h  inter-stressor  8.  l e v e l of  the s u b j e c t s '  a l s o be a  reactors. be n e g a t i v e l y  produce a g r e a t e r  reactivity will  and i m p o r t a n c e  n e g a t i v e l y c o r r e l a t e d with perceived performance. response decreases w i l l  session. with  and  The m a g n i t u d e  and i m p o r t a n c e , and p o s i t i v e l y  of task  correlated  performance.  Synopsis  In order  to test  the foregoing hypotheses a between-within  d e s i g n was e m p l o y e d i n t h e p r e s e n t conditions were v i s i t s  (2), trials  The b e t w e e n - g r o u p s  the w i t h i n - s u b j e c t  ( 3 ) , and m i n u t e s ( 3 ) .  repeated or s i n g l e  laboratory v i s i t .  systolic  study.  and r e a c t i v i t y g r o u p s , w h i l e  involved either first  decreased  be n e g a t i v e l y c o r r e l a t e d w i t h p e r c e i v e d  difficulty,  with perceived task Method  correlated  be p o s i t i v e l y c o r r e l a t e d  perceived task stressfulness, d i f f i c u l t y ,  stressfulness,  repeated  r e a c t i v i t y d u r i n g the second e x p e r i m e n t a l  l e v e l of  of  interval.  repeated exposure to the s t r e s s o r w i l l initial  There w i l l  decreases i n response w i l l  w i t h the l e n g t h of 7.  low  i n c r e a s e the magnitude  e x p o s u r e by r e a c t i v i t y i n t e r a c t i o n s u c h t h a t  exposure w i l l 6.  i n t h e two  high  groups.  repeated exposure to the s t r e s s o r w i l l decreases  occur  a l s o be  factorial factors  repeated  The c o n d i t i o n s  variable  i n terms of  heart rate  blood pressure responses to a mental a r i t h m e t i c plus noise  administered during the f i r s t  3-minute  experimental s e s s i o n s over a four-week displayed i n Table  3.  measures  exposure to the s t r e s s t a s k d u r i n g  R e a c t i v i t y was d e f i n e d  trial  i n the f i r s t  interval.  were  each of  the and  stressor  two  The e x p e r i m e n t a l d e s i g n  is  48 TABLE 3  EXPERIMENTAL  Condition  1  (N = 4 5 ) High r e a c t o r s Low r e a c t o r s  Condition  2  (N = 4 5 ) High r e a c t o r s Low r e a c t o r s  DESIGN:  Visit  1  20 m i n . , a d a p t a t i o n 3 X 3 min. stress tasks 3 X 3 min. i n t e r - s t r e s s o r  Visit  - 4 week i n t e r - v i s i t  interval  Visit  2  same a s v i s i t rest  1  periods  1  Visit  20 m i n . , a d a p t a t i o n 1 X 3 min. stress task 15 m i n . r e c o v e r y p e r i o d  Note: The s u b j e c t s i n e a c h o f t h e e x p e r i m e n t a l c o n d i t i o n s a ) b l o o d p r e s s u r e a n d , b) h e a r t r a t e change s c o r e s .  2  same a s C o n d i t i o n  will  be d i v i d e d  into reactivity  terciles  1,  on t h e b a s i s  Visit  of  1  their  Method  Subjects'  characteristics.  Ninety-seven, normotensive, female  f r o m a u n i v e r s i t y campus p o p u l a t i o n v o l u n t e e r e d t o p a r t i c i p a t e study.  Their  for  their  to completing the f u l l  participation.  170 l b s .  interval.  present  forty-five  S u b j e c t s were  offered  Seven s u b j e c t s chose t o drop out  experimental procedure.  s u b j e c t s was 2 2 . 5 y e a r s (SD = 7 . 6 ) . years.  i n the  p a r t i c i p a t i o n i n v o l v e d two e x p e r i m e n t a l s e s s i o n s o f  m i n u t e s d u r a t i o n s e p a r a t e d by a f o u r - w e e k course c r e d i t  subjects  The mean a g e o f  the  remaining  S u b j e c t s r a n g e d i n a g e f r o m 17 t o  T h e i r mean body w e i g h t was 1 2 4 . 2 l b s  prior  45  (SD = 1 5 . 5 ) w i t h a r a n g e o f  The mean r e s t i n g h e a r t r a t e was 7 2 . 0 (SD = 1 0 . 1 )  beats per  86  to  minute.  Mean b l o o d p r e s s u r e l e v e l s w e r e 1 0 8 . 3 (SD = 1 0 . 7 ) mm H g , 6 0 . 2 (SD = 8 . 1 ) mm H g , a n d 7 8 . 5 (SD = 1 1 . 2 ) mm Hg f o r s y s t o l i c ,  diastolic,  pressure respectively.  first  At the time of  s u b j e c t s were m e n s t r u a t i n g , w h i l e s e s s i o n f o u r week l a t e r .  their  a n d mean  laboratory  arterial  session  eighteen  f i f t e e n were m e n s t r u a t i n g d u r i n g t h e  The number o f  decreased from twenty during the f i r s t  subjects  taking birth control  second pills  s e s s i o n to eighteen during the  second  session. Experimental s e t t i n g . cardiovascular  All  e x p e r i m e n t a l s e s s i o n s were c o n d u c t e d i n  psychophysiology l a b o r a t o r y a t the U n i v e r s i t y of  Columbia, Department of P s y c h o l o g y .  Throughout  c o n n e c t e d v i a an i n t e r c o m and a one-way m i r r o r .  All  communications were e x e c u t e d over t h e i n t e r c o m .  In addition,  and c a b l e were f e d t h r o u g h a w a l l  m i c r o c o m p u t e r and r e c o r d i n g u n i t were A p p a r a t u s and e q u i p m e n t .  British  the experimental procedure  s u b j e c t and t h e e x p e r i m e n t e r were l o c a t e d i n s e p a r a t e rooms.  pressure cuff  the  the  These rooms were  subject-experimental the  blood  t o a s e p a r a t e room w h e r e  the  located.  B l o o d p r e s s u r e and h e a r t r a t e measures  c o l l e c t e d v i a a Dinamap 8 4 5 , V i t a l S i g n s M o n i t o r  were  ( C r i t i k o n C o r p o r a t i o n , Tampa,  -  Florida).  50  -  The D i n a m a p 8 4 5 i s a n a u t o m a t e d m o n i t o r w i t h d i g i t a l  u s e s t h e o s c i l l o m e t r i c method o f  data c o l l e c t i o n .  ( Y e l d e r m a n & Ream, 1 9 7 9 ; B o r o w & N e w b u r g e r ,  Previous  self-calibration  1982) have d e m o n s t r a t e d t h a t  The D i n a m a p 8 4 5 i s  function  for  increased  C a r d i o v a s c u l a r dependent measures. of  four  pressure.  a l s o equipped w i t h  a  reliability. The D i n a m a p 8 4 5 p r o v i d e d a n  s y s t o l i c and d i a s t o l i c  S y s t o l i c blood pressure i s  maximal c o n t r a c t i o n of pressure l e v e l s present muscle.  the heart.  estimation  each c a r d i a c c y c l e .  These  b l o o d p r e s s u r e , a n d mean a r t e r i a l  an e s t i m a t i o n of  system pressure  D i a s t o l i c blood pressure  during diastole  Mean a r t e r i a l p r e s s u r e i s  the  invasive  c a r d i o v a s c u l a r d e p e n d e n t m e a s u r e s a t one m i n u t e i n t e r v a l s .  included heart rate,  which  researchers  D i n a m a p 8 4 5 p o s s e s s e s e x c e l l e n t r e l i a b i l i t y when c o m p a r e d t o measurement p r o c e d u r e s .  displays  represents  or maximal r e l a x a t i o n of  defined as the l a r g e s t  The b e h a v i o r a l s i g n i f i c a n c e  during  the  heart  volume change  during  o f mean a r t e r i a l p r e s s u r e  has  not been e s t a b l i s h e d . S e l f - r e p o r t measures.  During each of  t h e two e x p e r i m e n t a l  sessions  s u b j e c t s were a s k e d t o c o m p l e t e a S t r e s s P e r c e p t i o n Q u e s t i o n n a i r e the f i n a l is  post-stressor recovery period.  c o n t a i n e d i n Appendix 3.  Likert  Stress  task.  present study.  and i n f l u e n c e  task d i f f i c u l t y ,  o f mood on  five,  task  10-point  importance,  performance.  A m e n t a l a r i t h m e t i c p l u s n o i s e s t r e s s o r was e m p l o y e d i n For  the f i r s t  s u b t r a c t a g i v e n number, i . e . , initially  Questionnaire  T h i s q u e s t i o n n a i r e was c o m p o s e d o f  scales regarding perceived stress,  perceived performance,  The S t r e s s P e r c e p t i o n  following  trial,  s u b j e c t s were i n s t r u c t e d t o  7 f r o m t h e number 1 , 0 0 0 .  modeled the p r o c e d u r e .  S u b j e c t s were a l s o t o l d  The  consecutively  experimenter  that  the  e x p e r i m e n t e r was l i s t e n i n g v i a t h e i n t e r c o m a n d w o u l d c o u n t t h e number e r r o r s made.  E a c h s t r e s s t a s k was t h r e e m i n u t e s i n d u r a t i o n .  the  In order  of to  -  reduce the p o s s i b i l i t y changed f o r task while  practice effects  each t a s k p e r i o d .  All  -  t h e number t o be s u b t r a c t e d  s u b j e c t s completed the mental  was  arithmetic  l i s t e n i n g t o a 9 0 db w h i t e n o i s e p r e s e n t e d v i a a u d i o c a s s e t t e  s t e r e o headphones. db l e v e l  of  51  The n o i s e  and  s t i m u l u s t a p e was i n i t i a l l y c a l i b r a t e d t o a 9 0  by t h e U n i v e r s i t y o f  B r i t i s h Columbia Audiology  Department.  Procedure Pre-experimental preparations. and s c h e d u l e d f o r earlier  their  first  All  s u b j e c t s were c o n t a c t e d v i a  laboratory session.  S u b j e c t s were s c r e e n e d  p a r t i c i p a t i o n i n s i m i l a r s t r e s s response experiments ( E l l i o t t ,  No s u b j e c t s n e e d e d t o be e x c l u d e d o n t h e b a s i s o f their  telphone  participation, all  this  criterion.  s u b j e c t s were g i v e n i n s t r u c t i o n s  engaging i n strenuous p h y s i c a l e x e r c i s e , or use of 2 hours p r i o r  for  factors  has p r e v i o u s l y been i d e n t i f i e d as h a v i n g an i n f l u e n c e  1981; Lane,  function  (Jennings,  1984; Dembroski,  Pre-stress adaptation.  scheduled appointment.  Each of  Berg, Hutcheson, O b r i s t ,  or  these  on  Porges,  & Turpin,  1984). Upon a r r i v a l a n d f o l l o w i n g  familiarization  t h e l a b o r a t o r y s e t t i n g , e a c h s u b j e c t was i n f o r m e d o f h e r r i g h t s a s a and asked t o s i g n a c o n s e n t  to  from  caffeine,  alcohol  cardiovascular  to t h e i r  tobacco,  1966).  Prior  to r e f r a i n  for  form.  with  subject  S u b j e c t s were then i n f o r m e d t h a t t h e y  would  be c o m p l e t i n g a t w e n t y - m i n u t e a d a p t a t i o n p e r i o d a n d o n e o r more m e n t a l arithmetic plus noise tasks. explained.  S u b j e c t s were a l s o  the blood pressure c u f f standardized script, cuff  The n a t u r e o f given a brief  and m o n i t o r .  which i s  t h e s t r e s s o r s i n v o l v e d was explanation of  briefly  the f u n c t i o n s  of  T h i s i n f o r m a t i o n was p r e s e n t e d u s i n g a  contained i n Appendix 4.  The b l o o d  pressure  was t h e n a t t a c h e d t o t h e s u b j e c t ' s n o n - d o m i n a n t a r m . During the a d a p t a t i o n p e r i o d s u b j e c t s r e s t e d comfortably  i n an a r m c h a i r .  S u b j e c t s were a s k e d t o r e f r a i n f r o m moving so a s t o d e c r e a s e t h e i n f l u e n c e  of  movement a r t i f a c t s  on t h e c a r d i o v a s c u l a r d e p e n d e n t m e a s u r e s .  completed a Par-Q Screening Questionnaire Health,  1975).  The P a r - Q i d e n t i f i e s  problems and c u r r e n t  usage of  contained i n Appendix 2.  previous or c u r r e n t  cardioactive medications.  Following  the adaptation period a l l  Hg. of  and r e s t i n g d i a s t o l i c  two e x p e r i m e n t a l c o n d i t i o n s .  All  fitness. for  cardiovascular  p a r t i c i p a t i o n on t h e  Forty-four  basis  experimental session.  task during the f i r s t  of  subjects i n C o n d i t i o n 1 completed  e x p e r i m e n t , w h i l e 46 s u b j e c t s d i d so i n C o n d i t i o n 2 .  The f i r s t  their  s u b j e c t s were randomly a s s i g n e d t o one  assigned to C o n d i t i o n 1 completed a s e r i e s of first  aerobic  is  criteria.  Experimental conditions.  entire  This questionnaire  b l o o d p r e s s u r e l e v e l g r e a t e r t h a n 9 0 mm  No s u b j e c t s n e e d e d t o be e x c l u d e d f r o m f u r t h e r these screening  cardiovascular  s u b j e c t s were s c r e e n e d  c a r d i o a c t i v e m e d i c a t i o n , previous or c u r r e n t  difficulties,  of  Subjects also provided information regarding b i r t h c o n t r o l , and l e v e l o f  use of  also  ( B r i t i s h Columbia Department  m e n s t r u a l phase, use of completion of  Subjects  Those  the  subjects  three stress tasks during  the  S u b j e c t s i n C o n d i t i o n 2 c o m p l e t e d o n l y one  stress  session.  e x p e r i m e n t a l s e s s i o n i n C o n d i t i o n 1 began w i t h a  prestress adaptation period.  20-minute  T h i s a d a p t a t i o n p e r i o d was f o l l o w e d  p r e - t a s k i n s t r u c t i o n p e r i o d d u r i n g w h i c h s u b j e c t s were g i v e n  by a  specific  i n s t r u c t i o n s r e q u i r e d to complete the mental a r i t h m e t i c s t r e s s t a s k .  Subjects  were encouraged t o c o n t i n u e c o u n t i n g f o r  pre-task  i n s t r u c t i o n p e r i o d was f o l l o w e d Following  the b a s e l i n e  the e n t i r e  by a t w o - m i n u t e p r e - t a s k w a i t i n g  p e r i o d each s u b j e c t  arithmetic plus noise tasks. t a s k p e r i o d was f o l l o w e d  task period.  completed a s e r i e s of  The  period. three  E a c h t a s k was t h r e e m i n u t e s i n d u r a t i o n .  by a f i v e - m i n u t e r e c o v e r y p e r i o d .  P e r c e p t i o n Q u e s t i o n n a i r e was c o m p l e t e d f o l l o w i n g  the f i n a l  The  mental Each  Stress  recovery  period.  -  The f i r s t  53 -  e x p e r i m e n t a l s e s s i o n i n C o n d i t i o n 2 began w i t h  adaptation,  p r e - t a s k i n s t r u c t i o n , and p r e - t a s k b a s e l i n e p e r i o d s w h i c h were i d e n t i c a l t h o s e a d m i n i s t e r e d i n C o n d i t i o n 1, p r e - t a s k b a s e l i n e was f o l l o w e d t a s k was f o l l o w e d  by a s i n g l e  At the completion of their  the f i r s t  All  This extended  their  subjects  second v i s i t  subjects  periods.  3-minute s t r e s s t a s k s . All  the i n i t i a l  i.e.,  a b s t e n t i o n from  i n both experimental The f o r m a t o f  of  Every subject  potential to  the  tobacco,  conditions the second  by  the second v i s i t  visit  session 1.  The  pre-task  then completed a s e r i e s  E a c h s t r e s s t a s k was f o l l o w e d  by a  of  3-minute  s e s s i o n s were c o m p l e t e d w i t h i n  26-31  session.  Following  the completion of  s u b j e c t s were p r o v i d e d w i t h a b r i e f  stress responses.  Subjects  and e x e r c i s e .  i n s t r u c t i o n and b a s e l i n e  all  were  s c h e d u l e d a p p o i n t m e n t t i m e and  s e s s i o n b e g a n w i t h a n a d a p t a t i o n p e r i o d w h i c h was f o l l o w e d  Debriefing.  Stress  period.  was i d e n t i c a l t o t h a t a d m i n i s t e r e d t o s u b j e c t s i n C o n d i t i o n 1 ,  days of  time  s u b j e c t s were c o n t a c t e d v i a t e l e p h o n e a few d a y s p r i o r  caffeine,  recovery period.  recovery  the experiment w i t h other  completed i d e n t i c a l experimental p r o t o c o l s .  three,  single  t o s p e n d t h e same l e n g t h o f  experimental session a l l  necessary pre-experimental preparations,  During t h e i r  the  This  commitment t o a s e c o n d s e s s i o n f o u r weeks l a t e r .  second v i s i t and reminded o f  alcohol,  task period.  the 15-minute recovery  were asked not t o d i s c u s s the format of  their  3-minute  1,  Subjects i n C o n d i t i o n 2 completed the  Q u e s t i o n n a i r e a t t h e end o f  participants.  In C o n d i t i o n 2, v i s i t  both c o n d i t i o n s  under e x p e r i m e n t a l c o n d i t i o n s .  reminded of  1.  by a 1 5 - m i n u t e r e c o v e r y p e r i o d .  period allowed subjects in  Perception  visit  to  their  second e x p e r i m e n t a l  e x p l a n a t i o n of  their  resting  and  H e a r t r a t e and b l o o d p r e s s u r e r e a d i n g s were compared  n o r m s f o r women a g e d 1 8 - 6 4 y e a r s .  These d a t a a r e p r e s e n t e d i n T a b l e  session  4.  to  - 54 -  TABLE 4 Blood Pressure Norms for Women aged 18 - 64 Years*  SYSTOLIC** Age 18-24 25-34 35-44 45-54 55-64  Mean yrs. yrs. yrs. yrs. yrs.  Standard error of mean  110.9 112.2 119.4 128.6 137.4  0.64 0.67 0.85 0.96 1.03  070.0 072.5 077.1 080.9 081.7  0.45 0.56 0.59 0.73 0.58  DIASTOLIC L8-24 25-34 35-44 45-54 55-64  YRS. YRS. YRS YRS. YRS.  -  *Data are drawn U . S . Government Survey 1976-1980. **Blood pressure i s expressed i n mm Hg. A l l measurements are based on the average of 3 measurements.  -  55  -  S u b j e c t s were a l s o a d v i s e d t o engage i n r e g u l a r  preventive blood  pressure  check-ups.  E x p e r i m e n t a l D e s i g n and S t a t i s t i c a l The e x p e r i m e n t a l presented  d e s i g n was a m i x e d - m o d e l f a c t o r i a l  i n Table 3.  Between group f a c t o r s  exposure v e r s u s 2: s i n g l e high).  Within-subject  minutes  (3).  e x p o s u r e ) and c a r d i o v a s c u l a r  & Bent,  for  (1:  of  (low  versus  (3)  by  the d a t a .  (Nie,  is  repeated  ( 2 ) by t r i a l s  the S o c i a l Sciences  1970) and t h e B i o m e d i c a l  The d e s i g n  reactivity  packages were used i n t h e a n a l y s i s  the S t a t i s t i c a l Package  Steinbrenner,  design.  were c o n d i t i o n s  r e p e a t e d measures were v i s i t s  Several s t a t i s t i c a l included  Analyses  Hull,  Data Program ( D i x o n ,  These  Jenkins, 1981).  Results  In order inferential  to test  t e s t s were p e r f o r m e d .  cardiovascular analyses of versus  the experimental hypotheses  baseline,  self-report  low r e a c t i v i t y  results  of  each of  reactivity dependent  groups,  study.  cardiovascular These i n c l u d e d  and s t r e s s  measures,  analyses of  these t e s t s  Descriptive Charcteristics Four  These i n c l u d e d  is  heart  rate,  descriptive  Dependent  represent  dependent  responses  tests.  The  present  diastolic  blood  T h e mean a n d  measure d u r i n g b a s e l i n e ,  r e c o v e r y p e r i o d s were computed.  the average of  high  Measures  blood pressure,  for  of  sections.  measures were a n a l y z e d i n t h e systolic  and  descriptive  a n a l y s e s of  reviewed i n the f o l l o w i n g  deviation  and p o s t - s t r e s s  analyses  and p o s t - h o c  a n d mean a r t e r i a l p r e s s u r e r e s p o n s e m e a s u r e s .  task,  descriptive  response measures,  pressure,  each c a r d i o v a s c u l a r  of  descriptive  covariance,  of C a r d i o v a s c u l a r  dependent  a series  Baseline  d u r i n g m i n u t e s 19 a n d 20 o f  standard stress  values the  adaptation  -  period. 1,  S t r e s s response and r e c o v e r y  56  values represent  2, and 3 of each r e s p e c t i v e p e r i o d .  experimental  "  the average o f minutes  These v a l u e s f o r each o f the two  c o n d i t i o n s d u r i n g each o f the two l a b o r a t o r y s e s s i o n s a r e  displayed i n Table  5.  Data from the repeated  d i s p l a y e d i n F i g u r e s 1, 4, 7 and 10.  stressor condition are also  Subjects  d i s p l a y e d i n c r e a s e s o f +14  beats per minute i n h e a r t r a t e and +16 mm Hg, +14 mm Hg, +15 mm Hg f o r systolic,  diastolic,  and mean a r t e r i a l p r e s s u r e ,  p o s t - i n s t r u c t i o n b a s e l i n e p e r i o d t o the i n i t i a l experimental  session.  a r t e r i a l pressure respectively. first  During  readings  r e s p e c t i v e l y from the s t r e s s task during the f i r s t  the second v i s i t s y s t o l i c ,  diastolic  and mean  i n c r e a s e d +10 mm Hg, +10 mm Hg and +11 mm Hg,  Heart r a t e i n c r e a s e d 15 beats per minute i n response t o the  s t r e s s o r d u r i n g t h e second v i s i t .  ,  D e s c r i p t i v e C h a r a c t e r i s t i c s o f S e l f - R e p o r t Dependent Measures F i v e s e l f - r e p o r t dependent measures were a n a l y z e d  through responses t o the  f i v e s c a l e s i n c l u d e d i n the S t r e s s P e r c e p t i o n Q u e s t i o n n a i r e . questionnaire i s contained  i n Appendix 3.  This  The s e l f - r e p o r t measures i n c l u d e d  p e r c e i v e d t a s k s t r e s s f u l n e s s , t a s k d i f f i c u l t y , t a s k importance, performance, and p e r c e i v e d and  standard  task  i n f l u e n c e o f mood on t a s k performance.  d e v i a t i o n f o r each s e l f - r e p o r t measure a r e presented  The mean i n Table  6.  Responses t o measures o f p e r c e i v e d s t r e s s f u l n e s s , d i f f i c u l t y , and importance ranged from 5.9 t o 7.0 on a 10-point = very  stressful.  Likert scale, i . e . , 0 =  not s t r e s s f u l ,  10  These r e s u l t s c o n f i r m the s u b j e c t i v e v a l i d i t y o f t h e mental  a r i t h m e t i c t a s k as a v a l i d  experimental  stressor.  D e s c r i p t i v e C h a r a c t e r i s t i c s o f C a r d i o v a s c u l a r R e a c t i v i t y Groups R e a c t i v i t y groups were formed on the b a s i s o f c a r d i o v a s c u l a r change scores.  In the present  study,  change was d e f i n e d as the average response  d u r i n g minutes 1, 2 and 3 of the i n i t i a l  s t r e s s t a s k p e r i o d i n V i s i t 1 minus  J 57 -  TABLE 5 Means, a n d S t a n d a r d D e v i a t i o n s  Visit  1  Baseline Task 1 Recovery Task 2 Recovery Task 3 Recovery Visit  1 2 3  Cardiovascular  SBP  Response  Measures  DBP  MAP  72.6(10.0) 96.0(13.5) 72.3(10.3) 84.9(12.2) 70.6(10.0) 81.5(13.3) 70.6( 9.3)  108.6(11.5) 124.3(13.0) 112.3(12.0) 123.7(10.4) 109.0(10.3) 117.3(10.2) 108.0(10.7)  61.1( 8.2) 75.3(10.7) 62.3( 8.7) 68.2( 8.4) 62.0( 8.7) 66.6( 8.2) 59.9( 8.3)  79.1(10.5) 94.0(10.8) 80.7( 9.5) 87.9(10.0) 78.0( 7.8) 86.1( 9.7) 77.7( 7.9)  72.1( 9.3) 87.0(12.9) 71.6(10.0) 83.8(12.2) 70.6( 9.3) 81.4(11.7) 71.6( 9.0)  106.3( 8.9) 116.7(11.9) 108.3( 8.2) 114.0( 9.6) 106.7( 8.6) 111.8( 9.9) 108.3( 8.2)  60.0( 69.7( 61.6( 65.8( 59.9( 64.4( 59.2(  76.5( 87.6( 78.5( 84.2( 77.6( 83.6( 76.6(  2  Baseline Task 1 Recovery Task 2 Recovery Task 3 Recovery  Note: during  HR  of  1 2 3  The v a l u e s f o r t h e s e c o n d a n d t h i r d s t r e s s V i s i t 1 a r e b a s e d on r e s p o n s e s o f s u b j e c t s  A l l values 1 and 2.  represent  the average  responses  of  all  6.2) 8.3) 6.6) 7.9) 7.3) 7.1) 7.0)  6.8) 9.3) 7.2) 9.1) 7.9) 8.9) 7.8)  t a s k s and r e c o v e r y p e r i o d s in Condition 1 only. subjects  in  both  conditions  FIGURE 1  CONDITION I: REPEATED EXPOSURE HEART RATE DATA  Legend  1  ST1 RC1 S T 2 RC2 S T * RC3  1  "ST1 R C f S T 2 Rt2  i  »HGHs»siaxtTAaag/vi  3  -Ht^ SYSTOCRE>CICR^V2  4  'UJWaSICUCRDCIORS^Q  ST3 RC3  oo  FIGURE 4  CONDITION l:REPEATED EXPOSURE SYSTOUC BLOOD PRESSURE DATA 150-1  VISIT I  uoH  VISIT II  jr.  E E c  130 H  CO  120-  10  Legend j_ 'UGHHRREACTTJRSyVl 2  UJ  3 °HGH HR REAGTORyV2  0£ 0_  Q O  s  4 •L0WHRF€ACTTJR^V2 110 H  CD O  o  •LCWHRREACTCRSArl  100  H  10  >oo  4 WK. INTERVAL 90H  80ST1  1 1 1 RC1 ST2 RC2 ST3 RC3  ST1  RC1 ST2 RC2 ST3 RC3  FIGURE 7  CONDITION I DIASTOUC BLOOD PRESSURE DATA 85-|  55  H 4 WK.  50  1 ST1  RC1  1 ST2  RC2  1 ST3  INTERVAL  1 RC3  1 ST1  RC2  1 ST2  RC2  1 ST3  r RC3  FIGURE 10  TABLE 6 Means a n d S t a n d a r d D e v i a t i o n s o f S e l f - R e p o r t  Measure  Mean  S.D.  4.04 5.02  1.75 1.54  6.12 5.90  2.22 2.05  1 2  6.97 6.38  2.11 1.97  Perceived Importance 1 P e r c e i v e d Importance 2  6.57 6.69  2.08 1.98  Influence Influence  5.59 5.37  2.19 2.50  Perceived Performance Perceived Performance Perceived Stress Perceived Stress  1 2  Perceived D i f f i c u l t y Perceived D i f f i c u l t y  o f Mood 1 o f Mood 2  *A11 s e l f - r e p o r t  1 2  r a t i n g s w e r e done on a 1 0 - p o i n t L i k e r t  Measures  Scale.  -  t h e a v e r a g e o f m i n u t e s 19 a n d 20 o f definition  of  63  -  the adaptation p e r i o d .  The  c h a n g e was b a s e d on p r e v i o u s o b s e r v a t i o n s t h a t  p r e s s u r e and h e a r t r a t e undergo s i g n i f i c a n t  both  & Frankish,  in press).  r a t e and s y s t o l i c dependent Descriptive statistics  (Linden,  s c o r e s were computed f o r  for  the d i s t r i b u t i o n of  heart rate  the d i s t r i b u t i o n of  H i g h and l o w r e a c t i v i t y g r o u p s were  h e a r t r a t e change s c o r e s .  composed  lower  The c u t - o f f  points  t h e h i g h a n d l o w r e a c t i v i t y g r o u p s w e r e >+27 b e a t s p e r m i n u t e ( h i g h ) ,  <+15 b e a t s p e r m i n u t e  (low).  These h e a r t r a t e c u t - o f f  et a l . , i n p r e s s ) . between-group  pressure responses. confounding e f f e c t s measure,  for  dependent  ( L i n d e n , 1984;  H e a r t r a t e r e a c t i v i t y was s u b s e q u e n t l y e m p l o y e d a s  c l a s s i f i c a t i o n v a r i a b l e i n analyses of  covariance of  G r o u p s w e r e f o r m e d i n t h i s manner t o a v o i d p r o d u c e d by s i m u l t a n e o u s l y u s i n g a g i v e n  example h e a r t  and  scores are s i m i l a r  t h o s e f o u n d i n p r e v i o u s r e s e a r c h on a s i m i l a r p o p u l a t i o n  to  Linden a  blood  the  cardiovascular  r a t e , a s b o t h a c l a s s i f i c a t i o n v a r i a b l e and a  variable.  I n order- t o a n a l y z e t h e s t a b i l i t y and c h a r a c t e r i s t i c s of of  heart  reactivity  t h o s e s u b j e c t s w h o s e c h a n g e s c o r e s p l a c e d them i n t h e u p p e r a n d  t e r c i l e s of for  Reactivity  the  measures.  s c o r e s are p r e s e n t e d i n T a b l e 7. of  blood  changes from t h e end o f  adaptation to the p o s t - i n s t r u c t i o n , pre-task waiting period McEachern,  present  the  h e a r t r a t e r e a c t i v i t y a c r o s s t h e two e x p e r i m e n t a l s e s s i o n s ,  reactivity  to the f i r s t  reactivity  in Visit  heart  t a s k i n t h e s e c o n d s e s s i o n was c a l c u l a t e d .  1 was t h e n c o m p a r e d t o t h a t f r o m V i s i t  The mean h e a r t r a t e r e a c t i v i t y i n V i s i t In a d d i t i o n the range,  distribution  2 was 8 . 5 b e a t s l o w e r  In V i s i t  Heart  2 (see Table  s t a n d a r d d e v i a t i o n , and p e r c e n t a g e o f  were r e d u c e d i n t h e second s e s s i o n .  rate  8).  than v i s i t heart  2 the d i s t r i b u t i o n of  rate  1.  reactors heart  r e a c t i v i t y was more l e p t o k u r t i c a n d more p o s i t i v e l y s k e w e d t h a n i n V i s i t  rate 1.  -  64  -  TABLE 7 Frequency D i s t r i b u t i o n of Cardiovascular Reactivity Scores  Heart Rate Reactivity**  S y s t o l i c Blood Pressure Reactivity*** 14.52 21.16 13.33 -2.17 41.67 43.8 71.37 8.45  Mean Mode Median Minimum Maximum Range Variance Standard Deviation  22.44 14.17 21.58 -3.33 66.67 70.0 209.68 14.48  High r e a c t i v i t y cut-off Low r e a c t i v i t y cut-off  > +27 bpm < +15 bpm  > +18 mm Hg < +11 mm Hg  High reactors Low reactors  N_ = 33 N = 30  N = 30 N = 33  * R e a c t i v i t y was defined as the average f i r s t 19 and 20 of the adaptation period.  task response l e v e l minus minutes  **Heart rate measures are expressed i n beats per minute. * * * B l o o d pressure measures are expressed i n mm Hg. A l l values represent the average of responses i n both Conditions 1 and 2.  -  65  -  TABLE 8 Comparison of Reactivity  Heart Rate  H e a r t R a t e and S y s t o l i c P r e s s u r e Across Experimental Sessions  Reactivity Visit  Mean S.D. Minimum Maximum Range % > +2 S . D . % > +1 S . D . Skewness Kurtosis % Low R e a c t o r s % High Reactors  Systolic  1  Visit  22.44 14.48, -3.33 66.67 70 5% 13% .681 .567 36% 36%  13.91 9.90 -4.67 55.83 60.5 0% 6% 1.11 2.66 61% 9%  14.52 8.45 -2.17 41.67 43.8 2% 13% . 561 .605 34% 31%  10.56 6.83 -6.67 29.67 36.3 0% 4% .240 .517 61% 13%  Reactivity  Mean S.D. Minimum Maximum Range % > + 2 S.D. % > + 1 S.D. Skewness Kurtosis % Low R e a c t o r s % High Reactors  Heart r a t e i s expressed i n beats per SBP i s e x p r e s s e d i n mm H g .  minute.  2  -  Descriptive s t a t i s t i c s for reactivity  -  66  the d i s t r i b u t i o n of  s c o r e s a r e p r e s e n t e d i n T a b l e 7.  s y s t o l i c blood  The c u t - o f f  points  pressure  for  the  high  a n d l o w s y s t o l i c r e a c t i v i t y g r o u p s w e r e >+18 nun Hg ( h i g h ) , a n d < + l l mm Hg (low).  S y s t o l i c b l o o d p r e s s u r e r e a c t i v i t y was u s e d a s a  c l a s s i f i c a t i o n v a r i a b l e i n the analyses of A comparison of  session.  and p e r c e n t a g e o f The p e r c e n t a g e o f  t o 61% i n V i s i t  2.  4 . 1 mm Hg i n V i s i t  The r a n g e ,  The s k e w n e s s a n d k u r t o s i s o f  r e v e a l e d no s i g n i f i c a n t  reduced i n the  revealed that  100% o f  the d i s t r i b u t i o n of  h e a r t r a t e r e a c t i v i t y and  differences  i n t h e number o f  91% o f  low s y s t o l i c r e a c t i v i t y  systolic  reactors  scores  Finally,  fell  a  versus  v e r s u s no  birth  These data are p r e s e n t e d i n T a b l e 10.  a n d l o w h e a r t r a t e r e a c t o r s c o u l d be d e s c r i b e d a s  The  These r e s u l t s suggest t h a t  responses to psychological  stress.  low  non-menstruating, both b i r t h  a n d m e n s t r u a t i o n n e e d t o be i n v e s t i g a t e d a s p o t e n t i a l m e d i a t o r s  cardiovascular  were  the low h e a r t r a t e r e a c t o r s (see Table 9 ) .  all  t h a t d u r i n g the second e x p e r i m e n t a l s e s s i o n a m a j o r i t y of  n o t on b i r t h c o n t r o l s u b j e c t s . pills  results  as h i g h s y s t o l i c r e a c t o r s  n o n - m e n s t r u a t i n g , and s u b j e c t s t a k i n g b i r t h c o n t r o l p i l l s  results indicate  The  h i g h and low  r e a c t i v i t y across menstruating  c o n t r o l p i l l s was p e r f o r m e d .  systolic  A subsequent c r o s s - t a b u l a t i o n of  t h o s e women i d e n t i f i e d  c r o s s - t a b u l a t i o n a n a l y s i s of  1  systolic  b o t h s y s t o l i c and h e a r t r a t e r e a c t i v i t y  also high heart rate reactors; while the category of  second  sessions.  t h e two c o n d i t i o n s .  s u b j e c t s on t h e b a s i s o f  sessions  standard  a c r o s s t h e two e x p e r i m e n t a l c o n d i t i o n s was c o n d u c t e d .  assigned to each of  responses.  l o w s y s t o l i c r e a c t o r s c h a n g e d f r o m 34% i n V i s i t  A e r o s s - t a b u l a t i o n a n a l y s i s of  into  2.  h i g h r e a c t o r s were a l l  r e a c t i v i t y d i d n o t change a c r o s s  reactivity  heart rate  s y s t o l i c r e a c t i v i t y a c r o s s t h e two e x p e r i m e n t a l  r e v e a l e d a mean d e c r e a s e o f deviation,  covariance of  between-group  However a  follow-up  control of  -  67  -  TABLE 9 C l a s s i f i c a t i o n o f S u b j e c t s by H e a r t R a t e v e r s u s S y s t o l i c Blood Pressure R e a c t i v i t y  High S y s t o l i c (N = 3 1 )  Low S y s t o l i c (N = 3 4 )  High Heart Rate Reactors  (N = 3 0 )  Low H e a r t R a t e R e a c t o r s  (N = 0 )  High Heart Rate Reactors  (|[ = 3 )  Low H e a r t R a t e R e a c t o r s  (N = 3 0 )  Reactors  Reactors  ^ R e a c t i v i t y s c o r e s were c a l c u l a t e d as t h e a v e r a g e of the f i r s t t a s k s t r e s s r e s p o n s e m i n u s t h e a v e r a g e o f m i n u t e s 19 a n d 20 o f t h e p r e - s t r e s s a d a p t a t i o n p e r i o d during the f i r s t experimental s e s s i o n .  -  68  -  TABLE 10 C r o s s - T a b u l a t i o n o f S u b j e c t s by B i r t h C o n t r o l , M e n s t r u a t i o n and R e a c t i v i t y V a r i a b l e s  Visit 1 Systolic Reactivity  Birth  Control Yes No  High  Low  Visit 2 Systolic  Reactivity  High  Low  6 23  7 22  0 12  15 37  7 22  4 25  3 9  6 46  Menstruation Yes No  Visit 1 Heart Rate R e a c t i v i t y Birth  Control Yes No  High  Low  Visit 2 Heart Rate High  Reactivity Low  12 23  6 24  2 7  8 44  10 25  3 27  3 6  7 45  Menstruation Yes No  -  69 -  a n a l y s i s of covariance with age and baseline as c o v a r i a t e s , and b i r t h c o n t r o l (yes or no) and menstruating (yes or no) as between group f a c t o r s revealed no s i g n i f i c a n t between-group d i f f e r e n c e s on any of the cardiovascular dependent measures.  In a d d i t i o n , t e t r a c h o r i c c o r r e l a t i o n s between b i r t h c o n t r o l ,  menstruation, and cardiovascular r e a c t i v i t y were not s i g n i f i c a n t when Bonferroni-corrected  to reduce the l i k e l i h o o d of alpha e r r o r s .  C o r r e l a t i o n a l Analyses Three sets of c o r r e l a t i o n a l analyses were conducted.  F i r s t , the  i n t e r c o r r e l a t i o n s between subject age, baseline, f i r s t task s t r e s s response, and r e a c t i v i t y measures were computed f o r each of the four dependent measures.  Second, i n t e r c o r r e l a t i o n s of the s e l f - r e p o r t measures were  computed.  F i n a l l y , the i n t e r c o r r e l a t i o n between each of the s e l f - r e p o r t and  cardiovascular baseline, f i r s t task s t r e s s response, f i n a l task s t r e s s response, and r e a c t i v i t y measures was assessed.  In order to reduce the  l i k e l i h o o d of alpha e r r o r s the s i g n i f i c a n c e c r i t e r i o n f o r each c o r r e l a t i o n matrix was set at _p_ < .001 through the use of a Bonferroni procedure (Larzelere & Mulaik, 1977). The i n t e r c o r r e l a t i o n s between cardiovascular dependent measures were c a l c u l a t e d i n two stages.  F i r s t , c o r r e l a t i o n s between each of the four  dependent v a r i a b l e s on baseline, f i r s t s t r e s s task, and r e a c t i v i t y measures were c a l c u l a t e d independently f o r each of the two experimental  sessions.  Second, the i n t e r c o r r e l a t i o n s between baseline, s t r e s s response, and r e a c t i v i t y measures across the two sessions were computed.  These c o r r e l a t i o n s  are presented i n Table 11. The i n t e r c o r r e l a t i o n s between cardiovascular measures and age of subject are presented i n Table 12. correlated  Subject age was found to be s i g n i f i c a n t l y  < .001) with baseline measures of blood pressure taken during  -70-  T A B L E 11 Intercorrelations  Within  of C a r d i o v a s c u l a r  Dependent  S e s s i o n 1*  Baseline  1  Within Session 2  HR  HR SBP MAP DBP  SBP  .8935  —  DBP  Baseline  HR  —  —  .6899  .3768 .8709 .8131  HR SBP DBP MAP  —  —  1 .7056  .5408 .5355  —  —  —  —  —  —  —  —  .7216  Across Experimental  HR SBP DBP MAP  .6426 .6580  —  DBP  MAP  .7223  .6283 /.6283  .6467 .7657  —  —  —  —  —  —  —  —  —  2  .7508  —  Reactivity —  SBP  —  S t r e s s Response .3847  HR SBP MAP DBP  2  HR SBP DBP MAP  —  1  HR SBP MAP DBP Reactivity  MAP  .8935  —  S t r e s s Response  Measures  —  —  —  —  —  —  .3556  .3095 .5055  —  —  —  —  —  —  —  —  DBP  Baseline  .6117  .6222  .6801  •  5595  Task  .6869  .7623  .6679  •  6860  .6649  .3175  .1290**  *0nly s i g n i f i c a n t  .8553  .5982 —  .6648  Sessions SBP  Reactivity***  —  2  HR  Response L e v e l  .8358  within-session  correlations  **These between s e s s i o n c o r r e l a t i o n s purposes of c l a r i t y o n l y .  are  MAP  2271**  displayed.  were n o n s i g n i f i c a n t  and a r e i n c l u d e d  * * * R e a c t i v i t y was d e f i n e d a s c h a n g e f r o m t h e l a s t two m i n u t e s o f adaptation period to average f i r s t task response l e v e l s .  the  for  - 71 -  TABLE 12 Correlations of Subject Age with Baseline and Stress Response Measures Repeated Stressor SBP*  DBP**  MAP***  SBP  DBP  MAP  .4979  .4515  .4932  .5896  .5814  .6158 .4505 .5647 .4341 .4937 .4011 .5667  .6115 .4593 .6085 .6018 .5413 .5623 .6602  .5851 .4426 .4919 .5118 .4265 .4491 .5524  .5088 .4279 .4441  .4504  Visit 1 Baseline 1 Stress Response 1 Recovery 1 Stress Response 2 Recovery 2 Stress Response 3 Recovery 3  .4460 .5055  .4595  Visit 2 Baseline 2 Stress Response 4 Recovery 4 Stress Response 5 Recovery 5 Stress Response 6 Recovery 6 *Systolic Blood Pressure **Diastolic Blood Pressure ***Mean Arterial Pressure  .4856 .4678 .5072  .4814  - l i -  the, f i r s t  experimental session.  (r_ = . 6 0 ) i n d i c a t e d  that  The a v e r a g e m a g n i t u d e o f  the s u b j e c t ' s age a c c o u n t e d f o r  these  a p p r o x i m a t e l y 35% o f  the variance i n b a s e l i n e  blood pressure l e v e l s .  correlated with systolic  b a s e l i n e d u r i n g the second s e s s i o n  .001).  correlations  Age was a l s o  significantly  ( r = . 5 0 , ]3 <  S y s t o l i c , d i a s t o l i c a n d mean a r t e r i a l p r e s s u r e a n d s t r e s s r e s p o n s e  recovery period values during V i s i t subjects'  age  (r_ = . 4 0 t o  v a l u e s were s i g n i f i c a n t l y stressor fitness  condition. l e v e l of  7.1/10.  periods.  During V i s i t  i n the  repeated  physical activity  p h y s i c a l a c t i v i t y and p e r c e i v e d f i t n e s s  correlated with either  Blood of  recovery pressure  t h e two  B o t h f i t n e s s measures were r e l i a b l e a c r o s s v i s i t s  of  were  c o r r e l a t e d w i t h h e a r t r a t e d u r i n g s t r e s s t a s k and  r_ = . 7 7 ; a c t i v i t y l e v e l :  recovery  s t u d y r e p o r t e d a mean p e r c e i v e d  These c o r r e l a t i o n s a r e p r e s e n t e d i n T a b l e 1 3 .  measures.  with  pressure  subjects  6 . 4 5 / 1 0 , a n d a mean r e p o r t e d l e v e l o f  measures were not s i g n i f i c a n t l y  fitness:  correlated  2 diastolic  c o r r e l a t e d w i t h age f o r  Subjects i n the present  Both l e v e l of  significantly  .66).  2 were s i g n i f i c a n t l y  and  fitness  (perceived  r_ = . 7 1 ) a n d showed g o o d c o n v e r g e n t  validity  (r = .56). Within Sessions Cardiovascular  Correlations  During a given experimental session s y s t o l i c , p r e s s u r e b a s e l i n e measures were s i g n i f i c a n t l y  diastolic,  correlated.  response measures d i s p l a y e d i n t e r c o r r e l a t i o n s of  .76 t o  Cardiovascular  .90 d u r i n g  pre-task baseline period during V i s i t  1.  correlations  H e a r t r a t e b a s e l i n e was  ranged from  correlated with baseline visit. visit  .63 t o  During the second v i s i t  were a l s o s i g n i f i c a n t l y  l e v e l s during the f i r s t correlated.  the these  significantly  blood p r e s s u r e measures d u r i n g the second  Average blood pressure  t a s k was s i g n i f i c a n t l y  .77.  a n d mean a r t e r i a l  laboratory  stress task in a  Heart rate during the f i r s t  c o r r e l a t e d w i t h mean a r t e r i a l a n d s y s t o l i c  given stress  pressure  - 73 -  TABLE 13 Correlations of Self-Reported Fitness Level and Frequency of Physical A c t i v i t y with Stress Response and Recovery Period Heart Rate* Perceived Fitness  HR Measure Stressor Recovery Stressor Recovery Stressor Recovery  1 1 2 2 3 3  Visit 1  Visit 2  *r  r  n.s. -.4562 -.3656 -.4329 -.3973 -.4932  -.2850 -.4381 -.3047 -.4032 -.3047 -.4037  Visit 1  Visit 2  n.s. -.3935 -.3272 -.3748 -.3748 -.4589  -.3043 -.4235 -.3109 -.4035 -.3109 -.4450  Physical A c t i v i t y Level  Stressor Recovery Stressor Recovery Stressor Recovery  1 1 2 2 3 3  *Unless otherwise indicated a l l correlations are s i g n i f i c a n t at JD < .002.  -  levels  during  the 1st l a b o r a t o r y  mean a r t e r i a l correlated  pressure  significantly of  -  (r_ = . 3 8 ) .  Systolic,  t a s k p e r i o d were  1 a n d 2 (_r = . 6 8 t o  cardiovascular  related.  blood pressure  session  during the f i r s t  i n both V i s i t s  A l l measures of  74  diastolic  significantly  .87).  reactivity  taken i n  the f i r s t  visit  D u r i n g t h e second s e s s i o n f o u r weeks l a t e r ,  r e a c t i v i t y were s i g n i f i c a n t l y  correlated while  between h e a r t r a t e  during V i s i t  1 a n d r_ = . 3 6 d u r i n g V i s i t  sympathetically-mediated between d i a s t o l i c independent  neurogenic  mechanisms of  In order  control  heart  control  to t e s t  for  the r e l i a b i l i t y  i n Table 11.  First  measures were s i g n i f i c a n t l y experimental  session.  These r e s u l t s suggest in  heart rate  second v i s i t reactivity  argues against  t h e s e two r e s p o n s e  and s t a b i l i t y  session baseline  ranged from  and s t r e s s  (r^ = . 6 7 ) a n d s y s t o l i c  r a t e and s y s t o l i c measure of  mean a r t e r i a l  pressure  of  a common  correlation the existence  of  dimensions.  of  baseline,  stress  These data  and 1 s t t a s k s t r e s s taken i n the  .5595 t o  for  blood pressure  cardiovascular  reactivity.  r e a c t i v i t y were not  response  the  Measures  reactivity  i n second  Heart r a t e appears Measures  significantly  of  of  (r =  correlated.  the variance  respectively.  are  second  response measures.  45% a n d 10% o f  visit  . 7 6 2 3 (ja < . 0 0 1 ) .  t h e two s e s s i o n s w e r e a l s o h i g h l y  reactivity,  more r e l i a b l e  (r_ = . 7 1  1 s t v i s i t m e a s u r e s e x p l a i n 30% - 60% o f  session r e a c t i v i t y accounted  The  b e t w e e n 1 s t a n d 2nd  c o r r e l a t e d with those  baseline  .32) taken during each of  The  i n t e r v a l was a s s e s s e d .  Correlations that  the i n f l u e n c e  mechanism.  and r e a c t i v i t y measures t h e c o r r e l a t i o n  presented  heart  2)reflects  reactivity  rate  Correlations  measures taken over a four-week  variance  and s y s t o l i c  and h e a r t r a t e r e a c t i v i t y  Across Session Cardiovascular  response  reactivity  were  measures  r e a c t i v i t y was c o r r e l a t e d w i t h s y s t o l i c a n d mean a r t e r i a l m e a s u r e s . correlation  and  First session  t o be a  diastolic  correlated  across  and the  _ 75  two  _  visits.  I n t e r c o r r e l a t i o n s o f S e l f - R e p o r t Measures I n t e r c o r r e l a t i o n s between t h e s e l f - r e p o r t dependent measures were f i r s t c a l c u l a t e d on a w i t h i n - s e s s i o n b a s i s .  These d a t a a r e d i s p l a y e d i n T a b l e  14.  Only those c o r r e l a t i o n s which a r e s i g n i f i c a n t a t _p_ < .001 a r e d i s p l a y e d . During the f i r s t experimental s e s s i o n r a t i n g s of perceived s t r e s s explained approximately .4318).  19% of the v a r i a n c e i n r a t i n g s o f p e r c e i v e d t a s k d i f f i c u l t y  (r =  P e r c e i v e d performance was n e g a t i v e l y c o r r e l a t e d w i t h p e r c e i v e d t a s k  difficulty  ( r = .3710).  D u r i n g t h e second v i s i t , r a t i n g s o f p e r c e i v e d s t r e s s were p o s i t i v e l y correlated with perceived task d i f f i c u l t y  and i m p o r t a n c e ,  correlated with perceived task d i f f i c u l t y .  and n e g a t i v e l y  P e r c e i v e d performance measures  were a l s o n e g a t i v e l y c o r r e l a t e d w i t h p e r c e i v e d t a s k In o r d e r t o a s s e s s the t e s t - r e t e s t r e l i a b i l i t y  difficulty. o f each o f t h e s e l f - r e p o r t  measures, the i n t e r c o r r e l a t i o n between 1 s t and 2nd v i s i t r a t i n g s on each measure was computed.  These d a t a a r e p r e s e n t e d  perceived task d i f f i c u l t y visits. for  i n T a b l e 14.  Ratings of  were not s i g n i f i c a n t l y c o r r e l a t e d a c r o s s the two  F i r s t v i s i t r a t i n g s on t h e o t h e r f o u r s e l f - r e p o r t measures accounted  10% - 35% of t h e v a r i a n c e i n second v i s i t r a t i n g s ( r = .3169 t o r =  .5876), w h i c h i n d i c a t e s t h a t o n l y a modest p r o p o r t i o n o f response  variability  can be a t t r i b u t e d t o i n d i v i d u a l response s t e r e o t y p y i n s u b j e c t i v e a p p r a i s a l . I n t e r c o r r e l a t i o n s o f C a r d i o v a s c u l a r and S e l f - R e p o r t Measures The c o r r e l a t i o n between each o f the s e l f - r e p o r t measures and c a r d i o v a s c u l a r b a s e l i n e , f i r s t t a s k response, the two l a b o r a t o r y s e s s i o n s were computed.  and r e a c t i v i t y w i t h i n each o f  Heart r a t e r e a c t i v i t y and r a t i n g s  of p e r c e i v e d t a s k importance a c q u i r e d d u r i n g the second s e s s i o n were s i g n i f i c a n t l y c o r r e l a t e d (r_ = .3105).  C o r r e l a t i o n s between t h e s e l f - r e p o r t  - 76 -  TABLE 14 I n t e r c o r r e l a t i o n s o f S e l f - R e p o r t Dependent  Within V i s i t 1 PDl PS1 PDl  PPI  .4318 -.3710  Within V i s i t 2  PS2 PD2  Across  PD2  PI2  PPI  .4530  .4324  -.4217 -.4379  Visits  PS1 - PS2 PDl - PD2 P I I - PI2 PPI - PP2 PIM1 - PIM2  *PS = P e r c e i v e d *PD = P e r c e i v e d PI = P e r c e i v e d  .3449 .1182* .4823 .5876 .3169  Stress Difficulty Importance  PP = P e r c e i v e d Performance PIM = P e r c e i v e d I n f l u e n c e o f Mood on Performance *Nonsignificant correlations, included f o r c l a r i t y .  Measures  -  77  -  measures and cardiovascular response l e v e l s during the f i n a l stress task i n each session were not s i g n i f i c a n t .  Ratings of perceived performance were  s i g n i f i c a n t l y correlated (_r = .280, JJ < .005) with each of the three heart rate recovery values i n the second  visit.  Analyses of Covariance Three sets of analysis of covariance were performed cardiovascular dependent measures.  for each of the four  Subject age and pre-task baseline were  treated as covariates i n each analysis.  The three sets of analysis of  covariance were l a b e l l e d as Condition 1 ANCOVA, Task 1 ANCOVA, and V i s i t 2 ANCOVA, respectively. The Condition 1 ANCOVA was based on data from subjects i n the repeated stressor experimental condition. High and low r e a c t i v i t y was treated as a between-group factor, while v i s i t s (2),  t r i a l s (3), and minutes (3) were  treated as f a c t o r i a l within-subject repeated measures.  The Condition 1  ANCOVAs allowed for analyses of the e f f e c t s of repeated stress tasks for those 45 subjects exposed to a t o t a l of 2 x 3 t r i a l s .  However, they did not include  an analysis of the e f f e c t s of varying amounts of stressor exposure on cardiovascular responses.  In the Task 1 ANCOVA experimental conditions and  r e a c t i v i t y were between-group factors. analyzed as repeated measures.  V i s i t s (2) and minutes (3) were  The Task 1 ANCOVAs included an analysis of the  e f f e c t s of repeated versus single stress tasks across the high versus low r e a c t i v i t y groups.  They did not however allow for analysis of across t r i a l s  e f f e c t s within a given session only.  The V i s i t 2 ANCOVA was performed on data  gathered during the second experimental session.  Conditions and r e a c t i v i t y  were between-group variables, while t r i a l s (3) and minutes (3) were analyzed as f a c t o r i a l repeated measures.  The V i s i t 2 ANCOVAs included analyses of both  t r i a l s and minutes repeated measures following repeated versus single stressor  - 78  exposure during V i s i t the e f f e c t s  of  In order a n a l y s e s of  1.  The V i s i t  the four-week  2 ANCOVAs d i d n o t a l l o w f o r  inter-visit  covariance described below, the degrees of  Type I e r r o r  the value of  freedom (Greenhouse & G e i s s e r ,  presented below,  each a n a l y s i s of  covariance  four additional analyses  performed.  S e c o n d , N e w m a n - K e u l s t e s t s w e r e u s e d t o make a l l  significant  the v a r i a b l e significant trials,  interactions  ANCOVAs, t r e n d a n a l y s e s , heart rate,  arterial  freedom, p v a l u e , In each case the  between c a r d i o v a s c u l a r r e a c t i v i t y and t h e  and m i n u t e s r e p e a t e d measures were p l o t t e d .  Finally,  post-hoc  s y s t o l i c blood pressure,  pressure i n the f o l l o w i n g  diastolic  all  visits,  Scheffe's  The r e s u l t s o f  t e s t s , and g r a p h s a r e p r e s e n t e d  r  where  Third,  c o m p a r i s o n s b e t w e e n s e l e c t e d c e l l means f r o m t e r m i n a g i v e n ANCOVA.  hoc  effects.  l e v e l s encompassed i n a g i v e n c o m p a r i s o n ,  h i g h e s t - o r d e r ANCOVA i n t e r a c t i o n  and  were  l e v e l means h a v e b e e n a r r a n g e d i n o r d e r o f m a g n i t u d e .  w e r e u s e d t o make p a i r w i s e  for  involved  possible post  the degrees of  and r v a l u e a s s o c i a t e d w i t h each between l e v e l c o m p a r i s o n . t h e number o f  also  ANCOVA t e r m s was  the t r i a l s and m i n u t e s main  The N e w m a n - K e u l s t e s t s r e p o r t e d b e l o w i n c l u d e  value represents  1959; see  term.  First,  comparisons between l e v e l s of  was  the c o r r e c t e d p value  conducted.  pairwise  a trend a n a l y s i s of  of  measures  procedure  The F t e s t s , w h i c h  include  e p s i l o n a s s o c i a t e d with the e r r o r  Following  i n the repeated  an e p s i l o n - c o r r e c t i o n  Keselman & Rogan, 1980; Iacono & L y k k e n , 1984). r e p e a t e d measures a n d ' a r e  analysis  interval.  to reduce the l i k e l i h o o d of  used to a d j u s t  -  tests the the  separately  b l o o d p r e s s u r e , a n d mean  sections.  H e a r t R a t e ANCOVAS Three analyses of performed. types of  covariance of  These i n c l u d e d  ANCOVA.  h e a r t r a t e d a t a as o u t l i n e d above  t h e a f o r e m e n t i o n e d C o n d i t i o n 1, T a s k 1,  were  and V i s i t  The d a t a r e p r e s e n t e d i n t h e s e a n a l y s e s a r e p l o t t e d  in  2  -  Figures 6,  1,  and 7,  2, and 3 .  79  -  The summary ANCOVA t a b l e s a r e p r e s e n t e d i n A p p e n d i c e s  respectively.  d e f i n e d on t h e b a s i s o f  In each a n a l y s i s c a r d i o v a s c u l a r systolic  task i n the i n i t i a l experimental C o n d i t i o n 1 ANCOVA.  39.34, £ < -0001; T r i a l s , variables,  covariance a p p l i e d to the Condition  F ( 2 , 57) = 3 4 . 7 5 , £ < .0001,  significant  e = .710.  Visits, heart  Trials,  and M i n u t e s main e f f e c t s  r a t e a c r o s s the l e v e l s - of  was s i g n i f i c a n t l y significantly  lower  Differences  Significant 3,  effect  F_(l,  the was  27) = 5 4 . 4 8 , £ < .0001.  these v a r i a b l e s .  d u r i n g the second v i s i t .  of  The  differences  Average heart  in rate  The V i s i t s m a i n e f f e c t  the T r i a l s  main e f f e c t  yielded significant  was  trends,  F(l,  linear,  28) = 8 . 9 9 , £ <  Newman-Keuls t e s t s were p e r f o r m e d t o a s s e s s t h e d i r e c t i o n a l i t y  these trends. 8.  Minutes  i n h e a r t r a t e between  provide evidence  28) = 1 3 . 0 6 , £ < . 0 0 1 2 , and q u a d r a t i c  .0056.  e = . 6 9 9 ; and  r e l a t e d t o t h e b a s e l i n e c o v a r i a t e , F_(l, 2 8 ) = 2 9 . 2 5 , £ < . 0 0 0 1 .  A trend a n a l y s i s of F(l,  each of  28) =  Pre-task heart rate baseline  r e l a t e d to the groups e f f e c t ,  1  for  F(l,  The G r o u p s m a i n  differences  h i g h and low s y s t o l i c r e a c t i v i t y g r o u p s . significantly  main e f f e c t s  27) = 3 0 . 5 4 , £ < .0000; V i s i t s ,  F ( 2 , 58) = 5 2 . 5 6 , £ < . 0 0 0 1 ,  i n d i c a t e d the presence of  stress  session.  The a n a l y s i s o f  r e a c t i v i t y Groups, F ( l ,  was  blood pressure r e a c t i v i t y to the f i r s t  (repeated exposure) heart rate data yielded s i g n i f i c a n t systolic  reactivity  5,  The r e s u l t s o f  t h e Newman-Keuls t e s t s a r e p r e s e n t e d i n  in heart rate across  differences  and between t r i a l s  trials  1,  2, and 3 were  were found between t r i a l s  2 and 3 .  decreases i n heart  from t r i a l  r a t e were g r e a t e s t  Trend a n a l y s i s of  q ( 5 7 ) = 3 . 7 1 , r_ =  2 to t r i a l  No  These r e s u l t s 1 to t r i a l  Appendix  compared.  1 a n d 2 , q ( 5 7 ) = 3 . 0 8 , _r = 2 , £ < . 0 5 .  d i f f e r e n c e s were found between t r i a l s  decreases from t r i a l  1 and 3,  of  significant  indicate  2, w i t h  that  smaller  3.  the minutes v a r i a b l e y i e l d e d s i m i l a r l i n e a r ,  F_(l,  29) =  FIGURE 2  TASK I HEART RATE VISIT I  VISIT II  120-1  110  H  3  Legend 1 'HMS«SCUCIC»OCR5<XM>»Vl  £ © 100-  3  Q. W  5 -ms«njciocCT»cow»vi  o £  90H  \  <  a:  •io»srsiajiEAacR5<gMVVi  4 'uwagcucioooiscawva  80  H  70  H  8 •ia»staoucioQOHS<piBAa  60-  V1/FIRST TASK  4 WK. INTERVAL  V2/FIRST TASK  oo o  FIGURE 3  VISIT 2 HEART RATE DATA IIO-i  105 H  JD  c c3  95-  OL CO •+O (D X>  90-  ce  \\ \ \  85-  h-  < 80H  3  \  V  Ixl  X  Legend  \  100-1  1 2 •misBPtEianK&aa/tmu 3 »HmSg>BDOF3g<XK)/rm3 4 5 'tOWSBPBBICOtVCf3C»lHC2 6 •lQW»IOCCT5VCCHi|^W.3 7 •HMSgHDOCBS'tXKtVTWU 8 •HWSBPIEWICHS<XMai1ll»t2 9 10 -U»ygPRE*aCB5*XX>VBMU 11 •ia>»SBPipcos<iKiimi<i2 12  q  - O  11  6 12  75-  70-  -i  1 TRIAL 1  r  ~i  1 TRIAL 2  T  1 TRIAL 3  r  -  82 -  68.27, £ < .0001, and quadratic trends, F ( l , 29) = 8.95, £ < .0001.  The only  decreases i n heart rate occurred from minutes 1 to 2, q(29) = 3.6, r_= 2, £ < .05.  Decreases from minute 2 to minute 3 were not s i g n i f i c a n t (see Appendix  8). The s y s t o l i c r e a c t i v i t y Groups variable also showed a s i g n i f i c a n t i n t e r a c t i o n with each of the V i s i t s , F ( l , 28) = 10.96, £ < .0026; T r i a l s , F(2, 56) = 12.31, £ < .0003, e = .699; and Minutes v a r i a b l e s , F(2, 58) = 8.21, £ < .0007, e = .710.  High s y s t o l i c reactors displayed means of 94 and 82 beats  per minutes during v i s i t s 1 and 2. 85 and 79 beats per minute.  The mean heart rate for low reactors was  Across t r i a l s the mean heart rate was 99, 89, and  81 for high reactors and 83, 80, and 78 beats per minute for low reactors. The mean heart rate across minutes was 97, 89, and 83 for high reactors and 84, 79, 78 beats per minute for low reactors.  Inspection of these mean scores  indicates that high s y s t o l i c reactors show greater decreases i n heart rate across v i s i t s ,  t r i a l s and minutes.  A s i g n i f i c a n t V i s i t by T r i a l s by Groups  i n t e r a c t i o n also occurred, F_(2, 57) = 11.16, £ < .0001, e = .747.  This  i n t e r a c t i o n i s presented i n Figure 19.  i n heart  Between groups differences  rate across t r i a l s were greatest during the f i r s t laboratory session.  The  presence of s i g n i f i c a n t T r i a l s ( l i n e a r ) X Groups, F_(l, 28) = 8.53, £ < .0068, and Minutes ( l i n e a r ) X Groups, F_(l, 29) = 10.94, £ < .0025, interactions also suggests that the l i n e a r nature of heart rate changes across T r i a l s and Minutes varies as a function of s y s t o l i c r e a c t i v i t y .  A comparison of the  effects of short (3 minutes) versus long (4 weeks) i n t e r - s t r e s s o r intervals on high versus low s y s t o l i c reactors yielded no s i g n i f i c a n t  between-group  differences i n heart r a t e . Significant V i s i t s by T r i a l s , F(2, 57) = 12.47, £ < .0002, e = .747; V i s i t s by Minutes, F(2, 58) = 7.09, £ < .0032, e = .844; and T r i a l s by  83  FIGURE 19.  CONDITION 1 HEART RATE TRIALS X VISITS X GROUPS 110-1  i 1  1  r  2 TRIALS  3  - 84  Minutes,  F(4,  found.  in  1 1 6 ) = 1 1 . 6 5 , _p_ < . 0 0 0 1 , e = . 7 3 0 , i n t e r a c t i o n s w e r e  The r e s u l t s  were g r e a t e s t trial  suggest that  i n the f i r s t  decreases across T r i a l s  visit,  1 and l e s s i n t r i a l s  Scheffe's  -  and a c r o s s  visit  2 and  greatest  3.  t e s t s p e r f o r m e d on t h e c e l l means f r o m t h e h i g h e s t - o r d e r  i n heart r a t e during the f i n a l minute of  2 (p_ < . 0 5 ) .  Finally,  Minutes  and d e c r e a s e s a c r o s s m i n u t e s were  X v i s i t s X t r i a l s X m i n u t e s i n t e r a c t i o n r e v e a l e d no s i g n i f i c a n t differences  also  a number o f  between  the f i n a l  These r e s u l t s are p r e s e n t e d i n Appendix  groups group  stress task  9.  t r e n d i n t e r a c t i o n s were found w h i c h were n o t  of  primary importance w i t h regard to the present experimental hypotheses. included V i s i t s Trials  (linear) X Trials  ( l i n e a r ) X Minutes  (linear), F(l,  (linear), F(l,  ( l i n e a r ) X Groups, F ( l ,  (linear) X Trials  (quadratic) X Groups, F ( l ,  Visits  ( l i n e a r ) X Minutes  (linear), F(l,  T a s k 1 ANCOVA.  repeated measures. is  29) = 1 2 . 1 5 , £ < .0016.  The summary ANCOVA t a b l e  heart r a t e readings from the f i r s t c o v a r i a n c e of Task 1 h e a r t r a t e systolic  r e a c t i v i t y groups, F ( l ,  the presence of  r e g a r d l e s s of c o v a r i a t e of  2.  for  5.  reactivity factorial  the Task 1 h e a r t r a t e  s t r e s s task i n each v i s i t .  The a n a l y s i s  main e f f e c t s  5 5 ) = 5 2 . 1 8 , JJ < . 0 0 0 1 ; v i s i t s , F ( l , 114) = 6 6 . 3 5 .  significant  the groups v a r i a b l e s ,  The G r o u p s m a i n  between group d i f f e r e n c e s  experimental condition. F_(l,  ANCOVA  The m i n u t e s v a r i a b l e was b a s e d o n  data y i e l d e d s i g n i f i c a n t  5 6 . 0 4 , JJ < . 0 0 0 1 ; a n d m i n u t e s , F ( 2 , indicated  and  and  The  presented i n Appendix  and v i s i t s and m i n u t e s as  p r e s e n t e d i n A p p e n d i x 6 and F i g u r e  Visits  2 8 ) = 1 0 . 4 0 , JJ < . 0 0 3 2 ,  The T a s k 1 ANCOVA i n v o l v e d c o n d i t i o n s  groups as between group v a r i a b l e s ,  Visits  2 8 ) = 1 1 . 2 5 , JJ < . 0 0 2 3 ,  C o n d i t i o n 1 H e a r t R a t e Summary ANCOVA t a b l e i s  These  2 8 ) = 1 0 . 3 2 , JJ < . 0 0 3 3 ,  2 9 ) = 2 7 . 9 4 , _p_ < . 0 0 0 1 ,  (linear) X Trials  in  B a s e l i n e h e a r t r a t e was a 5 5 ) = 2 7 . 9 0 , JJ < . 0 0 0 1 .  of  for 56) =  effect  i n heart  rate,  significant Both  baseline  85  and f i r s t task heart rate were s i g n i f i c a n t l y higher in the high s y s t o l i c r e a c t i v i t y group.  The main effect for experimental conditions, i . e . ,  repeated  versus single stressor exposure during V i s i t 1 was non-significant, which indicated that on average heart rate levels during the f i r s t task of each session did not vary across conditions. The V i s i t s and Minutes main effects indicate the presence of s i g n i f i c a n t differences i n heart rate across the levels of each of these variables.  For  both experimental conditions average heart rate during task 1 was lower during the second v i s i t .  Pre-task baseline was a s i g n i f i c a n t covariate of the  e f f e c t , F ( l , 56) = 34.39, JJ_ < .0001.  visits  A trend analysis of the Minutes main  effect yielded a s i g n i f i c a n t linear trend, _F(1, 57) = 97.66, JJ < .0001. Newman-Keuls tests revealed s i g n i f i c a n t decreases i n heart rate from minute 1 to 2, q(57) = 7.25, jr = 2, and from minute 2 to minute 3, Q(57) = 5.35, p_ < .05.  r_ = 2,  The magnitude of heart rate decreases was greatest from minute 1 to  2 with lesser decreases from minute 2 to 3 (see Appendix 8). The r e a c t i v i t y Groups variable showed a s i g n i f i c a n t interaction with the V i s i t s , F ( l , 56) = 18.12, JJ < .0001, and the Minutes variables, F(2, 114) = 7.40, JJ < .0010, e = .8051.  High s y s t o l i c reactors showed a mean heart rate  of 107 beats per minutes (bpm) in v i s i t 1 and 94 bpm i n v i s i t 2. for low reactors across v i s i t s were 86 and 82 bpm.  The means  Across minutes the mean  heart rate for high reactors was 108, 101, and 92 bpm.  For low s y s t o l i c  reactors the respective minute heart rate means were 90, 82, and 81 bpm. These means reveal that high s y s t o l i c reactors show greater decreases i n heart rate than low reactors across v i s i t s and minutes.  In a d d i t i o n , a s i g n i f i c a n t  Conditions X Groups X V i s i t s i n t e r a c t i o n , F_(l, 56) = 4.39, JJ < .0406,  reveals  that between groups differences i n heart rate from v i s i t 1 to v i s i t 2 were greatest i n the repeated stress condition.  This interaction i s displayed in  -  F i g u r e 13. 7.63,  86  _  The presence o f s i g n i f i c a n t Minutes ( l i n e a r ) X Groups, F_(l, 56) =  £ < .0077, and Minutes ( q u a d r a t i c ) X Groups, F ( 2 , 57) = 6.91, £ < .0110,  t r e n d i n t e r a c t i o n s suggests  t h a t the l i n e a r i t y of decreases  a c r o s s minutes v a r i e s as a f u n c t i o n o f s y s t o l i c  i n heart rate  reactivity.  A s i g n i f i c a n t V i s i t s by Minutes, F ( 2 , 114) = 7.97, £ < .0011, e = .857, i n t e r a c t i o n was a l s o found. first visit.  Decreases a c r o s s minutes were g r e a t e s t d u r i n g the  F i n a l l y , two t r e n d i n t e r a c t i o n s which were not o f primary  importance were found.  These were V i s i t s ( l i n e a r ) X Minutes ( l i n e a r ) , F_(l,  57) = 14.21, £ < .0004 and V i s i t s  ( l i n e a r ) X Minutes ( l i n e a r ) X Groups, F ( l ,  57) = 4.01, £ < .0499. S c h e f f e ' s t e s t s were used t o make p a i r w i s e comparisons o f the C o n d i t i o n s X Groups X V i s i t s X Minutes c e l l means. The .05)  R e s u l t s a r e d i s p l a y e d i n Appendix 9.  S c h e f f e ' s t e s t i n d i c a t e d no s i g n i f i c a n t between group d i f f e r e n c e s (£ < i n h e a r t r a t e d u r i n g the f i n a l minute o f the f i n a l s t r e s s t a s k f o r  s u b j e c t s i n C o n d i t i o n 1, V i s i t  2.  The h e a r t r a t e responses o f the h i g h  s y s t o l i c r e a c t o r s were i n d i s t i n g u i s h a b l e from those o f the low r e a c t o r s . Visit  2 ANCOVA.  The v i s i t  2 h e a r t r a t e ANCOVA was based s o l e l y on data  c o l l e c t e d d u r i n g the second e x p e r i m e n t a l  session.  C o n d i t i o n s and r e a c t i v i t y  were between group f a c t o r s , T r i a l s and Minutes were f a c t o r i a l measures.  The summary ANCOVA t a b l e i s presented  d i s p l a y e d i n F i g u r e 3.  repeated  i n Appendix 7.  The data a r e  The a n a l y s i s of c o v a r i a n c e y i e l d e d s i g n i f i c a n t main  e f f e c t s f o r C o n d i t i o n s , F_(l, 55) = 4.57, £ < .0369, r e a c t i v i t y Groups, F_(l, 55) = 15.05, p < .0003, T r i a l s , F ( 2 , 113) = 12.52, £ < .0001, e = .782, and Minutes, F(2,114) = 61.93, £ < .0001, e = .742. Heart higher  i n C o n d i t i o n 2, i . e . , s i n g l e exposure.  d i s p l a y e d higher heart r a t e s during v i s i t  2.  r a t e was s i g n i f i c a n t l y  High s y s t o l i c r e a c t o r s a l s o Pre-task  b a s e l i n e , F_(l, 55) =  287.10, £ < .0001, and age of s u b j e c t , F ( l , 55) = 4.57, £ < .0370, were  87  FIGURE 13.  TASK I HEART RATE DATA VISIT X CONDITION X GROUP INTERACTION  - 88 -  s i g n i f i c a n t covariates of the conditions and groups main The T r i a l s and Minutes main effects  effects.  provided evidence of differences i n  heart rate across the l e v e l s of these two v a r i a b l e s .  The t r i a l s variable was  s i g n i f i c a n t l y related to the baseline covariate, F_(l, 113) = 21.96, JJ < .0001.  The l i n e a r and quadratic trends for the t r i a l s effects  non-significant.  were  Newman-Keuls tests revealed s i g n i f i c a n t decreases i n heart  rate from T r i a l 1 to 2, q(113) = 7.7, r_ = 2, and from T r i a l 2 to T r i a l 3, q(57 = 3.56, r_=2,  JD< .05.  A trend analysis of the minutes main effect yielded a  s i g n i f i c a n t l i n e a r trend, F_(l, 57) = 74.19, JJ < .0001.  S i g n i f i c a n t decreases  in heart rate occurred from Minute 1 to Minute 2, q(57) = 6.44, r_ = 2, J J < .05.  Decreases from minutes 2 to 3 were not s i g n i f i c a n t (see Appendix 8 ) . The s y s t o l i c r e a c t i v i t y groups variable showed a s i g n i f i c a n t two-way  i n t e r a c t i o n with Minutes, F_(2, 114) = 7.69, JJ < .0024, e = .742 and a s i g n i f i c a n t three-way i n t e r a c t i o n with T r i a l s X Minutes, _F(4, 228) = 3.08, JJ < .0296.  The three-way i n t e r a c t i o n i s displayed i n Figure 14.  High s y s t o l i c  reactors showed a greater decrease i n heart rate across minutes than did low reactors.  The mean heart rate for high reactors across Minutes was 95, 88,  and 85 bpm.  Low reactors displayed means of 83, 78, 78 bpm across minutes.  These between group differences across minutes were greatest on t r i a l 1 and smaller on subsequent t r i a l s .  The presence of s i g n i f i c a n t Minutes ( l i n e a r ) X  Groups, F ( l , 57) = 9.71, JJ < .0029 and T r i a l s (quadratic) X Groups, F ( l , 56) = 6.07, jj < .0169 trend interactions indicates that the slope of heart rate changes across t r i a l s and minutes p a r a l l e l s l e v e l of s y s t o l i c r e a c t i v i t y . A s i g n i f i c a n t T r i a l s X Minutes i n t e r a c t i o n , F(4, 228)) = 4.39, JJ < .0055, e = .739 was found.  Decreases i n heart rate across minutes were greatest on  t r i a l 1 and less on subsequent t r i a l s .  Additional trend interactions which  89  FIGURE 14.  VISIT 2 HEART RATE DATA TRIAL X MINUTE X GROUP INTERACTION 105-i  100 H  •§ c  95-  CD Q.  jo  D  90-  CD •Q C  UJ 85-  i2  80-  Legend A X • B  75 H  70-  MINUTES  ~~T~ 3  TRIAL 1/H SBP REACTORS TRUL2/H SBP REACTORS TRUU. 3/H SBP REACTORS TRIAL VLO SBP REACTORS  -  were not of  direct  interest with respect  ( l i n e a r ) X Minutes Minutes  (linear), F(l,  Scheffe's  selected conditions critical  t e s t s were used t o c o n d u c t  X Groups X T r i a l s  differences  t h e C o n d i t i o n 1, the f i n a l  pairwise  differences  Three a n a l y s e s of performed.  t e s t s are d i s p l a y e d i n Appendix 9.  indicate  No  in heart rate r e a c t i v i t y  t o make  of  minute  t h a t a r e p e t i t i o n of  of  six  initial  disappear.  ANCOVAS  covariance  of  s y s t o l i c blood pressure data  The d a t a r e p r e s e n t e d i n  were  5 and 6.  these analyses are presented  and 1 2 , r e s p e c t i v e l y .  In each a n a l y s i s c a r d i o v a s c u l a r  experimental  The a n a l y s i s o f  c o v a r i a n c e of  heart r e a c t i v i t y groups, 4 4 . 4 4 , JJ < . 0 0 0 1 , T r i a l s ,  F(l,  the  F(2,  65) = 1 8 . 6 3 , £ < . 0 0 0 1 ,  c o v a r i a t e of  F(l,  group.  for  32) =  e = . 9 8 0 , and  S y s t o l i c blood pressure  i n the high heart r a t e r e a c t o r  (repeated  main e f f e c t s  31) = 2 1 , 3 1 , £ < .0001, v i s i t s ,  66) = 7.54, £ < .0016, e = . 9 2 3 .  was a s i g n i f i c a n t  was  stress task in  Condition 1  exposure) s y s t o l i c blood pressure data y i e l d e d s i g n i f i c a n t  higher  10,  session.  C o n d i t i o n 1 ANCOVA.  significantly  reactivity  2  in  The summary ANCOVA t a b l e s a r e p r e s e n t e d i n A p p e n d i c e s  d e f i n e d on t h e b a s i s o f h e a r t r a t e r e a c t i v i t y t o t h e f i r s t  F(2,  The means a n d  T h e s e i n c l u d e d t h e a f o r e m e n t i o n e d C o n d i t i o n 1, T a s k 1, and V i s i t  ANCOVAS.  F i g u r e s 4,  of  (JJ < . 0 5 ) i n h e a r t r a t e w e r e f o u n d i n a c o m p a r i s o n  These r e s u l t s  S y s t o l i c Blood Pressure  (linear)  comparisons  X M i n u t e s c e l l means.  p r e s e n t a t i o n s o v e r two s e s s i o n s was s u f f i c i e n t  between-group  initial  (linear) X  h i g h v e r s u s low s y s t o l i c r e a c t o r s d u r i n g the f i r s t  stress task.  Trials  57_ = 6.13, £ < .0163.  v a l u e s used i n the S c h e f f e ' s  significant  11,  t o t h e p r e s e n t h y p o t h e s e s were  57) = 1 1 . 4 6 , £ < .0013, T r i a l s  (quadratic) X Groups, F ( l ,  Finally,  types of  _  ( l i n e a r ) X C o n d i t i o n s , J _ ( l , 5 7 ) = 4 . 3 6 , JJ < . 0 4 1 3 , a n d T r i a l s  X Minutes  stressor  90  Minutes,  was  Pre-task  baseline  t h e r e a c t i v i t y v a r i a b l e , F_(l, 3 1 ) = 1 2 4 . 8 5 , £ <  FIGURE 5  TASK I SYSTOLIC BLOOD PRESSURE DATA HO-i  VISIT I  VISIT II  135 H  CD sz  E E C  1 2 3 4 5  130-  OO  to UJ £ Q O  6 7  125"  3 CO O  120-  00  >to 115-  4 WK. INTERVAL 110-  FIRST TASK  FIRST TASK  Legend  hPHrRREQ3RS*X>Cyv2  FIGURE 6  VISIT 2 SYSTOUC BLOOD PRESSURE DATA 130-.  125-1  cn E E c  Legend *HGHWIBClCR5<XHVimi 'WwipgoB»tOK)»Tw»a -TOwic«cioH5ytoivni«L3  7  -HGHHR HDOCRS/COCg/lTMtJ  8  -mH>ia>goHS«M]g/iiwta  120-  LJ  9*  cm  CO CO UI £ 115-  7  4/  o o  10  3 m y  _l  1 2 3  Q  ii  iio-  CO  >-  6  CO  12 H *  105-  ffl  100-  ~i  1 TRIAL 1  1  —  i  —  : TRIAL 2  1  r  ~i  1 TRIAL 3  r  •1W«WWEBBC»CR5A2  11  'iwKieqcHs/mm  12  •Wt<'POgB/llW3  _  .0001.  The m a i n e f f e c t s  for  significant  differences  variables.  Mean s y s t o l i c  second v i s i t . Visits  _  9 3  Visits, Trials,  and M i n u t e s p r o v i d e d e v i d e n c e  in s y s t o l i c pressure across  b l o o d p r e s s u r e was s i g n i f i c a n t l y  main e f f e c t ,  F(l,  main e f f e c t  trends,  The r e s u l t s o f  S i g n i f i c a n t decreases  The m a g n i t u d e o f  trials.  A significant  effect,  this  quadratic  32) = 4 . 9 7 , £ < .0330.  a s s e s s the changes i n  t o 2 t o 3,  (65) = 3.75,  1 to  No s i g n i f i c a n t  differences  interaction with  Low  The  I n s p e c t i o n of  that high heart rate reactors  .0115,  Visits  by T r i a l s  1 and  during v i s i t  1.  in systolic  A comparison of  (3 minutes) v e r s u s l o n g (4 weeks) i n t e r - s t r e s s o r h e a r t r a t e r e a c t o r s y i e l d e d no s i g n i f i c a n t  2.  showed low  i n t e r a c t i o n , F_(2, 6 5 ) = 5 . 2 0 , £ <  e = .859, revealed that across t r i a l decreases  p r e s s u r e were g r e a t e s t  the  visit  decreases i n s y s t o l i c pressure across v i s i t s than did  A significant  in  reactors  119 a n d 1 1 1 mm Hg d u r i n g v i s i t s  reactors.  main  were found  v a r i a b l e , F_(l, 3 2 ) = 7 . 2 9 , £ < . 0 1 1 0 .  t h e s e means i n d i c a t e s  of  levels.  h i g h h e a r t r a t e r e a c t o r s w e r e 124 a n d 115 mm H g .  larger  trial  pressure  d i s p l a y e d mean s y s t o l i c p r e s s u r e o f  slightly  Appendix  r. = 2 , £ <  On a v e r a g e , mean s y s t o l i c  r e p e a t e d m e a s u r e showed a s i g n i f i c a n t  between-groups  systolic  these t e s t s are presented i n  c o m p a r i s o n s o f m i n u t e by m i n u t e p r e s s u r e  reactivity means f o r  F(l,  F(l,  t r e n d was f o u n d w i t h r e g a r d t o M i n u t e s  l e v e l s were h i g h e s t d u r i n g m i n u t e 2.  Only the V i s i t s  the  d e c r e a s e was i n v e r s e l y r e l a t e d t o t h e number  F_(2, 6 6 ) = 1 6 . 5 2 , £ < . 0 0 0 3 .  pairwise  the  linear,  i n s y s t o l i c pressure occurred from t r i a l  q ( 6 5 ) = 4 . 7 5 , r_ = 2 , a n d f r o m t r i a l  .05.  during  c o v a r i a t e of  yielded significant  Newman-Keuls t e s t s were p e r f o r m e d t o f u r t h e r  2,  these  32) = 2 9 . 7 1 , £ < .0001.  3 2 ) = 1 8 . 4 3 , _p_ < . 0 0 0 2 , a n d q u a d r a t i c  pressure across t r i a l s .  each of  lower  B a s e l i n e s y s t o l i c p r e s s u r e was a s i g n i f i c a n t  A t r e n d a n a l y s i s of T r i a l s  13.  l e v e l s of  of  blood  the e f f e c t s  of  short  i n t e r v a l s on h i g h v e r s u s  between group d i f f e r e n c e s  in  low  -  systolic  blood pressure.  for V i s i t s .0360,  Finally,  (linear) X Trials  and V i s i t s  significant  (linear) X Trials  group d i f f e r e n c e s  measures.  Results indicated that  variables,  The summary ANCOVA f o r  taken during the f i r s t  t h e end o f  differences  and  repeated  t h e two s e s s i o n s .  6 2 ) = 7 0 . 6 0 , JJ < . 0 0 0 1 ,  Visits,  F ( 2 , 128) = 1 0 . 2 4 , £ < .0001,  i n d i c a t e d the presence of  is  B a s e l i n e h e a r t r a t e was a s i g n i f i c a n t _F(1, 6 2 ) = 1 1 2 . 6 3 , £ < . 0 0 1 .  The m a i n e f f e c t  F(l,  The h e a r t  for  analysis for  63) = 5 1 . 0 4 , p < The m a i n rate  between  experimental  c o v a r i a t e of  The  readings  main e f f e c t s  e = .964.  significant  i n s y s t o l i c pressure r e g a r d l e s s of  stress  reactivity  The M i n u t e s v a r i a b l e was b a s e d on s y s t o l i c  e x p e r i m e n t a l c o n d i t i o n s was n o t s i g n i f i c a n t .  group main e f f e c t  the f i n a l  the Task 1 s y s t o l i c blood p r e s s u r e  c o v a r i a n c e of Task 1 s y s t o l i c data y i e l d e d s i g n i f i c a n t  .0001 and M i n u t e s ,  between  14.  and V i s i t s a n d M i n u t e s a s  s t r e s s task i n each of  r e a c t i v i t y Groups, F ( l ,  groups X v i s i t s  significant  The T a s k 1 ANCOVA i n v o l v e d c o n d i t i o n s  presented i n Appendix 11.  not  comparisons of  The S c h e f f e ' s v a l u e s a r e p r e s e n t e d i n A p p e n d i x  groups as between-group  for  3 2 ) = 1 3 . 4 9 , JJ < . 0 0 0 9 .  interest.  i n s y s t o l i c pressure remained at  T a s k 1 ANCOVA.  of  primary  found  ( l i n e a r ) F ( 2 , 65) = 4 . 7 8 , £ <  (linear), F(l,  t e s t s w e r e u s e d t o make p a i r w i s e  X t r i a l s X m i n u t e s c e l l means.  task.  t r e n d i n t e r a c t i o n s were  ( l i n e a r ) X Minutes  These t r e n d i n t e r a c t i o n s were not of Scheffe's  94 -  effect  reactivity group  condition.  the groups main  effect,  experimental conditions  was  significant. The v i s i t s a n d m i n u t e s m a i n e f f e c t s  systolic  indicate  significant  differences  b l o o d p r e s s u r e l e v e l s a c r o s s t h e v i s i t s and m i n u t e s .  p r e s s u r e was h i g h e r significant  during the f i r s t  covariate  A trend a n a l y s i s of  of  visit.  P r e - t a s k b a s e l i n e was a l s o  the V i s i t s main e f f e c t ,  the M i n u t e s main e f f e c t  Systolic  in blood a  F_(l, 6 3 ) = 6 . 3 8 , £ < . 0 1 4 1 .  yielded significant  linear,  F_(l,  _  64) = 4 . 0 6 , £ < .0481 and q u a d r a t i c  _  95  trends,  F(l,  Newman-Keuls t e s t s r e v e a l e d a s i g n i f i c a n t  64) = 1 8 . 6 9 , £ < .0001.  increase  in systolic  from m i n u t e 1 t o m i n u t e 2,  q ( 6 4 ) = 3 . 7 5 , r_ = 2 , a n d a s i g n i f i c a n t  from minute 2 t o minute 3,  q(64) = 1.75,  p r e s s u r e was h i g h e s t p a t t e r n of  results  r_ = 2 , £ < . 0 5 .  d u r i n g the second minute of  pressure decrease  Mean s y s t o l i c  the task p e r i o d .  This  s u g g e s t s s y s t o l i c b l o o d p r e s s u r e showed a s l o w e r  response than heart r a t e to the mental a r i t h m e t i c s t r e s s o r . d i s p l a y e d i n Appendix  e = .964.  low r e a c t o r s .  1 2 1 , 1 2 5 , a n d 120 mm H g .  1 1 5 , 116 a n d 115 mm H g .  Across minutes high  Low r e a c t o r s  found.  d e c r e a s e i n s y s t o l i c p r e s s u r e a c r o s s v i s i t s and a  trend for minutes i s  heart rate r e a c t i v i t y group.  Finally,  The V i s i t s  significant,  Scheffe's  means d u r i n g t h e f i r s t  the task p e r i o d .  much s t r o n g e r  ( l i n e a r ) X Minutes  F_(l, 6 4 ) = 4 . 6 5 , £ < . 0 3 4 8 .  t e s t s w e r e u s e d t o make p a i r w i s e t a s k i n the second v i s i t .  comparison of  first  between group d i f f e r e n c e s  2 ANCOVA.  the second  rate  in  systolic  visit.  i n s y s t o l i c pressure remained during  R e s u l t s are presented i n Appendix  The v i s i t  cell  H i g h and low h e a r t  stress task in  the t a s k .  low  (linear)  pressure during the f i r s t minute of  Visit  A  i n the  ( 2 ) showed no d i f f e r e n c e  f i n a l minute of  reactors  greater  r e a c t o r s i n the s i n g l e exposure c o n d i t i o n  Significant  reactors  ( l i n e a r ) X G r o u p s i n t e r a c t i o n , F_(l, 6 4 ) = 6 . 7 3 , £ < . 0 1 1 8  The l i n e a r  i n t e r a c t i o n was a l s o  high  showed m i n u t e means  T h e s e means r e v e a l t h a t h i g h h e a r t r a t e  decrease i n s y s t o l i c p r e s s u r e from minute 2 t o 3 of  was a l s o  F(2,  The v i s i t means w e r e 129 a n d 1 2 0 f o r  r e a c t o r s a n d 116 a n d 115 mm Hg f o r  s i g n i f i c a n t Minutes  interaction  63) = 1 5 . 4 8 , £ < .0002 and t h e M i n u t e s v a r i a b l e s ,  128) = 5 . 1 0 , £ < .0081,  show a g r e a t e r  are  13.  w i t h the V i s i t s , F ( l ,  of  arousal  The r e s u l t s  The h e a r t r a t e r e a c t i v i t y g r o u p s v a r i a b l e showed a s i g n i f i c a n t  d i s p l a y e d means o f  blood  the  14.  2 s y s t o l i c b l o o d p r e s s u r e ANCOVA was b a s e d  on  96  data c o l l e c t e d  d u r i n g the second s e s s i o n .  C o n d i t i o n s and h e a r t  r e a c t i v i t y were between group f a c t o r s and T r i a l s repeated measures.  The ANCOVA summary t a b l e i s  S i g n i f i c a n t main e f f e c t s trials,  F(2,  < .0011, groups,  were found f o r  F(l,  groups,  12.  F_(l, 6 2 ) = 3 0 . 6 9 , JJ < . 0 0 0 1 ;  P r e - t a s k b a s e l i n e was a s i g n i f i c a n t  for  pressure across decreases  l e v e l s of  and M i n u t e s  changes  2 to t r i a l  increase in systolic r_ = 2 , w h i l e  3,  in  variables.  i n s y s t o l i c b l o o d p r e s s u r e were found from t r i a l  minute 2, q ( 1 2 8 ) = 2 . 1 7 , significantly  the  significant.  assess the nature of  the T r i a l s  q ( 1 2 7 ) = 2 . 9 2 , £ = 2, and from t r i a l A significant  c o v a r i a t e of  F ( l , 1 2 7 ) = 1 3 . 4 9 , JJ < . 0 0 0 4 .  e x p e r i m e n t a l C o n d i t i o n s was n o t  Newman-Keuls t e s t s were used t o f u r t h e r  .05.  factorial  presented i n Appendix  6 2 ) = 1 6 1 . 2 9 , JJ < . 0 0 0 1 a n d t r i a l s ,  The m a i n e f f e c t  Significant  and M i n u t e s were  1 2 7 ) = 3 . 7 1 , £ < . 0 3 1 7 , e = . 8 9 8 ; a n d m i n u t e s , F ( 2 , 1 2 8 ) = 6 . 3 5 , JJ  e = .975.  systolic  rate  q(127) = 6.42,  1 to  2,  r_ = 2 , £ <  p r e s s u r e was s e e n f r o m m i n u t e 1 t o  systolic  pressure  decreased  f r o m m i n u t e 2 t o m i n u t e 3 , q ( 1 2 8 ) = 1 0 . 1 7 , r_ = 2 , £ < . 0 5 .  R e s u l t s are d i s p l a y e d i n Appendix 13. A significant  Trials  i n t e r a c t i o n was f o u n d . decreases i n  This result  In a d d i t i o n ,  r e l a t e d to the T r i a l s  63) = 6 . 4 3 , £ < .0137  that the l i n e a r nature v a r i e d as a f u n c t i o n of  t h e b a s e l i n e c o v a r i a t e was  (linear) effect,  trend for Minutes,  significant.  indicated  s y s t o l i c pressure across t r i a l s  rate reactivity.  quadratic  ( l i n e a r ) X Groups, F ( l ,  F(l,  of heart  significantly  63) = 2 2 . 4 1 , £ < .0001.  F_(l, 6 4 ) = 1 6 . 8 1 , £ < . 0 0 0 1 was  The  also  S y s t o l i c p r e s s u r e v a l u e s showed a n i n c r e a s e f r o m m i n u t e 1 t o  m i n u t e 2 and a d e c r e a s e  from minute 2 to 3 i n each t a s k p e r i o d .  Subjects  in  b o t h c o n d i t i o n s a n d b o t h r e a c t i v i t y g r o u p s d i s p l a y e d t h e h i g h e s t mean s y s t o l i c levels  d u r i n g the second minute of  each t a s k p e r i o d .  three-way C o n d i t i o n s X Groups X T r i a l s ,  F(2,  Finally,  a  significant  127) = 4 . 0 5 , £ < .0238, e = .898  -  i n t e r a c t i o n was f o u n d .  97  -  This interaction i s  presented i n Figure  15.  h e a r t r a t e r e a c t o r s showed g r e a t e r  changes i n s y s t o l i c  trials.  i n the repeated s t r e s s o r c o n d i t i o n .  This effect  was s t r o n g e s t  presence of a s i g n i f i c a n t  C o n d i t i o n s X Groups X T r i a l s  F_(l, 6 3 ) = 5 . 4 1 , £ < . 0 2 3 2 f u r t h e r strongest  i n the s i n g l e exposure  Scheffe's systolic  indicates  Three a n a l y s e s of performed.  R e s u l t s of  stress task for  the S c h e f f e ' s  covariance of d i a s t o l i c  The summary ANCOVA t a b l e s  i n these analyses are g r a p h i c a l l y C o n d i t i o n 1 ANCOVA.  for  blood pressure data  t h e C o n d i t i o n 1, T a s k 1,  The d a t a 7, 8 and  In  V i s i t s main e f f e c t  The G r o u p s m a i n e f f e c t in diastolic  c o v a r i a t e of  was s i g n i f i c a n t l y  the  9.  pressure  levels  32) =  Minutes, the the  F_(l, 3 2 ) =  indicate  these v a r i a b l e s .  r e l a t e d to the b a s e l i n e  F(l,  levels.  the groups e f f e c t ,  of  1  main  Subjects in  and M i n u t e s main e f f e c t s  pressure across  each  indicates  pressure.  2  represented  e = . 9 5 9 ; and  group d i s p l a y e d h i g h e r d i a s t o l i c  The V i s i t s , T r i a l s  in diastolic  14.  covariance a p p l i e d to the C o n d i t i o n  F ( 2 , 65) = 2 7 . 6 7 , £ < .0001,  P r e - t a s k b a s e l i n e was a s i g n i f i c a n t  differences  both  and V i s i t  blood pressure data yielded s i g n i f i c a n t  between group d i f f e r e n c e s  6 0 . 1 5 , JD < . 0 0 0 1 .  in  heart rate responses to  displayed in Figures  3 3 ) = 5 . 8 7 , _p_ < . 0 0 5 7 , e = . 9 2 3 .  high heart rate reactor  in  were  r e a c t i v i t y g r o u p s , F ( l , 3 1 ) = 1 2 . 4 7 , _p_ < . 0 0 1 3 ; V i s i t s ,  3 1 . 5 3 , _p_ < . 0 0 0 1 ; T r i a l s ,  presence of  subjects  1 5 , 1 6 , and 1 7 , r e s p e c t i v e l y .  The a n a l y s i s o f  (repeated exposure) d i a s t o l i c  F(2,  is  t e s t s are i n Appendix  s t r e s s task i n the i n i t i a l experimental s e s s i o n .  for  effect  between group d i f f e r e n c e s  a n a l y s i s r e a c t i v i t y was d e f i n e d on t h e b a s i s o f  effects  effect,  ANCOVAS  ANCOVAs a r e p r e s e n t e d i n A p p e n d i c e s  first  (quadratic)  The  condition.  pressure remained during the f i n a l  D i a s t o l i c Blood Pressure  across  that the quadratic  tests revealed that significant  experimental conditions.  pressure  High  The  covariate,  F_(l,  98  FIGURE 15.  VISIT 2 SYSTOLIC PRESSURE TRIAL X CONDITION X GROUP INTERACTION 130 n  125 H  JZ  E E  jc  120 H  Ul CE CO CO Lxl  O O  3 m o  —i no 4 CO  >CO  105 H  Legend A X • B  100 2  TRIALS  COWPyX HR REACTORS COND1/L0 HR REACTORS CONDZ/HI HR REACTORS COND2AJ0HR REACTORS  FIGURE 8  TASK I D I A S T O U C B L O O D P R E S S U R E  D A T A  90 -i VISIT I  VISIT II  85-  Legend  CT  JZ  | 80Ul  or  oo to  .  7 5 7 5  Ld  7 'U)WWRDCI0^<XNXyV1  CL  8  OC O  to  •iQMMivaaPGfiae&a  70 H  < Q  65H  4 WK. INTERVAL  60-  i FIRST TASK  r FIRST TASK  vo vo  FIGURE 9  VISIT 2 DIASTOLIC BLOOD PRESSURE DATA 8O-1  77 H  CO  74 H  Legend  XT.  E E c 3  1 2 3  7H  4 5  68-  to Ul  £  65-  ^3  Q O  3 62H 00  o O  6 7 8 9 10 11 12  •HmhsiocgRvccMynwj  •tqyHRREAocRs^xxymj •UWHBRaCCT5/XHyniW3 •HWHRIBODaSyttMayTIMU  •HmHRtoaaf^oa^m^ •lDWHBR&aD35/<XKgrtR*U •\0Uy*l£MXfSAXKB/mL5  59  H  to  <  Q 5653-  50-  1  1 TRIAL 1  TRIAL 2  TRIAL 3  -  32) = 13.12, £ < .0010.  101  -  D i a s t o l i c pressure l e v e l s were lower during the  second experimental session. A trend analysis of the T r i a l s main effect yielded s i g n i f i c a n t l i n e a r , F ( l , 37) = 9.37, £ < .0044 and quadratic trends, F ( l , 32) = 7.10, £ < .0120. Newman-Keuls tests showed that s i g n i f i c a n t decreases i n d i a s t o l i c blood pressure occurred from t r i a l 1 to t r i a l 2, q(32) = 5.42, from t r i a l s 2 to 3, q(32) = 3.16, r_ = 2. to 2.  r_ = 2, £ < .05 and  Decreases were largest from t r i a l s 1  A s i g n i f i c a n t quadratic trend, F_(l, 33) = 11.33, £ < .0019 for minutes  was found.  D i a s t o l i c pressure were highest during minute 2.  between-minute differences i n d i a s t o l i c pressure were found.  No s i g n i f i c a n t Results are  displayed i n Appendix 18. The heart rate r e a c t i v i t y groups variable showed a s i g n i f i c a n t two-way i n t e r a c t i o n with V i s i t s , F_(l, 32) = 11.03, £ < .0023, and a s i g n i f i c a n t three-way interaction with T r i a l s X Minutes, F(4, 132) = 3.98, £ < .0080, e = .816.  The three-way i n t e r a c t i o n i s displayed i n Figure 16.  High heart rate reactors showed a greater decrease i n d i a s t o l i c pressure across v i s i t s . Hg.  The mean d i a s t o l i c pressure for high reactors.was 75 and 68 mm  Low reactors displayed v i s i t means of 67 and 65 mm Hg.  High heart rate  reactors also showed greater changes i n d i a s t o l i c pressure across minutes of the stress task. third t r i a l s .  Between-group differences were greatest during the f i r s t and  High and low heart rate reactors showed no differences i n  d i a s t o l i c blood pressure across short (3 minutes) versus long (4 weeks) inter-stressor intervals. Significant V i s i t s X T r i a l s , F(2, 65) = 5.76, £ < .0065, e = .912, and T r i a l s X Minutes, F(4, 132) = 3.11, £ < .0258, e = .816 interactions were also found.  Decreases i n d i a s t o l i c pressure across t r i a l s were greatest during the  first visit.  Changes i n d i a s t o l i c pressure across minutes were larger during  FIGURE 16.  CONDITION 1 DIASTOUC PRESSURE TRIALS X MINUTES X GROUPS 80-,  Legend  n 1  1  2  MINUTES  r 3  A  TRIAL t/H HR REACTORS  X  TRIAL 1M HR REACTORS  •  TRIAL VHl HR REACTORS  B  TRIAL y\0 HR REACTORS  X  TRIAL VtO HR REACTORS  - 103  the f i r s t  trial.  Several significant  p r i m a r y i n t e r e s t , were f o u n d . (linear),  F(l,  t r e n d i n t e r a c t i o n s , w h i c h were not  These i n c l u d e d V i s i t s  3 2 ) = 6 . 6 0 , _p_ < . 0 1 5 1 , T r i a l s  33) = 8 . 0 5 , £ < .0077, V i s i t s £  -  < .0037, T r i a l s  . 0 0 2 4 , and V i s i t  ( l i n e a r ) X Minutes  (linear) X Trials  ( l i n e a r ) X Minutes (linear) X Trials  (linear) X  of  Trials (linear),  (quadratic), F ( l ,  F(l,  32) = 9179,  ( l i n e a r ) X Groups, F ( l , 33) = 1 0 . 8 0 , £ <  (quadratic) X Groups, F ( l ,  32) = 5 . 9 6 , £ <  .0203. Scheffe's  t e s t s w e r e u s e d t o c o m p a r e c e l l means d u r i n g t h e f i n a l  task.  H i g h and low h e a r t r a t e r e a c t o r s d i d n o t d i f f e r  levels  during the f i n a l minute of  final  3 minute s t r e s s  T a s k 1 ANCOVA. between-group  £  presented i n Appendix 16.  groups, F ( l ,  for Conditions,  groups,  f o r m i n u t e s was n o t s i g n i f i c a n t .  and i n t h e s e c o n d v i s i t .  main e f f e c t ,  62) = 8 9 . 6 2 , £ < .0001. q u a d r a t i c t r e n d was f o u n d f o r Diastolic  the task p e r i o d .  Finally,  p r e s s u r e was h i g h e s t a significant  was  each  63) = 3 4 . 2 6 ,  Diastolic  i n the repeated exposure c o n d i t i o n ,  r e l a t e d to both the c o n d i t i o n s  5.54, £ < .0216.  The  F_(l, 6 2 ) = 6 . 7 6 , £ < . 0 1 1 6 ,  was s i g n i f i c a n t l y  A significant  as  yielded  62) = 4 1 . 2 2 , £ < . 0 0 0 1 , and V i s i t s , F ( l ,  p r e s s u r e l e v e l s were h i g h e r  F(l,  stress task in  c o v a r i a n c e of Task 1 d i a s t o l i c d a t a  The m a i n e f f e c t  heart rate reactor  the  and r e a c t i v i t y  The m i n u t e s v a r i a b l e  pressure r e a d i n g s from the f i r s t  main e f f e c t s  < .0001.  s t r e s s task or during  The T a s k 1 ANCOVA i n v o l v e d c o n d i t i o n s  The a n a l y s i s o f  reactivity  pressure  v a r i a b l e s , and v i s i t s and m i n u t e s as r e p e a t e d m e a s u r e s .  b a s e d on d i a s t o l i c  significant  in diastolic  task.  summary ANCOVA t a b l e i s  visit.  the second l a s t  stress  i n the  The b a s e l i n e  main e f f e c t  high  covariate  and t h e  the minutes e f f e c t ,  groups  F_(l, 6 4 ) =  during the second minute  V i s i t s X Groups,  .0404 i n t e r a c t i o n i n d i c a t e d t h a t h i g h h e a r t r a t e r e a c t o r s  of  ( 1 , 63) = 4 . 3 8 , £ < showed a  greater  -  decrease  in diastolic  78 a n d 71 mm Hg f o r visits  Scheffe's  f o u n d no s i g n i f i c a n t  t e s t s of  between-group  2 minutes of  the repeated exposure c o n d i t i o n .  Visit  the l a s t  2 ANCOVA.  The v i s i t  factors,  and T r i a l s  in  age  diastolic  stress task for  subjects  in  in  F(l,  groups,  < .0000, e = .977.  Groups main e f f e c t ,  trend e f f e c t s .  high heart rate  1 t o 2,  the c o n d i t i o n  during v i s i t  indicated significant  Diastolic  2,  second minute of  I n s p e c t i o n of F i g u r e low r e a c t o r  2 w e r e h i g h e r among  the  pressure  2 t o 3 , Q;(127) =  during the f i r s t  trial.'  17 r e v e a l s t h a t w i t h t h e e x c e p t i o n  group d i a s t o l i c  p r e s s u r e was h i g h e s t  the s t r e s s task period i n V i s i t  changes i n d i a s t o l i c  related to t r i a l  not  t h e M i n u t e s e f f e c t , _F(1, 6 4 ) =  M i n u t e s i n t e r a c t i o n , F_(4, 2 5 6 ) = 6 . 7 7 , £ < . 0 0 0 1 , magnitude of  63) = 5.46, £ <  decreases i n d i a s t o l i c  p r e s s u r e was h i g h e s t  q u a d r a t i c t r e n d was f o u n d f o r  4.00, £ < .0497.  (linear),  C o n d i t i o n s and M i n u t e s were  q ( 1 2 7 ) = 3 . 6 6 , jr = 2 , and f r o m t r i a l s  r_ = 2 , £ < . 0 5 ' .  A significant  pressure l e v e l s  for  the  reactors.  Newman-Keuls t e s t s from t r i a l s  The m a i n e f f e c t s  Diastolic  r e l a t e d to  62) = 2 9 4 . 9 0 , £ < .0001) and t o t h e T r i a l s (quadratic), F ( l ,  were  F ( 2 , 127) = 1 4 . 5 0 ,  The b a s e l i n e c o v a r i a t e was s i g n i f i c a n t l y F(l,  as  The  S i g n i f i c a n t main e f f e c t s  62) = 1 2 . 3 8 , £ < . 0 0 0 8 , and t r i a l s ,  63) = 1 2 . 9 7 , £ < . 0 0 0 6 , and T r i a l s  significant.  and r e a c t i v i t y  and M i n u t e s as r e p e a t e d m e a s u r e s .  found f o r  7.07,  differences  was  during  c e l l means a d j u s t e d f o r  2 ANCOVA i n c l u d e d c o n d i t i o n s  presented i n Appendix 17.  .0226,  low r e a c t o r s  These S c h e f f e v a l u e s a r e d i s p l a y e d  summary ANCOVA i s  F(l,  pressure  19.  between-group  £  The mean d i a s t o l i c  h i g h r e a c t o r s a n d 70 a n d 68 mm Hg f o r  pressure during the f i n a l  Appendix  -  pressure across v i s i t s .  1 and 2 r e s p e c t i v e l y .  and b a s e l i n e  104  2.  during  The s i g n i f i c a n t  of the  Trials  e = .880, i n d i c a t e d that  p r e s s u r e a c r o s s m i n u t e s was  X the  inversely  number.  The r e a c t i v i t y g r o u p s v a r i a b l e showed s i g n i f i c a n t  three-way  interactions  105  FIGURE 17.  VISIT 2 DIASTOLIC PRESSURE CONDITIONS X MINUTES X GROUPS 70  n  68 H  CT  E E .£  66-  a: to to Ld QC Q_  O  64H  to  < 62 H  Legend  60 J  ,  1  1  2  MINUTES  r  3  A X • B  CONDl/W HR REACTORS CONDt/LO HR REACTORS CON02/H1 HR REACTORS COND2/L0 HR REACTORS  106  with Minutes X Conditions, Minutes  F ( 2 , 1 2 8 ) = 3 . 8 3 , _p_ < . 0 2 7 9 , e = . 9 1 6 , a n d  (linear) X Conditions,  Conditions X Minutes  F ( l , 64) = 5.19, £ < .0260.  interaction is  displayed in Figure  The G r o u p s X  17.  Two  i n t e r a c t i o n s w h i c h were n o t r e l a t e d t o t h e p r e s e n t e x p e r i m e n t a l were f o u n d .  These were T r i a l s  1 1 . 5 5 , _p_ < . 0 0 1 2 , a n d T r i a l s F(l,  (quadratic) X Minutes  (quadratic) X Minutes  trend hypotheses  ( l i n e a r ) , F_(l, 6 4 ) =  (quadratic) X Conditions,  6 4 ) = 4 . 4 3 , _p_ < . 0 3 9 3 . Scheffe's  t e s t s w e r e u s e d t o make p a i r w i s e  a d j u s t e d c e l l means. significant  differences  in diastolic  Mean A r t e r i a l P r e s s u r e ANCOVAS. artierial  pressure  pressure during the f i n a l  and V i s i t  and 2 2 , r e s p e c t i v e l y .  stress  task.  c o v a r i a n c e of  The summary ANCOVA t a b l e s  mean  for  2 ANCOVAs a r e p r e s e n t e d i n A p p e n d i c e s  to the f i r s t  s t r e s s task i n the  the  20, 21, heart  initial  The d a t a r e p r e s e n t e d i n t h e s e a n a l y s e s a r e p r e s e n t e d  The a n a l y s i s o f  in  covariance a p p l i e d to the c o n d i t i o n  ( r e p e a t e d e x p o s u r e ) MAP d a t a y i e l d e d s i g n i f i c a n t 31) = 1 1 . 5 7 , £ < .0019, V i s i t s , F ( l , = 19.59, £ < .0001, Pre-task  effect,  no  1 0 , 11 a n d 1 2 .  C o n d i t i o n 1 ANCOVA.  .090.  showed  C a r d i o v a s c u l a r r e a c t i v i t y was d e f i n e d i n t e r m s o f  r a t e changes from b a s e l i n e experimental session.  baseline  19.  Three a n a l y s e s of  (MAP) w e r e c o m p u t e d .  C o n d i t i o n 1, T a s k 1,  Figures  comparisons of  H i g h and low r e a c t o r s i n b o t h c o n d i t i o n s  The S c h e f f e v a l u e s a r e p r e s e n t e d i n A p p e n d i x  F(l,  main e f f e c t s  for  Groups,  32) = 2 9 . 0 8 , £ < . 0 0 0 1 , T r i a l s ,  F(2,  b a s e l i n e MAP was s i g n i f i c a n t l y  32) = 8 . 0 4 , £ < .0079.  r e l a t e d to the groups  MAP was h i g h e r  during v i s i t  A trend a n a l y s i s of  t h e t r i a l s main e f f e c t  32) = 1 1 . 1 7 , £ < . 0 0 2 1 , and q u a d r a t i c  1.  High  reactors.  yielded significant  trends, F ( l ,  main  linear,  32) = 5.57, £ <  1  F_(l, 65)  e = . 9 5 3 , and M i n u t e s , F ( 2 , 66) = 4 . 7 0 , £ < . 0 1 5 1 , e =  h e a r t r a t e r e a c t o r s d i s p l a y e d h i g h e r MAP l e v e l s t h a n l o w  F(l,  with  FIGURE 11  TASK I MEAN ARTERIAL PRESSURE 110-1  VISIT I 105-  cn  sz  E E  Legend 1 •HraHRREKTORS/XTOM  100 A  3 •UJWHRIEAaOR^OMJVVl ZD 00  to  £ 95Q_ _l  <  OH DC  < z <  90H  I-B7  Ld  2  85 H  4 WK. INTERVAL 80V1/FIRST TASK  V2/FIRST TASK  4  •IXWf«REAQClMXK3yV2  5  •HPHWREACTOR^XKI^Vl  6  •HPHHRHDOOR^OMX^fl  7  •bOWHRRDCTJRVCCNI&'Vl  8  »L0yHRHE*CTO5>tCHgA2  FIGURE 12  VISIT 2 MEAN ARTERIAL PRESSURE DATA 100-  . 95 cn  Legend  JO  1 •HmHHRaacRs<xMynMu  E  3 -HmHRREACcRsyteMVims  £ QJ  / / ^  g0-  cc  4-UJWWR£AqCR5/XHVIRW 5 •IQWKRRETOCRS/XXVTBWt^ 2 ^ /  >  s  ^_  8-HD<HRIC»CIOi5>eCNPViat2  0_ < g  85-  10^  \ \  8 ® 5 O  \  P  12 • lOW HR RDOCRS/<X>Bg/TRHl3  11  < < Ixl 80-  9 *t^J*J¥^9!5$?$B^!!*y 10-UWHRR£ACCT5/CQCyWIU 11 •WHRRDCTOS/XNXyffiWJZ  9  0 6 X 12 a  / '  -x,--  a  "109  .0245.  Newman-Keuls t e s t s  to t r i a l  2,  q(32) = 5.25,  not s i g n i f i c a n t . quadratic, effect.  indicated significant r_ = 2 , JJ < . 0 5 .  Significant  F_(l,  "  linear,  F(l,  decreases  Decreases from t r i a l s  during minute 2 of  the task p e r i o d .  from minute 1 t o minute 2 were not s i g n i f i c a n t . were a l s o not s i g n i f i c a n t . d i s p l a y e d i n Appendix  and  the  Minutes  Increases i n  MAP  Decreases from minutes 2 to  t h e Newman-Keuls t e s t s  3  are  23.  The G r o u p s X V i s i t s ,  87 mm H g .  The r e s u l t s o f  1  2 t o 3 were  3 3 ) = 4 . 5 5 , JJ_ < . 0 4 0 5 ,  3 3 ) = 4 . 9 8 , JJ < . 0 5 t r e n d s w e r e a l s o f o u n d f o r  MAP was h i g h e s t  significant.  i n MAP f r o m t r i a l  F(l,  3 2 ) = 9 . 8 1 , JJ < . 0 0 3 7 ,  High heart rate reactors  interaction  was  d i s p l a y e d a c r o s s - v i s i t s means o f  Low r e a c t o r s showed a c r o s s - v i s i t s MAP means o f  95 a n d  85 a n d 83 mm H g .  Q  T h e s e means show t h a t h i g h h e a r t r a t e r e a c t o r s MAP a c r o s s v i s i t s .  t r e n d i n t e r a c t i o n s were n o t of (linear) F(l,  (quadratic, F(l,  F(l,  F(l,  Scheffe's  These were V i s i t  32) = 1 0 . 4 7 , £ < .0028, V i s i t s  32) = 4 . 2 8 , £ < .0468, T r i a l s  Several  (linear) X  differences significant (linear) X  Trials  ( l i n e a r ) X Minutes  (linear) X Trials  in  (quadratic,  ( l i n e a r ) X Minutes  33) = 4 . 3 5 , £ < .0448. t e s t s of  and low r e a c t o r final  intervals.  primary i n t e r e s t .  33) = 5 . 1 2 , £ < . 0 3 0 3 , and V i s i t s  (linear),  decrease  H i g h v e r s u s l o w h e a r t r a t e r e a c t o r s showed no  i n MAP a c r o s s s h o r t v e r s u s l o n g i n t e r - s t r e s s o r  Trials  display a greater  b a s e l i n e a d j u s t e d c e l l means i n d i c a t e d t h a t t h e  groups d i d not d i f f e r  stress task.  T a s k 1 ANCOVA.  i n MAP d u r i n g t h e f i n a l m i n u t e o f  These r e s u l t s are d i s p l a y e d i n Appendix The T a s k 1 ANCOVA i n v o l v e d c o n d i t i o n s  groups as between group f a c t o r s , The summary ANCOVA t a b l e i s  high the  24.  and  reactivity  and V i s i t s and M i n u t e s as r e p e a t e d m e a s u r e s .  presented i n Appendix 2 1 .  was b a s e d on MAP r e a d i n g s t a k e n d u r i n g t h e f i r s t S i g n i f i c a n t main e f f e c t s were found f o r  The M i n u t e s  variable,  s t r e s s t a s k i n each  conditions,  visit.  F_(l, 62) = 4 . 9 7 , £ <  -  .0294,  r e a c t i v i t y groups,  F(l,  62) = 3 9 . 8 8 , £ < . 0 0 0 1 , V i s i t s ,  3 7 . 0 7 , _p_ < . 0 0 0 1 , a n d M i n u t e s , F ( 2 , B a s e l i n e MAP was s i g n i f i c a n t l y effects,' F(l,  visit.  second minute of  the M i n u t e s main e f f e c t  64) = 1 2 . 5 0 , £ < .0008.  the s t r e s s task p e r i o d .  q(64) = 2.87,  m i n u t e s 2 t o 3 were n o t  r = 2, £ <  significant.  63) =  e x p o s u r e c o n d i t i o n and  yielded a  the  significant  MAP was h i g h e s t  the  I n c r e a s e s i n MAP f r o m m i n u t e 1 t o decreases  63) = 9 . 1 2 , £ < .0037 i n t e r a c t i o n showed g r e a t e r  from  low r e a c t o r s .  was  d e c r e a s e s i n MAP  The a c r o s s v i s i t MAP means w e r e 97 a n d 9 0 mm Hg f o r  0  during  . 0 5 , were s i g n i f i c a n t w h i l e  High heart rate r e a c t o r s  87 a n d 8 5 mm Hg f o r  across  high reactors  S i g n i f i c a n t Groups X C o n d i t i o n s  and  X Minutes,  128) = 4 . 4 3 , £ < . 0 1 6 3 , e = .920 and Groups X C o n d i t i o n s X M i n u t e s  (linear),  F_(l, 6 4 ) = 6 . 8 0 , £ < . 0 1 1 4 , i n t e r a c t i o n s w e r e a l s o  Groups X C o n d i t i o n s between-group exposure  X Minutes i n t e r a c t i o n i s  differences  found.  displayed in Figure  i n MAP a c r o s s m i n u t e s w e r e g r e a t e s t  18.  The repeated  condition.  Significant  between group d i f f e r e n c e s  Task 1 i n the second Visit  2 ANCOVA.  measures.  i n MAP r e m a i n e d d u r i n g t h e f i n a l  2 MAP ANCOVA i n v o l v e d c o n d i t i o n s  v a r i a b l e s and t r i a l s and m i n u t e s as  The summary ANCOVA i s  were found f o r  means. minute  visit.  The v i s i t  groups as between-group  effects  The  i n the  S c h e f f e ' s t e s t s were used t o compare b a s e l i n e - a d j u s t e d c e l l s  of  F(l,  significant.  The V i s i t s X G r o u p s , F ( l ,  F(2,  i n both the s i n g l e  main  H i g h h e a r t r a t e r e a c t o r s a l s o d i s p l a y e d h i g h e r MAP v a l u e s .  quadratic trend, F ( l ,  visits.  1 2 8 ) = 5 . 7 0 , _p_ < . 0 0 5 4 , e = . 9 2 0 .  r e l a t e d t o t h e c o n d i t i o n s and groups  MAP was h i g h e r  A t r e n d a n a l y s i s of  m i n u t e 2,  F ( l , 63) =  62) = 4 4 . 6 4 , £ < .0001 and t h e V i s i t s m a i n e f f e c t ,  4.72, £ < .0336. first  no -  presented i n Appendix  the Groups, F ( l ,  22.  and  reactivity  repeated Significant  6 2 ) = 9 . 8 3 , £ < . 0 0 2 6 , and  main  Trials,  Ill  FIGURE 18.  TASK 1 MEAN ARTERIAL PRESSURE CONDITIONS X MINUTES X GROUPS 100 T  CT  95  H  E E oc  z> CO CO UI  oc  90 H  Q.  <  oc UI  I—  oc < 85H  Legend  80-  A X • B  T  1  2  MINUTES  ~T~ 3  COMD t/HI HR REACTORS COHD VLO HR REACTORS COUP 3/HI HR REACTORS COHD 2 A j Q HR REACTORS  112  F(2,  127) = 5.04, £ < .0089, e = .951 v a r i a b l e s .  C o n d i t i o n s and M i n u t e s were n o t s i g n i f i c a n t . significant  c o v a r i a t e of  and t h e l i n e a r ,  F(l,  < .0001 t r e n d s of  = 2 , _p_ < . 0 5 .  £  the t r i a l s  indicated significant,  1 to t r i a l  2, and from t r i a l  These were T r i a l s  63) = 1 7 . 4 6 ,  r_ = 2 ,  trials.  2 t o t r i a l 3 , q ( 1 2 7 ) = 4 . 9 2 , r_ 23.  Two  ( l i n e a r ) X Groups X C o n d i t i o n s ,  In a d d i t i o n ,  (linear), F(l,  £  decreases  significant  F(l,  64) -  5.15,  D e c r e a s e s i n MAP a c r o s s m i n u t e s v a r i e d i n v e r s e l y a s a f u n c t i o n  (quadratic),  two t r e n d i n t e r a c t i o n s w h i c h w e r e n o t These were T r i a l  64) = 7 . 5 3 , £ < . 0 0 7 9 , and T r i a l s  of of  (linear)  X  ( l i n e a r ) X Minutes  F ( l , 64) = 6 . 9 3 , £ < .0106.  Scheffe's  t e s t were employed t o compare c e l l means.  i n the repeated s t r e s s o r c o n d i t i o n s d u r i n g the f i n a l minute of d i s p l a y e d i n Appendix Summary o f  the f i n a l  showed no s i g n i f i c a n t stress task.  H i g h and low difference  reactors i n MAP  The S c h e f f e v a l u e s  are  24.  ANCOVA E f f e c t s .  c o v a r i a n c e were computed f o r  effects,  a  X M i n u t e s , _F(4, 2 5 6 ) = 4 . 1 3 , £ <  p r i m a r y i n t e r e s t w e r e f o u n d t o be s i g n i f i c a n t .  summary o f  F(l,  q(127) = 3.25,  These r e s u l t s a r e d i s p l a y e d i n Appendix  t h e number o f  Minutes  b a s e l i n e was  variable.  e = . 9 6 2 , and M i n u t e s  < .0266.  for  t h e g r o u p s v a r i a b l e , F_(l, 6 2 ) = 1 5 8 . 6 6 , £ < . 0 0 0 1 ,  i n t e r a c t i o n s were f o u n d . .0033,  Pre-task  6 3 ) = 1 5 . 7 , _p_ < . 0 0 0 2 a n d q u a d r a t i c ,  Newman-Keuls t e s t s i n MAP f r o m t r i a l  The m a i n e f f e c t s  the s i g n i f i c a n t  trend effects,  As p r e v i o u s l y n o t e d , t h r e e a n a l y s e s  each of  the four  ANCOVA t e r m s i s  and i n t e r a c t i o n s  v a r i a b l e a r e summarized i n the f o l l o w i n g The e x p e r i m e n t a l c o n d i t i o n s e x p o s u r e showed a s i g n i f i c a n t DBP a n d MAP d u r i n g T a s k 1 .  variable,  main e f f e c t  dependent measures.  presented i n Table 15.  i n v o l v i n g the r e a c t i v i t y  of An  overall  The  main  groups  section. i.e,  repeated exposure versus  on h e a r t r a t e d u r i n g v i s i t  single  2 a n d on  The r e a c t i v i t y g r o u p s v a r i a b l e was s i g n i f i c a n t  on  -  113  -  TABLE 15 Summary o f C o n d i t i o n  1, T a s k 1 and V i s i t  Dependent Effect  HR  SBP  conditions (c) groups (g) vist trials (t) m i n u t e s (m) t(lin) t(quad) m(lin) m(quad) c x g v x g g x t g x m baseline V x t V x t x g v x m t x m t x m x g v x c X m x c x g t x m x c  V2 C1.T1.V2 Cl.Tl C1.V2 C1.T1.V2 Cl Cl C1,T1,V2 Cl  C1.T1.V2 Cl.Tl C1.V2 C1.T1.V2 Cl Cl Tl C1.T1.V2  Cl.Tl Cl C1,T1,V2 Cl Cl Cl Cl.Tl C1.V2 V2 Tl  2 ANCOVA E f f e c t s  Measure DBP  MAP  Tl C1.T1.V2 Cl.Tl V2 Cl Cl Cl C1,T1,V2  Tl Cl.Tl Cl.Tl C1.V2 Cl.Tl Cl Cl Cl Cl.Tl  Cl.Tl  C1,T1  Cl.Tl  Tl Cl Cl  Cl Cl  C1.V2 Cl  V2  V2 V2  C l = C o n d i t i o n 1 ANCOVA T l = T a s k 1 ANCOVA V2 = V i s i t 2 ANCOVA  T1.V2  - 114 "  measures of HR, SBP, DBP, and MAP for each of the three sets of analyses of covariance.  The V i s i t s repeated measure was s i g n i f i c a n t for each of the four  dependent measures in both the Condition 1 and Task 1 ANCOVAs. effects were found for the T r i a l s v a r i a b l e .  Similar  Heart rate and SBP measures  showed s i g n i f i c a n t Minutes effects for each analysis of covariance.  DBP and  MAP showed a Minutes effect during the Condition 1 ANCOVA. S i g n i f i c a n t l i n e a r and quadratic trends were found for the T r i a l s variable for  each of the four cardiovascular dependent measures during the Condition 1  ANCOVA.  The Minutes variable displayed a l i n e a r trend for heart rate across  analyses, and a s i g n i f i c a n t quadratic trend for SBP, DBP and MAP during each analysis. A s i g n i f i c a n t V i s i t s X Groups i n t e r a c t i o n was found for each of the four dependent measures during each a n a l y s i s .  The Minutes X Groups i n t e r a c t i o n was  s i g n i f i c a n t for heart rate only during each a n a l y s i s .  A s i g n i f i c a n t groups X  t r i a l s interaction was found for heart rate i n the repeated exposure condition.  A l l other T r i a l s X Groups and Conditions X Groups interactions  were consistently  non-significant. DISCUSSION  The r e s u l t s of the present study indicate that heart rate and blood pressure responses to a repeated mental arithmetic plus noise decrease both within and across experimental sessions.  stressor  High s y s t o l i c and  heart rate r e a c t i v e , normotensive women displayed greater i n i t i a l r e a c t i v i t y and greater decreases i n responsivity to the repeated stressor than did low reactors.  Stress response l e v e l s i n V i s i t 2 were only minimally different i n  subjects exposed to one versus three stress tasks i n V i s i t 1.  In general,  measures of cardiovascular baseline r e a c t i v i t y , stress response and recovery l e v e l s were not correlated with psychological s e l f - r e p o r t measures of stress  - 115 -  task perceptions.  The age of the subject was s i g n i f i c a n t l y related to  d i a s t o l i c blood pressure l e v e l s during post stress recovery periods.  Aerobic  fitness and l e v e l of physical a c t i v i t y were correlated with heart rate a c t i v i t y l e v e l s through a l l phases of the study. The experimental results and their significance with respect to the present experimental hypotheses are discussed i n the following  sections.  F i r s t , relevant subject c h a r a c t e r i s t i c s and the composition of the cardiovascular r e a c t i v i t y groups are reviewed.  Second, the nature of the  cardiovascular baseline, r e a c t i v i t y , stress response and recovery values and their i n t e r c o r r e l a t i o n s are discussed.  Third,  the descriptive c h a r a c t e r i s t i c s  of the s e l f - r e p o r t measures and the correlations between the cardiovascular response measures and task perceptions are presented.  Fourth, the results of  the analyses of covariance, trend analyses, and post-hoc tests for each of the Condition 1, Task 1 and V i s i t 2 types of ANCOVAs are discussed.  Finally, a  summary of the major conclusions pertaining to each experimental hypothesis and suggestions regarding future research are presented. Subject C h a r a c t e r i s t i c s and Reactivity Groups Ninety, normotensive female subjects participated i n the present study. The mean resting blood pressure l e v e l s for the present sample were s l i g h t l y lower than blood pressure norms for women of similar age. blood pressure l e v e l s ,  Given the resting  age (17-45 y r s . ) and weight (86-170 l b s . ) of the  subjects involved i t can be assumed that the present sample i s of a normal, healthy female population.  representative  This i s further strengthened by the  fact that subjects with a previous history of cardiovascular problems or with current use of cardioactive medications were excluded. The number of subjects who were menstruating and/or taking b i r t h control p i l l s decreased s l i g h t l y from V i s i t 1 to V i s i t 2.  Previous researchers  - 116 -  ( C a r r o l l et a l . , 1984) have noted i n d i v i d u a l - s p e c i f i c l e v e l s of cardiovascular r e a c t i v i t y across menstrual cycles.  This finding i s supported by the r e s u l t s  of the present study which found a s i g n i f i c a n t amount of i n d i v i d u a l s p e c i f i c i t y in heart rate r e a c t i v i t y and to a lesser extent i n s y s t o l i c pressure r e a c t i v i t y across a single four-week menstrual c y c l e .  The presence  or absence of b i r t h control medication and/or menstruation were not s i g n i f i c a n t l y correlated with r e a c t i v i t y , stress response or recovery  levels.  The apparent s h i f t of a larger proportion of low r e a c t i v i t y subjects to the no b i r t h control non-menstruation groups during V i s i t 2 warrants further research. Subjects i n the present study reported a mean physical a c t i v i t y l e v e l of 7.1/10 and a mean self-perceived fitness l e v e l of 6.45/10. subjects'  As expected the  self-reported l e v e l of physical a c t i v i t y and self-perceived aerobic  fitness l e v e l were s i g n i f i c a n t l y correlated.  While previous authors  (Hollander & Seraganian, 1984) have noted that aerobic fitness l e v e l was s i g n i f i c a n t l y correlated with post task heart rate recovery l e v e l s ,  the  present study found that both fitness measures were s i g n i f i c a n t l y correlated with stress response and recovery heart rate values.  Aerobic fitness was more  strongly related to heart rate recovery than to stress response l e v e l s .  The  magnitude of these correlations increased with the number of stress tasks and recovery periods administered.  Heart rate during the i n i t i a l stress task was  not s i g n i f i c a n t l y correlated with the fitness measures.  It appears that the  magnitude of decreases i n heart rate responsivity to repeated stress vary as a function of one's aerobic fitness l e v e l .  Given the nature of the fitness  measures administered i n the present study, these findings should be cautiously interpreted.  The possible preventive effects of aerobic exercise  on cardiovascular responses to psychological stress should however continue to be explored.  The apparent lack of relationship between blood pressure  - 117  -  r e a c t i v i t y and aerobic fitness i n response to a mental arithmetic stressor  is  consistent with previous findings (Lake, Suarez, Schneiderman, & T o c c i , 1985). As previously noted, subjects i n the present study ranged i n age from 17-45 years.  I t i s interesting to note that within a normotensive sample  covering a r e l a t i v e l y limited age range (28 y r s . ) age was found to be s i g n i f i c a n t l y correlated with both stress response and recovery period blood pressure l e v e l s for subjects i n the single stressor condition. of these correlations was consistent across s y s t o l i c , a r t e r i a l pressure measures (r_ = ,40 to r = .62).  The magnitude  d i a s t o l i c , and mean  During V i s i t 1 age was  s i g n i f i c a n t l y correlated with recovery period blood pressure l e v e l s only for subjects i n the repeated stressor condition.  For subjects i n the  single  stressor condition age was related to the magnitude of their stress t a s k and recovery period blood pressure l e v e l s .  During V i s i t 2 age was related to  recovery but not to stress response l e v e l s .  D i a s t o l i c blood pressure l e v e l s  of subjects i n the repeated stressor condition were s i g n i f i c a n t l y correlated with age for recovery period values during V i s i t 2. several conclusions.  These findings suggest  F i r s t , blood pressure and heart rate responses to stress  were not s i m i l a r l y affected by increases i n age. rate and age was found.  No c o r r e l a t i o n between heart  Second, on an o v e r a l l basis age was more  s i g n i f i c a n t l y related to cardiovascular recovery from stress than to r e a c t i v i t y or the stress response l e v e l .  Heart rate and s y s t o l i c  were not s i g n i f i c a n t l y correlated with age.  reactivity  T h i r d , the presence of  s i g n i f i c a n t correlations between age and d i a s t o l i c pressure during the f i r s t , second and t h i r d post-stress recovery periods i n V i s i t 2 for subjects i n the repeated stressor condition suggests that the effects of age on d i a s t o l i c responsivity may increase as the number of stressor repetitions  increases.  These findings j u s t i f y the use of age as a covariate i n analyses of repeated  - 118  -  stressor effects as was done i n the present study.  The absence of  significant  correlations between heart r a t e , s y s t o l i c pressure and mean a r t e r i a l pressure and age during post-stress recovery suggests that changes i n peripheral resistance may mediate these i n t e r a c t i o n s . Subjects were c l a s s i f i e d as either high or low cardiovascular reactors on the basis of their change i n heart rate and s y s t o l i c blood pressure.  Subjects  i n the upper and lower t e r c i l e s of the d i s t r i b u t i o n of r e a c t i v i t y scores were assigned to the high and low reactor groups. several improvements over previous studies.  This procedure represents F i r s t , the present d e f i n i t i o n of  change minimizes the effect of anticipatory arousal on stress response l e v e l s i n that s p e c i f i c ,  pre-task instructions were not administered u n t i l after  completion of the adaptation period.  the  These instructions were then followed by  a p o s t - i n s t r u c t i o n , pre-task waiting period.  The potential effect of  differences i n i n i t i a l values was further controlled in that values from the f i n a l two minutes of the adaptation period were treated as a covariate i n a l l subsequent analyses of cardiovascular data.  Second, the inclusion of multiple  measures of cardiovascular r e a c t i v i t y revealed a complete overlap of the high heart rate and high s y s t o l i c r e a c t i v i t y groups, and a 91% overlap of the low heart rate and low s y s t o l i c r e a c t i v i t y groups. as low s y s t o l i c ,  high heart rate reactors.  Three subjects were c l a s s i f i e d  While previous authors (Manuck &  Schaeffer, 1978; Manuck & Garland, 1980) have employed both heart rate and s y s t o l i c blood pressure as measures of r e a c t i v i t y the overlap between these two response dimensions was not assessed.  This overlap i n heart rate and  s y s t o l i c pressure a c t i v i t y seems to r e f l e c t the common influence of sympathetic mediation of cardiovascular changes (Lacey & Lacey, 1966). A subsequent analysis of the c o r r e l a t i o n between r e a c t i v i t y to the f i r s t stress task i n each of the two experimental sessions revealed a c o r r e l a t i o n of  - 119 -  .67 for heart rate and .32 for s y s t o l i c r e a c t i v i t y across v i s i t s .  These  correlations suggest that f i r s t v i s i t heart rate r e a c t i v i t y explains approximately four times as much of the variance i n second v i s i t responses as does s y s t o l i c r e a c t i v i t y .  Given the r e l a t i v e ease of measurement, low cost  and apparent r e l i a b i l i t y of heart rate measures, i t appears that heart rate would be the measure of choice i n analyses of cardiovascular r e a c t i v i t y to stress.  The use of SBP r e a c t i v i t y as a c l a s s i f i c a t i o n variable i s recommended  for analysis of heart rate data only. Equal numbers of high and low heart rate and s y s t o l i c reactors were assigned to each of the two experimental conditions.  The c u t - o f f points for  the high (>+27 bpm) and low (<+15 bpm) heart rate r e a c t i v i t y t e r c i l e s are similar to those reported i n previous mental arithmetic paradigms (Linden et al.,  1985).  of i n t e r e s t .  The wide range of heart rate r e a c t i v i t y i n the present study i s The responses of subjects i n the high reactor groups ranged from  +27 to +67 beats per minute, while the responses of low reactors ranged from +15 to -3 bpm.  Within the high reactor group one would argue that an increase  of 67 beats may be more c l i n i c a l l y s i g n i f i c a n t than one of 27 beats per minute.  At the very least one i s struck by the v a r i a b i l i t y i n responses of a  group already singled out as the upper t e r c i l e of the d i s t r i b u t i o n of heart rate r e a c t i v i t y scores. t h i s group may affect  The presence of extreme scores or o u t l i e r s within  the v a l i d i t y of between group analyses.  During V i s i t 2  the d i s t r i b u t i o n of HR r e a c t i v i t y was much more leptokurtic and p o s i t i v e l y skewed.  This change i n the shape of the d i s t r i b u t i o n provides further  evidence of the i n s t a b i l i t y of the upper end of the f i r s t v i s i t HR r e a c t i v i t y scores. The range of s y s t o l i c blood pressure r e a c t i v i t y in the present study requires similar attention.  Previous authors have c l a s s i f i e d individuals i n  - 120  -  terms of blood pressure r e a c t i v i t y (Manuck & Schaeffer, 1978; Manuck & Garland, 1980).  However, SBP r e a c t i v i t y has not previously been employed as a  c l a s s i f i c a t i o n variable i n the analysis of heart rate data.  The responses of  subjects i n the high s y s t o l i c r e a c t i v i t y group ranged from +18 mm Hg to +42 mm Hg.  While the number of high SBP reactors decreased i n the second  session,  the o v e r a l l shape of the d i s t r i b u t i o n of SBP r e a c t i v i t y did not change s i g n i f i c a n t l y across sessions.  Numerous authors have provided evidence of  fluctuations i n s y s t o l i c blood pressure of up to 30 mm Hg during normal daily activities  (Harshfield et a l . , 1982).  Given such "normal" fluctuations i n SBP  i t may be d i f f i c u l t to argue that the magnitude of SBP responses shown by the high SBP reactors i n the present study i s predictive of increased cardiovascular r i s k .  The study of i n d i v i d u a l s who are both high reactors to  laboratory-induced psychological stress and highly l a b i l e during d a i l y a c t i v i t i e s may serve to reveal a better predictive l i n k to heart disease. Cardiovascular Dependent Measures The means and standard deviations of the cardiovascular dependent measures and the correlations between baseline,  stress response and r e a c t i v i t y l e v e l s  are presented i n Tables 6 and 11, respectively.  As previously noted, the  magnitude of heart rate and s y s t o l i c pressure responses observed are t y p i c a l of responses to a mental arithmetic task (see Table 2).  The fact that the  mental arithmetic plus noise stressor produced approximately equal increases in SBP, DBP and MAP l e v e l s i s somewhat discrepant with the t y p i c a l pattern of blood pressure responses associated with an active coping task (cf. 1981).  Obrist (1981) predicts smaller d i a s t o l i c than s y s t o l i c  Obrist,  responses.  Linden et a l . (in press) noted however that t h i s difference may be a t t r i b u t a b l e to O b r i s t ' s use of a shock avoidance paradigm rather than mental arithmetic.  - 121  -  Inspection of the c o r r e l a t i o n between cardiovascular baseline measures within sessions revealed s i g n i f i c a n t correlations (r_ = .67 to _r = .90) between each of the three pressure measures. stable,  These correlations provide evidence of  i n d i v i d u a l - s p e c i f i c baseline blood pressure l e v e l s .  In contrast,  heart rate baseline was s i g n i f i c a n t l y correlated with SBP and MAP baseline during V i s i t 2 only.  This finding confirms the d i r e c t i o n a l fractionation of  HR and DBP measures and the r e l a t i v e independence of their control mechanisms. The magnitude of within-session  stress task l e v e l correlations between the  cardiovascular dependent measures i s t y p i c a l of those reported elsewhere (Foerster et a l . , 1983).  Blood pressure l e v e l s during the f i r s t stress task  within each session were highly c o r r e l a t e d .  HR, SBP and MAP stress task  l e v e l s were correlated during the f i r s t session only.  These r e s u l t s are  i n d i c a t i v e of i n d i v i d u a l - s p e c i f i c effects on blood pressure stress response levels.  The s i m i l a r i t y i n magnitude of these correlations within each session  reflects  some r e l a t i v e s t a b i l i t y of blood pressure control mechanisms.  The  absence of a s i g n i f i c a n t c o r r e l a t i o n between HR, SBP and MAP l e v e l s during the f i r s t task i n V i s i t 2 however suggests a lack of response s t a b i l i t y which may be due to differences i n habituation of heart rate and blood pressure across the two sessions. An analysis of the across session baseline, l e v e l s i s presented i n Table 11.  stress response and r e a c t i v i t y  Baseline measures were stable across the  four-week i n t e r v a l for each of the four dependent measures (_r = .63). Responses to the f i r s t task were also consistent  (r = .70).  These findings  are supportive of those of previous researchers (Lacey & Lacey, 1966; Manuck & Schaeffer, 1978; Manuck & Garland, 1980) who noted that subjects displayed r e l a t i v e l y stable, i d i o s y n c r a t i c a l l y determined cardiovascular response l e v e l s during psychological s t r e s s .  As previously noted, heart rate r e a c t i v i t y (r_ =  - 122  -  .66) proved to be more r e l i a b l e than s y s t o l i c r e a c t i v i t y (r = .32) as a measure of stable across session cardiovascular r e a c t i v i t y .  DBP and MAP  r e a c t i v i t y were not s i g n i f i c a n t l y correlated across sessions.  Manuck and  Garland (1980) also found i n s t a b i l i t y of DBP r e a c t i v i t y across a s i m i l a r time i n t e r v a l suggesting the involvement of different or more complex control mechanisms. Self-Report Measures The mean scores for ratings of perceived stress (PS), perceived performance (PP), perceived task d i f f i c u l t y (PD), and perceived importance of the task (PI) r e f l e c t the fact that on average subjects perceived the mental arithmetic plus noise stressor to be important, s t r e s s f u l and d i f f i c u l t . During the second v i s i t ratings of PP and PI increased while ratings of PS and PD decreased.  While these changes were not s t a t i s t i c a l l y  s i g n i f i c a n t they do  suggest the possible presence of practice effects and changes i n task appraisal across sessions. The lack of c o r r e l a t i o n between psychological s e l f - r e p o r t and cardiovascular response measures i s consistent with reports elsewhere (Linden, in press; Linden et a l . , i n press).  In the present study only heart rate  r e a c t i v i t y and recovery rate were correlated with PI and PP, respectively V i s i t 2.  in  Subjects who appraised the task to be more important were more  highly r e a c t i v e .  Linden et a l . ( i n press) suggested that the academic-like  nature of a mental arithmetic task may serve to influence perceptions of task performance and importance in some subjects.  The results of the present study  suggest that HR recovery from repeated stress i s influenced by one's perception of task performance such that self-perceptions delay heart rate recovery.  of poor performance  Such delay i n heart rate recovery i f chronic may  lead to p o t e n t i a l l y pathogenic i n s u l t to the cardiovascular system.  -  123=-  Condition 1 ANCOVAs The r e s u l t s of the Condition 1 (repeated exposure) ANCOVA for each of the four cardiovascular dependent measures are discussed i n the following section.  The average heart rate and SBP l e v e l s displayed by" the high s y s t o l i c  and high heart rate reactors were consistently higher than those of low reactors across v i s i t s ,  t r i a l s and minutes within Condition 1.  Significant  v i s i t s X groups, t r i a l s X groups and minutes X groups interactions also indicated that high s y s t o l i c reactors showed greater decreases i n HR across each of the repeated measures.  It i s important to note that differences were  independent of i n i t i a l response l e v e l s i n that baseline measures were treated as a covariate i n a l l analyses.  High s y s t o l i c reactors appear to be more  sympathetically l a b i l e than do low reactors. The blood pressure X HR r e a c t i v i t y interactions are less consistent.  The  v i s i t s X groups interaction on each of the three pressure measures indicated that high HR reactors displayed greater decreases i n blood pressure across the four-week i n t e r - v i s i t i n t e r v a l .  The absence of s i g n i f i c a n t t r i a l s X groups or  minutes X groups interactions suggests that changes i n blood pressure occur more slowly than do changes i n heart rate.  The time span involved i n a given  experimental session may not have been s u f f i c i e n t for between group differences i n blood pressure to become evident. Each of the four dependent measures showed s i g n i f i c a n t T r i a l s ( l i n e a r ) and T r i a l s (quadratic) e f f e c t s .  While Figures 1, 4, 7 and 10 indicate that  decreases i n cardiovascular responsivity across T r i a l s are primarily l i n e a r i n nature, the s i g n i f i c a n t quadratic trend indicates that heart rate and blood pressure show the greatest decreases from t r i a l 1 to t r i a l 2.  This r e s u l t  is  supported by the r e s u l t s of the Newman-Keuls test between l e v e l s of the t r i a l s variable.  Heart rate displayed similar l i n e a r and quadratic trends with  _  respect to the minutes v a r i a b l e .  124 _  The greatest decreases in heart rate  occurred from minute 1 to minute 2 within a given t r i a l .  The trend analysis  of the blood pressure data across minutes revealed a s i g n i f i c a n t quadratic trend.  Blood pressure l e v e l s were generally highest during the second minute  of each task.  These results provide further evidence of the slower-changing  nature of blood pressure responses.  Task-induced arousal did not become  evident u n t i l the second minute of each task period. Scheffe's tests indicated that high and low HR reactors differed only i n terms of SBP during the f i n a l minute of the f i n a l task. or MAP were found.  No differences i n DBP  High and low SBP reactors did not d i f f e r i n heart rate  during the f i n a l minute.  It appears that between group differences i n HR, DBP  and MAP disappear over the presentation of six stressor t r i a l s .  The use of  cardiovascular r e a c t i v i t y as a c l a s s i f i c a t i o n measure i n the analysis of cardiovascular responses to a repeated stressor may be confounded by the greater habituation of responses i n the high reactor groups. Task 1 ANCOVAs The results of the Task 1 (Conditions X Groups X V i s i t s X Minutes) ANCOVAs for HR, SBP, DBP and MAP measures are discussed i n the following section.  The  Task 1 ANCOVAs yielded main effects for groups, v i s i t s and t r i a l s s i m i l a r to those i n the Condition 1 ANCOVA for HR, SBP and MAP measures.  The minutes  effect displayed a s i m i l a r l i n e a r trend for HR and quadratic trend for blood pressure measures.  Several results were unique to the Task 1 analyses.  The repeated versus single exposure conditions variable yielded main effects on measures of DBP and MAP such that responses were lower i n the repeated stressor condition.  HR and SBP measures taken during the f i r s t task  in the second v i s i t were not affected by varying amounts of prior exposure to the stressor.  These results suggest that HR and SBP outcome measures  ~  125 "  involving the single presentation of a psychological stressor i n each of two sessions w i l l not provide evidence of the potential effects of prior exposure to the stressor. V i s i t 2 ANCOVAs The r e s u l t s of the V i s i t 2 (conditions X groups X t r i a l s X minutes) ANCOVAs are discussed i n the following section.  The V i s i t 2 ANCOVAs yielded  main effects for groups, t r i a l s and minutes for HR and SBP s i m i l a r to those i n the Condition 1 analyses.  DBP and MAP showed main effects for groups and  t r i a l s only. Within V i s i t 2 the condition variable yielded a main effect for HR only. Heart rate was lower i n those subjects who had undergone repeated stress tasks in V i s i t 1.  The absence of a conditions effects on blood pressure measures  suggests that habituation of blood pressure measures across a four-week i n t e r v a l i s more resistant to the effect of varying exposure to the stress task. No s i g n i f i c a n t l i n e a r or quadratic trends were found for the t r i a l s effect within V i s i t 2.  Blood pressure responses yielded s i g n i f i c a n t minutes  (quadratic) trend e f f e c t s .  The absence of s i g n i f i c a n t t r i a l trends suggests  that as the number of stressor t r i a l s increases the patterns of habituation of HR and blood pressure responses becomes more v a r i a b l e . A comparison of high versus low reactors during the f i n a l minute of the f i n a l task i n V i s i t 2 showed no differences i n HR, DBP and MAP for subjects i n the repeated stressor condition. single task condition. i n both conditions.  Between group differences remained i n the  Between group differences i n SBP remained for subjects  As previously noted, the lack of r e l i a b l e between group  differences after r e l a t i v e l y few stress tasks presents problems for the u n c r i t i c a l use of cardiovascular r e a c t i v i t y as a c l a s s i f i c a t i o n v a r i a b l e .  - 126 ~  Major Conclusions and Recommendations The aforementioned experimental hypotheses and major conclusions regarding each hypothesis are l i s t e d i n the following section.  In a d d i t i o n , outstanding  issues and recommendations regarding future research are discussed. F i r s t , i t was hypothesized that both heart rate and blood pressure would decrease within and across experimental sessions. .001) main effects for v i s i t s ,  The highly s i g n i f i c a n t (_p_ <  t r i a l s and minutes on each of the four  dependent measures provides strong support for t h i s hypothesis.  Second, i t  was hypothesized that high reactors would show greater decreases i n heart rate and blood pressure than low reactors across l e v e l s of the repeated measures. The most r e l i a b l e effect was the s i g n i f i c a n t v i s i t s X groups i n t e r a c t i o n which indicated that high reactors showed greater decreases across v i s i t s on each of the four cardiovascular dependent measures.  A groups X t r i a l s effects was  found for HR only i n the repeated stressor condition. effects was also found for a l l HR ANCOVAs.  A groups X minutes  Between group differences i n blood  pressure were mot evident on a within-session basis.  I t was also hypothesized  that repeated exposure to the stressor would f a c i l i t a t e cardiovascular habituation.  No support for t h i s hypothesis was found i n that one-way  interactions between the conditions variables and the repeated measures were non-significant.  There was p a r t i a l support for the hypothesis that repeated  exposure would have a greater effect on the high r e a c t i v i t y groups. Significant conditions X v i s i t s X groups and conditions X minutes X groups interactions were found for HR i n the Task 1 ANCOVA and for DBP i n V i s i t 2, respectively.  High reactors showed greater decreases i n heart rate during the  f i r s t task across v i s i t s i n the repeated stressor condition.  They also  displayed greater decreases i n DBP across minutes of the f i r s t task i n V i s i t 2, Condition 1.  - 127-  The results of the present study indicate that highly reactive show the greatest decreases i n cardiovascular response l e v e l s .  subjects  Bohlin (1973)  i n a review of factors influencing cardiovascular habituation, had concluded that increases i n arousal produce a corresponding delay i n physiological habituation.  I t appears that the l e v e l of arousal produced by the present  stressor was not s u f f i c i e n t to produce a delay i n response habituation.  High  reactors were generally more l a b i l e than low reactor throughout a l l phases of the experimental sessions.  Acute r e a c t i v i t y to an i n i t i a l stress task may  represent only one facet of an o v e r a l l pattern of increased cardiovascular lability. The hypothesized s i g n i f i c a n t negative c o r r e l a t i o n between cardiovascular habituation and length of i n t e r - s t r e s s o r i n t e r v a l was found for each of the dependent measures.  The effect was strongest for HR data.  The delayed impact  of the stressor on blood pressure responses complicated the i n t e r p r e t a t i o n of blood pressure data with respect to t h i s  hypothesis.  It was also hypothesized that repeated exposure to the stressor would produce a greater decrease i n the i n i t i a l l e v e l of HR and SBP r e a c t i v i t y during the second session.  HR and SBP r e a c t i v i t y to the f i r s t stress task i n  v i s i t 2 were only s l i g h t l y lower for subjects i n the repeated stressor condition (-2.2 statistically  beats per minute; -0.80 mm Hg).  These differences were not  significant.  The hypothesis of an overlap i n the groups formed by measures of HR and SBP r e a c t i v i t y was strongly supported.  The present evidence also suggests  that HR r e a c t i v i t y i s a more r e l i a b l e across-session  classification variable.  Limited evidence was found in support of the hypothesized relationship between cardiovascular r e a c t i v i t y and task perceptions.  Perceived performance during  V i s i t 2 was negatively correlated with HR recovery l e v e l s ; while HR r e a c t i v i t y  -128  -  was negatively correlated with perceived task importance.  No relationship was  found between blood pressure responses and s e l f - r e p o r t measures of  subjects'  task perceptions. The present study included several methodological improvements and additions to previous studies.  These included:  a)  the use of a female population.  b)  the i n c l u s i o n and comparison of different i n t e r - s t r e s s o r  c)  the i n c l u s i o n and comparison of repeated versus single stress tasks.  d)  the use of multiple dependent measures.  e)  a comparison of HR versus SBP r e a c t i v i t y .  f)  the treatment of age and baseline as covariates.  g)  the use of a d e f i n i t i o n of cardiovascular change which accommodates  intervals.  both the problem of i n i t i a l values and the problem of anticipatory arousal. h)  i t controls for the possible effects of caffeine, exercise,  age, aerobic f i t n e s s ,  menstruation, and b i r t h control or  cardioactive medications on response i)  a l c o h o l , tobacco,  levels.  i t provides an analysis of the relationship between acute cardiovascular r e a c t i v i t y and subsequent response habituation.  The results of the present study c l e a r l y support the majority of the experimental hypotheses.  However they also r a i s e a number of potential  questions for future research.  Future researchers must continue to  distinguish between the s t a t i s t i c a l and c l i n i c a l significance of cardiovascular responses to a given stressor.  Given the large range and  variance within the high HR reactor group, i n d i v i d u a l s at the upper and lower l i m i t s of t h i s group may be at different l e v e l s of cardiovascular r i s k .  Other  researchers (Manuck & Schaeffer, 1978; Manuck & Garland, 1980) have found a  - 129 -  different d i s t r i b u t i o n of HR and SBP r e a c t i v i t y to a concept formation task among male subjects.  These authors employed upper and lower t e r c i l e cut-off  points of +13.4 bpm and +4.0 bpm for heart r a t e , and +20.1 mm Hg and +4.0 mm Hg for SBP r e a c t i v i t y .  The upper t e r c i l e c u t - o f f point for HR r e a c t i v i t y  14..beats lower than that employed i n the present study.  is  This difference i n  cut-off points may r e f l e c t the effects of gender or different tasks.  The  c l i n i c a l appropriateness of a given r e a c t i v i t y c r i t e r i o n remains an open question.  Researchers should explore the predictive v a l i d i t y of various  reactivity c r i t e r i a .  They should also assess the potential benefits of  simultaneously employing multiple response measures i n their attempts to i d e n t i f y r e l i a b l e , predictive r e a c t i v i t y groups.  Krantz and Manuck (1984)  concluded i n a review of the l i t e r a t u r e that cardiovascular r e a c t i v i t y per se was not yet a proven r i s k f a c t o r . The results of the present study also indicate that r e a c t i v i t y group differences i n response l e v e l s are not stable across repeated stress tasks. The question a r i s e s as to how acute r e a c t i v i t y can be predictive of long term r i s k when a r e l a t i v e l y mild, repeated experimental stressor eradicates between group differences i n response l e v e l s .  In the present study high versus low  r e a c t i v i t y groups were not affected d i f f e r e n t l y by single versus repeated exposure to the stress task.  These r e s u l t s pose a question as to the role of  necessary stressor frequency i n the transduction of acute responses into chronic coronary pathology. Aerobic fitness l e v e l was correlated with HR recovery following repeated stress tasks i n the present study.  Age was related to DBP recovery values.  Menstruation and b i r t h control were linked to higher HR and SBP r e a c t i v i t y i n the second experimental session.  Each of these subject c h a r a c t e r i s t i c s ' s h o u l d  be further assessed as potential mediators of cardiovascular responsivity to  - u n -  stress. Finally,  the present r e s u l t s  cardiovascular  indicate  that  significant  habituation  r e s p o n s e s o c c u r s w i t h r e l a t i v e l y few s t r e s s o r  Habituation effects  are r e t a i n e d over a four-week  interval.  presentations. Previous  r e s e a r c h e r s have employed s t r e s s t a s k r e s p o n s e s as p r e - p o s t measures treatment e f f i c a c y .  of a treatment  Decreased response l e v e l s observed during a post-treatment  allow  for  l a b e l l e d as treatment e f f e c t s . comparison of  treatment groups  The u s e o f  intervention. s t r e s s t e s t may be  c o n t r o l groups  R e s e a r c h e r s a r e however s t i l l  i s o l a t i n g treatment versus habituation e f f e c t s  given treatment group.  This problem i s  c o m p l i c a t e d by t h e f a c t  i n d i v i d u a l s d i s p l a y s u b s t a n t i a l h a b i t u a t i o n over the course of task.  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Wright, R . , Contrada, R . , & Glass, D. correlates of Type A behavior. Advances i n Behavioral Medicine. Yelderman, M . , & Ream, A.  (1979).  pressure i n the anesthetized Zwaga, H.  (1973).  ,or stress?  (1984).  Cold pressor  Hypertension, 6^, 301-306.  (in press).  Psychophysiologic  In E . Katkin & S. Manuck ( E d s . ) , Greenwich, CT: J A I . Indirect measurement of mean blood  patient.  Anesthesiology,  50, 253-256.  Psychophysiological reactions to mental tasks: E f f o r t s  Ergonomics, 16(1), 61-67.  - 155 -  APPENDIX 1 CONSENT FORM I, freely and v o l u n t a r i l y and without undue inducement or any element of force, fraud, deceit, or other form of constraint or coercion consent to be a participant i n the research project e n t i t l e d "Habituation and Cardiovascular Responses" to be conducted i n the Cardiovascular Psychophysiology Laboratory in the Kenny Building for 2 experimental sessions each of a duration of 30 to 40 minutes with Dr. W. Linden as p r i n c i p a l investigator. The procedures to be followed and their purposes, including i d e n t i f i c a t i o n of any procedures which are experimental, have been explained to me. As a understand i t , the study i s concerned with the cardiovascular changes. In order to a s s i s t i n obtaining t h i s information, i t w i l l be necessary to undergo the following experiences: 1.  Assignment at random to one of two treatment conditions: (a) single stress or (b) repeated stressor. The stressor w i l l be a mental arithmetic task.  2.  Measurement of heart rate and blood pressure i n the cardiovascular psychophysiology l a b . During the session which w i l l l a s t 30-40 minutes, I w i l l be connected to a non-invasive blood pressure monitor, completely non-dangerous, and only minimally discomforting.  I understand that there are no foreseeable attendant r i s k s i n my p a r t i c i p a t i o n i n t h i s project. I understand that I may refuse to participate or may withdraw at any time without influence on class standing. I also r e a l i z e that a l l information obtained i s s t r i c t l y c o n f i d e n t i a l . While findings may be used i n future studies, there w i l l be no i d e n t i f i c a t i o n of me personally on any permanent records. A l l information w i l l be reported i n group form and w i l l remain s t r i c t l y anonymous. I have been given the right to ask and have received answers on any inquiry concerning the foregoing. Questions, i f any, have been answered to my satisfaction. I have read and understand the foregoing. I have received a copy of this consent form.  Witness  Research Participant  - 156 -  APPENDIX 2 MODIFIED PAR-Q (PHYSICAL ACTIVITY READINESS QUESTIONNAIRE)  1.  Has your doctor ever said you have heart trouble?  Yes  No  2.  Do you frequently suffer from pains in your heart or chest?  Yes  No  3.  Do you f e e l f a i n t or have s p e l l s of severe dizziness?  Yes  No  4.  Has your doctor ever said your blood pressure was too high?  Yes  No  5.  Have you ever taken medication for a heart problem?  Yes  No  6.  Are you presently taking any medications?  Yes  No  7.  Do you smoke?  Yes  No  8.  Do you regularly engage i n vigorous exercise?  Yes  No  Reference:  Par-Q Validation Report B r i t i s h Columbia Department of Health June 1975 (modified version)  - 157 -  APPENDIX 3 POST-STRESSOR QUESTIONNAIRE  You have just completed the stressor phase. We would l i k e to find out how you perceived the experience. Please c i r c l e on the following scales the number which best approximates your view. How do you rate your performance on the mental arithmetic i n comparison to other people with your age and background? 1  2  3  4  5  a lot worse  2.  6  7  8  9  equal  a lot better  How s t r e s s f u l  did you find the mental arithmetic task?  1  3  2  4  5  6  7  8  9  10  not at all  3.  very much so  How d i f f i c u l t did you find the mental arithmetic task? • 1  2  3  4  5  6  7  8  9  not at all 4.  very much so  How much did your current mood influence your performance on the mental arithmetic task? 1  2  3  4  5  6  7  8  9  not at all  5.  10  10 very much so  How important was your performance on the mental arithmetic task? 1 not at all  2  3  4  5  6  7  8  9  10 very much so  - 158 -  APPENDIX 4 EXPERIMENTAL SCRIPT INTRODUCTION H i , I'm and I ' l l be your experimenter for today. As I mentioned on the phone, we are interested i n the physiological events during a 20-minute waiting period, and the events during a mental arithmetic task which i s f a i r l y easy i n nature. I w i l l be asking you to perform the task (CHOOSE APPROPRIATE ONE) CONDITION 1:  3 times for 3 minutes each, with periods of rest i n between  CONDITION 2:  For one 3-minute period  During the 20-minute waiting period, I'd l i k e you to f i l l out some questionnaires for me. The task w i l l be accompanied by 90 db of noise which you w i l l hear over t h i s set of headphones. 90 db i s the maximum l e v e l allowed by the Worker's Compensation Board for an 8-hour working day, so a few minutes w i l l not be harmful. During the experiment, I w i l l be i n the room next door. There i s a one-way mirror behind you, but my primary concern i s not to watch you. There i s also an intercom so I ' l l be able to hear you i f you have any questions. During the experiment, you w i l l be wearing this blood pressure cuff. It's similar to the one used i n a doctor's o f f i c e . Have you had your blood pressure taken before? This cuff automatically expands once every minute. During expansion i t may be rather uncomfortable but that discomfort w i l l go away within 20 seconds or so. The procedure i s safe, so you needn't be concerned. "Now I ' l l put the cuff on. Which hand do you write with? I ' l l put t h i s on your other arm then. I t ' s important that you keep t h i s hand s t i l l during the measurement. When the cuff i s pumping up, some people have an urge to wiggle their fingers around, but the instrument won't function properly i f you do. Please try to remain s t i l l and breathe normally throughout the experiment. For the next 20 minutes, I would l i k e you to f i l l these out while I record your blood pressure and heart r a t e . The time period w i l l begin with the f i r s t expansion of the cuff. I ' l l come i n and l e t you know when i t i s over. I'll also t e l l you how your f i r s t reading i s over the intercom." STRESS TASK "This i s the end of the 20-minute period. "Next w e ' l l be doing the Mental Arithmetic Task. would l i k e you to: (CHOOSE APPROPRIATE ONE)  As I mentioned e a r l i e r , I  CONDITION 1:  Do the task three times for 3 minutes each with three minute resting periods i n between.  CONDITION 2:  Do the task for three minutes and then I ' l l ask you to quietly for f i f t e e n minutes afterward.  sit  -  159 -  "The task w i l l be accompanied by 90 db noise over t h i s set of headphones and I ' l l be asking you to consecutively subtract numbers. I ' l l give you s p e c i f i c instructions i n a moment, but f i r s t w e ' l l start with two minutes of readings to r e - e s t a b l i s h a resting l e v e l , and then I ' l l give you the instructions for the task over the set of headphones." "Can you hear me OK? For the mental arithmetic task, I would l i k e you to continuously subtract aloud, beginning with the number 1,000. For example, you would say "1,000, 993, 986, 979, etc." Please do this as quickly as you can, and i f you get l o s t or confused please begin again at the number 1,000. I would l i k e you to continue trying for the f u l l three minutes. Although you may not be able to hear yourself speaking, I would l i k e you to speak c l e a r l y because I w i l l be l i s t e n i n g to your answers and rating your performance. You can begin as soon as you hear noise through the headphones." "OK, that's the end of the task."  (CHOOSE APPROPRIATE ONE)  CONDITION 1:  Please s i t quietly for three minutes. I ' l l l e t you know when the time i s up, and then I ' l l ask you to do a s i m i l a r task.  CONDITION 2:  Please s i t quietly for another fifteen minutes.  AFTER FINAL THREE MINUTE RESTING PERIOD: (OR FIFTEEN MINUTE RESTING PERIOD FOR CONDITION 2) GIVE SUBJECT "POST STRESSOR" QUESTIONNAIRE "OK, here's a questionnaire that I ' d l i k e you to f i l l out. I ' l l return i n a minute and t e l l you your results and a l i t t l e about the experiment."  - 160 -  APPENDIX 5 Condition I: Heart Rate ANCOVA  Term  F  J2 <  groups (9) heart rate baseline (hbl) age/dbl  30.5A 54.48 28.15  .0000 .0000 .0000  v i s i t (v) V x g hbl  39.34 10.96 29.25  .0000 .0026 .0000  t(lin) t(lin) x g t(quad) t r i a l (t) t x g  13.06 8.53 8.99 34.75 12.31  .0012 .0068 .0056 .0000 .0000  v(lin) x t(lin) v(lin) x t(lin) x g v ( l i n ) x t(quad) x g  10.32 11.25 10.40  .0033 .0023 .0032  V  x t v x t x g  12.47 11.16  .0000 .0001  m(lin) m(lin) x g m(quad) minutes (m) m x g v ( l i n ) x m(lin)  68.27 10.94 8.95 52.56 8.21 12.15  .0000 .0025 .0056 .0000 .0007 .0016  v x m t ( l i n ) x m(lin) t x m  7.09 27.94 11.65  .0018 .0000 .0000  Term(s)  Epsilon Factors  trials, t x g vxt, v x t x g minutes, m x g v x m t x m  .699 .747 .710 .844 .730  Greenhouse-Geisser corrected probability  .0003  .0002 .0004  .0000  .0032  -.161  -  APPENDIX 6 Task I ; Heart Rate ANCOVA  F  •E. <  52.18 27.90 15.44  .0000 .0000 .0000  56.04 18.12 4.39 34.39  .000001 .0001 .0406 .000001  97.66 7.63  .0000 .0077  minutes m x g  66.35 7.40  .0000 .0010  v(lin) x m(lin) v(lin) x m(lin) x g  14.21 11.25  .0004 .0499  7.97  .0006  Term groups hbl age/dbl (v) V  X  g  X g hbl m(lin) m(lin) x g V  X  C  v x m Term(s) minutes, m x g v x m  Epsilon Factors .805 .857  Greenhouse-Geisser corrected probability  .0000 .0022  .0011  - 162 -  APPENDIX 7 V i s i t 2: Heart Rate ANCOVA  F  Term  £<  4.57 15.05 287.10 4.57 146.24  .6369 .0003 .0000 .0370 .0000  hbl (T) T(quad) x g hbl  49.52 6.07 5.20  .0000 .0169 .0264  Trial hbl  12.52 21.96  .0000 .0000  m(lin) m(lin) x g minutes m x g  74.19 9.71 61.53 7.65  .0000 .0029 .0000 .0007  T ( l i n ) x m(lin) T ( l i n ) x m(lin) x c  11.46 4.36  .0013 .0413  T ( l i n ) x m(quad) x g  5.49  .0227  T x M T x mx c T x mx c  4.39 2.57 3.08  .0019 .0385 .0169  condition (c) groups hbl age age/dbl  Term trial minute, m x g txm, t x m x e ,  Epsilon Factor  t x m x g  .782 .742 .739  Greenhouse-Geisser corrected pi  .0001  .0000  .0055 .0500 .0296  -  -  1 6 3  APPENDIX 8 Newman-Keuls Tests of Heart Rate Data Condition 1 Observed Difference Between Means  Comparison trial 1 - trial 3 trial 1 - trial 2 trial 2 - trial 3 minute 1 minute 1 minute 2  minute 3 minute 2 minute 3  C r i t i c a l Value of Q  8.72 6.24 2.48  3.71 3.08 n.s.  10.09 7.00 3.09  4.32 3.59 n.s.  Task 1 minute 1 minute 1 minute 2  minute 3 minute 2 minute 3  11.26 7.70 3.56  1.99 1.67 1.67 Visit 2  trial 1 trial 2 trial 1  trial 3 trial 3 trial 2  minute 1 - minute 3 minute 1 - minute 2 minute 2 - minute 3  11.26 7.70 3.56  1.99 1.67 1.67  7.35 6.44 0.91  2.01 1.67 n.s.  -  164 -  APPENDIX 9 Scheffe's Tests of Heart Rate Data  Condition 1  Contrast  Input Means  high vs low reactors 1st minute, f i n a l task  79.8-76.5  Scheffe Value 1.75  Critical Value  _p  2.05  n.s.  2.02  2.05  n.s.  3.116  2.05  n.s.  Task 1 high vs low reactors/ cond. 1, 3rd minute f i n a l task  83.8-78.7  Visit 2 high vs low reactors/ cond. 1, 1st minute f i n a l task  80.6-75.0  - 165 -  APPENDIX 10 Condition 1: S y s t o l i c Blood Pressure ANCOVA  F_  _p_ <  21.31 124.85 85.17  .0001 .0000 .0000  v v x g Sbl  44.44 7.29 29.77  .0000 .0110 .0000  t(lin) t(quad) trial Sbl  18.43 4.97 18.63 5.09  .0002 .0330 .0000 .0310  v x t m(quad) min  5.20 16.52 7.54  .0080 .0003 .0011  4.78  .0360  Term groups Sbl age/Sbl  v ( l i n ) x t ( l i n ) x m(lin) Term(s) v ( l i n ) x t ( l i n ) x m(lin) v x t minutes m x g  Epsilon Factors .980 .859 .923 .886  Greenhouse-Geisser corrected probability  .0000 .0115 .0016  - 166 -  APPENDIX 11 Task 1: S y s t o l i c Blood Pressure ANCOVA  Term  F  Ii <  70.60 112.63 100.98  .0000 .0000 .0000  V  x g visit hbl  15.48 51.04 6.38  .0002 .0000 .0141  m(lin) m(lin) x g m(quad)  4.06 6.73 18.69  .0481 .0118 .0001  minutes m x g  10.24 5.10  .0001 .0074  4.65  .0348  group hbl age/abl  v ( l i n ) x m(lin)  Term minute, m x g  Epsilon Factor .964  Greenhouse-Geisser corrected probability  .0001 .0081  -  167 -  APPENDIX 12 V i s i t 2: S y s t o l i c Blood Pressure ANCOVA  Term group sbl age/sbl t(lin) x g sbl t ( l i n ) T(quad) x c x g Trial T x c x g sbl m(quad) min Term trial, t x c x g minutes  F  R <  30.69 161.29 104.23  .0000 .0000 .0000  22.41 5.41 3.71 4.05 13.49  .0000 .0232 .0271 .0000 .0004  16.81 7.35  .0001 .0010  Epsilon Factor .898 .975  Greenhouse-Geisser corrected probability  .0317 .0238  .0011  - 168 -  APPENDIX 13 Newman-Kuels Tests of S y s t o l i c Blood Pressure Data  Condition 1 Observed Difference Between Means  Comparison trial 1 trial 1 trial 2 minute 2 minute 2 minute 3  trial 3 trial 2 trial 3 minute 1 minute 3 minute 1  C r i t i c a l Value of Q  8.50 4.75 3.75  3.19 2.65 2.65  < .05 < .05 < .05  2.25 1.50  3.01 2.50 2.50  n.s. n.s. n.s.  2.03 1.69 1.69  < .05 < .05 < .05  4.34 6.42 2.92  2.35 1.95 1.95  < .05 < .05 < .05  10.17 8.00 2.17  1.82 1.51 1.51  < .05 < .05  Task 1 minute 2 minute 2 minute 1  minute 1 minute 3 minute 3  3.75 2.00 1.75 Visit 2  trial 1 - trial 3 trial 2 - trial 3 trial 1 - trial 2 minute 2 - minute 3 minute 1 - minute 3 minute 2 - minute 1  < .05  - 169 -  APPENDIX 14 Scheffe's Tests of S y s t o l i c Blood Pressure Data  Condition 1 Scheffe Value  Contrast  Input Means  high vs low reactors, f i n a l minute, f i n a l task  112.3-107.7  Critical Value  2.42  2.03  2.68  2.032  2.53  2.032  Task 1 high vs low reactors, cond. 2, f i n a l minute f i n a l task  119.0 - 113.7  Visit 2 high vs low reactors/ cond. 1, f i n a l minute f i n a l task  112.8-108.3  - 170 -  APPENDIX 15 Condition 1: D i a s t o l i c Blood Pressure ANCOVA  Term  F  £ <  groups Dbl age/Dbl  12.47 60.15 44.97  .0013 .0000 .0000  visit V x g Dbl  31.53 11.03 13.12  .0000 .0023 .0010  t(lin) t(quad) trial  9.37 7.10 27.67  .0044 .0120 .0000  v(lin) x t(lin) v ( l i n ) x t(quad) v ( l i n ) x t(quad) x g  6.60 9.79 5.96  .0151 .0037 .0203  v x t  5.76  .0050  11.33 5.87 8.05 10.80  .0019 .0045 .0077 .0024  3.11 3.98  .0174 .0044  m(quad) minutes t ( l i n ) x m(lin) t ( l i n ) x m(lin) x g t x m t x m x g Term trial v x t minutes txm, t x m x g  Epsilon Factor .960 .912 .923 .816  Greenhouse-Geisser corrected probability  .0000  .0065  .0057  - 171 -  APPENDIX 16 Task 1: D i a s t o l i c Blood Pressure ANCOVA  Term  F  2. <  conditions groups hbl age/hbl  6.76 41.22 89.62 80.09  .0116 .0000 .0000 .0000  V  x g  34.26 4.38  .0000 .0404  m(quad)  5.54  .0216  V  - 172 -  APPENDIX 17 V i s i t 2: D i a s t o l i c Blood Pressure ANCOVA  Term group dbl age/dbl  F  2. <  12.38 294.90 182.46  .0008 .0000 .0000  dbl (t l i n ) dbl (t quad)  12.97 5.46  .0006 .0226  Trial  14.50  .0000  m(lin) x c x g m (quad)  5.19 4.00  .0260 .0497  m x c x g  3.83  .0243  11.55 4.43  .0012 .0393  6.77  .0000  t(quad) x m(lin) t(quad) x m(quad) x c T x m  Term trial mx c x g t x m  Epsilon Factor .977 .916 .880  Greenhouse-Geisser corrected probability  .0000  .0279  .0001  - 173  -  APPENDIX 18 Newman Kuels Tests of D i a s t o l i c Blood Pressure Data  Condition 1 Comparison  Observed Difference Between Means  C r i t i c a l Value of Q  trial 1 - trial 3 trial 1 - trial 2 trial 2 - trial 3  8.58 5.42 3.16  2.71 2.26 2.26  < .05 < .05 < .05  minute 2 - minute 1 minute 2 - minute 3 minute 1 - minute 3  1.68 1.08 0.00  1.93 1.93 n.s.  n.s. n.s.  1.76 1.46 1.46  < .05 < .05 < .05  Task 1 Not  significant  Visit 2 trial 1 - trial 3 trial 2 - trial 3 trial 1 - trial 2  10.73 7.07 3.66  - 174 -  APPENDIX 19 Scheffe's Tests of D i a s t o l i c Blood Pressure Data  Condition 1  Contrast  Input Means  high vs low reactors, f i n a l minute, 2nd l a s t task  67.49 -  Scheffe Value  65.10  Critical Value  2  1.35  2.03  n.s.  1.34  2.03  n.s.  1.39  2.03  n.s.  Task 1 high vs low reactors, cond. 1, f i n a l 2 minutes f i n a l stress task  72.8 -  70.8  Visit 2 high vs low reactors/ cond. 1, f i n a l minute 2nd l a s t task  68.1-65.9  - 175 -  APPENDIX 20 Condition 1: Mean A r t e r i a l Pressure ANCOVA  Term  F  J2 <  groups mbl mbl/age  11.57 50.82 32.30  .0019 .0000 .0000  V  mbl  29.08 9.81 8.04  .0000 .0037 .0079  t(lin) t(quad) trial v(lin) x t(lin) v ( l i n ) x t(quad) mbl  11.17 5.57 19.59 10.47 4.28 8.52  .0021 .0245 .0000 .0028 .0468 .0064  m(lin) m(quad) minutes  4.55 4.98 4.70  .0495 .0325 .0124  t ( l i n ) x m(quad) v ( l i n ) x t ( l i n ) x m(lin)  5.12 4.35  .0303 .0445  V  X  g  Term trial minute  Epsilon Factor .953 .909  Greenhouse-Geisser corrected probability  .0000  .0151  - 176 -  APPENDIX 21 Task 1: Mean A r t e r i a l Pressure ANCOVA  Term  F  R <  conditions groups mbl  4.97 39.88 44.64  .0294 .0000 .0000  V  mbl  37.07 9.12 4.72  .0000 .0037 .0336  m(lin) x c x g m(quad) minutes mx c x g  6.50 12.50 5.70 4.43  .0114 .0008 .0043 .0138  V  X  g  Term minute, m x c x g  Greenhouse-Geisser corrected probability  Epsilon Factor .920  /  .0054 .0163  - 177 -  APPENDIX 22 V i s i t 2: Mean A r t e r i a l Pressure ANCOVA  Term  F  J2 <  9.83 158.66 96.81  .0026 .0000 .0000  15.17 17.46  .0002 .0001  Trial  5.04  .0078  m(lin) x g t ( l i n ) x m(lin) t ( l i n ) x m(quad)  5.15 7.53 6.93  .0266 .0079 .0106  T x m  4.13  .0029  groups hbl age/hbl hbl x (t) ( l i n ) hbl (t quad)  Term trial t x m  Epsilon Factor .951 .962  Greenhouse-Geisser corrected probability  .0089  - 178 -  APPENDIX 23 Newman Keuls Tests of Mean A r t e r i a l Pressure Data Condition 1 Comparison  Observed Difference Between Means  C r i t i c a l Value of Q  trial 1 - trial 3 trial 1 - trial 2 trial 2 - trial 3  6.5 5.25 1.25  3.19 2.66 n.s.  < .05 < .05  minute 2 - minute 1 minute 1 - minute 3 minute 2 - minute 3  2.19 1.89 .30  n.s. n.s. n.s.  < .05  1.98 1.64 1.64  < .05 n.s. n.s.  2.21 1.85 1.85  < .05 < .05 < .05  Task 1 minute 2 - minute 1 minute 2 - minute 3 minute 3 - minute 1  2.87 1.57 1.30 Visit 2  trial 1 - trial 3 trial 2 - trial 3 trial 1 - trial 2  8.17 4.92 3.25  - 179 -  APPENDIX 24 Scheffe's Tests of Mean A r t e r i a l Pressure Data  Condition 1  Contrast high vs low reactors, f i n a l minute, f i n a l task  Input Means 86.3 -  84.0  Scheffe Value  Critical Value  1.48  2.03  n.s.  2.42  2.032  < .05  1.19  2.03  n.s.  Task 1 high vs low reactors, cond. 1, f i n a l minute f i n a l task  89.8 -  84.4  Visit 2 high vs low reactors/ cond. 1, f i n a l minute f i n a l task  84.8 -  83.5  

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