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Interpersonal influences on pain expressions Prkachin, Kenneth Martin 1978

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INTERPERSONAL  INFLUENCES ON P A I N EXPRESSIONS  by  KENNETH MARTIN M.A.,  University  PRKACHIN  of B r i t i s h  A T H E S I S SUBMITTED  Columbia,  I N P A R T I A L FULFILLMENT OF  THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF  PHILOSOPHY  in THE FACULTY OF GRADUATE STUDIES THE DEPARTMENT OF PSYCHOLOGY  We a c c e p t t h i s  t h e s i s as  to t h e r e q u i r e d  conforming  standard  THE U N I V E R S I T Y OF B R I T I S H June, (c) Kenneth  1976  COLUMBIA  1978  M a r t i n P r k a c h i n , 1978  In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this  thesis  for scholarly purposes may be granted by the Head of my Department or by his representatives.  It  is understood that copying or publication  of this thesis for financial gain shall not be allowed without my written permission.  Department of  Psychology  The University of B r i t i s h Columbia  2075 Wesbrook Place Vancouver, Canada V6T 1W5  D a t e  June 30, 1978.  ii  ABSTRACT  Increasing  evidence suggests that s o c i a l experiences  critically  d e t e r m i n e t h e manner i n w h i c h i n d i v i d u a l s r e s p o n d t o p a i n f u l e v e n t s . the v a r i e t y o f s o c i a l d e t e r m i n a n t s o f p a i n b e e n among t h e m o s t e x t e n s i v e l y s t u d i e d .  responses, s o c i a l modeling has Conclusive  evidence i s a v a i l a b l e  s h o w i n g t h a t e x p o s u r e t o m o d e l s who e x h i b i t t o l e r a n c e noxious e l e c t r i c a l subjects.  r e l a t e d t o t h e b r e a d t h o f t h e changes i n -  duced, and the a p p l i c a b i l i t y p a i n f u l experiences require  of these f i n d i n g s to n a t u r a l l y - o c c u r r i n g further investigation.  s t u d i e s e x a m i n e d some o f t h e s e i s s u e s .  Following  a baseline  t o l e r a n c e , 30 f e m a l e s u b j e c t s  The p r e s e n t s e r i e s o f  Experiment 1 re-evaluated  p a c t o f s o c i a l m o d e l i n g on s e n s o r y - d e c i s i o n  and  or intolerance f o r  s t i m u l a t i o n p r o d u c e s m a t c h i n g b e h a v i o u r on t h e p a r t o f  However, q u e s t i o n s  response to pain.  Of  theory  the im-  (SDT) i n d i c e s o f t h e  pre-assessment o f p a i n  threshold  were exposed t o models d i s p l a y i n g  toler-  a n c e o r i n t o l e r a n c e f o r t h e s t i m u l a t i o n , o r an i n a c t i v e c o m p a n i o n . conditions After  o f i n f l u e n c e , s u b j e c t s ' behaviour approximated t h a t o f t h e model.  these e f f e c t s had been i n d u c e d , s u b j e c t s  i n g w h i c h they were exposed t o s t i m u l i of c u r r e n t  intensity.  associated with lation.  Under  Results  increased  Tolerant  from l o w , moderate, and h i g h  sensory s e n s i t i v i t y  that previous  p e r i m e n t 2 was c o n c e r n e d w i t h expressive  dur-  levels  i n d i c a t e d t h a t i n t o l e r a n t m o d e l i n g was at noxious l e v e l s of  m o d e l i n g was n o t a s s o c i a t e d w i t h  sensitivity-, suggesting  e l i n g on o v e r t  u n d e r w e n t a SDT s e r i e s  stimu-  d i f f e r e n t i a l values  p o s i t i v e f i n d i n g s be q u a l i f i e d .  of Ex-  t h e e f f e c t s o f t o l e r a n t a n d i n t o l e r a n t mod-  displays.  Videotapes taken of subjects i n  iii Experiment 1 were presented to 15 female observers'who attempted to pre^ diet the levels of current that observed subjects were experiencing. SDT analyses of observers' judgments indicated that responses to intense stimuli were more readily discriminated than responses to less intense* stimuli.  The behaviour of subjects exposed to a tolerant model was less  discriminable than that of intolerant subjects.  The behaviour of intol-  erants was less discriminable than that of controls. It was argued that tolerant modeling produces reductions in overt^ nonvocal expressions of pain.  Experiment 3 examined whether modeling effects could be obtained  with naturally-occurring groups, and the relative power of pain tolerant and intolerant behaviour.  127 female undergraduates underwent a screen-  ing for pain threshold levels.  In a subsequent session, subjects partici-  pated either individually, or in pairs comprised of a l l combinations of subjects having high and low thresholds.  Unidirectional influence was  observed, with low threshold subjects inducing high threshold subjects to report pain sooner, and accept fewer currents.  These results indicated  that pain intolerant behaviour may be a more powerful social influence than pain tolerant behaviour, probably as a result of i t s imperative nature.  Since the modeling effect was observable among naturally-occurr-  ing groups, the generalizability of laboratory to naturally-occurring pain phenomena was supported.  Relationships between measures of pain based on  psychophysical judgments and overt behaviour were examined within the context of a model that suggests that inducing alterations in pain behaviour may modulate the experience of pain.  iv  TABLE OF CONTENTS  ABSTRACT  i  i  TABLE OF CONTENTS  iv  L I S T OF TABLES  v i  L I S T OF FIGURES L I S T OF APPENDICES ACKNOWLEDGEMENTS  v i i viii "ix  INTRODUCTION  1  RATIONALE  26  EXPERIMENT 1: SOCIAL MODELING INFLUENCES ON P A I N THRESHOLD, P A I N TOLERANCE, AND SENSORY-DECISION THEORY I N D I C E S 28 Introduction  28  Method  33  Results  43  Discussion  61  EXPERIMENT 2: A SENSORY-DECISION THEORY A N A L Y S I S OF SOCIAL MODELING INFLUENCES ON NONVOCAL P A I N EXPRESSIONS 70 Introduction  70  Method  74  Results  78  Discussion  87  EXPERIMENT 3: AN I N V E S T I G A T I O N OF VICARIOUS INFLUENCES ON P A I N COMMUNICATIONS EMPLOYING NATURALLY-OCCURRING GROUPS  95  Introduction  95  Method  98  Results  102  Discussion  110  V  GENERAL D I S C U S S I O N  116  REFERENCE NOTES  121  REFERENCES  122  APPENDIX A  130  APPENDIX B  132  APPENCIX C  136  vi  L I S T OF TABLES  T a b l e 1:1.  Mean d i s c r i m i n a b i l i t y i n d i c e s a t s t i m u l u s p a i r s . 3-4 t o 5-6 f o r T o l e r a n t , I n t o l e r a n t a n d C o n t r o l subjects. 56  T a b l e 2:1.  Means o f l o w , medium, a n d h i g h c u r r e n t administered to observed subjects.  T a b l e 2:2.  Mean d_' v a l u e s interaction.  f o r t h e Squads X R e p l i c a t i o n s  Mean d_' v a l u e s interaction.  f o r t h e Squads X  T a b l e 2:3.  T a b l e 2:4.  intensities 77  81 Discriminations 83  Mean d_' v a l u e s f o r t h e Squads X M o d e l i n g X Discriminations interaction.  Groups 84  T a b l e 2:5.  Mean d i f f i c u l t y r a t i n g s a s s o c i a t e d w i t h e a c h S q u a d when o b s e r v e r s made j u d g e m e n t s o f s u b j e c t s from the three s o c i a l i n f l u e n c e c o n d i t i o n s of S t u d y 1. 86  T a b l e 3:1.  Results of planned orthogonal pain threshold data.  comparisons f o r 104  vii  L I S T OF FIGURES  Figure  1:1.  Mean i n t e n s i t y o f c u r r e n t p r o v o k i n g a r a t i n g of "10" ( p a i n t h r e s h o l d ) under u n i n f l u e n c e d and i n f l u e n c e d c o n d i t i o n s f o r s u b j e c t s i n G r o u p s T, C, a n d I .  46  Figure  1:2.  Mean i n t e n s i t y o f c u r r e n t p r o v o k i n g a " t e r m i n a t e " r a t i n g under u n i n f l u e n c e d and i n f l u e n c e d c o n d i t i o n s f o r s u b j e c t s i n G r o u p s T, C, a n d I . 49  Figure  1:3.  Mean f r e q u e n c y o f c h o i c e o f e a c h r a t i n g s c a l e p o i n t a t h i g h , medium, a n d l o w s h o c k i n t e n s i t i e s f o r s u b j e c t s i n G r o u p s T, C, a n d I . 52  Figure  3:1.  Mean i n t e n s i t y o f c u r r e n t p r o v o k i n g a r a t i n g o f "10" ( p a i n t h r e s h o l d ) o v e r a l l s h o c k s e r i e s i n S e s s i o n 1 and S e s s i o n 2 f o r s u b j e c t s i n a l l groups. 103  Figure  3:2.  Mean i n t e n s i t y o f c u r r e n t a t t h e p o i n t w h e r e s u b j e c t s t e r m i n a t e d each shock s e r i e s ( p a i n tolerance) during Session 2 f o r a l l groups.  108  viii  L I S T OF APPENDICES  A P P E N D I X A.  Psychometric  data from Experiment  1.  130  A P P E N D I X B.  Consent Forms.  132  A P P E N D I X C.  Q u e s t i o n n a i r e s a d m i n i s t e r e d i n E x p e r i m e n t 1.  136  X X  ACKNOWLEDGEMENTS  A l a r g e number o f p e o p l e h a v e c o n t r i b u t e d s i g n i f i c a n t l y development committee  of t h i s  dissertation.  A l l members o f t h e  h a v e made d i r e c t , s i g n i f i c a n t , a n d  They a r e : D r s . L a w r e n c e M.  Kenneth  Ward.  D.  I owe  Dri. Kenneth  2 under  independent  contributions.  t o my  and  Craig special gratitude for his  t h r o u g h o u t my  good f r i e n d ,  a s s i s t a n c e i n a l laspects of the p r o j e c t ; Experiment  dissertation  C r a i g , P a r k 0. D a v i d s o n , R o b e r t K n o x ,  c o n t i n u o u s s u p p o r t and a s s i s t a n c e S p e c i a l t h a n k s a l s o go  to the  graduate  career.  Cindy G o s l i n e , f o r her i n particular  f o r conducting  sometimes e x t r e m e l y a d v e r s e c i r c u m s t a n c e s .  Luz  P i e d r a h i t a , D i a n a P i e d r a h i t a a n d L i z Z i s c h k a s e r v e d as m o d e l s i n Experiment  1.  Dani McCullough  gave g e n e r o u s l y o f h e r t i m e t o a i d  i n some o f t h e more t e d i o u s a n d a v e r s i v e c h o r e s . N a y l o r , a n d H.  Boudreau  v e r y dear f r i e n d , period  h e r h e l p and  typed v a r i o u s parts of the manuscript.  G e o r g i a N e m e t z , came t o my  of emergency.  Judy Hawkins,  Finally,  I would  like  encouragement d u r i n g a l l phases  r e s c u e d u r i n g one  L. My particular  to thank Glenda M i d g l e y f o r of t h i s  dissertation.  INTRODUCTION  The physiology, shift  current p r o l i f e r a t i o n of research  i n t o t h e anatomy, n e u r o ^  and psychology o f p a i n has been a t t r i b u t e d , i np a r t , t o a  from a disease-model o r i e n t a t i o n that considered  w o r t h y o n l y a s a symptom o f u n d e r l y i n g p a t h o l o g y , ing  p a i n a s a phenomenon w o r t h y o f s t u d y  or i n r e l a t i o n this  t o , p a t h o l o g i c a l processes  pain  t o be note-  to a perspective  view-  i n i t s own r i g h t , i n d e p e n d e n t o f , (Fordyce,  1976b).  Coupled  with  change i n p e r s p e c t i v e and e x p a n s i o n o f r e s e a r c h h a s been an i n c r e a s e d  appreciation o f thecomplexity  o f theexperience.  To a l a r g e  extent,  s u c h a p p r e c i a t i o n h a s d e r i v e d f r o m m o d u l a t i o n s t u d i e s w h i c h h a v e demonstrated  t h a t r e s p o n s e s t o p a i n f u l e v e n t s c a n be i n f l u e n c e d by a w i d e  variety of chemical,  s u r g i c a l , and environmental  manipulations.  s e v e r a l t h e o r i e s attempt t o i n t e g r a t e the processes l a t i o n occurs  (Chapman, 1977;  t h r o u g h w h i c h modu-  M e l z a c k & W a l l , 1965;  Mayer, 1974), the v a r i a b l e s that a r e capable p a i n a r e s o d i v e r s e t h a t no c u r r e n t  Although  Melzack, 1973;  o f modulating  responses t o  f o r m u l a t i o n seems e n t i r e l y  satis-  factory. The  research  t o be reported h e r e i n d e a l t w i t h t h e e f f e c t s o f s o c i a l  environment manipulations represented  o n human p a i n r e s p o n s e s .  an attempt t o examine the b r e a d t h  In part, this  o f t h e changes i n d u c e d  a v a r i e t y o f i n d i c e s o f response t o noxious s t i m u l a t i o n . was  to collect  research across  A f u r t h e r aim  data p e r t i n e n t t o socio^behavioural accounts o f the o r i -  gins o f i n d i v i d u a l d i f f e r e n c e s i n response t o p a i n f u l events. In thef o l l o w i n g s e c t i o n , current formulations reviewed  briefly.  o f pain w i l l be  S u b s e q u e n t l y , a more d e t a i l e d e x p l i c a t i o n o f t h e r r o l e  of s o c i a l events i n determining  responses t o p a i n w i l l be o u t l i n e d .  F i n a l l y , a t t e n t i o n w i l l be p a i d t o m e t h o d o l o g i c a l  issues relevant to the  2  studies to be reported in the sequel,  Pain Perspectives;  Ah overview  Traditional perspectives have characteristically employed a stimulus-response  formulation in accounting for pain (Fordyce, 1976b).  The basic model is as follows. Adequate stimulation activates peripheral nociceptors which convey nociceptive information centrally to lower and higher brain centers.  Activity in these centers determines  the perception of pain and the behavioural response to noxious stimulation.  Research deriving from this perspective has focussed on the bio-  physical characteristics of relevant peripheral structures, the anatomy and physiology of ascending sensory systems, the localization of painrelevant structures in the brain, and the psychophysical characteristics and capacities of the molar system. This traditional perspective, most closely associated with the specificity theory of von Frey (reviewed in Melzack & Wall, 1970), has had major consequences for pain research such as the identification of peripheral and central structures and systems that are c r i t i c a l l y involved iii pain processes.  Equally important, however, have been advances brought  about through recognition of the empirical inadequacies of this position. As Melzack (1973) and others have pointed out, the traditional perspective fails to account for a variety of puzzling phenomena, such as phantomlimb pain, the unpredictable effects of surgical lesions of pain^-relevant neural pathways and structures, and the not infrequent observation of lack of correspondence between the occurrence of noxious events and evidence of pain.  Further, i t has l i t t l e to say about central or  3  experiential factors involved in pain modulation. Since modulation of pain responses* can be brought about through a variety of physiological and psychological procedures (cv. Bonica & Albe-Fessard, 1976; Weisenberg, 1977), a complete account of pain must adequately deal with both sources of such modulation, employing principles appropriate to each.  Currently, the most comprehensive and integrated  formulation of pain processes derives from anatomical, biochemical, and neurophysiological work. Gate-Control Theory (GCT) (Melzack & Wall, 1965; Melzack, 1973) has been a c r i t i c a l impetus to the expansion of pain research (Liebeskind & Paul, 1977), and represents an attempt to account more fully for the paradoxes facing earlier formulations.  As such i t involves an increase  in complexity and a departure from the strict stimulus-response of earlier formulations.  nature  GCT rests upon a description of current know-  ledge of the anatomical substrate of pain-related behaviour; however, i t s fundamentally novel contribution lies in i t s application of the principle of inhibitory control of sensory input.  According to this position, pro-  cesses producing modulation of nociceptive input can be activated either presynaptically, prior to the central evocation of pain perception, or via descending inhibitory activity resulting from the action of central regulatory mechanisms,  Pain modulation is presumed to occur via activa-  tion of a gating mechanism, the anatomical locus of which is to be found in the spinal cord substantia gelatinosa,  In addition to the hypothetical  spinal gating mechanism, GCT proposes that different ascending spinal tracts mediate different aspects of pain perception:  a neospinothalamic  tract-  thalamus-somatosensory-cortex system subserving sensory-discriminative  4 aspects  o f p a i n , a n d a paramedian, a s c e n d i n g  system path Dennis  subserving  system^thalamus-limbic  affective^piotivational aspects,  (Recently  and Melzack(1978) have reviewed.evidence f o r a t l e a s t t h r e e .  1  ascending hibitory  p a i n - s i g n a l l i n g systems. ) c o n t r o l has been robust  of v a r i o u s  The GCT n o t i o n o f d e s c e n d i n g i n - ^  and r e c e n t  a c c o u n t s o f t h e mode o f a c t i o n  a n t i n o c i c e p t i v e procedures such as morphine a n a l g e s i a ,  lation-produced  stimu-  a n a l g e s i a , and a c u p u n c t u r e have r e l i e d h e a v i l y upon i t  ( M a y e r & P r i c e , 1 9 7 6 ; M a y e r , P r i c e , R ' a f f i '&•; B'arher.L, 1 9 7 6 ) .  Further,  since  t h e p a i n s y s t e m s i m p l i c a t e d i n GCT a l l p r o j e c t t o a n d r e c e i v e p r o j e c t i o n s from h i g h e r b r a i n c e n t e r s , i t has been argued t h a t these  s y s t e m s may med-  i a t e t h e p a i n - m o d u l a t o r y e f f e c t s o f v a r i o u s e x p e r i e n t i a l and " c o g n i t i v e " influences.  Hall  (1977),  f o r example, has argued t h a t h y p n o t i c  or waking,  imagined a n a l g e s i a i s produced through an i n h i b i t i o n o f a c t i v i t y a t t h e s p i n a l g a t i n g mechanism. are  capable  ever,  The d e m o n s t r a t i o n  that e x p e r i e n t i a l variables  o f a f f e c t i n g p a i n r e s p o n s e s may b e c o n s i s t e n t w i t h GCT.  s u c h d e m o n s t r a t i o n s do n o t r e p r e s e n t  confirmatory  evidence,  n o r does  the e x i s t e n c e o f a mechanism f o r c e n t r a l r e g u l a t i o n o f n o x i o u s i n p u t that this  i s t h e system through which such i n f l u e n c e s exert  Concurrent with recent i c a l , biochemical,  advances i n t h e understanding  and n e u r o p h y s i o l o g i c a l f a c t o r s s u b s e r v i n g  their  How-  imply" , 1  effect.  o f t h e anatomp a i n has been  an i n c r e a s e i n a t t e n t i o n d i r e c t e d toward t h e r o l e p l a y e d b y p s y c h o s o c i a l v a r i a b l e s i n the modulation of p a i n responses.  I t has long been  accepted  t h a t f a c t o r s i n v o l v e d i n an o r g a n i s m ' s b e h a v i o u r a l h i s t o r y and c u r r e n t s o c i a l c o n d i t i o n s may i n f l u e n c e r e s p o n s e s t o n o x i o u s s t i m u l a t i o n o r t h e emission  of behaviour  f r o m many s o u r c e s ,  indicative of pain.  E v i d e n c e f o r t h i s p o i n t h a s come  i n c l u d i n g c a s u a l and c l i n i c a l  o b s e r v a t i o n , and a m u l t i t u d e  5  of systematic  s t u d i e s o f s u c h d i v e r s e v a r i a b l e s as p e r s o n a l i t y t r a i t s ,  cognitive styles,  cognitive strategies, affective states, preparatory i n "  formation, hypnosis, there i s l i t t l e  and  s o on  (see W e i s e n b e r g , 1977,  disagreement regarding the substance  there i s equally l i t t l e  agreement w i t h r e g a r d  i n v o l v e d , t h e i r l o c u s o f o p e r a t i o n , and Additionally,  the very  of a coherent, a c t i o n w o u l d be Since  adequately  the r e s e a r c h  socio-environmental  theoretical  In  t o be  f a c t o r s d e f i e s the  f r a m e w o r k w i t h i n w h i c h t h e i r modes o f  o f how  i t w i l l be  d e s c r i b e d as a p r i v a t e , s u b j e c t i v e  d i s c u s s i o n s o f the  topic typically  pain."  to  pain  Sternbach something  ...  i n order  S i m i l a r l y , Fordyce  mechanisms.  become i n c r e a s i n g l y a p p a r e n t t h a t a  of p a i n - r e l a t e d processes  ( 1 9 6 8 , p.8)  experience.  deal w i t h sensory  P a i n f u l events  consequences; i n f a c t , p a i n i s i n v a r i a b l y i n f e r r e d  ing  of  necessary  such f a c t o r s are r e l e v a n t to  gation of t h e i r behavioural aspects.  t o do  development  processes.  d u c t i v e approach to the study  son  findings.  r e p o r t e d h e r e i n d e a l t w i t h the r o l e  r e c e n t y e a r s , h o w e v e r , i t has  servation.  research,  t o the a c t i v e mechanisms  v a r i a b l e s i n pain modulation,  Pain i s ordinarily Scientific  While  accounted f o r .  discuss current understanding modulation  of this  the g e n e r a l i t y of the  d i v e r s i t y of these  systematic  for a review).  notes: f o r us  "...  lies  investi-  have b e h a v i o u r a l  from b e h a v i o u r a l  i t i s necessary  t o d e t e r m i n e t h a t he  (1976, p.153) has  in  h a v e made s i m i l a r p o i n t s  is  1; S z a s z ,  per-  experienc-  stated:  (Craig,Note  ob-  f o r the  C l i n i c a l l y , p a i n c a n n o t become a p r o b l e m u n t i l someone communicates t h a t p a i n i s b e i n g e x p e r i e n c e d . The p a t i e n t g r i m a c e s o r m o a n s , t a l k s a b o u t t h e q u a l i t y and l o c a t i o n o f t h e p a i n , l i m p s o r o t h e r w i s e moves i n a g u a r d e d m a n n e r , or d i s p l a y s autonomically mediated i n d i c a t i o n s of d i s t r e s s . Other authors  pro-  1968;  6 Zborowski, 1969) . Virtually a l l studies of pain in intact organisms employ behav^ iourally-based dependent measures-''-although some make use of concurrently^ recorded physiological responses as well (Craig-frrPrkachin, 1978). Since pain i s a phenomenon that i s intimately tied to behavioural expression, three related consequences follow. First, pain expressions are capable of exerting an influence upon the social environment in which they occur.  Thus, pain expressions are likely to provoke characteristic  changes in the behaviour of members of the social milieu (Craig, 1978b). The nature of the changes that occur w i l l be dependent upon a variety of factors including the situational context in which they occur, behavioural characteristics of those present when they occur, and parametric characteristics of the displays themselves, including their intensity, frequency, and chronicity.  Second, social consequences are likely to exert recipro-  cal influence, provoking immediate and long term effects on the expressions themselves..  Third, expressions of pain are likely to be subject to modu-  lation via other social processes effective i n controlling behaviour.  Social events, pain experience, and behaviour There are two major areas of interst when considering interrelationships between social events and pain expressions,  The f i r s t concerns  characteristic effects of pain expressions on the behaviour of other. The second deals with the question of what influence these events have upon current and subsequent pain experience and expression. Effects on the behaviour of others.  It i s a common observation  that expressions of pain and suffering have a powerful impact on the  7  behaviour sequelae  of others.  i n the behaviour  diffuse "emotional"  of acute p a i n provoke r a p i d a n d  Episodes,,  of others:  responses,  of d i s t r e s s , to l i s t but  and  a few.  expressions  observations  of sympathy,  comforting,  interventions that a l l e v i a t e  The  the  over  among c a r e t a k e r s who  o f e x p o s u r e t o p a i n d i s p l a y s i s i l l u s t r a t e d by  of p a t i e n t - s t a f f  source  power t h a t s u c h e x p r e s s i o n s have  o t h e r s e v e n d u r i n g p e r i o d s o f p r o t r a c t e d p a i n and extended experience  salient  i n t e r a c t i o n s on a b u r n - p a i n  have  clinical  unit:  S t a f f members a r e c o n s t a n t l y s a y i n g t o t h e p a t i e n t , " I t w i l l be o v e r s o o n . " "Just a b i t longer." P a t i e n t s a r e c o n s t a n t l y c r y i n g o u t " F o r God's s a k e , h u r r y ."' ( F a g e r h a u g h , 1 9 7 4 , p . 6 4 6 ) , When a p a i n p r o b l e m b e c o m e s c h r o n i c , t h e c o r r e s p o n d i n g  increase i n  d u r a t i o n o f e x p o s u r e o f members o f t h e i m m e d i a t e s o c i a l m i l i e u i s to produce permanent adjustments i n t h e i r b e h a v i o u r Sternbach, a l l o w an  1974).  U n f o r t u n a t e l y , the  to the s u f f e r i n g of o t h e r s  mediated events  demonstrated the p r o v o c a t i v e  that are n e c e s s a r i l y c r i t i c a l  However, l a t e r r e s e a r c h has  suggested  subjects  autonomic/emotional Such  autonomically-  i n the s o c i a l  influence pro-  that the occurrence  at r e l i e f  not  changes.  C r a i g & Lowery, 1968).  the o v e r t accompaniments of  responses i s p r e d i c t i v e of overt attempts Krebs,  1976b;  i n v o l v i n g v i c a r i o u s exposure of  consequences o f p a i n d i s p l a y s ( B e r g e r , 1962; investigations neglected  likely  c u r r e n t s t a t e o f knowledge does  a d e q u a t e amount o f p r e c i s i o n i n p r e d i c t i n g t h e s e  Early laboratory research  cess.  (Fordyce,  the  and  comfort  of  such  (Bleda,  1975;  1975). S o c i a l events  are p u b l i c l y  i m p l i c a t e d i n pain modulation.  observable  to b e l i e v e t h a t they  and  occur  in a social  Since p a i n  behaviours  context there i s every  reason  a r e s u s c e p t i b l e t o m o d i f i c a t i o n and m a i n t e n a n c e b y  any  8  of a host of variables shown to be pertinent to the modification and maintenance of other forms of behaviour.  While  this is clearly an area of  great research potential, few large-scale, systematic studies have been attempted and, therefore, evidence bearing on the issue is largely the result of clinical observation. Fordyce  (1976b)  has provided a detailed analysis of historical and  current environmental factors that predispose an individual toward the emission of high rates of pain behaviour,  First  of all, pain behaviour  may, historically or currently, have been consequated by direct positive reinforcement in several forms, social attention, protection, and reassurance from significant others, compensation, or iatrogenic reinforcement represent a few examples).  Particularly  interesting is the potential  for mutual reinforcement in dyadic interaction. The person exhibiting pain may be reinforced for so doing by the behaviour of the other.  Recip-  rocally, the act of reinforcing pain behaviour may be Reinforced by reductions in the pain displays of the individual whose pain behaviour was reinforced.  Secondly,  pain behaviour may acquire strength through processes  of avoidance learning. F o r example, pain behaviour emitted in the context of personally aversive social situations may be successful in terminating or avoiding them.  Thirdly,  an elaborate repetoire of pain behaviours may  occur among individuals lacking a history of sufficient reinforcement for "well behaviour^'  0  The numerous case examples and single-subject experiments reported by Fordyce  and his co-workers provide ample illustrations of the modicication  of pain behaviour occurring as the result of alterations in the response of the social environment to pain displays  (Fordyce,  1976a, 1976b;  Fordyce,  9 Fowler,  Lehmann, D e L a t e u r , Sand, & T r i e s c h m a n n ,  DeLateur,  response to pain i s l a r g e l y  of information suggesting  perimental  exhibit characteristic  (Sternbach  t h e c o n c l u s i o n t h a t members o f some  and s t e r e o t y p e d  from the response of other  & Tursky,  experiences.  e t h n i c groups t o d i s e a s e - s t a t e s o r ex-  pain are consistent with  differentiable  that the  and s e n s i t i v e l y m o d u l a t e d by s o c i a l  of the response of various  cultures  &  1968).  There a r e a l t e r n a t i v e sources  Studies  1973; F o r d y c e , F o w l e r ,  pain behaviour  groups.  1965; T u r s k y & S t e r n b a c h ,  that i s  Several investigators  1967; W e i s e n b e r g , 1975)  have d e m o n s t r a t e d s o c i a l and e t h n i c d i f f e r e n c e s i n r e s p o n s e t o e x p e r i m e n t ally  induced  p a i n among v a r y i n g e t h n i c a n d s o c i a l  ethnically-defined i n pain behaviour designed 1960).  Further,  g r o u p s h a v e b e e n shown t o e x h i b i t c h a r a c t e r i s t i c i n response to the manipulation  to provoke intergroup Subjects  groups.  from Jewish  competitiveness  bariables  (Lambert, Libman, &  Poser,  a n d P r o t e s t a n t b a c k g r o u n d s who d i d n o t d i f f e r  i n a p r e t e s t o f p a i n t o l e r a n c e , were t o l d  that t h e i r p a r t i c u l a r  group c o u l d n o t t o l e r a t e p a i n as w e l l as t h e o t h e r exposed t o t h i s m a n i p u l a t i o n  of s o c i a l  changes  groups.  ethnic  Jewish  subjects  e x h i b i t e d a subjequent increase i n pain  tolerance which Protestants d i d not. As  Craig,(1978b) has p o i n t e d  out, the existence of s i m i l a r i t i e s i n  t h e r e s p o n s e o f members o f a p a r t i c u l a r represents iences  c u l t u r a l group t o p a i n f u l events  presumptive evidence f o r the operation of s o c i a l i z a t i o n  i n determining  pain behaviour.  Relevant  experiences  exper-  are l i k e l y to  i n c l u d e e x p o s u r e t o g r o u p members d i s p l a y i n g c u l t u r a l l y - a c c e p t a b l e r e s ponses i n circumstances another source  o f p a i n and d i s t r e s s .  of environmental  influence —  This observation s o c i a l modeling —  implicates i nthe  10  a c q u i s i t i o n of s t y l e s of The  response tQ pain.  u b i q u i t y a n d i m p o r t a n c e o f v i c a r i o u s e x p e r i e n c e i n t h e acquiT-  s i t i o n o f complex r e p e r t o i r e s of b e h a v i o u r have been c o m p r e h e n s i v e l y  docu-  mented o v e r the y e a r s by Bandura  (Bandura & W a l t e r s , 1963; B a n d u r a ,  1971,  ' v i r t u a l l y a l l l e a r n i n g phenomena r e -  1 9 7 6 ) , who  n o t e s t h a t "...  s u l t i n g from d i r e c t e x p e r i e n c e s can o c c u r on a v i c a r i o u s b a s i s s e r v a t i o n o f o t h e r p e r s o n s ' b e h a v i o u r and i t s c o n s e q u e n c e s (Bandura, 1969,  p.118).  a c q u i s i t i o n o f new in  forms  1969,  through  f o r them"  Modeling processes are i m p l i c a t e d not only i n the of behaviour v i a o b s e r v a t i o n a l l e a r n i n g , but  the a l t e r a t i o n of p r o b a b i l i t i e s  a l r e a d y i n the i n d i v i d u a l ' s  exposure  repertoire.  i n the r e d u c t i o n of avoidance b e h a v i o u r s .  of  Research  a p p l y i n g modeling procedures to subjects e x h i b i t i n g phobic avoidance demonstrated  t h a t m o d e l e d d i s p l a y s o f p r o g r e s s i v e l y more i n t e n s e  w i t h and a p p r o a c h i o u r comparable  to phobic o b j e c t s produce  1969).  The  r e d u c t i o n s i n avoidance behav-  Bandura,  Blanchard, &  of Ritter,  i m p l i c a t i o n s of such s t u d i e s f o r p a i n r e s e a r c h are c l e a r ,  avoidance comprises larly,  (Rachman, 1 9 7 2 ;  has  interaction  t o o r g r e a t e r t h a n t h o s e o b s e r v e d as a c o n s e q u e n c e  systematic desensitization  also  of occurrence of p a t t e r n s of behaviour  Of p a r t i c u l a r i n t e r e s t i n t h e p r e s e n t c o n t e x t i s t h e e f f i c a c y vicarious  ob-  since  much o f w h a t i s c h a r a c t e r i z e d a s p a i n b e h a v i o u r .  Simi-  t o t h e e x t e n t t h a t a v o i d a n c e b e h a v i o u r can be r e d u c e d v i a m o d e l i n g  p r o c e d u r e s , i t may  a l s o be enhanced by modeled d i s p l a y s o f  avoidance.  R e s e a r c h on s o c i a l i n f l u e n c e v i a m o d e l i n g p r o c e d u r e s h a s h a d p o r t a n t consequences has uncovered  a major  m o d e l i n g r e s e a r c h has  i n three not unrelated respects.  First,  source of v a r i a t i o n i n s o c i a l behaviour. led directly  to the development  of  im-  such r e s e a r c h Second,  procedures  11  effective i n a l t e r i n g problematic c t e r i z e d by' a v o i d a n c e ,  b e h a v i o u r s . ., p a r t i c u l a r l y  Third, principles  those  derived from modeling  chara-  studies  have been employed i n t h e o r e t i c a l a c c o u n t s of the o r i g i n s of v a r i o u s of s o c i a l / e m o t i o n a l behaviour.  As  one  example of the l a t t e r ,  t i o n o f f e a r f u l a v o i d a n c e i n the n a t u r a l environment has to the modeling of f e a r f u l behaviour stimulus present  cues ' (Rachman, 1972; d i s c u s s i o n , Fordyce  observed i n the  B a n d u r a , 1969,  (1976a),  Craig  argued that modeling e f f e c t s are d i r e c t responses to pain.  tic  l a r g e l y be  a l s o are l i k e l y  the product  have  determinants  of p a i n expressions  t o be m e d i a t e d b y m o d e l i n g  emitted  been noted c l i n i c a l l y  are o p e r a t i v e i n the  study  (Gentry,  (Fordyce,  1 9 7 6 b ) , and  Stylisi n such  modulation  i n an  S c h o w s , & Thomas, 1974)  sources. uncon-  that a  p r o p o r t i o n a t e p e r c e n t a g e o f c h r o n i c low back p a i n p a t i e n t s r e p o r t p r e s e n c e , i n t h e i r i m m e d i a t e f a m i l i e s , o f r e l a t i v e s who back p a i n or o t h e r p h y s i c a l d i s a b i l i t i e s , as m o d e l s f o r p a i n b e h a v i o u r .  management o f p a i n e x p r e s s i o n  and  who  dis-  processes.  i n n a t u r a l s e t t i n g s comes f r o m a v a r i e t y o f  trolled questionnaire  served  of  of exposure to others  forms of p a i n behaviour  Evidence that modeling processes  I t has  others  tolerance or i n t o l e r a n c e of s i m i l a r s t i m u l a t i o n .  d i f f e r e n c e s i n the p a r t i c u l a r  contexts  significant  and  the  In p a r t i c u l a r , r e l a t i v e tolerance or i n t o l e r a n c e of  n o x i o u s s t i m u l a t i o n may playing relative  of c e r t a i n  M o r e germane t o  (.197.8b)- .,  and  acquisi-  been a t t r i b u t e d  context  1976).  the  forms  dis-  the  s u f f e r e d from  conceivably  could  have  F a g e r h a u g h (1974) i n d i s c u s s i n g  on a b u r n - p a i n  unit  notes:  The p a t i e n t s on a b u r n u n i t r e p r e s e n t a g r o u p who a r e i n v a r i o u s s t a g e s o f t h e b u r n and p a i n t r a j e c t o r i e s . These c o n d i t i o n s g i v e e v e r y p a t i e n t a c h a n c e t o r e h e a r s e and i n t e r p r e t h i s own i l l n e s s and i t s p a i n t r a j e c t o r y and t o compare h i s s t a t e to that of o t h e r s . Through these a c t i v i t i e s  low  the  12  he learns the norms and limits of pain expression and rel i e f associated w;ith various phases of the Illness; the probable duration .of the various phases; the various methods of tolerating pain; and.the complications that may alter his pain trajectory, (p.647) Several studies of children with abdominal pain provide further naturalistic evidence interpretable in terms of modeling effects.  Apley and  Naish (1958) contrasted 100 children exhibiting recurrent abdominal pains with comparable children not experiencing pain.  The incidence of similar  complaints among members of symptomatic children's immediate families was approximately  six times greater than the incidence among control children.  Oster (1972), in a questionnaire study, contrasted the family pain histories of children suffering frpmrabdominal, headache, and limb pains with those of children without pain.  Twenty-four percent of parents of children with pain  reported pain problems in childhood or at the time of investigation in contrast with 14% among parents of children without pain. reached in both of these studies were similar:  The conclusions  recurrent pain problems  in children may often represent a characteristic familial reaction mediated through imitative processes. Direct evidence that modeling processes are active sources of pain modulation comes from laboratory studies.  Craig and Weiss (1971) exposed  undergraduate volunteers to six series of electric shocks gradually i n creasing in intensity.  Subjects rated each shock on a categorical judg-  ment scale ranging from "undetectable" to "painful".  A confederate peer  model who was ostensibly another subject undergoing the same procedure either dissimulated greater or lesser tolerance than the actual subject by making lower.or higher ratings, or made ratings that were not contingent upon those of the subject.  Subjects' behaviour matched that of the models  13 in the active modeling conditions W/i,th thos.e subjected to a tolerant ?  model accepting substantially greater current intensities before reporting pain than those exposed to an intolerant model.  Subjects exposed to the  noncontingent co-participant accepted intermediate levels.  The  robustness  of this phenomenon was demonstrated in later studies that employed a different methodology (Craig & Weiss, 1972; Craig, Best, & Reith, 1974).  A stan-  dard current intensity, invariably described as non-noxious by uninfluenced subjects, was rated ,ay volunteers over a series of t r i a l s .  Subjects ex-  posed to an intolerant model rated the current as painful 77% of the time while control subjects only did so 3% of the time. Pain modulating effects of modeling were also demonstrated by Neufeld and Davidson (1971) , who employed radiant-heat stimulation for pain induction.  Subjects who observed another person experiencing the  stimulation without distress showed an amount of pain reduction equal to that induced when subjects listened to detailed descriptions of the heatinduction process.  Chaves and Barber (1974), employing pressure-induced  pain, reported that observing an experimenter modeling "cognitive control" strategies resulted in reductions in pain reports among subjects who  had  high pretest pain thresholds.  Conceptual and Methodological Issues The evidence reviewed demonstrates that modeling procedures have an impressive impact on verbal pain expressions and suggests that such processes may be active determinants of pain behaviour in natural settings, It i s relatively easy to produce changes in pain expressions through manipulation of  14  social conditions,  However, simple demonstrations of such effects have  raised more complex issues pertaining not only to the parameters governing them, but also to alternative and concurrent processes through which the effects may be mediated. Of particular concern in recent pain research, have been two  issues:  how dependent are pain modulation effects upon where the investigator chooses to look for them (i.e., how general are the effects across a variety of dependent measures), and are the effects superficial or fundamental (i.e., do the effects merely represent examples of the plasticity of behaviour, or are they mediated by changes in basic perceptual systems?) These questions are of particular significance because the wide variety of procedures that can effectively yield alterations in indices of pain may govern changes in different indices or may yield their effects via different mechanisms. Owing to the presence of a comprehensive and perhaps paradigmatic formulation of pain processes •— Gate Control Theory —  i t has become re-  latively common to relate observed phenomena of pain modulation to i t s concepts, or to imply that they are accounted for in i t s terms, thus halting inquiry much in the manner of Skinner's concept of the "explanatory fiction" (Skinner, 1974).  However, as Liebeskirid andPaul (1977) point out in their  review of measurement issues in physiological studies of pain modulation in animals, studies often pay insufficient attention to the fact that the different pain indices measured are organized in different ways and at different levels in the nervous system.  Treatments failing to affect spinal  reflex manifestations of pain, for example, may vocalization.  affect pain measured by  The point is equally pertinent to studies of environmental or  15 psychological variables,  Different indices, may exhibit differential re-  activity to different treatments;. A, mapping of the variety of parameters that are influenced by a given procedure should give clues not only to the generality of the changes that i t produces, but is also likely to suggest further mechanisms that may mediate or modulate the effect,  For this  reason, i t has been advocated that studies of putative pain modulation procedures evaluate their effects over a range of dependent measures. One manner in which this has been attempted i n studies of modeling influences on human pain has been through the assessment of changes in autonomically-mediated responses,  In an early study, Craig and Niedermayer  (1974) monitored skin conductance and heart-rate activity among subjects exposed to •".differentially pain-tolerant models.  Subjects were exposed to  two series of incremental electric shocks, signalled by the onset, six seconds prior to shock administration, of a light, and rated each on a 5point categorical judgment scale.  The study replicated earlier ones in  that subjects exposed to a tolerant model accepted higher current intensities and those exposed to an intolerant model accepted lower•intensities before describing them as painful than did subjects in two control conditions.  Interestingly, in spite of the fact that the groups differed sub-  stantially in the amount of current accepted, they could not be differentiated on measures of the magnitude of skin-conductance or heart-rate change to the shocks.  The authors took these findings as evidence that the  modeling procedure had produced alterations in the biophysical processes subserving subjective experiences' of pain and discomfort.  Three major  difficulties with this study required cautious interpretation of the findings.  First, the findings were essentially negative and the  16 conclusions were taken as evidence that the. null hypothesis Has correct. Second, the use .of a warning stimulus may-have'introduced  alterations In  the dependent measures that masked more directly interpretable effects. Third, the choice of skin conductance as a dependent measure may have been inappropriate.  As Tursky (1974.) subsequently pointed out, skin-conductance  tends to exhibit ceiling effects and may thus f a i l to differentiate higher from lower current intensities.  As an alternative measure, Tursky advo-  cated the use of skin potential recorded from forearm and abdominal sites. In an attempt to re-evaluate and extend this earlier study, Craig and Prkachin (197 8) monitored skin-conductance, heart-rate, forearm and abdominal skin-potential responses to electric shock among subjects exposed to either a tolerant or an inactive "co-participant".  Subjects generated  numerical magnitude estimates to shocks presented during a single ascending series, and a series of randomly-presented shocks at five standard i n tensities.  Subjects exposed to a tolerant model exhibited significantly  lower degrees of heart-rate acceleration to the current, and, unlike control subjects, the magnitude of their forearm skin-potential responses habituated over the course of the random series.  Thus, this study provided  positive evidence for the reduction of autonomically-mediated responses as a function of exposure to pain-tolerant social modeling. The question of whether pain modulation resulting from social i n fluence procedures may be mediated by fundamental alterations in sensory/ perceptual processes has been addressed ..in two different ways.  The f i r s t  has been to employ S.S, Stevens' power law (Stevens, 1975) and numerical magnitude estimation tasks. The power law states that the perceived magnitude of a sensation (  grows as a function of the physical magnitude  of the stimulus ( < j > .) raised to some power ( U ).  The c r i t i c a l parameter  in this procedure is the exponent ( n ) which Is traditionally interpreted to reflect the operating characteristic of sensory receptors with separate sensory modalities possessing a "true" value (Craig, Note 1)  While a l -  ternative interpretations are available, there seems to be agreement that the exponent is descriptive of rates of growth of perceptual magnitude. Craig, Best, and Ward (1975) employed the standard tolerant modeling, intolerant modeling, and control conditions while requiring subjects to generate estimates of the magnitude of discomfort provoked by, and physical intensity of electric shocks presented in ascending series on 10-poiht scales.  Power functions were fitted to the data of individual  subjects via linear regression of the logarithms of numerical responses on the logarithms of the geometric mean of stimuli associated with each response category.  No differences between the groups on the value of the  exponent were found.  However, since individual subjects' data were not  well fitted by the standard procedure, an alternative method was employed to estimate ideal power functions. This method (Teghtsoonian, 1971) expresses the value of the exponent as a function of the ratio of the largest to the smallest response value divided by the ratio of the largest to the smallest stimulus value, and thus is range-corrected.  Exponents derived  by this technique were significantly lower in the tolerant group than in the two other conditions. This finding prompted the conclusion that the tolerant modeling strategy had altered fundamental qualities of the experience of pain.  Craig (1978) employed power function analysis in a study  that manipulated communication channels across different groups.  Five groups  of subjects generated numerical estimates of the magnitude of electric  18 current applied in ascending series.  Subjects employed an open-ended  scale modified from Hilgard, Ruch, Lange, Lenox, Morgan, and Sachs (1974) that anchored their responses at'0" for^uiadetectabley" ' "1" for "detectr  ablei" "10" for the point at which they would ordinarily wish to stop accepting currents.  Subjects were encouraged to continue accepting shocks  and to make proportionate ratings after giving a rating of "10."  In group  1, standard tolerant modeling procedures were employed, with both subject and model providing concurrent ratings. Other groups varied according to whose information was available to whom. In group 2, only the subject verbalized her responses, in group 3 only the model verbalized, in group 4, both were silent, and in group 5, only the subject underwent the task, while the confederate remained explicitly inactive.  Conventional linear  regression of response magnitudes on stimulus magnitudes was employed i n order to derive parameters of the power function. Analyses of values of the exponent revealed that the group exposed to standard interactive tolerant modeling and the group in which information regarding the model's rating was available to the subject exhibited lower values of the exponent relative to the inactive model control group.  Why the conventional mode  of analysis failed to discriminate groups in the f i r s t study yet did in the second is unclear.  The reason for this may have had to do with differences  in the tasks employed across the two studies,  In the Craig, Best, and Ward  (1974) study, subjects employed a 10 point rating scale anchored at the upper end by the descriptors "high intensity" or "painful." terminated each test series,  A rating of 10  By contrast., subjects in Craig (1978) employed  an open-ended scale and were instructed to use a rating of "10" for the  19  point at which, they would ordinarily w/lsh to terminate the series,  The  nature of the subjects' task in the f i r s t study may h.ave art i f actually altered their rating behaviour.  A further possible source of the dis-  crepancy may have been due to differences in the subjects' behaviour in the two studies.  The mean of terminal current levels accepted by a l l groups  in Craig, Best, and Ward (1974) was 5.7 milliamperes Craig (1978) was 10.8 mA.  (mA) while that in  Finally, in Craig e_t al_. (1975) subjects only  rated the currents up to their f i r s t report of pain ("threshold") while in Craig (1978) subjects rated currents beyond this point.  The above-  noted methodological issues aside, i t would seem that the exponent of the power function relating stimulus intensity to sensation magnitude may  ex-  hibit systematic alterations associated with variations in modeling conditions . A second approach to assessing the nature of the changes produced in verbal rating indices of pain behaviour as a function of exposure to social influence conditions has been the use of signal-detection, or sensory-decision theory (SDT) methods (Green & Swets, 1966; McNicol, 1972; Pastore & Scheirer, 1974.) Since the present research made extensive use of SDT methods, and since there is currently a great deal of activity and controversy with respect to the application of SDT methods to pain research, this approach w i l l be reviewed in some detail.  Signal Detection Theory and Experimental Studies of Pairi Modulation Traditionally, studies of pain modulation have employed verbal rating tasks, and have been concerned with determining the extent to which the independent variables of interest are associated with alterations in  20  pain  threshold or.pain tolerance,  The p o i n t h a s a l r e a d y b e e n made t h a t a  l a r g e number o f v a r i a b l e s a r e c a p a b l e parameters; i n f a c t ,  the r e a c t i v i t y  of producing  a l t e r a t i o n s i n these  o f such measures t o m u l t i p l e  sources  o f i n f l u e n c e was p a r t i a l l y r e s p o n s i b l e f o r t h e d e v e l o p m e n t o f t h e d o u b l e b l i n d experimental  design  (Beecher, 1959).  t h a t such measures p r o v i d e  (1969),  however, argued  l i m i t e d i n f o r m a t i o n because they  confound the s u b j e c t ' s p e r c e p t u a l his  Clark  unavoidably  c a p a b i l i t i e s w i t h independent aspects o f  o r h e r t e s t - t a k i n g behaviour.  When a s u b j e c t ' s p e r f o r m a n c e i n a p a i n  e x p e r i m e n t changes such t h a t a l e v e l o f s t i m u l a t i o n p r e v i o u s l y d e s c r i b e d as painful  i s no l o n g e r s o d e s c r i b e d ,  unrelated the  changes:  (1) s e n s o r y  s u b j e c t no l o n g e r p e r c e i v e s  ory processes  this  c h a n g e may r e f l e c t  processes  may h a v e b e e n a l t e r e d s u c h  may h a v e r e m a i n e d u n a f f e c t e d  a g e n e r a l i z e d tendency t o a l t e r  emits  a p a r t i c u l a r response  (e.g.,  methodology based on p r o b a b i l i t y  a n d t h e s u b j e c t may s i m p l y e x -  the frequency  tasks i s p a r t i a l l y  theory  f o rassessing  including  SDT p r o v i d e s these  a  two a s p e c t s o f  and response b i a s .  s t a t e s t h a t a s u b j e c t ' s performance on p e r c e p t u a l  d e t e r m i n e d by d e c i s i o n - m a k i n g  of d e c i d i n g t o which o f n c l a s s e s o f stimulus belongs,  w i t h w h i c h he o r s h e  "that i s painful").  p e r f o r m a n c e , r e s p e c t i v e l y termed d i s c r i m i n a b i l i t y SDT c o n c e p t i o n  that  t h e s t i m u l i i n t h e same w a y , o r ( 2 ) s e n s -  hibit  The  a t l e a s t two  the subject's response w i l l the p r i o r p r o b a b i l i t y  processes.  Given the task  event a p a r t i c u l a r  exemplar  b e d e t e r m i n e d b y a number o f f a c t o r s ,  of occurrence  of a given  class,  the reward  a s s o c i a t e d w i t h an e r r o r , and t h e magnitude o f t h e d i f f e r e n c e s between t h e pertinent  classes of event.  In the s i m p l e s t type presented  Only the l a t t e r r e f l e c t s  sensory  performance.  o f s i g n a l ^ d e t e c t i o n t a s k , an i n d i v i d u a l i s  with a series of t r i a l s  d u r i n g w h i c h o n e o f two e v e n t s may  occur.  21  The  s u b j e c t i s simply r e q u i r e d to r e p o r t whether a p a r t i c u l a r  nal)  d i d or d i d not occur.  k i n d o f t a s k : (1)  of  the f a c t  ectly  s/he  that i t d i d not  r e p o r t t h a t the event  a s s u m e d t h a t t h e s i g n a l and  correctly  (2)  (a " h i t " ) ,  ( a " m i s s " ) , (3)  not occur  may  s/he  may  n o i s e , the p o s i t i o n s  o f m a k i n g a h i t and  v a l u e a l o n g the continuum  be  any  experience which  identified  probabilities  t o one  as n o i s e .  a n o t h e r by  each  e x p e r i e n c e , and  does n o t exceed  I f these assumptions  the areas  S i n c e t h e two  c u t o f f by  t h e i r d i s t a n c e f r o m one  another  It is provoke each  distribution  examining  This follows  pro-  adopts  a  decision-rule; be  h o l d , then  identified value  the  respectively,  signal distributions  the c r i t e r i o n ,  lying  in relation  i t i s possible  the  particular  criterion  curves are f i x e d  the  the  from  set, at a  this  o f o c c u r r e n c e o f f a l s e - a l a r m s and h i t s ,  r i g h t of the c r i t e r i o n .  bution.  corr-  of the experience  a fixed criterion,  t h e a r e a under t h e c u r v e o f t h e n o i s e and  a n o t h e r by  events  e x p e r i e n c e t h a t exceeds the c r i t e r i o n v a l u e w i l l  as a s i g n a l , will  of sensory  did  of the curves d e s c r i p t i v e of  a f a l s e alarm.  t h a t the observer adopts  sensory  may  that the magnitude of  distributions  e x p e r i e n c e s c a n be p l o t t e d i n r e l a t i o n  any  s/he  (a " c o r r e c t r e j e c t i o n " ) .  the n o n - s i g n a l ("noise")  Assuming normal  v o k e d by s i g n a l and  assumption  (4)  the  occurred i n spite  e x p e r i e n c e v a r i e s a c c o r d i n g t o some s p e c i f i a b l e  ( t y p i c a l l y normal).  probabilities  r e p o r t t h a t the event  (a " f a l s e a l a r m " ) , o r d i d not occur  this  r e p o r t the o c c u r r e n c e of  r e p o r t t h a t the event  a n e x p e r i e n c e on t h e p a r t o f t h e s u b j e c t , and event-provoked  (a s i g  Four p o s s i b l e outcomes a r e a s s o c i a t e d w i t h  t h e i n d i v i d u a l may  e v e n t on a g i v e n t r i a l  event  to  to to  the one  express  i n standard-score u n i t s of the n o i s e  T h i s d i s t a n c e , t e r m e d d_', i s a p u r e m e a s u r e o f s e n s o r y  define  distri-  sensitivity,  22  or the discriminability of the two events,  The procedure also provides a  second independent parametr descriptive of where the observer has placed his or her criterion,- thus indexing the subject's bias toward reporting or not reporting the event.  This parameter may be expressed in terms of likelihood-  ratio '— the ratio of the height of the ordinate of the signal distribution at the criterion to the height of the ordinate of the noise distribution at the criterion (L or g) — —x —  or as the value of the criterion in standard-  score units of the noise distribution.  Individuals may adopt very lax or  very strict criteria for reporting the occurrence of the event.  If the  criterion is very strict, false-alarm rates w i l l be reduced, hut so w i l l hits.  Alternatively, i f the criterion is very lax, both hits and false-  alarms w i l l be increased.  In the case of  or jB_ , a value exceeding 1.00  indicates bias against reporting the event, while a value of less than 1.00 indicates bias in favour of reporting i t . This basic paradigm can be modified to accommodate a variety of stimulus presentations and a variety of rating tasks and, therefore, is readily adaptable to pain research. The f i r s t application of SDT methods to pain research was performed by Clark (1969) who evaluated the effect of placebo administration on ratings of thermal pain via traditional (threshold) and SDT procedures.  Since that  time, pain modulation studies employing SDT procedures have expanded vigorously.  There is no need to review the substantive findings from this overall  field of research since comprehensive reviews are available elsewhere (Hall, 1977; Lloyd & Appel, 1976; Rpllman, 1977), Applications of SDT methods to the study of.social modeling influences on pain w i l l be discussed presently.  23  C r i t i c i s m s o f SDT The  SDT  pain  research,  a p p r o a c h has  provoked considerable  p a i n r e s e a r c h , owing to i t s a b i l i t y criptive set  of subjects' sensory  (response-bias).  a p p r o a c h on  excitement  i n the  to e x t r a c t independent parameters  performance  (discriminability)  B e n n e t t , & M a y e r , 1975;  methodological,  and  substantive  McBurney,.1975, 1976;  B o t h M c B u r n e y and  grounds  Rollman,  R o l l m a n h a v e c h a r g e d i n one  des-  the  (Hayes,  1977).  way  or another  d e f i n e d by  s i n c e t h e SDT  deal d i r e c t l y w i t h a f f e c t i v e responses,  i n a p p r o p r i a t e as a m e t h o d f o r t h e s t u d y argued, however, t h i s pain.  Current  C a s e y , 1968; are  criticism reflects  As  important,  this  dimensional  experience,  study by  is trivial.  has  nature  (Melzack  While a f f e c t i v e  &  components  Because p a i n i s a m u l t i -  i n c l u d i n g both sensory  C r a i g and  o f d_' and  i t is  a l i m i t e d v i e w o f t h e phenemena o f  may  provide  Prkachin  and  affective  particularly  (1978),  components,  important  cited earlier,  reductions  i n a u t o n o m i c and  infor-  provided  e v i d e n c e t h a t exposure to a p a i n - t o l e r a n t s o c i a l model i s a s s o c i a t e d reduced values  that  d o e s n o t mean t h a t i n f o r m a t i o n r e g a r d i n g i t s  t h a t examine both aspects The  and  Chapman ( 1 9 7 6 )  accounts emphasize i t s m u l t i - d i m e n s i o n a l  s e n s o r y - d i s c r i m i n a t i v e aspects  mation.  of pain.  C r o c k e t t , P r k a c h i n , & C r a i g , 1977).  crucially  studies  a f f e c t i v e responses,  that  pain i s a subjective experience a p p r o a c h does n o t  of  and t e s t - t a k i n g  However, s e v e r a l r e c e n t p a p e r s have c r i t i c i z e d  conceptual,  field  with  s e l f - r e p o r t i n d i c e s of  distress. Rollman and  (1977) has  there i s vigorous  criticisms  attacked  debate i n the  (Chapman, 1977;  Hall,  the  SDT  a p p r o a c h on  l i t e r a t u r e on  1977),  Two  the  a v a r i e t y of l e g i t i m a c y of  major conceptual  points  grounds the are  24 levelled.  The f i r s t is that SDT pain researchers tend to equate the sensi-  tivity parameter with physiological processes, and the bias parameter with emotional or psychological processes,  While there are instances in which  researchers have made such claims (Lloyd & Wagner, 1976), they are neither essential nor common in SDT pain research (Chapman, 1977).  tollman's  second major conceptual point is that a l l SDT pain research adheres to four assumptions: (1) a reduction in neural activity can produce a reduction in experienced pain, (2) a reduction in neural activity w i l l produce a reduction in d_' , (3) a reduction in d_' indicates a reduction in experienced pain, (4) a reduction in experienced pain w i l l be reflected in a reduction in d_' . Examples are cited of instances in which any or a l l of these assumptions might be incorrect. Chapman (1977, p.300), however, has pointed out that inferences about neural processes are both unnecessary for and irrelevant to SDT pain studies which employ the technique "... as a probability model for perception and decision making that has no particular physiological reality." A major methodological point is discrimination, not detection.  that SDT pain experiments measure  The measurement of detection requires the use  of a "zero stimulus", which subjects rarely confuse with noxious stimuli. There are methodological alternatives to this problem (Chapman, 1977). However, as Hall (1977) has pointed out, Rollman's suggestion may involve a confusion between zero stimulus units and zero units on the "sensory continuum."  In any event, SDT pain studies that do not employ a zero stimulus  s t i l l measure discrimination which is a fundamental aspect of the pain experience.  Despite these methodological and interpretive controversies, i t  25 can s t i l l be asserted that SPX methodology- can be effectively employed in separating discriminative capabilities and decision processes in relation to painful experiences.  26  RATIONALE  Developing an account of the role that social events play as deter^ minants of pain processes requires the collection of information pertinent to a series of issues.  The clear lack of isomorphism among alternative measures  of pain demands a careful analysis of the ways in which pain modulating effects may be organized.  SDT research, which rests upon the recognition  that personal reports of pain reflect both sensory and decision-making processes represents one particular example of this type of approach.  Evalu-  ation of social influences on pain, like evaluation of the effects of other potentially pain-modulating procedures, requires an analysis of effects on psychophysical parameters based upon the subject's vocal report.  An issue  of equal importance for models of social effects on pain derives from the point made earlier that pain is largely inferred from behavioural observation.  Since social influences operate in a milieu wherein evidence of pain  is a c r i t i c a l determinant of the responses of others, i t is of substantial interest to evaluate the effects of socially-based pain modulation procedures on behaviours that control the responses of others.  While vocal report  represents one such datum, also of c r i t i c a l interest is the nonvocal expressive behaviour of the subject.  Finally, an account of the role that  social events play in pain-modulation requires information regarding how such factors may operate in the natural environment. In light of the above considerations, the following studies addressed 3 major issues,  First was the issue of whether changes in expressions of  pain resulting from social modeling influence procedures are reflected in  27  c o n c o m i t a n t changes i n s e n s o r y - d i s c r i m i n a t i o n c a p a b i l i t i e s , b i a s e s of or a g a i n s t r e p o r t i n g the experience uated  o f p a i n , .or".'-both.  t h e i n f l u e n c e o f e x p o s u r e t o t o l e r a n t and  t r a d i t i o n a l and provided  SDT  measures o f p a i n p e r c e p t i o n .  d i s c r e t e behaviour  e n a c t e d by  affected individual.  undergoing the to naive  SDT  observers  of current  i n f l u e n c e , beyond the  t a s k i n E x p e r i m e n t 1. i n a SDT  of the behaviour  exposed t o .  expressions  i n the n a t u r a l environment.  analog  n a t u r a l l y - o c c u r r i n g v a r i a t i o n s i n pain behaviour i n an  adaptation  of  of the s t a n d a r d  levels  Experiment 3  was  o f t h e manner i n w h i c h Subjects  w e r e e x p o s e d t o one  modeling paradigm.  This  pain  displaying an-  procedure  a p a r t i a l e v a l u a t i o n o f the r e l a t i v e power o f p a i n t o l e r a n t  i n t o l e r a n t behaviour  subjects  I n E x p e r i m e n t 2 t h e s e w e r e shown  t h a t observed s u b j e c t s were b e i n g  might operate  the  d i s p l a y s of  t a s k r e q u i r i n g them t o d i s c r i m i n a t e t h e  experimental  1  social  l e v e l of  the model, t o the o v e r t e x p r e s s i v e  V i d e o t a p e s were taken  on  In a d d i t i o n , Experiment  an  allowed  Experiment 1 e v a l -  i n t o l e r a n t s o c i a l models  concerned w i t h developing  other  favour  d a t a u s e d i n an e v a l u a t i o n o f t h e s e c o n d . m a j o r i s s u e : w h e t h e r  m o d e l i n g i n f l u e n c e s h a v e a more g e n e r a l  the  in  i n a s i t u a t i o n p r o v i d i n g f o r mutual i n f l u e n c e .  and  28 E x p e r i m e n t 1.  The  S o c i a l m o d e l i n g I n f l u e n c e s on p a i n t h r e s h o l d , p a i n t o l e r a n c e and s e n s o r y - d e c i s i o n t h e o r y i n d i c e s .  impact of exposure to s o c i a l models e x h i b i t i n g r e l a t i v e  ance o r i n t o l e r a n c e f o r p a i n f u l e l e c t r i c a l itial  pain sensation  of s t u d i e s Best,  ( p a i n t h r e s h o l d ) has  ( C r a i g & W e i s s , 1971,  & W a r d , 1976;  Craig, Best,  T h e s e p r o c e d u r e s a l s o h a v e an has  1972;  s t i m u l a t i o n on  reports of i n -  been amply documented i n a s e r i e s  C r a i g , Best  & Best,  1978;  & R e i t h , 1974;  1978; Barber  c u r r e n t s up  Craig & Best,  impact at supra-pain  The  1977),  Neufeld  and  Davidson  threshold levels.  ( 1 9 7 1 ) and  to  e f f e c t s o f s o c i a l m o d e l i n g p r o c e d u r e s on  i n p a i n r e s e a r c h , however, recent  the response current  been focussed  upon  methods, e v i d e n c e has  t h e p o s i t i o n t h a t e x p o s u r e t o t o l e r a n t and  C o r e n (1975) exposed male  to t o l e r a n t or i n t o l e r a n t s o c i a l models w h i l e  ing this,  c u r r e n t s w h i c h were terminated  evalu-  been  of  response  undergraduates  they judged ascending  at f i r s t  con-  report of p a i n .  series Follow-  5 s t i m u l i were s e l e c t e d from the range of c u r r e n t s a d m i n i s t e r e d  each s u b j e c t d u r i n g a random o r d e r . cated  trends  intolerant social  models produces a l t e r a t i o n s i n s e n s o r y - d i s c r i m i n a t i v e a s p e c t s C r a i g and  to  methodology.  I n 3 s t u d i e s t h a t h a v e e m p l o y e d SDT  to noxious s t i m u l a t i o n .  and  pain-induction  Consistent with  i n t e r e s t has  a t i o n o f s o c i a l m o d e l i n g e f f e c t s v i a SDT  of e l e c t r i c  This  continue  Chaves  similar e f f e c t s using different  noxious s t i m u l a t i o n have been s u b s t a n t i a l .  sistent with  1974).  to the p o i n t at which they p r e f e r r e d to q u i t ( C r a i g ,  (1974) have r e p o r t e d  techniques.  Craig,  Craig & Niedermayer,  been demonstrated i n s t u d i e s where s u b j e c t s were r e q u e s t e d  accepting  toler-  the  t r a i n i n g s e r i e s and w e r e p r e s e n t e d  Analyses  t h a t e x p o s u r e t o an  of the r a t i n g s obtained i n t o l e r a n t m o d e l was  v i a SDT  12  times  techniques  associated with  to  each i n indi-  enhanced  29  ability  to d i s c r i m i n a t e betyeen the various stimulus  levels while tolerant  m o d e l i n g h a d no i m p a c t o n t h e d i ^ s c r i j n i n a b i l i t y m e a s u r e e m p l o y e d , Stimuli administered ions  to subjects i n this  o f t h e maximum c u r r e n t s a d m i n i s t e r e d  study were b a s e d upon proport-  during  the training  s u b j e c t s o n l y r a t e d c u r r e n t s up t o p a i n t h r e s h o l d d u r i n g t h e s e  s e r i e s , and series.  C o n s e q u e n t l y , t h e i m p a c t o f t h e m o d e l i n g c o n d i t i o n s o n SDT p a r a m e t e r s measured a t c l e a r l y n o x i o u s l e v e l s l a t e r study  o f s t i m u l a t i o n c o u l d n o t be a s s e s s e d .  A  e m p l o y e d SDT m e t h o d o l o g y t o i n v e s t i g a t e r e s p o n s e s t o s u p r a -  t h r e s h o l d l e v e l s o f s t i m u l a t i o n ( C r a i g & Ward, Note 2 ) . Male rated e l e c t r i c  currents i n ascending  t e c t a b l e " and "very  undergraduates  s e r i e s on a s c a l e a n c h o r e d a t "unde-  painful", i n 2 sessions.  During  the ascending  series,  s u b j e c t s w e r e e x p o s e d t o a c o - p a r t i c i p a n t who was e i t h e r i n a c t i v e  (i.e.,  n e i t h e r r a t e d n o r r e c e i v e d s h o c k s ) o r a c t i v e and t o l e r a n t ( i . e . , o s t e n s i b l y b o t h r e c e i v e d and r a t e d s h o c k s ) .  A n SDT s e r i e s was t h e n a d m i n i s t e r e d ,  s i s t i n g o f 10 r a n d o m p r e s e n t a t i o n s from v a r i o u s p r o p o r t i o n s series.  Results  o f e a c h o f 10 s t i m u l u s  o f maximum c u r r e n t s a c c e p t e d  levels,  during  con-  selected  the ascending  i n d i c a t e d t h a t e x p o s u r e t o a t o l e r a n t m o d e l was a s s o c i a t e d  w i t h reduced a b i l i t y  t o d i s c r i m i n a t e between t h e v a r i o u s  stimuli  These s t u d i e s have been c r i t i c i z e d on s e v e r a l grounds. though i t i s standard  practice to administer  individualized  employed.  First, a l -  stimulus  levels  i n SDT p a i n s t u d i e s , t h e m a n n e r i n w h i c h s t i m u l i w e r e i n d i v i d u a l i z e d i n these  s t u d i e s confounded s t i m u l u s  In t h e study by C r a i g and Coren  i n t e n s i t i e s w i t h groups  (Hall,  1977).  (1975) s u b j e c t s exposed t o an i n t o l e r a n t  m o d e l accep'ted.Hower. c u r r e n t s a n d s u b j e c t s e x p o s e d t o a t o l e r a n t m o d e l accepted during  higher  currents  than d i d c o n t r o l s ,  t h e SDT s e r i e s w e r e l o w e r  Thus, s t i m u l u s  i n absolute value  levels  employed  and d i f f e r e n c e s between  30  a d j a c e n t p a i r s were s m a l l e r values  and  f o r IntoXerants, t h a n c o n t r o l s , w h i l e  p a i r d i f f e r e n c e s were h i g h e r  h e l d i n t h e C r a i g and argued that t h i s  Ward  ( N o t e 2)  for tolerants,  study.  On  one  confound r e s u l t e d i n a conservative  since i n t o l e r a n t subjects  i n t h e C r a i g and  d i s c r i m i n a t i o n i n s p i t e of  the  r e c e i v e d were s m a l l r e l a t i v e  hand, i t can  t e s t of  the  f a c t t h a t d i f f e r e n c e s between the  to those i n the  Ward s t u d y , t o l e r a n t s u b j e c t s  criminate  stimuli, while  them w e r e l a r g e , r e l a t i v e  same p r o b l e m  the  other  groups.  intensities  I f Weber's law h o l d s f o r the the  f i n d i n g s m i g h t be  showed r e d u c e d a b i l i t y  i n control conditions.  On  reduced d i s c r i m i n a t i o n at higher  a c c o u n t e d f o r on  this basis  parameters  McNicol  (Rollman, 1977).  ( 1 9 7 2 ) h a v e a r g u e d t h a t SDT  50 p r e s e n t a t i o n s A  third  Despite  the  reduction by  the use  dis-  the  Lloyd pain  and  on  the  Appel  studies  to  other  stimulus  intensities. studies,  ground t h a t  too  few  estimation  of  (1976), f o l l o w i n g  should  include  at  least  a r e a o f a m b i g u i t y i n t h e C r a i g and about the  discriminabllity  i n f l u e n c e of t o l e r a n t modeling  of s u p r a - p a i n - t h r e s h o l d  of suprathreshold  employed i n t h i s  Ward s t u d y p e r t a i n s  stimulus  study involved  levels, the  stimulus  t h e mode o f  c a l c u l a t i o n o f an  to  I t could not  be  d e t e r m i n e d , t h e r e f o r e , whether the  the  pro-  levels. datao v e r a l l index  t a k i n g t h e mean o f a l l d i s c r i m i n a t i o n m e a s u r e s c a l c u l a t e d f o r e a c h -  subject.  in  of each stimulus i n t e n s i t y .  attempt to.draw conclusions c e d u r e s on  they  alone.  s t i m u l i were p r e s e n t e d a t each i n t e n s i t y t o a l l o w r e l i a b l e SDT  to  l e v e l s of s t i m u l a t i o n employed i n t h e s e  These s t u d i e s have a l s o been c r i t i c i z e d •  the  stimuli  d i f f e r e n c e s between l e v e l s administered  to subjects  and  hypotheses  Similarly,  h a n d , Weber's law w o u l d p r e d i c t enhanced d i s c r i m i n a t i o n b e t w e e n p a i r s a t low  be  C o r e n s t u d y showed e n h a n c e d  t h e C r a i g and the  the  The  absolute  reduced  31  discrimination ability  o b s e r v e d among s u b j e c t s e x p o s e d t o a t o l e r a n t m o d e l  r e f l e c t e d reduced d i s c r i m i n a b i l i t y  o f t h e more i n t e n s e s h o c k p a i r s ,  the l e s s  intense p a i r s , or both. A study  b y C r a i g and P r k a c h i n  (1978) overcame t h e  l e v e l confounding by a d m i n i s t e r i n g standard  current i n t e n s i t i e s  ant m o d e l i n g group and a no m o d e l i n g c o n t r o l group. ant in  group e x h i b i t e d lower  overall ability  t h e C r a i g and Ward s t u d y .  group/stimulus  Subjects  to a  i n the t o l e r -  t o d i s c r i m i n a t e t h e c u r r e n t s , as  However, s i n c e s t a n d a r d  stimulus  intensities  w e r e e m p l o y e d , some o f t h e s t i m u l i may h a v e b e e n w e l l b e y o n d n o x i o u s for  some s u b j e c t s , b u t n o t f o r o t h e r s .  about p a i n s e n s i t i v i t y , stimulus  intensities  j e c t as n o x i o u s .  I f valid  of stimulus  levels  i n f e r e n c e s a r e t o be drawn  i t w o u l d seem p r e f e r a b l e t o e n s u r e t h a t some o f t h e  e m p l o y e d h a v e a t some t i m e b e e n d e s c r i b e d b y t h e s u b -  Other problems w i t h  this  study  i n c l u d e t h e f a c t t h a t no  a t t e m p t was made t o d e t e r m i n e w h e t h e r d_' was r e d u c e d a t a l l , o r o n l y pairs  toler-  intensities.  some  T h u s , i t i s unknown w h e t h e r t h e f i n d i n g s  r e f l e c t e d an o v e r a l l r e d u c t i o n i n t h e d i s c r i m i n a b i l i t y o f c u r r e n t s , o r o n l y a r e d u c t i o n a t noxious o r non-noxious The applied ures to  present  to previous  s t u d y was d e s i g n e d SDT a n a l y s e s  t o o v e r c o m e some o f t h e c r i t i c i s m s •  of the e f f e c t s o f s o c i a l modeling  o n p a i n . To e n s u r e t h a t t h e d a t a  obtained would r e f l e c t  n o x i o u s and non-noxious i n t e n s i t i e s ,  were s e l e c t e d from 3 l e v e l s uninfluenced hold, and  intensities.  responses  These were:  d u r i n g an  (1) around d e t e c t i o n t h r e s -  ( 2 ) j u s t b e l o w p a i n t h r e s h o l d , and (3) midway b e t w e e n p a i n  pain  tolerance.  Determination  both  s t i m u l i e m p l o y e d i n t h e SDT p r o c e d u r e  d e f i n e d by t h e s u b j e c t ' s behaviour  preassessment s e s s i o n .  proced-  of the locus, along  the shock  d i m e n s i o n , o f any e f f e c t o f t h e s o c i a l i n f l u e n c e c o n d i t i o n on  threshold intensity  32 discriminability was to be evaluated by comparing groups at each stimulus pair.  Including an uninfluenced preassessment session also allowed random  assignment of subjects to one of 3 social influence groups, thus avoiding the problem of group/stimulus  intensity confounding.  Further, Lloyd and  Appel's (1976) recommendation that at least 50 presentations of each stimulus intensity be employed was adopted. The task employed i n the SDT portion of the present study required subjects to rate each stimulus on a 7-point scale of pain intensity.  A con-  current forced-choice rating was also employed. At each overall level of intensity (detection threshold, sub-pain-threshold,  supra-pain-threshold),  2 stimuli were presented, differing by 0.25 milliamperes (mA). The forcedchoice task required subjects to identify whether the higher member of the pair was the f i r s t or the second to be presented.  Previous research employ-  ing thermal nociceptive stimulation has indicated that different SDT procedures are not equivalent, in that indices of discriminability (d_') based on rating scale tasks are less reliable than those based on 2-alternative, binary decision tasks (Clark & Dillon, 1973; Clark & Mehl, 1973). The forced-choice procedure was included in this study as an alternative means of assessing stimulus discriminability. The design of the experiment called for an i n i t i a l assessment of pain threshold and tolerance i n the absence of social influence.  In a subsequent  influence session, subjects were exposed to tolerant modeling, intolerant modeling, or control procedures, followed by assessment of the impact of the procedures on SDT parameters. Various alternatives were available in the choice of rating tasks.  Categorical judgment procedures are most appropriate  in SDT tasks since subjects tend to use them consistently, and under  33  favourable  c o n d i t i o n s they  several points  a l l o w the e s t i m a t i o n of sensory  ( c r i t e r i a ) along  the r a t i n g s c a l e .  sensitivity  H o w e v e r , a number o f  c o n s i d e r a t i o n s s u g g e s t e d t h a t m a g n i t u d e e s t i m a t i o n w o u l d be  a more a p p r o -  p r i a t e p r o c e d u r e to employ d u r i n g  the p r e s e n t a t i o n of the ascending  occurring prior  F i r s t , magnitude e s t i m a t i o n  t o t h e SDT  task.  reliable  and  induced  p a i n and  are p a r t i c u l a r l y s u i t e d f o r paradigms that i n v o l v e  tinuous  increases  1967,  1969;  the p a i n  the s u b j e c t  continuum w h i l e  magnitude of induced M o r g a n , and  Sachs  quired subjects induced  by  procedure. serve  intensity  (Grossberg  C r a i g , B e s t , & Ward, 1975).  manner t h a t a l l o w s along  s e n s i t i v e measures of.changes i n  pain.  For  adapted i n a  of d i s c r e t e p o i n t s  generating  r a t i n g s of  proportionate  to continuously  c o l d - p r e s s o r p a i n up  assign numerical  r a t i n g s to the  to the p o i n t a t which they  I n s t r u c t i o n s i n the use  t h i s l a b o r a t o r y has  the  example, H i l g a r d , Ruch, Lange, Lenox,  of the  sensations  scale required subjects  ratings.  re-  terminated  f o r t h a t p o i n t at w h i c h they would l i k e  c o n t i n u i n g t o make p r o p o r t i o n a t e  cedures.  c a n be  Hilgard,  ( 1 9 7 4 ) u s e d an o p e n - e n d e d s c a l i n g p r o c e d u r e t h a t  a r a t i n g o f "10"  ticularly  1976;  con-  to r e p o r t the occurrence  p r o c e d u r e ; however, they were encouraged to p e r s e r v e r e while  experimentally-  & Grant,  Second, they  series  procedures  provide  i n stimulus  at  to  re-  to stop  beyond t h i s  Third, recent  the  the  point  experience  suggested that magnitude e s t i m a t i o n procedures are  s e n s i t i v e to the e f f e c t s of v a r i a t i o n s i n s o c i a l i n f l u e n c e  in  par-  pro-  ( C r a i g , 1978).  Method Subjects.  S u b j e c t s w e r e 36  female undergraduate volunteers  i n t r o d u c t o r y Psychology courses  at the U n i v e r s i t y of B r i t i s h  (M age=18.6S.D. = l . . l . ) . S u b j e c t s w e r e c o n t a c t e d  by t e l e p h o n e  r e c r u i t e d from Columbia  and  o f f e r e d $4.00  34  f o r p a r t i c i p a t i o n i n an i n g two  sessions.  refused while  Of  e x p e r i m e n t on p e r c e p t i o n  t h o s e who  Session  was  2,  session.  e x c u s e d on m e d i c a l  grounds.  l y assigned  t o one  A p p a r a t u s and  their participation of three  experimental  Experimental  Electric  ( T u r s k y , Watson, and ectrostimulator  i n Session  sec.  The  experimental  v i a a 60 Hz  ually isolated The  videotape  s u b j e c t and  the  a 1 cm.  arrange  s u b j e c t s were random-  the  Model A-6158).  2.  electrodes  Videotape  s t i m u l a t i o n e q u i p m e n t , and  two  a wooden p a r t i t i o n w h i c h , i n S e s s i o n A wooden p a r t i t i o n the  also  2 meters i n f r o n t of  o f t h e s u b j e c t ' s h e a d a n d was  f o r a d u r a t i o n of 5 sec.  located behind  c o n t r o l l e d by  to the p a r t i t i o n  isolating  of t h i s p a r t i t i o n ,  isolated  A wooden p a r t i t i o n was  and  the  on slight-  timing remain  located at right  the s u b j e c t from the experimenter. f r o m t h e s u b j e c t ' s v i e w , was  vis-  the  to i n d i c a t e stimulus occurrences  d i a m e t e r j e w e l l i g h t was  2,  c o n t r o l equipment.  e q u i p m e n t t o i l l u m i n a t e c o n c u r r e n t l y w i t h s t i m u l u s p r e s e n t a t i o n and on  revideo-  the model.  In order  a Hunter  u s i n g a Sony M o d e l AV-3400  s i t u a t e d approximately  i n f u l l view.  to the l e f t  beside  s u b j e c t and  c a m e r a was  to  controlled-current e l -  t h e s u b j e c t f r o m t h e e x p e r i m e n t e r and  the v i d e o t a p e s , ly  room c o n t a i n e d  S u b j e c t s were s e a t e d isolated  them,  second  d e l i v e r e d through concentric annular  ( L a f a y e t t e I n s t r u m e n t Co.,  camera.  1,  to  d u r a t i o n were c o n t r o l l e d by  O ' C o n n e l l , 1965)  and  visually  contacted  conditions for. Session  c o r d i n g s w e r e made on h a l f - i n c h v i d e o t a p e ,  chairs.  Upon b e i n g  1, f o u r  Environment  c u r r e n t s o f 0.5  Decade I n t e r v a l t i m e r and  corder  been d e s c r i b e d  8 more i n d i c a t e d t h e i r u n w i l l i n g n e s s t o r e t u r n f o r a Following  attend-  a r r i v e d at the l a b o r a t o r y f o r Session  t o p a r t i c i p a t e when the, e x p e r i m e n t h a d one  that would i n v o l v e  To  a 1 cm.  angles  the jewel  right  35  light.  During  both s e s s i o n s , sheets  s c a l e s were a f f i x e d experimenter.  the rating  t o the p a r t i t i o n blocking the subject's view ofthe  Subjects were seated  c l u d i n g a second person, to  o f paper that depicted  i n t h e same c h a i r i n b o t h s e s s i o n s .  t h e model, i n Session  2 r e q u i r e d t h a t she be  In-  seated  t h e s u b j e c t ' s r i g h t s o t h a t t h e "dummy" e l e c t r o d e c o u l d b e a t t a c h e d t o  her. Procedure.  Session  1  S u b j e c t s were g r e e t e d  a t the l a b o r a t o r y by the experimenter,  who i n -  d i c a t e d t h a t a n o t h e r s u b j e c t would be coming and t h e n t h e e x p e r i m e n t w o u l d be u n d e r way.  The p u r p o s e o f t h i s  r u s e was t o a v o i d a r o u s i n g  suspicions  a t t h e i n t r o d u c t i o n o f an o s t e n s i b l e c o - p a r t i c i p a n t i n S e s s i o n  2.  After a  few m i n u t e s ' c o n v e r s a t i o n w i t h t h e s u b j e c t , t h e e x p e r i m e n t e r s t a t e d , "As l o n g as we're w a i t i n g , I might as w e l l g e t y o u s t a r t e d by g i v i n g y o u a couple  of questionnaires  Inventory jective  t o work o n . " S u b j e c t s  o f General  Trait Anxiety  ( E n d l e r and Okada, 1975) and t h e Sub-  Stress Scale  (SSS; N e u f e l d  and D a v i d s o n , 1972).  were c o m p l e t i n g  subject ." 1  While  subjects  the q u e s t i o n n a i r e s , the experimenter completed p r e p a r a t i o n ,  o f t h e e q u i p m e n t , a n d made a c o u p l e "other  t h e n c o m p l e t e d t h e S-R  of forays  t o t h e door t o l o o k f o r t h e  When t h e s u b j e c t h a d c o m p l e t e d t h e q u e s t i o n n a i r e s , t h e  experimenter suggested that t h e experiment should proceed without subject. discomfort and to  T h e e x p e r i m e n t was t h e n d e s c r i b e d resulting  from m i l d e l e c t r i c a l  as a study  i n "the perception of  s t i m u l a t i o n . " The p r o c e d u r e s  s t i m u l a t i o n w e r e d e s c r i b e d , a n d t h e s u b j e c t was g i v e n withdraw.  When c o n s e n t h a d b e e n o b t a i n e d ,  the e x p e r i m e n t a l  the other  the opportunity  t h e s u b j e c t was s e a t e d i n  room and t h e f o l l o w i n g i n s t r u c t i o n s were  read:  I'm g o i n g t o p r e s e n t y o u w i t h a s e r i e s o f l o w c u r r e n t s t h a t w i l l s t a r t a t u n d e t e c t a b l e l e v e l s and w i l l g r a d u a l l y i n c r e a s e i n i n t e n s i t y and d i s c o m f o r t . Y o u r t a s k w i l l b e t o i n d i c a t e how  36  u n c o m f o r t a b l e each momentary c u r r e n t f e e l s b y a s s i g n i n g i t a n u m b e r r a n g i n g f r o m z e r o up t o 1 0 , a n d t h e n b e y o n d . I n i t i a l l y , t h e c u r r e n t w i l l be so low t h a t you w i l l probably feel nothing. I f t h i s i s the case, the r a t i n g "zero", f o r "undetectable", i s appropriate. T h e r e a f t e r , they w i l l gradu a l l y i n c r e a s e i n i n t e n s i t y and d i s c o m f o r t . We w o u l d l i k e y o u to r a t e e a c h s u b s e q u e n t s h o c k i n p r o p o r t i o n t o t h e amount o f d i s c o m f o r t t h a t y o u f e e l , s o t h a t , f o r e x a m p l e , i f o n one c u r r e n t y o u g i v e a r a t i n g o f " 2 " , and then a l a t e r one f e e l s t w i c e a s u n c o m f o r t a b l e , y o u g i v e t h e l a t e r one a r a t i n g o f "4". (These r a t i o i n s t r u c t i o n s w e r e b a s e d o n t h o s e e m p l o y e d by C r a i g & P r k a c h i n , 1978, and C r a i g , 1978a). Higher r a t ings should r e f l e c t increases i n p h y s i c a l discomfort. You w i l l e v e n t u a l l y reach a l e v e l o f current that you would desc r i b e as g i v i n g y o u a s e n s a t i o n o f " v e r y f a i n t p a i n . " We would l i k e y o u t o g i v e t h a t c u r r e n t a r a t i n g o f "10" and t h e n we'd l i k e y o u t o c o n t i n u e a c c e p t i n g c u r r e n t s f o r a s l o n g as p o s s i b l e a f t e r you've reached t h i s l e v e l . When y o u r e a c h t h e p o i n t where y o u don't w i s h t o a c c e p t any f u r t h e r s t i m u l i , give that current your f i n a l r a t i n g , c a l l outthe w o r d " t e r m i n a t e " a n d no more w i l l b e g i v e n t o y o u . After  the subject had i n d i c a t e d h e r understanding  e x p e r i m e n t e r s t a t e d , "We l i k e check on t h e accuracy focussed  to videotape  o f my r e c o r d i n g s , "  of the instructions, the  each s e s s i o n so t h a t I can and t h e v i d e o t a p e  c a m e r a was t h e n  on h e r .  R e d u x p a s t e was t h e n a p p l i e d t o t h e s u b j e c t ' s l e f t  forearm,  and t h e  e l e c t r o d e p o s i t i o n e d as n e c e s s a r y  t o reduce the r e s i s t a n c e i n the e l e c t r o d e -  skin circuit  e_t a l . , 1 9 6 5 ) .  two  ascending  levels  t o 5 0 0 0 ohms ( T u r s k y series  of the psychophysical  were taken  I n t e r - s t i m u l u s i n t e r v a l s w e r e 10 s e c .  continuously  series, subjects  then underwent  method o f l i m i t s w i t h  s t a r t i n g a t 0.0 mA a n d i n c r e a s i n g i n 0.5 mA s t e p s  r a t i n g was g i v e n .  throughout both s e r i e s .  until Video  current  a  "terminate" recordings  A t t h e end o f the second  c o m p l e t e d t h e SSS a n d t h e a d j e c t i v e c h e c k l i s t p o r t i o n o f  the M c G i l l P a i n Q u e s t i o n n a i r e structions to rate the highest with  Subjects  (MPQ; M e l z a c k & T o r g e r s o n , 1 9 7 1 ) w i t h i n shock"accepted.  S u b j e c t s were then  i n s t r u c t i o n s n o t t o t a l k about t h e experiment.  dismissed  37  Session 2 Subjects returned for Session 2 a mean of 15 .,3days (S.D.= 12. 4) after Session 1. The model typically arrived several minutes later than the subject. Four females, aged 20, 21, 21, and 28 served as models. The model was always treated as i f she were a naive subject. When both had arrived, subject and model were introduced and given the SSS to f i l l out.  They were then escorted to the experimental room, seated i n their  appropriate chairs, and had the following instructions read to them: The f i r s t part of what we w i l l do today i s going to be identical to what occurred during the f i r s t session. Let me review things briefly to refresh your memory. I w i l l again present you with a series of low currents starting at undetectable levels that w i l l gradually increase in intensity. As before, I would like you to rate them on the 0 to 10 scale with 0 standing for undetectable, 10 standing for very faint pain, and so on. As before, make your ratings in proportion to the amount of discomfort that you feel. When you reach the point where you don't wish to accept any further stimuli, give that current your final rating, call out the word "terminate", and no more w i l l be given to you. Electrodes were then attached to both subject and model.  Immediately be-  fore commencing shock administration, the experimenter instructed the subject that she should give her rating f i r s t , followed by the model. Subjects then went through 3 series of electric shocks, each increasing in 0.5 mA steps from 0.0 mA until they gave their "terminate" rating, or until a maximum current of 18.0 mA had been accepted. During this session, subjects were exposed to one of 3 experimental treatments.  Those assigned to the tolerant (T) group made their ratings  concurrently with a model who consistently assigned ratings to the shocks that were 25% lower than those of the subject. When the subject had given her "terminate" rating, the experimenter informed her that no more shocks  38  would be given to her, but shocks would continue for the model.  On the  following t r i a l , the model gave the same rating she had given on the subject's "terminate" t r i a l .  On the next two t r i a l s , the model gave  ratings increasing by one rating-scale unit and then gave her "terminate" rating.  These contingencies did not, of course, apply when subjects had  taken currents up to the maximum of 18.0  mA.  In the intolerant (I) condition, subjects were exposed to a model who  consistently rated the shocks to be 25% higher than did the subject.  Further contingencies f o r the role required that the model rate the f i r s t current at "0" and the second at "1). rating above "10",  When the subject gave her f i r s t  the model gave her corresponding rating, and then gave  a "terminate" rating.  The model was  then informed that no more shocks  would be given to her, and the series proceeded u n t i l the subject gave a "terminate" rating. In the control (C) condition, following reading of the preliminary instructions, the experimenter  stated that for the f i r s t part of the ex-  periment, only the subject would be receiving shocks and should  respond.  Videotape recordings were made of subjects during a l l 3 ascending series i n Session 2. SDT Series Following completion of the 3 ascending s e r i e s , a second phase of the experiment, concerned with SDT analyses, began.  In this phase, sub-  jects were exposed to a series of pairs of shocks that had been selected on the basis of the subject's performance during the second ascending series of Session 1.  The f i r s t pair consisted of that current f i r s t report-  ed as detectable during the second ascending series of Session 1 ( i . e . , the f i r s t nonzero r a t i n g ) , and a current l e v e l 0.25 mA lower.  The second pair  39  consisted When no  of the  "8"  current  r a t i n g had  t h a t l e v e l m i n u s 0.25 current and  level  t i o n s was  occurred, mA  the  were used.  corresponding to the  "terminate", Prior  l e v e l r a t e d as  and  "8"  the  t h a t l e v e l m i n u s 0.25  c l o s e s t r a t i n g l o w e r t h a n "8" The  third pair consisted  of  SDT  mA.  and the  r a t i n g o c c u r r i n g halfway between  t h a t l e v e l m i n u s 0.25  to i n i t i a t i n g  and  "10"  mA.  s e r i e s , the  f o l l o w i n g set of i n s t r u c -  read:  The n e x t p a r t o f t h e e x p e r i m e n t i s g o i n g t o be q u i t e a b i t different. I n t h i s p a r t , I'm g o i n g t o p r e s e n t y o u w i t h a s e r i e s o f p a i r s o f c u r r e n t s t h a t w i l l o c c u r i n random o r d e r . Each p a i r w i l l occur very q u i c k l y . In t h i s part your task w i l l be a l i t t l e b i t more c o m p l i c a t e d . Instead of r a t i n g t h e c u r r e n t s on t h e 0 t o 10 and a b o v e s c a l e t h a t y o u ' v e b e e n u s i n g , we w o u l d l i k e y o u t o r a t e e a c h c u r r e n t u s i n g t h e c a t e g o r i e s t h a t I am g o i n g t o p u t up on t h e s e s h e e t s . The  experimenter than replaced  the  0-10  scale with  Undetectable,  3 —  Very F a i n t P a i n ,  6 —  Strong Pain.  associates  1 —  Faint Sensation, 4 —  This  s c a l e was  (Chapman, G e h r i g ,  as  Mild Pain,  5 —  b a s e d on  & Wilson,  below p a i n  the  representation  of  a 7-point c a t e g o r i c a l judgment  f o l l o w i n g d e s c r i p t o r s and  shock induced s e n s a t i o n s continued  sheets containing  sheets that depicted  s c a l e c o n s i s t i n g of the 0 —  the  2 —  rating scale  Pre-Pain  Moderate  threshold.  Sensation,  Pain,  t h a t used by  1975), but  Chapman and  modified  The  numbers:  to allow  his for  i n s t r u c t i o n s then  follows:  I n d i c a t e y o u r c h o i c e by a s s i g n i n g e a c h c u r r e n t a number c o r r e s p o n d i n g t o a c a t e g o r y on t h e s h e e t . Take a c l o s e l o o k a t t h e c a t e g o r i e s f o r we w a n t y o u t o l e a r n w h i c h number g o e s w i t h w h i c h l a b e l as s o o n as y o u c a n . N o t i c e t h a t und e t e c t a b l e i s s t i l l g i v e n a r a t i n g o f 0 j u s t l i k e i t was on t h e o l d s c a l e . H o w e v e r , v e r y f a i n t p a i n , w h i c h was on t h e o l d s c a l e was 1 0 , i s now t o b e g i v e n a r a t i n g o f 3. One w o u l d , be u s e d t o i n d i c a t e t h a t y o u c a n j u s _ t ~ d e t e c t t h e s h o c k , w h i l e 2 i n d i c a t e s t h a t you can d e f i n i t e l y f e e l the shock b u t i t i s not yet p a i n f u l .  40  I w i l l a l s o a s k y o u t o make a s e c o n d t y p e o f r a t i n g . As I s a i d , I am g o i n g t o p r e s e n t t h e s t i m u l i t o y o u i n p a i r s . A f t e r y o u h a v e r a t e d b o t h s t i m u l i on t h e 0 - 6 scale, I w o u l d l i k e y o u t o t e l l me w h e t h e r y o u t h i n k t h a t t h e h i g h e r , o r t h e m o r e i n t e n s e s t i m u l u s o f t h e p a i r was the f i r s t one t o be p r e s e n t e d o r t h e s e c o n d . I n d i c a t e your c h o i c e by c a l l i n g o u t t h e w o r d s " f i r s t " o r " s e c o n d . " At  this  currents in  p o i n t , s u b j e c t s were a l s o informed  t o be  the past.  stood  the  equally  administered The  task.  f o r low,  w o u l d be  One  medium, a n d  p a i r s were a l s o balanced s e c o n d o f t h e p a i r was l o w , medium, and  was  3 s e r i e s of  magnitude for  (i.e.,  the order  subject-by-subject occurred the  on  the  at  first  and and  .33 The  each of low,  s e r i e s of B l o c k  second b l o c k of  3.  medium and  o f e a c h p a i r was  Thus, v i d e o t a p e s  trials,  of  the occurrence  and  pairs.  of  1/3  was  current  high pairs.) higher.  and  Within  r a n d o m i z e d on t h e SDT  of  a One-minute r e s t p e r i o d  2,  stimulus  corresponded to the Upon c o m p l e t i o n  a  series  1, t h e s e c o n d s e r i e s o f B l o c k  18 s t i m u l u s 54  or  series  equally for  of s u b j e c t s d u r i n g  series occurred,  n i n t h s e r i e s of  first  Stimulus  W i t h i n each b l o c k  o f p r e s e n t a t i o n o f e a c h s e r i e s was Videotaping  the  as w e r e p r i o r p r o b a b i l -  o f 54 s t i m u l u s p a i r s .  or second stimulus  i n t h e SDT  to  into blocks.  e n t i r e SDT  18 s t i m u l u s p a i r s , b a l a n c e d  t h i r d s e r i e s of B l o c k  presentations fifth,  3 blocks  basis.  first  subject  presentations  Thus, the p r i o r p r o b a b i l i t i e s  6 presentations  whether the f i r s t  each b l o c k ,  and  of t r i a l s  h i g h p a i r s were equal  b r o k e n down i n t o  under-  balanced  e q u a l l y i n terms of whether the  higher.  accepted  t h e r e w e r e 54  i n a random o r d e r , grouping  the  had  that the s u b j e c t  high pairs (i.e.,  f o r the b i n a r y d i s c r i m i n a t i o n (.50).  included  than they  hundred s i x t y - t w o stimulus p a i r s ,  c o n d i t i o n d e s c r i b e d below i n the  ities  higher  experimenter then insured  of each p a i r ) were then presented  of  any  t h a t none of  of  first, the  occurred.  41  To m a i n t a i n t h e m o d e l i n g i n f l u e n c e the  SDT s e r i e s , t h e m o d e l r e m a i n e d a c t i v e t h r o u g h o u t .  during  this  series differed slightly  In conditions  T, t h e m o d e l made d i s c r e p a n t  (roughly  r a t i n g s one s c a l e p o i n t  higher.  below the subject's  I , t h e m o d e l made  discrepant  ratings  t h o s e o f "the s u b j e c t .  forced-choice  D i s c r e p a n t r a t i n g s occurred randomly  When t h e m o d e l was n o t s p e c i f i c a l l y  I n circumstances" where g i v i n g a d i s c r e p a n t  r a t i n g was i l l o g i c a l  ( e . g . , when t h e s u b j e c t  t h e second s t i m u l u s  the m o d e l gave r a t i n g s  signalled  r a t i n g , she gave r a t i n g s t h a t were i d e n t i c a l t o  as h i g h e r ,  have c a l l e d f o r t h e model t o emit t h e i l l o g i c a l  had given  forced-  a rating  which would o r d i n a r i l y  r a t i n g "3-4, f i r s t  higher")  t h a t were i d e n t i c a l t o t h o s e o f t h e s u b j e c t .  I n c o n d i t i o n C, t h e m o d e l ' s p r e s e n c e a s a n a c t i v e was b r o u g h t a b o u t b y t h e e x p e r i m e n t e r i n f o r m i n g  subject  co-participant and model  that,  t h e SDT s e r i e s , t h e m o d e l w o u l d b e r e c e i v i n g s h o c k s , b u t , u n l i k e t h e  m o d e l , s h o u l d w r i t e h e r r a t i n g s on a mimeographed izing  In condition  D i s c r e p a n t c a t e g o r y s c a l e and b i n a r y - c h o i c e  to perform a.discrepant  during  i n the appro-  (roughly  throughout the SDT.series.  "3-4" and r a t e d  ratings  r a t i n g s o n 30  were i n d e p e n d e n t o f one a n o t h e r .  of  role  To e n h a n c e t h e c r e d i b i l i t y o f t h e m o d e l ' s  b e h a v i o u r , s h e a l s o made d i s c r e p a n t of) a l l trials.  The m o d e l ' s  24% o f a l l t r i a l s ) .  i n condition  during  i n the ascending s e r i e s .  r a t i n g s one s c a l e p o i n t  r a t i n g s on t h e s e t r i a l s , w h i l e  choice  from that  T a n d I , t h e m o d e l made d i s c r e p a n t  p r i a t e d i r e c t i o n o n 39 t r i a l s  19%  f o r experimental groups  them a l o u d .  sheet r a t h e r  than  The e x p e r i m e n t e r t h e n g a v e t h e m o d e l a c l i p b o a r d ,  verbalsheet  and  p e n c i l a n d s p e n t some t i m e o s t e n s i b l y i n s t r u c t i n g h e r i n how t o w r i t e  her  ratings.  Prior to initiating  t h e SDT s e r i e s , t h e e x p e r i m e n t e r  cautioned  the model t o r e a d t h e i n s t r u c t i o n s a t t h e t o p o f t h e sheet c a r e f u l l y and  42  understand  them t h o r o u g h l y b e f o r e  Inter-pair intervals while  the series  started.  d u r i n g t h e SDT s e r i e s v a r i e d f r o m 10 - 20 s e c ,  t h e s p a c i n g between s t i m u l i  i n e a c h p a i r was r o u g h l y 1 - 2 s e c .  When t h e SDT s e r i e s h a d b e e n c o m p l e t e d , c o r t e d t o t h e a d j o i n i n g room where t h e y When s u b j e c t s h a d f i n i s h e d  s u b j e c t and model were e s -  c o m p l e t e d t h e SSS a n d t h e MPQ.  completing  the questionnaires, the nature  o f t h e d e c e p t i o n was r e v e a l e d t o t h e m , a n d t h e y w e r e f u l l y  d e b r i e f e d as t o  the background and purposes o f t h e experiment.  t o use the v i d e o -  tapes  t a k e n o f them i n l a t e r  forms i n d i c a t i n g  and  requested  r e s e a r c h was e x p l a i n e d , a n d t h e y  t h a t they were agreeable  ployed i s presented  The i n t e n t  i n A p p e n d i x B.)  to this.  (The c o n s e n t  -consent  f o r m em-  F o l l o w i n g t h i s , s u b j e c t s were p a i d ,  n o t t o t a l k t o anyone i n t h e i r  f o r a p e r i o d o f about a month.  signed  c l a s s e s about t h e experiment  43  Results  Subject  attrition During  Session Of  the  course  1 indicated 38  g r o u p T,  returned  and  1 was  i n g r o u p C. Session  Of  of s u b j e c t s  2,  7 terminated  pain  i n group I d u r i n g S e s s i o n  itial  pain threshold  (first  Session  ascending  f r o m a l l s u b j e c t s who including  t h o s e who  the  for 2.12  (i.e.,  The  15  or S e r i e s , F  of  - ' i !  Y  attrition of  variance during  p a i r of analyses  included  series of Session  t h e SDT  i n g r o u p I , and  The  of  tolerance  tolerance values  first  during  r e v e a l e d no  p >.05.  p a i n t o l e r a n c e r e v e a l e d no p > ,05,  currents  .-  or greater) or pain  current i n t e s i t y provoking  threshold)  ( 2 , 3 3 ) = 0.94,  1.  dropped out  a n a l y s i s p e r f o r m e d on  erences,  1.  in  of subjects e x h i b i t i n g d i f f e r e n t i n -  completed the 3 ascending  i n g r o u p T,  or greater  accepted  Accordingly, analyses  s e r i e s of Session  on s a m p l e s i z e s o f 11  10  session  the subsequent replacement  (ANOVAs) w e r e p e r f o r m e d on p r e t e s t t h r e s h o l d and  (i.e.,  the  tolerance  2 and  r a t i n g o f 10  (maximum c u r r e n t a c c e p t e d ) v a l u e s .  data  Session.  of concern to e v a l u a t e whether the g r e a t e r r a t e of  subjects resulted i n a t t r i t i o n  two  completed  t h e s e , 5 w e r e i n g r o u p I , 1 was  2 than during  these  the  s u b j e c t s who  A l l w e r e s u b j e c t s who  r e p o r t s o f p a i n t h r e s h o l d and I t was  8 o f t h e 44  f o r Session  signal detection series.  intensity during  Verbal  of the study,  t h e i r u n w i l l i n g n e s s to r e t u r n f o r a second  s u b j e c t s who  during the  lower  the  s e r i e s ) and 10  i s based  i n g r o u p C.  an i n i t i a l  The  rating  s i g n i f i c a n t between group  a n a l y s i s on  the c u r r e n t  2  of diff-  intensity  s i g n i f i c a n t b e t w e e n g r o u p s , F_ ( 2 , 3 3 ) =  ( 1 , 3 3 ) = 2.16,  p > -.05,  effects.  Thus,  there  44 were no d i f f e r e n c e s between groups on t h e s e measures a t t h e end o f S e s s i o n 1 t h a t were s t a t i s t i c a l l y  reliable.  The same a n a l y s e s were performed e x c l u d i n g t h e d a t a from t h o s e subj e c t s who dropped o u t d u r i n g t h e s i g n a l d e t e c t i o n s e r i e s . a n a l y s i s r e s u l t e d i n no s i g n i f i c a n t between-group  The t h r e s h o l d  e f f e c t s , F (2.27) = 1.65,  p > .05. The a n a l y s i s o f p a i n t o l e r a n c e w i t h dropouts e x c l u d e d r e s u l t e d i n a between groups e f f e c t t h a t approached, b u t d i d n o t a t t a i n , c o n v e n t i o n a l l e v e l s o f s t a t i s t i c a l r e l i a b i l i t y , F_ (2,27) = 2.79, p_=.08, and no o t h e r noteworthy terms. the  O v e r a l l , t h e r e f o r e , i t was r e a s o n a b l e t o c o n c l u d e t h a t  groups were comparable i n terms o f p a i n t h r e s h o l d and p a i n t o l e r a n c e  v a l u e s p r i o r t o u n d e r g o i n g t h e i n f l u e n c e c o n d i t i o n s o f S e s s i o n 2. T h r e s h o l d and t o l e r a n c e d a t a were examined f u r t h e r i n o r d e r t o det e r m i n e e f f e c t s o f exposure t o t h e s o c i a l i n f l u e n c e c o n d i t i o n s . of a n a l y s i s proceeded as f o l l o w s .  First,  The p l a n  t h e d a t a were a n a l y z e d i n a 3  (Groups) X 5 (Shock S e r i e s ) ANOVA d e s i g n w i t h r e p e a t e d measures on t h e Series factor.  F o l l o w i n g t h i s , s i m p l e main e f f e c t s were e v a l u a t e d f o r  statistical reliability.  F i n a l l y , a s e r i e s o f planned orthogonal compari-  sons was conducted w i t h i n each group, a c r o s s t h e S e r i e s d i m e n s i o n .  Between  group comparisons were conducted u s i n g Dunnett's t e s t f o r comparing t r e a t e d groups w i t h a c o n t r o l group.  F u r t h e r a p o s t e r i o r i comparisons were con-  ducted as n e c e s s a r y u s i n g Tukey.'s  HSD p r o c e d u r e ( K i r k , 1968).  I n the o v e r a l l  a n a l y s i s , l e v e l s 1 and 2 o f t h e S e r i e s v a r i a b l e r e p r e s e n t e d performance d u r i n g - t h e ^ p r e t e s t i r i g ' i s e s s i o n , ahd>levels- 3ife6 -5 r e p r e s e n t e d performance T  under t h e s o c i a l i n f l u e n c e c o n d i t i o n s o f S e s s i o n 2.  Data from a l l s u b j e c t s  who completed t h e a s c e n d i n g s e r i e s o f S e s s i o n 2 were i n c l u d e d . The ANOVA for  threshold data resulted i n s i g n i f i c a n t effects f o r the Series v a r i a b l e ,  45 F_, ( 4 , 1 3 2 ) = 3 . 7 6 , p_ <.01, a n d f o r t h e S e r i e s ( 8 , 1 3 2 ) = 4 . 6 1 , p_ <.01,  F i g u r e l : l p o r t r a y s mean t h r e s h o l d  t h r e e groups across t h e 5 shock s e r i e s . differences  between  term suggested by K i r k  group d i f f e r e n c e s  1.41 a n d 0 . 1 7 , r e s p e c t i v e l y  occurred at a l l series during 5.14,  5.20 f o r S e r i e s  variable,  (1968), revealed  ( a = .05) a t S e r i e s  -- w h e r e a s  values f o r a l l  Analyses of simple effects f o r  groups a t each l e v e l o f the S e r i e s  ing the pooled error a t i c between  X g r o u p s i n t e r a c t i o n , F_  no s y s t e m -  1 a n d 2, F_ ( 2 , 1 6 5 ) =  s i g n i f i c a n t between  the influence  employ-  session,  group  effects  F_ ( 2 , 1 6 5 ) = 3 . 4 8 ,  3 t h r o u g h 5, r e s p e c t i v e l y .  F u r t h e r a n a l y s e s o n t h e s e s i g n i f i c a n t e f f e c t s w e r e p e r f o r m e d , employing trol not  Dunnett's t e s t f o r comparisons o f e x p e r i m e n t a l groups w i t h  group. differ  Results  of this analysis  from c o n t r o l subjects  shock s e r i e s during model, however,  i n mean p a i n  the influence  exhibited  showed t h a t  session.  subjects^in  threshold  between  4.17)  a n d 7.95 mA  w e r e 5.20 mA analyses with  Mean p a i n  i n g r o u p T a t s e r i e s 4 a n d 5 w e r e 7.95 mA  (S.D. = 3 . 9 7 ) .  thresh(S.D. =  F o r group C t h e c o r r e s p o n d i n g v a l u e s  ( S . D . = 1.58) a n d 5.40 mA Tukey's  threshold  g r o u p T means a n d g r o u p C  means a t s e r i e s 4 a n d 5 = 2.75 a n d 2 . 5 5 , r e s p e c t i v e l y ) . values f o r subjects  tolerant  4 and,5 ( D u n n e t t ' s  7  old  a t any o f t h e  mean p a i n  v a l u e s r e l a t i v e t o c o n t r o l subject s on^shock s e r i e s t e s t c r i t i c a l v a l u e = 2.29; d i f f e r e n c e s  group I d i d  Subjects exposed t o a  significantly, elevated  a con-  (S.D, = 1.26).  HSD p r o c e d u r e r e v e a l e d  that  Further post-hoc  the s i g n i f i c a n t be-  tween groups e f f e c t d u r i n g  s e r i e s 3 o c c u r r e d between  (Tuke'yj'sHSD c r i t i c a l v a l u e  ( a = .05) = 2 . 5 3 ; g r o u p T g r o u p I d i f f e r e n c e  2.58 mA).  groups T and I  Means f o r g r o u p s T a n d I a t t h i s l e v e l w e r e 7.68 mA  a n d 5.10 ( S . D . = 1 . 9 3 ) , r e s p e c t i v e l y .  =  ( S . D . =3.60)  Planned o r t h o g o n a l comparisons were  46  F i g u r e 1: 1. Mean i n t e n s i t y of c u r r e n t p r o v o k i n g a r a t i n g of "10" (pain t h r e s h o l d ) under u n i n f l u e n c e d (Alone) and i n f l u e n c e d (With Model) cond i t i o n s f o r s u b j e c t s i n Groups T, C, and I.  12  Alone  With  Model •—  «/>  Q)  •  l O  0  8  c c  CD  -  # r•  i_  a £ .2  — • Tolerants  4  c CD  1  3  Shock Series  4  Controls Intolerants  47  conducted along The  critical  t h e S e r i e s v a r i a b l e a t each l e v e l o f the groups v a r i a b l e .  contrast  e x a m i n e d was t h a t b e t w e e n  and t h e r e m a i n i n g t h r e e revealed in  (influence session)  a significant pretest  pretest session session  p_ <.01.  Since  analyses  among  subjects increased  f r o m a mean o f 4.85 mA i n t h e  to this  those  i n the analysis.  subjects  The o v e r a l l  e f f e c t f o r S h o c k S e r i e s , F_ ( 4 , 1 0 8 ) =  i t was t h e S e r i e s X G r o u p s e f f e c t t h a t was o f c r i t i -  i n t e r e s t , f u r t h e r analyses  tributing  These  threshold values  (S.D. = 3 . 9 1 ) . A s i m i l a r p i c t u r e emerges i f o n l y  analysis resulted i n a significant  cal  change  (pretest)  (S.D. = 2.09) t o a mean o f 7.86 mA i n t h e i n f l u e n c e  who c o m p l e t e d t h e SDT s e r i e s a r e i n c l u d e d  6.02,  Pain  exposed t o a t o l e r a n t model  two  shock s e r i e s .  to influence session  g r o u p T o n l y ; j t ( 1 3 2 ) = 6 . 5 1 , p_ <.01.  among s u b j e c t s  the f i r s t  term.  were c o n d u c t e d on t h e s i m p l e  These  analyses  revealed  e f f e c t s con-  significant  between-  g r o u p d i f f e r e n c e s a t l e v e l s 3, 4, a n d 5 o f t h e s e r i e s v a r i a b l e , F s ( 2 , 1 3 5 ) = 4.26 (p_ <  . 0 5 ) , 5.52 (p_ <  . 0 1 ) , a n d 5.40 (p_ <  effects reflected significant 3, 4, a n d 5, a n d b e t w e e n Dunnett's t e s t s ) . only  across  nificant  d i f f e r e n c e s between  groups T and C a t S e r i e s 4 and 5 (Tukey's and group a n a l y s e s  P_  resulted i n significant .01.  S e r i e s e f f e c t w i t h i n group T r e f l e c t e d an i n c r e a s e p r e t e s t and i n f l u e n c e  t o l e r a n c e Idata were s u b j e c t e d  analysis including a l l subjects sessions  groups  groups T and I a t S e r i e s  s e r i e s w i t h i n g r o u p T, F_ ( 4 , 1 0 8 ) = 1 3 . 1 2 , p_<  t h r e s h o l d between Pain  Within  . 0 1 ) . The b e t w e e n  sessions,  effects The s i g -  i n pain  t_ ( 1 0 8 ) = - 7 . 1 8 , p_< . 0 1 .  to s i m i l a r analyses.  The o v e r a l l  who c o m p l e t e d t h e a s c e n d i n g s e r i e s o f b o t h  resulted i n significant  e f f e c t s f o r G r o u p s , F_(2,33) =  10.98,  < . 0 1 , S e r i e s , F_(4,132) = 3 . 6 5 , p_ < . 0 1 , a n d t h e G r o u p s X S e r i e s  a c t i o n , F_(8,132) = 9.34, p_<.01.  Analyses of simple  effects  inter-  revealed  48 s i g n i f i c a n t between-groups  d i f f e r e n c e s a t l e v e l s 3, 4, a n d 5 o f t h e S e r i e s  v a r i a b l e , F s ( 2 , 1 6 5 ) = 1 6 . 0 9 , 1 7 . 1 2 , a n d 1 6 . 3 3 , a l l p_s < . 0 1 . of experimental  groups w i t h  t h e c o n t r o l group b y D u n n e t t ' s t e s t  t h a t on a l l 3 i n f l u e n c e s e s s i o n  revealed  s e r i e s , group T d i f f e r e d s i g n i f i c a n t l y  ( a = .05) f r o m g r o u p C ( D u n n e t t ' s c r i t i c a l 4.53,  Comparisons  value  4 . 5 3 , a n d 4.40 mA f o r s e r i e s 3, 4 a n d 5 ) .  = 2 . 9 6 ; T-C d i f f e r e n c e s = Group I d i f f e r e d s i g n i f i -  c a n t l y f r o m g r o u p C o n s e r i e s 4 ( C - I d i f f e r e n c e = 2.97 mA) a n d t h e r e a t r e n d i n t h e same d i r e c t i o n o n t r i a l  5 ( d i f f e r e n c e = 2.92 mA).  gonal t_-tests c o n t r a s t i n g p r e t e s t w i t h  influence  for  session  p_ <  These  terms r e f l e c t e d s i g n i f i c a n t  subjects  . 0 1 , a n d g r o u p I , _ t ( 1 3 2 ) = 2 . 4 6 , p_ < .05 ( b o t h  (M s e s s i o n 1 = 9.69 mA,  increases  tolerance  values  S.D. = 2 . 9 2 ; M s e s s i o n  S.D. = 2.39; M s e s s i o n  mained  stable  S.D. = 3 . 4 3 ) . The jects  2 = 7.28 mA,  (M s e s s i o n  These d a t a a r e d e p i c t e d  results f o r pain  tolerance  r e s u l t e d i n t h e same s i g n i f i c a n t  1:2.  a l lp s  Group T e x h i b i t e d s i g n i f i c a n t e l e v a t i o n s differences exceeding the c r i t i c a l  This  analy-  .01; and Groups X S e r i e s ,  <.01.  the Series  variable 3 t h r o u g h 5,  A t s e r i e s 3, 4, a n d 5,  i n tolerance  value  those sub-  G r o u p s , F_(2,27) =  groups d i f f e r e n c e s a t S e r i e s  Fs(2,135) = 20.02, 17.98, 16.07,  2 = 1 0 . 1 5 mA,  i n the analysis.  Simple e f f e c t s along  suggested s i g n i f i c a n t between  1 = 8.48,  M session  overall effects:  1 3 . 1 3 , p < .01; S e r i e s , F ( 4 , 1 0 8 ) = 6.10, p_ < F'.(8.;i08-> = 8 . 9 5 , p <.01.  2 = 14.64 mA,  d i f f e r e d somewhat i f o n l y  c o m p l e t i n g t h e SDT s e r i e s w e r e i n c l u d e d  T  The c o n t r o l g r o u p r e -  S.D. = 2 , 7 0 ; i n Figure  among g r o u p  (M s e s s i o n  S.D. = 2 . 9 9 ) .  1 = 1 0 , 4 3 mA,  tests 2-tailed) .  i n tolerance  S.D. = 4,19) a n d d e c r e a s e s among g r o u p I s u b j e c t s  all  Ortho-  a l l 3 g r o u p s r e s u l t e d i n s i g n i f i c a n t e f f e c t s w i t h i n g r o u p T, _ t ( 1 3 2 ) =  8.69,  sis  was  relative  t o group  f o r Dunnett's t e s t  C,  ( a=.05) o f  49  Figure 1: 2. Mean intensity of current provoking a "terminate" (pain tolerance rating under uninfluenced (Alone) and influenced (With Model) conditions for subjects in Groups T, C, and I.  <  2  3 SHOCK  4 SERIES  5  < Group  C  50  2.93.  Subjects  i n group 1 e x h i b i t e d reduced t o l e r a n c e t h a t  but  d i dnot attain s t a t i s t i c a l  in  groups were o n l y s i g n i f i c a n t  tolerance from Session 15.55  significance.  f o r group T w h i c h e x h i b i t e d e l e v a t i o n s i n  summarized as f o l l o w s .  of the ascending  1 to Session  2.  This  a c c o u n t e d f o r s u b j e c t s i n group T e x h i b i t i n g s i g n i f i c a n t  change  elevations i n  the influence session, relative to subjects i n  g r o u p C.  On p a i n  ascending  series of Session  t o l e r a n c e , when d a t a  from a l l s u b j e c t s  decrease.  completing  the  2 were i n c l u d e d , group T e x h i b i t e d a s i g n i f i -  cant p r e t e s t t o i n f l u e n c e s e s s i o n i n c r e a s e , w h i l e ted a s i g n i f i c a n t  s e r i e s may b e  On p a i n t h r e s h o l d , o n l y s u b j e c t s i n g r o u p T e x -  changes from S e s s i o n  pain threshold during  2 (M =  = 9.60, p_ < . 0 1 .  In general, the r e s u l t s of analyses  significant  Main e f f e c t s of Series w i t h -  1 (M = 1 0 . 0 0 mA., S.D. = 2.24) t o S e s s i o n  mA, S.D. = 3 .04, t_ (108)  hibited  approached,  This  those  i n group I e x h i b i -  change r e s u l t e d i n an o v e r a l l e l e v a t i o n  i n p a i n t o l e r a n c e among s u b j e c t s i n g r o u p T, r e l a t i v e  t o those  C, a n d a somewhat w e a k e r r e d u c t i o n i n t o l e r a n c e among t h o s e  i n group  i n group I .  When o n l y  those  s u b j e c t s who c o m p l e t e d t h e SDT s e r i e s w e r e i n c l u d e d i n t h e  analysis,  t h e r e s u l t s w e r e i n t h e same d i r e c t i o n , b u t t h e e f f e c t s i n g r o u p  I were n o t s t a t i s t i c a l l y subjects  SDT DATA;  reliable.  i n group C m a i n t a i n e d  Preliminary  In order  On b o t h p a i n t h r e s h o l d a n d t o l e r a n c e ,  stable values  from Session  1 to Session  analyses  t o d e t e r m i n e w h e t h e r t h e d i f f e r e n t i a l d r o p o u t r a t e among  group I s u b j e c t s h a d i n f l u e n c e d t h e o v e r a l l c u r r e n t i n t e n s i t i e s ed  during  2.  administer-  t h e SDT s e r i e s , a n d t o c h e c k o n r a n d o m a s s i g n m e n t , a 3 ( g r o u p s )  x 6 ( S t i m u l u s L e v e l s ) ANOVA was p e r f o r m e d o n t h e s e  values.  This  analysis  51  revealed all  t h a t t h e r e w e r e no s i g n i f i c a n t b e t w e e n - g r o u p d i f f e r e n c e s i n o v e r -  levels  o f c u r r e n t a d m i n i s t e r e d , F_(2,25) = 0.19, p_< . 0 5 , n o r was t h e  i n t e r a c t i o n between Groups and t h e 6 S t i m u l u s  levels significant,  = 0 . 8 5 , p>.05.  effect,  A significant  Stimulus  levels  F(5,140)  = 2 2 0 . 1 0 , p_<.01, m e r e l y r e f l e c t e d t h e i n c r e a s e i n c u r r e n t from low t o h i g h  shocks.  the c u r r e n t i n t e n s i t i e s Following  administered  at a l l levels.  t h i s , judgmental d a t a were a n a l y z e d  at each o f t h e 6 s t i m u l u s three blocks  intensities  Thus, t h e groups were comparable w i t h r e g a r d t o  according  f r e q u e n c i e s w i t h w h i c h s u b j e c t s employed each c a t e g o r y  into  F_(10,140)  intensities  o f 18 t r i a l s  employed.  to the  of the rating  T h e s e s s i o n was d i v i d e d  a t each s t i m u l u s i n t e n s i t y and t h i s  was i n c l u d e d i n t h e 3 ( G r o u p s ) X 3 ( T r i a l B l o c k s ) X 6 ( C u r r e n t X 7 ( R a t i n g C a t e g o r i e s ) ANOVA.  Of s o l e i n t e r e s t  p a t t e r n o f r a t i n g s e x h i b i t e d by t h e 3 groups.  scale  factor  Intensities)  i n t h i s a n a l y s i s was t h e  Therefore,  only  those  inter-  a c t i o n terms i n v o l v i n g Groups and R a t i n g C a t e g o r i e s were examined f o l l o w i n g t h e o r i g i n a l ANOVA. both  t h e s e v a r i a b l e s was t h e G r o u p s X C u r r e n t  gories effect, This  exhibited  effect i s depicted i nFigure choice across  m o d a l r e s p o n s e was a t c a t e g o r y  categories  Cate-  1:3 w h e r e t h e d i f f e r e n t i a l  choice  pair  of stimuli.  and a l l groups'  thereafter.  frequen-  None o f t h e b e t w e e n -  p a i r o f s t i m u l u s i n t e n s i t i e s was s i g n i f i c a n t .  stimulus pair  (current levels  1 (faint sensation)  T a n d I was a t c a t e g o r y  A l l 3 groups  to the lowest  0 (undetectable)  choice declined rapidly  group d i f f e r e n c e s a t t h i s the middle  involving  Intensities X Rating  groups c a n be observed.  t h e same p a t t e r n o f c a t e g o r y  cies of category  For  i n t e r a c t i o n term  F ( 6 0 , 7 8 0 ) = 1.50, p <.01.  pattern o f category  The  The o n l y s i g n i f i c a n t  3 and 4 ) , a l l groups  t o 3 (very f a i n t p a i n ) .  favoured  The mode f o r g r o u p s  1, w h e r e a s t h e mode f o r g r o u p C was a t c a t e g o r y  2.  52 Figure 1: 3. Mean frequency of choice of each rating scale point at high, medium, and low shock intensities for subjects in Groups T, C, and I. Note: Rating scale point descriptors are Undetectable (0), Faint Sensation (1), Pre-Pain Sensation (2), Very Faint Pain (3), Mild Pain (4), Moderate Pain (5) , Strong Pain (6).  52a  0  1  2  3  4  5  R A T I N G SCALE CATEGORY  6  53 Frequency of choice  o f c a t e g o r y 1'was  i n g r o u p T t h a n among t h o s e ( c r i t i c a l value  , a =  group C = 4.19). frequency  1.58).  The  of stimulus  .05 = 2.52; m e a n s : g r o u p T = 7.87,  Subjects  and C f e l l tively,  1.52; At  d i f f e r e n c e between groups C and I a t t h i s i n t e n s i t i e s was  occurred  not s i g n i f i c a n t  intensities,  a t c a t e g o r i e s fc ( s t r o n g p a i n )  greater  subjects in.group T  and  (0.92) and C  frequency  of choice of  stimulus pairs.  choice  of  cateI  respec-  categories  g r o u p I = 1.37,  g r o u p I = 1.37,  group C =  significantly  I ' s ( 1 . 7 8 ) a n d g r o u p T's  of category  For  f o r groups  1.65). 1  group  significantly  (1.75).  O v e r a l l then,  occurred  group C =  greater than  A t c a t e g o r y .6 ,  I e x h i b i t e d a n e l e v a t e d mean ( 6 . 0 3 ) r e l a t i v e  ences i n frequency  T=  t o g r o u p s I a n d C, w h i c h d i d  g r o u p T = 4.50,  (1.50) w h i c h d i d n o t d i f f e r .  group  and p a i r  5 (moderate p a i n ) ,  a n d a t c a t e g o r y 5/, g r o u p C's mean ( 7 . 6 9 ) was  than b o t h group  judg-  (mean: g r o u p I = 2 . 2 8 ) .  relative  a t c a t e g o r y 3;: g r o u p T = 5 . 6 3 ,  (1.75),  category  a t c a t e g o r y 3 / ( f a i n t - p a i i i ) ,whereas t h o s e  (means a t c a t e g o r y  4.83,  greater  g r o u p T's m o d a l f r e q u e n c y  c a t e g o r y 4-., g r o u p C's mean.,(4.80) was  I's  group I =  t h a n d i d s u b j e c t s i n g r o u p T when  g r o u p T e x h i b i t e d an e l e v a t e d  differ  procedure  i n group C e x h i b i t e d a s i g n i f i c a n t l y  2 a n d ^3 a t t h i s p a i r o f i n t e n s i t i e s not  HSD  subjects  f r o m t h e m i d d l e s t i m u l u s p a i r (means: g r o u p C = 4.30,  the h i g h p a i r o f s t i m u l u s gory choice  g r e a t e r among  i n g r o u p s 1 and C by Tukey's  of choice of category 3  ing currents  significantly  t o groups  the major  a t t h e m i d d l e and  At both stimulus i n t e n s i t y l e v e l s , subjects  differ-  high  i n group  T  selected response categories i n d i c a t i n g l e s s pain than d i d subjects i n groups C and I . highest Subjects  D i f f e r e n c e s between groups I and C o n l y emerged a t t h e  s t i m u l u s p a i r and t h e r e s p o n s e c a t e g o r y i n group I employed  t h e i r response' to the h i g h e s t T„ a n d  C.  this  category  indicative of greatest  pain.  more f r e q u e n t l y i n d e s c r i b i n g  s t i m u l u s p a i r than d i d s u b j e c t s i n groups  54  To  s u m m a r i z e , i t was  apparent  p r e l i m i n a r y analyses of data from  from  t h e SDT  i n p a i n r e p o r t s r e s u l t e d from exposure  the t r a i n i n g series  s e r i e s , and  t h a t group d i f f e r e n c e s  to the v a r i o u s treatments.  effects  seemed m o s t s u b s t a n t i a l i n g r o u p T.  hibited  the most d r a m a t i c  Subjects i n this  changes d u r i n g the a s c e n d i n g  r a t i n g - s c a l e c a t e g o r i e s than d i d s u b j e c t s i n group I . next  i n o r d e r t t o determine  discriminability  SDT  SDT  The  group  s e r i e s , and  h i b i t e d a g r e a t e r discrepancy from C o n t r o l s u b j e c t s i n t h e i r  performed  from  exex-  selection  of  a n a l y s e s were  whether between-group d i f f e r e n c e s i n  o r r e s p o n s e - b i a s w o u l d emerge.  analyses SDT  cedure. likely  a n a l y s e s were conducted  Since s e n s i t i v i t y t o be  i n d i c e s d e r i v e d from  the f o r c e d - c h o i c e p r o forced-choice tasks  t h e one  containing "signal"  examined i n o r d e r t o determine  (McNicol, 1972),  whether such  o c c u r r e d and v a r i e d s y s t e m a t i c a l l y a c r o s s g r o u p s . b i a s was  c a l c u l a t e d f o r each s u b j e c t as  fications  of i n t e r v a l  2 with "signal"  interval 1 with "signal".  i n t e r v a l and  the second  An  interval index of  these  a data  biases interval  the r a t i o o f t h e number o f  identi-  t o t h e number o f i d e n t i f i c a t i o n s  T h i s i n d e x has  bias i s present, values less first  are  affected i f subjects exhibit preferences for i d e n t i f y i n g  g i v e n i n t e r v a l as were f i r s t  on d a t a f r o m  a v a l u e o f 1.00  when no  of  interval  t h a n 1 when a p r e f e r e n c e i s e x h i b i t e d f o r t h e  a value exceeding  1 when a p r e f e r e n c e i s e x h i b i t e d  for  interval.  Separate  a n a l y s e s o f v a r i a n c e were performed  forced-choice pair  (i.e.,  l o w , medium, arid h i g h ) ,  and h i g h f o r c e d - c h o i c e p a i r s ,  t h e r e was  no  evidence  on t h e s e For  data at each  t h e l o w , medium,  suggesting  differential  55  p r e f e r e n c e f o r one i n t e r v a l a c r o s s g r o u p s , 2.64, r e s p e c t i v e l y Estimates entered  F_s ( 2 , 2 6 ) = 0 . 9 9 , 0 . 3 7 , a n d  (p_ >.05).  o f d_' c a l c u l a t e d o n d a t a f r o m t h e f o r c e d - c h o i c e t a s k w e r e  i n a 3 ( G r o u p s ) X 3 ( P a i n I n t e n s i t y L e v e l s ) ANOVA d e s i g n .  the e f f e c t s i n t h i s a n a l y s i s approached s t a t i s t i c a l For occurrence  None o f  significance.  t h e m a j o r SDT a n a l y s e s , t h e c o n d i t i o n a l l p r o b a b i l i t i e s o f of a p a r t i c u l a r response  category  given the presentation of a  p a r t i c u l a r s t i m u l u s l e v e l were c a l c u l a t e d . These p r o b a b i l i t i e s were cumulated from the h i g h e s t t o the lowest response level.  category  The t a b l e s s o d e r i v e d w e r e e m p l o y e d t o e s t i m a t e  Initially,  v a l u e s o f d-- a n d L ^ b e t w e e n a d j a c e n t  a t each  t h e SDT  then stimulus  parameters.  s t i m u l u s p a i r s were  calcu-  l a t e d a t a l l p o i n t s o f t h e r a t i n g s c a l e where these measures were d e f i n e d ( i . e . , where t h e p r o b a b i l i t y false  alarm, P(FA- ), ;  o f a h i t , p ( H i t ) , and t h e p r o b a b i l i t y  4 0.00 o r 1 . 0 0 ) .  s t i m u l u s p a i r was t h e n c a l c u l a t e d . ministered  _  , w h e r e S„ a n d S., r e f e r 1  At  Since a c t u a l stimuls i n t e n s i t i e s ad-  as an o v e r a l l d i s c r i m i n a b i l i t y  2 - 1 . s t i m u l i of the p a i r b  lower  a t each  t o s u b j e c t s w e r e i n d i v i d u a l i z e d , e a c h o f t h e d e r i v e d mean d_'  v a l u e s was e x p r e s s e d DI =  F o r d ' , t h e mean v a l u e  of a  the lowest  t o t h e v a l u e s o f t h e h i g h e r and t h e  l  ( c f . C r a i g & Coren,  1975).  2 s t i m u l u s i n t e n s i t y p a i r s , t h e parameters were i n -  c a l c u l a b l e f o r 7 (23%) o f s u b j e c t s . were e v a l u a t e d o n l y a c r o s s those data were a v a i l a b l e  index ( D I ) :  (pairs  Consequently,  d i f f e r e n c e s i n mean D I  s t i m u l u s i n t e n s i t y p a i r s where  3-4 t o 5 - 6 ) .  3 (Groups) X 3 (Stimulus P a i r s ) f a c t o r i a l  complete  These d a t a were a n a l y z e d i n a design.  Results of this analysis  i n d i c a t e d no s i g n i f i c a n t b e t w e e n - g r o u p s , F ( 2 , 2 7 ) = 0.65, p_>.05, o r S t i m u l u s Intensity,-F  ( 2 , 5 4 ) = 1.16; p_>.05, e f f e c t s .  "However, t h e G r o u p s X Stimulus;'-  56  P a i r s i n t e r a c t i o n t e r m was s t a t i s t i c a l l y Mean D i s f o r t h e s e s t i m u l u s group d i f f e r e n c e s by  Dunnett's  s i g n i f i c a n t , F_(4,54) = 3 86,p_<.01.  p a i r s a r e p r e s e n t e d i n T a b l e 1: 1.  w i t h i n each stimulus  Between-  i n t e n s i t y p a i r were f u r t h e r  procedure.  Table Mean D i s c r i m i n a b i l i t y I n d i c e s 5-6 f o r T o l e r a n t ,  Stimulus Pair  1:1 at Stimulus Pairs  Intolerant,  and C o n t r o l  3-4 t o  Subjects  3-4  4-5  5-6  Tolerant  1.36  0.77  1 .15  Control  0.64  0.81  0.67  Intolerant  0.39  1.71  0.84  Group  Note:  Higher values f o r the d i s c r i m i n a b i l i t y index greater d i s c r i m i n a b i l i t y .  indicate  evaluated  This analysis indicated that DT values for both groups T and I were not significantly different from those for group C at stimulus pairs, 3-4 and 5-6.  However, at stimulus pair 4-T'5 group 1 exhibited increased Dl values  relative to group C (Dunnett's c r i t i c a l value, (,a=.05) = 0.80; group I group C difference = .90).  Group T's mean DI value did not differ from  that for group C at any stimulus pair.  Thus, at this stimulus pair, dis-  criminability was increased among I subjects relative to those in groups C and T who exhibited comparable levels of discrimination. Values of the likelihood-ratio criterion, L , were examined in order —x to determine whether the social influence conditions were differentially associated with biases toward reporting greater or lesser pain. of different strategies are available for examining bias effect. Clark (1974) , mean values of  A variety After  were calculated across a l l stimulus levels  at the "very faint pain" rating category (L^™ )• This value was then analyzed in a one-way analysis of variance. Results of this analysis revealed no significant between-group differences, F_(2,20) = 1.66,p> .05. However, data from 8 subjects (27%) had to be excluded because the parameter was incalculable at this criterion.  A second strategy was to cal-  culate the overall mean L value across a l l rating scale categories at a l l —x pairs of stimulus intensities. Again, since many of these parameters were incalculable at the lowest 2 pairs of stimulus intensities, variation in mean L was assessed across stimulus levels 3-4, 4-5, and 5-6. —x  Results of  the analysis of variance again indicated no significant between-groups, F(2,27) = 0.64, p >.05, or Groups X Stimulus Pairs, F(4,54) = 0.74,p .05 >  effects.  The effect of stimulus-pair levels on mean L was significant —x F_(2,54) = 3.13, p_ = >.05, and indicated a trend for subjects to adopt  58 more s t r i n g e n t c r i t e r i a  f o r r e p o r t i n g p a i n a t s t i m u l u s p a i r 4-5 t h a n a t p a i r s  3-4 a n d 5-6 (Ms = 1 . 0 1 , 1.69, a n d 1.02 f o r l e v e l s tively).  T h i s t r e n d may s i m p l y b e a n a r t i f a c t  t h e r e were fewer p o i n t s a t which  estimates of L  3-4, 4-5, a n d 5-6, r e s p e c -  of the fact were  t h a t a t l e v e l 4-5  calculable.  Because o f t h e problems p r e s e n t e d by i n c a l c u l a b l e parameters above s t a n d a r d a n a l y s e s , a second nonparametric  i n the  s e t o f a n a l y s e s was c o n d u c t e d ,  m e a s u r e s o f t h e SDT p a r a m e t e r s .  employing  The d i s c r i m i n a b i l i t y o f p a i r s  o f s t i m u l u s i n t e n s i t i e s was i n v e s t i g a t e d b y e s t i m a t i n g t h e a r e a u n d e r t h e receiver-operating-characteristic two  p o i n t s were a v a i l a b l e  P(A)  (ROC) c u r v e .  for plotting  I n i n s t a n c e s where o n l y one o r  t h e p a t h o f t h e c u r v e , t h e measure  ( M c N i c o l , 1 9 7 2 ; P o l l a c k , N o r m a n , & C a l a n t e r , 1 9 6 4 ) was e m p l o y e d a s t h e  best e s t i m a t e o f the area under the curve. the p o i n t ( p ( F A ) , p ( H i t ) ) , the o r i g i n  through  and p r o j e c t i n g  t h e p o i n t a n d one f r o m  a n d p ( H i t ) = 1.0 t h r o u g h  T h i s measure i n v o l v e s p l o t t i n g two l i n e s  through  it:  t h e i n t e r s e c t i o n o f p(FA)  divide  t h e ROC p l o t  = 1.0  the estimated point i n the opposite d i r e c t i o n .  o n l y one p a i r o f h i t a n d f a l s e a l a r m c a t e g o r i e s i s a v a i l a b l e , will  one from  into  4 separate areas:  2 triangles  this  When  procedure  formed by t h e  l i n e s i n t e r s e c t i n g a t the p o i n t c o r r e s p o n d i n g t o t h e p l o t t e d h i t and f a l s e alarm p r o b a b i l i t i e s ,  an upper and a lower quandrangle.  vity  criteria,  a t a l l response  Assuming  iso-sensiti-  t h e a r e a bounded by t h e lower quadrangle  (W)  r e p r e s e n t s performance t h a t i s worse than t h a t i n d i c a t e d by t h e o b t a i n e d hit  and f a l s e a l a r m p r o b a b i l i t i e s , w h i l e t h e a r e a bounded by t h e upper quad-  rangle limit P(A)  (B) r e p r e s e n t s s u p e r i o r p e r f o r m a n c e . an a r e a o f u n c e r t a i n t y w i t h i n which  The 2 t r i a n g l e s  ( U ^ , U^) d e -  t h e s u b j e c t ' s p e r f o r m a n c e must  fall.  was o b t a i n e d b y a d d i n g h a l f o f t h i s a r e a o f u n c e r t a i n t y t o t h e a r e a r e -  p r e s e n t i n g i n f e r i o r performance. t h a n one p o i n t was a v a i l a b l e  The same p r o c e d u r e s  for plotting  w e r e e m p l o y e d when more  t h e ROC c u r v e .  When more t h a n 2  59 t h e a r e a o f u n c e r t a i n t y becomes e x c e e d i n g l y s m a l l , a n d  points are available,  the v a l u e o f P(A) c l o s e l y approximates  the value  t h a t w o u l d be o b t a i n e d by  d i r e c t l y measuring t h e a r e a under t h e curve, P ( A ) . were a v a i l a b l e An for  initial  f o rplotting  t h e ROC c u r v e ,  a n a l y s i s was c o n d u c t e d  l a t t e r m e a s u r e was e m p l o y e d .  on these v a l u e s o f P(A) c o r r e c t e d  t h e d i f f e r e n c e s i n s t i m u l u s i n t e n s i t y upon w h i c h t h e y were b a s e d b y t h e  following  formula: P(A)  standardized =  P(A)  o v e r a l l a n a l y s i s suggested  effect,  .  2 - V  S  The  this  When 3 o r more p o i n t s  t h a t t h e r e was n o s i g n i f i c a n t  F_(2,27) = 0 . 1 8 , p_> .10.  approached, b u t d i d n o t a t t a i n  The G r o u p s x S t i m u l u s P a i r s  between-groups interaction  conventional levels of s t a t i s t i c a l  c a n c e , _F(8,108) = 1 . 7 4 , p_> .10.  signifi-  I n t e r e s t i n g l y enough, however, t h e g r e a t e s t  d i f f e r e n c e s b e t w e e n means i n t h e i n t e r a c t i o n  term  o c c u r r e d a t l e v e l 4-5, t h e  same s t i m u l u s p a i r w h e r e s i g n i f i c a n t b e t w e e n - g r o u p d i f f e r e n c e s e m e r g e d when the parametric employing  D l m e a s u r e was e m p l o y e d .  When e v a l u a t e d b y D u n n e t t ' s  the c r i t i c a l value a s s o c i a t e d w i t h a o n e - t a i l e d  a  test  o f . 0 5 , t h e :.  d i f f e r e n c e b e t w e e n g r o u p s I a n d C was s i g n i f i c a n t , w i t h g r o u p I s u b j e c t s e x h i b i t i n g enhanced d i s c r i m i n a b i l i t y A nonparametric  measure o f r e s p o n s e - b i a s  c a l c u l a t e d f o r each s u b j e c t . along  relative  t o group C s u b j e c t s . —  13 ( M c N i c o l , 1 9 7 2 ) —  was  T h i s parameter i s an e s t i m a t e o f t h e p o i n t  t h e r a t i n g s c a l e where a s u b j e c t i s e q u a l l y d i s p o s e d toward  " s i g n a l " and " n o i s e " responses.  I t i s c a l c u l a t e d by determining  s c a l e p o i n t a t w h i c h t h e sum o f p ( F A ) a n d p ( H i t ) i s e q u a l  t o 1.0.  giving the r a t i n g Ini n -  s t a n c e s where one r a t i n g s c a l e p o i n t i s a s s o c i a t e d w i t h a p ( F A ) + p ( H i t ) value exceeding  1.0 a n d a n a d j a c e n t  + p(Hit) value of less  scale point i s associated w i t h a p(FA)  t h a n 1.0, t h e v a l u e  of  i s obtained by e x t r a p o l a t i o n .  60 The values of ]3 so derived were subjected to analysis of variance with Groups as a between subjects factor, and Stimulus Pairs as a within-subjects factor.  This analysis suggested that  did not vary systematically as a  function of groups, _F(2,27) = 0.67, p_ >.05.  6 1  DISCUSSION  The r e s u l t s o f t h e p r e s e n t s t u d y s u p p o r t a n d e x t e n d some o f t h e f i n d i n g s of p r e v i o u s a n a l y s e s o f s o c i a l modeling i n f l u e n c e s ascending shock s e r i e s ant  model upon v e r b a l  finding exactly and as  indicated  a substantial  the s o l i d l y - e s t a b l i s h e d  that  the e f f e c t  p r i o r exposure t o the s t i m u l a t i o n . Craig  tolerant  modeling  i n t e r e s t except  session.  co-participant  These a u t h o r s '  This l a t t e r  they demonstrated that  an i n i t i a l  from exposure t o a t o l e r a n t active  who became a c t i v e  findings  modeling influence  enhancement  finding  confirms  those o f  and t o l e r a n t  ensession  i n a second  of pain tolerance  resulting  m o d e l was s u b s e q u e n t l y m a i n t a i n e d when t h e  was r e m o v e d .  Taken t o g e t h e r , t h e s e  findings  they demonstrate t h e p l a s t i c i t y o f  pain behaviours i n response to v a r i a t i o n s  alterations  insofar  w e r e more s u b s t a n t i a l , h o w e v e r , i n t h a t  t h e o r e t i c a l l y i n t e r e s t i n g i n that  they c o n f i r m that  effect  i s o b s e r v a b l e e v e n when s u b j e c t s h a v e h a d  o f p a i n t o l e r a n c e when s u b j e c t s w e r e e x p o s e d i n a n i n i t i a l  t o an i n a c t i v e  toler-  This  a n d W a r d ( N o t e 2) who w e r e a b l e t o d e m o n s t r a t e a w i t h i n - s u b j e c t  hancement  are  and p a i n t o l e r a n c e .  i s o f r e l a t i v e l y minor t h e o r e t i c a l and e m p i r i c a l i t establishes  Data from the  impact o f exposure t o a  reports of pain threshold  replicates  on p a i n .  i n social  the manipulated variable  conditions.  Further,  was p o w e r f u l e n o u g h  to provoke  i n p a i n responses i n s p i t e o f p r i o r exposure t o the s t i m u l a t i o n .  This f i n d i n g represents s o l i d evidence that r e s p o n s i v e t o and s u b s t a n t i a l l y  controlled  pain behaviours are s e n s i t i v e l y by s o c i a l  The d a t a f r o m s u b j e c t s i n t h e i n t o l e r a n t to warrant separate consideration.  variables.  g r o u p was s u f f i c i e n t l y  The r e s u l t s  unusual  from analyses employing a l l  s u b j e c t s who c o m p l e t e d t h e a s c e n d i n g s e r i e s  of session 2 indicated  p o s u r e t o an i n t o l e r a n t model h a d no e f f e c t  upon p a i n t h r e s h o l d ,  that ex-  but pro-  62 duced a s i g n i f i c a n t r e d u c t i o n tolerance the  rating.  However, i f o n l y  SDT s e r i e s w e r e i n c l u d e d  pain  tolerance  i n current  levels associated with  t h e d a t a f r o m s u b j e c t s who  i n the a n a l y s i s , neither pain  a pain completed  threshold nor  l e v e l s d i f f e r e d from those observed d u r i n g b a s e l i n e  t i o n s o r from those observed i n t h e c o n t r o l group.  This  condi-  inconsistency be-  t w e e n t h e two a n a l y s e s  suggests that  ful  e x h i b i t i n g maximal i n f l u e n c e as a f u n c t i o n o f exposure  f o r those subjects  to the i n t o l e r a n t model. analysis represents  t h e SDT s e r i e s was e n t i r e l y  I t seems l i k e l y  a more a c c u r a t e  that  too s t r e s s -  t h e outcome o f t h e l a r g e r  characterization of the e f f e c t s of  i n t o l e r a n t modeling.  C e r t a i n l y , the d i f f e r e n t i a l  group I s u g g e s t s t h a t  t h e o v e r a l l e f f e c t o f e x p o s u r e t o an i n t o l e r a n t model  made s u b j e c t s  e s p e c i a l l y i n t o l e r a n t of the s t i m u l a t i o n .  those subjects  attrition  than d i d subjects  too, exhibited greater  i n the other  groups.  o f category choice  (Figure  rate i n  With regard to  i n g r o u p I who c o m p l e t e d t h e SDT s e r i e s , o t h e r  that these subjects,  frequencies  subject  data suggest •  i n t o l e r a n c e f o r the shocks  The f i n d i n g s f r o m t h e a n a l y s i s o f 1:3) show t h a t  subjects  i n group I  more f r e q u e n t l y  s e l e c t e d category r a t i n g s from t h e upper end o f t h e s c a l e  when d e s c r i b i n g  their reactions  data,  to the higher  then, support the conclusion  d i d , i n f a c t , make s u b j e c t s The in pain  fact that subjects threshold  These  t h a t e x p o s u r e t o an i n t o l e r a n t model  more i n t o l e r a n t o f t h e s t i m u l a t i o n . i n group I d i d n o t d i f f e r  l e v e l s was i n t e r e s t i n g , p a r t i c u l a r l y  s t u d i e s had found reductions  i n pain  to an i n t o l e r a n t model ( C r a i g & B e s t , C o r e n , 19 75;  i n t e n s i t y shocks.  threshold  since  subjects  earlier  as a consequence o f exposure  1977; C r a i g , B e s t ,  C r a i g & Niedermayer, 1974; C r a i g  determine whether the f a i l u r e  from c o n t r o l  & Ward; C r a i g  & W e i s s , 19 7 1 ) .  to observe a d i f f e r e n c e i n pain  h a v e b e e n a c o n s e q u e n c e o f h a v i n g t o r e c r u i t new s u b j e c t s  &  I n order t o threshold  i n order  may  to re-  63 place  those  who  dropped out  during  t h r e s h o l d v a l u e s was  re-conducted,  10  t o group I .  subjects assigned  hold values  still  pointed  t h a t the  out  d i d not  w o u l d have p r o v i d e d the  f i n d i n g o f no  the  SDT  series,  employing only  t h e o v e r a l l ANOVA on the data  This a n a l y s i s revealed  d i f f e r b e t w e e n g r o u p s I and  f i n d i n g of a s i g n i f i c a n t support  from the  that pain  C.  I t must  first thres-  be  difference i n this re-analysis  f o r the proposed a l t e r n a t i v e e x p l a n a t i o n ;  d i f f e r e n c e s c a n n o t be  taken  pain  as  supportive  however,  or non-support  tive. Comparison of i n f l u e n c e s e s s i o n p a i n t h r e s h o l d values in  the present  tolerant, T and  study w i t h  i n t o l e r a n t , and  those  r e p o r t e d i n the previous  H o w e v e r , t h e mean f o r g r o u p I (5.00  Best,  f o r an  & Ward, 1975).  studies  3  groups  employing  c o n t r o l g r o u p s r e v e a l e d t h a t t h e means f o r g r o u p s  C f e l l w i t h i n the midrange of  mean r e p o r t e d  f o r the  the v a l u e s mA)  was  reported i n previous  s l i g h t l y higher  i n t o l e r a n t group i n p r e v i o u s I n t e r e s t i n g l y , i n a l l but  studies  one  studies.  t h a n the  (4.20  mA;  highest Craig,  of the previous  studies  i n c o r p o r a t i n g a l l 3 groups, d i f f e r e n c e s i n current i n t e n s i t i e s provoking p a i n t h r e s h o l d r a t i n g have been s u b s t a n t i a l l y c o n t r o l t h a n b e t w e e n c o n t r o l and in  the  g r e a t e r between t o l e r a n t  i n t o l e r a n t groups.  D a t a t o be  t h i r d e x p e r i m e n t i n t h i s s e r i e s s u g g e s t an e x p l a n a t i o n  come, a n d  f u r t h e r d i s c u s s i o n of i t w i l l  be  postponed u n t i l  the  a and  presented  for this  out-  general  dis-  cussion. The confirmed  a n a l y s i s of current i n t e n s i t i e s t h a t t h e r e w e r e no  administered with  to the  groups and  3 groups.  administered  during  d i f f e r e n c e s i n o v e r a l l l e v e l s of  m o d e l i n g i n f l u e n c e s do n o t  apply  analysis of  category  of  SDT  to the present choice  study.  SDT  confounded  studies  Results of  i n d i c a t e d t h a t the  series  current  Thus, c u r r e n t i n t e n s i t i e s were not  therefore, c r i t i c i s m s applied to previous  frequencies  the  of  the  3 groups were,  64  in  fact,  cularly  d i f f e r e n t i a b l e i n terms of t h e i r response d i s t r i b u t i o n s ,  a t t h e m o d e r a t e and  high  shock i n t e n s i t i e s .  the m o d e l i n g i n f l u e n c e were m a i n t a i n e d  during  the  Thus, the e f f e c t s of  SDT  series.  As  s e e n i n F i g u r e 1:3,  the e f f e c t s of modeling were c o n s i s t e n t w i t h  observed during the  ascending  quently jects  parti-  can those  s e r i e s , w i t h s u b j e c t s i n group T l e s s  employing response categories i n d i c a t i v e  be  fre-  o f g r e a t e r p a i n , and  i n g r o u p I more f r e q u e n t l y e m p l o y i n g c a t e g o r i e s i n d i c a t i v e o f  subgreater  pain. Analysis w e r e no  of data  from the  forced-choice  between-group d i f f e r e n c e s i n the  currents  t h a t d i f f e r e d by  stimulus  intensity  a standard  levels.  The  (d.') a n d  stimulus  those  intensities.  C l a r k and  i n p a i n s t u d i e s t h a n do  the able  a n a l y s i s was  0.25  mA  those  Dillon  tasks provide  to conclude that i n t e r p r e t a t i o n of the  was  the  and  high  t h a t the  intensities  w h a t w o u l d be  standard  Since  as a r e s u l t  discriminability d i d not  p r e d i c t e d on  differ.  and  data forced-  derived  i t w o u l d seem  r a t i n g - s c a l e data  from reason-  does n o t  pre-  measurement.  from the f o r c e d - c h o i c e  of p a i r s of s t i m u l i at low,  task  medium,  outcome i s i n c o n s i s t e n t w i t h  t h e b a s i s o f Weber's law.  administered  same  reliable  of data  intensities,  pro-  (1973)  t h e outcome o f t h e  of i n f e r i o r  This  task  at the  Mehl  As  mentioned p r e v i o u s l y ,  s t u d i e s o f m o d e l i n g i n f l u e n c e s on p a i n h a v e b e e n c r i t i c i z e d  that current intensities  high  parametric  (P(A))  C l a r k and  there  of  forced-choice  more a c c u r a t e  f u r t h e r i n t e r e s t i n the a n a l y s i s of d a t a fact  this  b a s e d on  of p a i r s  medium, a n d  s i m i l a r t o t h e outcome o f a n a l y s e s  r a t i n g - s c a l e t a s k a t t h e same s t i m u l u s  Of  at low,  (1973) and  rating-scale tasks.  sent p a r t i c u l a r d i f f i c u l t i e s  SDT  discriminability  b a s e d on n o n p a r a m e t r i c p r o c e d u r e s  suggested that forced-choice  choice  task indicated that  f i n d i n g s b a s e d on  measure of d i s c r i m i n a t i o n p a r a l l e l e d cedures  SDT  on  the  were c o n f o u n d e d w i t h g r o u p s , and  grounds the  65 outcome o f t h e law.  Since  s t u d i e s c o u l d be  the  fully  discriminability  a c c o u n t e d f o r on  t h e b a s i s o f Weber's  of stimulus p a i r s did not  with overall stimulus  intensity  previous  o f m o d e l i n g i n f l u e n c e s on p a i n w o u l d seem t o be i n -  SDT  analyses  i n the present  study,  this  vary i n v e r s e l y criticism  of  appropriate . The support  o u t c o m e s o f SDT  analyses  t o the h y p o t h e s i s  of producing  of the  rating-scale task lent further  t h a t the modeling i n f l u e n c e procedures are  a l t e r a t i o n s i n sensory  analysis of d i s c r i m i n a b i l i t y  sensitivity  i n d i c e s b a s e d on  capable  to noxious s t i m u l a t i o n .  the p a r a m e t r i c  measure,  The  d/.,  i n d i c a t e d t h a t s u b j e c t s i n g r o u p I e x h i b i t e d e n h a n c e d d i s c r i m i n a t i o n when judging  the h i g h e s t  p a i n t h r e s h o l d and levels. was  Since  b a s e d met  dures,  of the s t i m u l i s e l e c t e d from j u s t below t h e i r the  i t was  lowest  of the  pretest  s t i m u l i s e l e c t e d from c l e a r l y p a i n f u l  unclear whether data  u p o n w h i c h c a l c u l a t i o n o f d.'  the s t r o n g G a u s s i a n assumptions u n d e r l y i n g p a r a m e t r i c  comparable analyses  e s t i m a t i n g the  w e r e c o n d u c t e d on  a r e a u n d e r t h e ROC  curve.  proce-  the n o n p a r a m e t r i c measure  This  analysis resulted i n a  similar  outcome; s u b j e c t s i n group I e x h i b i t e d enhanced d i s c r i m i n a t i o n o f the s h o c k p a i r s as The  fact  may  present  being  i n the p a r a m e t r i c  that this  some d i f f i c u l t i e s  t e s t e d was  conservative  f i n d i n g was  p r o c e d u r e r e l a t i v e t o s u b j e c t s i n group  C.  b a s e d on a o n e - t a i l e d t e s t o f s i g n i f i c a n c e in fully  d i r e c t i o n a l , and  than the  same  the  accepting  it;  t e s t employed  one-tailed orthogonal  however, the  hypothesis  ( D u n n e t t ' s ) was  _ t - t e s t s employed by  more  Craig  and  Ward ( N o t e 2 ) . This served  finding closely  r e p l i c a t e s t h a t o f C r a i g and  an e n h a n c e m e n t o f d i s c r i m i n a b i l i t y  at current  p a i n t h r e s h o l d among s u b j e c t s e x p o s e d t o an of the present  study  discriminability  extend the  occurred  Coren  levels slightly  i n t o l e r a n t model.  f i n d i n g o f C r a i g and  at c l e a r l y noxious stimulus  ( 1 9 7 5 ) who  The  Coren i n t h a t intensities.  ob-  below  results enhanced  66  I n none of on  p a i n has  In the with  the previous  parametric  .B was  m e a s u r e , L^,  faint pain.  employed,  However, bias  at  of  evidence  l a c k of  i n the  Prkachin,  in  1978;  other  the  were observed. with  a  proposed  O b s e r v a t i o n of F i g u r e  of  moderate  In  presented during  the  subjects'  and  high  1:3  intensity,  with  the SDT  1.0  o f C r a i g and  W a r d , 10  to  of  previous  mA  The each  studies  present  i n group  that  tolerant  (Craig  &  A c o n s i d e r a t i o n of  methodol-  s u g g e s t s some p o s s i b l e study,  stimulus  resolutions  intensities  s e r i e s were s e l e c t e d from 3 l e v e l s based  5 standard  were p r e s e n t e d stimulus  intensity subject  reports  reduced d i s c r i m i n a b i l i t y  Prkachin,  d i f f e r i n g by  frequently  discomfort  to d i s c r i m i n a b i l i t y  performance under u n i n f l u e n c e d  C r a i g and  series.  regard  C r a i g & Ward, N o t e 2 ) .  t h i s paradox.  sented  criterion  groups.  light  o g i c a l d i f f e r e n c e s among t h e  SDT  extimates  n o n p a r a m e t r i c measure  consistent  levels  findings with  modeling i s associated  s t u d y by  the  differences is  obtained  t h e mean o f b i a s  the r a t i n g s c a l e i n d i c a t i n g m i n i m a l  T i s problematic  on  response-bias.  p a i r s , or at the  when  between group  stimulus  than d i d subjects  of  influences  i n g r o u p T t e n d e d t o d i s t r i b u t e t h e i r r e s p o n s e s more  t h e end  The  stimulus  r e p o r t i n g p a i n i n g r o u p T.  that  subjects toward  no  and  i n terms of  Similarly,  alternative  against  reveals  of m o d e l i n g  between-group d i f f e r e n c e s were  calculated at a l l c r i t e r i a f o r very  studies  t h e r e been a d e m o n s t r a b l e e f f e c t upon  p r e s e n t s t u d y , no  the  SDT  was  conditions.  stimulus  In  intensities,  to a l l s u b j e c t s .  In the  study  i n t e n s i t i e s were p r e s e n t e d i n of 80%  the of  maximum the  the  stimulus  mean  the  pre-  terminal  current accepted stimuli  during the preceding  differed i n equal proportions  ascending  s e r i e s , and t h e o t h e r 9  ( 8 % o f t h i s maximum c u r r e n t ) .  v a s t m a j o r i t y o f s u b j e c t s , t h i s w o u l d h a v e meant t h a t a d j a c e n t d i f f e r e d b y 1.0 mA o r l e s s .  I n the present  d i f f e r e n c e s between s t i m u l i son,  study,  t o be g r e a t e r t h a n  reductions i n discriminability  model o n l y occur between s t i m u l i  resulting  study,  I f , f o r some r e a -  from exposure t o a t o l e r a n t than  the modal  Also, since the s t i m u l i  were s e l e c t e d from r e l a t i v e l y  d i s c r e t e p o i n t s , the sampling  quate than  i n previous  studies.  continuum, those tainly,  i n the present  study  o f responses ade-  d i f f e r e n c e s as a  at s p e c i f i c points along  p o i n t s may h a v e b e e n m i s s e d i n t h e p r e s e n t  this  study.  Cer-  t h e r e i s p r e c e d e n t f o r o b s e r v i n g s u c h a phenomenon i n SDT p a i n r e -  search.  I n the present  study,  d i f f e r e n c e s o n l y emerged i n t h e i n t o l e r a n t  g r o u p b e t w e e n one s p e c i f i c p a i r o f s t i m u l i . (1973),  differ-  c o n t i n u u m may h a v e b e e n l e s s  I f discriminability  function of t o l e r a n t modeling only occur  intensity  opportunity t o observe a  ence w o u l d have been m i s s e d .  at various points o f the pain i n t e n s i t y  stimulus pairs  i t was n o t u n u s u a l f o r  2.0 mA.  d i f f e r i n g by l e s s  d i f f e r e n c e employed i n the present  For the  i n a study  Chapman, M u r p h y , a n d B u t l e r  o f a n a l g e s i c e f f e c t s o f n i t r o u s o x i d e were o n l y a b l e t o  demonstrate d i s c r i m i n a b i l i t y  r e d u c t i o n s when d_' was c a l c u l a t e d b e t w e e n l o w ,  medium, ,and h i g h s t i m u l u s i n t e n s i t i e s  and a b l a n k  Gehrig, and Wilson  comparing a n a l g e s i c e f f e c t s o f acu-  puncture  (1975),  i n a study  and n i t r o u s o x i d e , argued from t h e i r  puncture,  n i t r o u s oxide  stimulus.  Chapman,  findings that, unlike  o n l y r e d u c e d _d' a t v e r y  low stimulus  intensities.  L l o y d a n d Wagner ( 1 9 7 6 ) r e p o r t e d t h a t a c u p u n c t u r e r e d u c e d d.' o n l y a blank  acu-  between  a n d v e r y weak s t i m u l u s .  An a l t e r n a t i v e e x p l a n a t i o n f o r t h e i n c o n s i s t e n c y b e t w e e n t h e p r e s e n t study  and e a r l i e r s t u d i e s t h a t r e p o r t e d p o s i t i v e  findings with regard  to the  68 i n f l u e n c e o f t o l e r a n t m o d e l i n g on c o n s i d e r a b l y more p r e s e n t a t i o n s the p r e s e n t I t has  study.  SDT  tasks  discriminability  of each s t i m u l u s  typically  b e e n a r g u e d t h a t i n SDT  derives  The  employ v e r y  l a r g e numbers o f  p a i n s t u d i e s w h e r e few  condition  stimulus  1977;  but  i m p l i c a t i o n i s t h a t when s u b j e c t s ' r a t i n g s do n o t  adequate degree of r e l i a b i l i t y ,  spurious  that reduces r e l i a b i l i t y  may  f i n d i n g s may  see  attain  result.  compound t h e p r o b l e m .  Since  s t u d y was  to t h i s p r o b l e m than were the  rating unreliability  tolerant modeling e f f e c t s , unless model produced d i f f e r e n t i a l l y  e m p l o y e d g r o u p s e x p o s e d t o an evaluate  this  A sent  study.  pointed can be  out  i n pain studies  discriminability  o f a p p l i c a t i o n s o f SDT  sensitivity  (Lloyd & Appel,  t e r m may  continuum of noxious experience, case r a i s e s the  a spurious  possible  s h o u l d have  to pain  had to  1976;  r e f e r to "zero  o r i t may  stimulus,  "blank  r e f e r to "zero  interesting possibility  have  stimuli  There i s ,  stimulus".  intensity"  on  pre-  nothing  to the  Rollman, 1977).  pro-  increased.  research  of subjects  a  differ-  the paradigm employed I n the  r e g a r d i n g w h a t i s meant by  (1977)has s t a t e d , the  latter  responding,  i n t o l e r a n t model would l i k e l y have  concerning  about the a b s o l u t e  h o w e v e r , some c o n f u s i o n  The  unstable  t h a t i n the absence of i n c l u s i o n of a b l a n k  concluded  presented  Hall  r a t i n g s , but  Recent reviews  previous  I f the presence of  i n t o l e r a n t m o d e l , i t w o u l d be  f i n a l point i s i n order  employed,  studies reporting positive findings  a l t e r n a t i v e , - s i n c e an  duced e q u a l l y u n s t a b l e  rating  previous  cannot account f o r  greater u n r e l i a b i l i t y .  I f the  any  i t i s p o s i t e d that exposure to a t o l e r a n t  t o l e r a n t model produced p a r t i c u l a r l y ence c o u l d have r e s u l t e d .  an  Also,  the p r e s e n t  However, s i m p l e  trials.  Chapman,  i s p r o p o r t i o n a l t o t h e number o f s t i m u l u s p r e s e n t a t i o n s  studies.  that  presentations  reliability  less subject  fact  i n t e n s i t y were employed i n  are employed, s u b j e c t s respond u n r e l i a b l y (Rollman, 1977).  from the  As  the  stimulus  energy".  t h a t some s t i m u l i  may  69 be c a p a b l e  of provoking events  t a k e on n e g a t i v e v a l u e s .  on the c o n t i n u u m o f n o x i o u s  experience  I f b y " b l a n k s t i m u l u s " i s meant " z e r o  energy", then  the measures i n the p r e s e n t study  s i n c e no s u c h  s t i m u l u s was p r e s e n t e d .  reflect  relative  that  stimulus sensitivity  I t i s unclear that inclusion of a  z e r o e n e r g y s t i m u l u s w o u l d h a v e p r o v i d e d more i n f o r m a t i o n , s i n c e , i n a r e c e n t SDT s t u d y  i n this  l a b o r a t o r y t h a t d i d employ a b l a n k , s u b j e c t s e x h i b i t e d  confusion In their ratings. the p r e s e n t  study  A t any r a t e , e v e n i f t h e measures r e p o r t e d i n  do n o t r e f l e c t  absolute s e n s i t i v i t y ,  e x p o s u r e t o an i n t o l e r a n t m o d e l f u n d a m e n t a l l y aspects o f s u b j e c t s ' response altered.  no  to noxious  the c o n c l u s i o n t h a t  alters sensory-discriminative  levels  o f s t i m u l a t i o n n e e d n o t be  70  E x p e r i m e n t 2. influences  The  A sensory-decision  on n o n v o c a l p a i n  theory  d e p e n d e n t v a r i a b l e i n m o s t s t u d i e s o f p a i n i n humans i s  Crockett, Prkachin, Hilgard,  1969).  reliable,  & C r a i g , 1977;  Hardy, W o l f f ,  regarding  to the i n t e r n a l experience  sensitivity  o t h e r measures p r o v i d e  and t e s t - t a k i n g s e t .  i s not interchangeable,  can e x h i b i t uncorrelated v a r i a t i o n s  1978).  Given the multidimensional  nature  dependent measures i s r e q u i r e d i n order  Laboratory to c l a r i f y ment.  the e f f e c t s  However, t h e i n f o r m a t i o n t h a t  indices  of s o c i a l influence  information  SDT p r o c e d u r e s  a r e of obvious importance i n assessing  i n f l u e n c e procedures.  inferences  Magnitude  to provide  t h e r a t e o f growth of noxious sensationa;  Such d a t a  effects  u s e d t o make  of the subject.  f o r example, a r e taken  e v i d e n c e on s e n s o r y  of s o c i a l  & G o o d e l l , 1952;  ( C r a i g & N i e d e r m a y e r , 1974; H i l g a r d ,  D a t a f r o m t h e s e methods a r e o r d i n a r i l y  estimation procedures,  and  (Agnew & M e r s k e y , 1 9 7 6 ;  F o r many p u r p o s e s , s u c h m e a s u r e s a r e s e n s i t i v e ,  and d i s c r i m i n a t i n g  w i t h regard  provide  modeling  expressions.  most o f t e n t h e s u b j e c t ' s v e r b a l r e p o r t  1969).  analysis of s o c i a l  they  and d i f f e r e n t  (Craig & Prkachin,  of pain, a v a r i e t y of  t o adequately  map t h e  procedures.  s t u d i e s o f s o c i a l i n f l u e n c e s on p a i n a r e d e s i g n e d  processes  thought t o be o p e r a t i v e i n t h e n a t u r a l  In the natural setting,  overt  expressive behaviour  environ-  i sof  71  critical  importance since i tprovides a basis f o r d i f f e r e n t i a l  o n t h e p a r t o f members o f t h e s o c i a l m i l i e u . investigating  s o c i a l modeling  responses  While previous studies  i n f l u e n c e s on p a i n have i n d i c a t e d  that  such procedures can have a s u b s t a n t i a l impact on p s y c h o p h y s i c a l measures thought the  to r e f l e c t subjective experience, evidence  procedures a l t e r  that  overt, nonvocal expressive behaviour would  p r o v i d e a p o w e r f u l d e m o n s t r a t i o n o f t h e i m p o r t a n c e and e x t e r n a l validity  of the findings  Observers  from such r e s e a r c h .  employ n o n v o c a l e x p r e s s i o n s as s u p p l e m e n t a r y , o r  sometimes fundamental s o u r c e s o f i n f o r m a t i o n r e g a r d i n g t h e i n t e r n a l state, or other conditions behaviour  controlling  guarded  the severity  of a pain  the nonprofessional responding to evidence of pain. l i t e r a t u r e h a s emerged s u g g e s t i n g t h a t a v a r i e t y  s t a t e s " may b e a c c u r a t e l y (Ekman & F r i e s e n ,  Grimaces,  p o s t u r e and t h e l i k e a r e c r i t i c a l  cues f o r t h e d i a g n o s t i c i a n e v a l u a t i n g  tial  individual's  ( F o r d y c e , 1978b; K r a u t , 1 9 7 8 ; S t e r n b a c h , 1 9 7 4 ) .  other signs of d i s t r e s s ,  and  the observed  inferred  problem,  A substan-  of " a f f e c t i v e  from n o n v o c a l e x p r e s s i v e d i s p l a y s  1 9 6 5 , 1 9 7 4 a , 1974b; W a x e r , 1974, 1 9 7 7 ) .  Some  authors have forwarded t h e p o s i t i o n t h a t n o n v o c a l e x p r e s s i o n s a r e less  s u b j e c t t o m o t i v a t e d d i s s i m u l a t i o n t h a n v e r b a l r e p o r t s , a n d may  t h e r e f o r e be more a c c u r a t e i n d i c e s o f p r i v a t e s t a t e s Friesen's,  ( c f . Ekman &  1969, c o n c e p t o f " n o n v e r b a l l e a k a g e " ) .  Despite their social variables  i m p o r t a n c e , few s t u d i e s have examined t h e i n f l u e n c e o f  on n o n v o c a l p a i n e x p r e s s i o n s .  L a n z e t t a , K l e c k , and t h e i r  72 c o l l e a g u e s have i n v e s t i g a t e d  parameters r e g u l a t i n g nonvocal expressive r e -  sponses t o noxious s t i m u l a t i o n sponses and i n d i c e s and  Kleck  and the r e l a t i o n s h i p between e x p r e s s i v e  of self-reported  (1976) r e p o r t e d  parallel  i n d i c e s o f s t r e s s among s u b j e c t s responses t o p a i n f u l s t i m u l i . C o l b y , and L a n z e t t a  distress.  Lanzetta,  Cartwright-Smith,  changes i n autonomic and s e l f - r e p o r t  instructed to i n t e n s i f y o r attenuate  Kleck,  Vaughan, C a r t w r i g h t - S m i t h ,  activity  and s e l f - r e p o r t e d p a i n  independent r a t i n g s  parallel  being  Subjects  d i m i n i s h e d e v i d e n c e o f d i s t r e s s as i n d i c a t e d by  of f a c i a l expressiveness, diminished electrodermal  s p o n s i v e n e s s , and l e s s s e l f - r e p o r t e d p a i n . supported the t h e s i s  be-  among s u b j e c t s  o b s e r v e d b y someone e l s e , o r u n d e r g o i n g t h e e x p e r i m e n t a l o n e . being observed e x h i b i t e d  facial  Vaughan,  (1976) examined r e l a t i o n s h i p s between e x p r e s s i v e  haviour, electrodermal  re-  I t was a r g u e d t h a t  that modulations i n expressive  changes i n s u b j e c t i v e  these  refindings  behaviour i n s t i g a t e  and a u t o n o m i c components o f r e s p o n s e t o n o x i o u s  stimuli. In studies  o f modeling influences  on p a i n ,  t h e a c t u a l b e h a v i o u r exem-  p l i f i e d by models has been t o l e r a n t o r i n t o l e r a n t c h a r a c t e r i z a t i o n stimuli.  The q u e s t i o n o f w h e t h e r t h e m o d e l i n g i n f l u e n c e  expressive not  been The  current  to overt  s i t u a t i o n s , has  addressed. p r e s e n t s t u d y was d e s i g n e d t o i n v e s t i g a t e  intensities  liably  generalizes  behaviour, important i n a f f e c t i v e interpersonal  whether observers ent  of noxious  can d i s c r i m i n a t e  expressive  o f noxious stimulation.  discriminate intensities,  the expressive  two i s s u e s .  behaviour r e s u l t i n g from  Assuming that  behaviour associated  behaviour of subjects  t o l e r a n t modeling or c o n t r o l  conditions  was  differ-  observers could r e with  different  t h e s e c o n d q u e s t i o n a d d r e s s e d was w h e t h e r  ratings of the expressive  The f i r s t  observers'  exposed t o t o l e r a n t o r i n -  would e x h i b i t systematic v a r i a t i o n s .  73  Sensory-de c i s i o n questions.  I f an  o f a n o t h e r and  methods.  The  the  task  data obtained  t o d i f f e r e n t i a t e the  of or against  r e p o r t i n g an  observed the behaviour of s u b j e c t s E x p e r i m e n t 1,  of observing  and  each of a s e r i e s of t r i a l s .  provide  Previous  SDT  a measure of the  ob-  h i s or her  as  bias  raters  3 influence conditions  l e v e l of current  research  and  indicated that  w e l l that  the  Evidence from p s y c h o p h y s i o l o g i c a l  tolerant modeling manipulation  to noxious s t i m u l a t i o n , while with  increased  s t u d y i t was subjects  reactivity.  On  expected that  the  t o be  the  the b a s i s  discrimination while  be  t o l e r a n t modeling c o n d i t i o n would  i n the  reactivity  hypothesized,  current influence therefore,  t o l e r a n t c o n d i t i o n would e x h i b i t poorer  observers r a t i n g subjects  would e x h i b i t enhanced d i s c r i m i n a t i o n .  I t was  as  associated  of t h i s e v i d e n c e , i n the  stimuli.  pain  with  indicates  produces diminished  i n t o l e r a n t c o n d i t i o n may  l e s s r e a c t i v e t o the  that observers r a t i n g subjects  studies  on  exposure  produces a l t e r a t i o n s i n avoidance behaviour c o n s i s t e n t  altered reports.  of  administered  to t o l e r a n t or i n t o l e r a n t models, r e s p e c t i v e l y , decreases or increases reports  has  with  I n the p r e s e n t s t u d y ,  exposed to the t o the  behaviour  analysed  c l a s s e s o f e v e n t s , and event.  made j u d g e m e n t s as  the  these  a p a r t i c u l a r event  f r o m t h e o b s e r v e r c a n be  o u t c o m e o f s u c h an a n a l y s i s w i l l  ability  favour  e m p l o y e d as a t e c h n i q u e f o r e v a l u a t i n g  s p e c i f y i n g w h e t h e r , o r to what e x t e n t  then the  in  was  i n d i v i d u a l i s given  occurred,  server's  theory  i n the  intolerant condition  74 METHOD  Subjects. graduate  F i f t e e n p a i d female  v o l u n t e e r s were r e c r u i t e d from  population of the U n i v e r s i t y  of B r i t i s h  f o u r s e p a r a t e s e s s i o n s as o b s e r v i n g j u d g e s . to  t h r e e groups o f f i v e persons Apparatus  and M a t e r i a l s .  Columbia to take p a r t i n  S u b j e c t s were randomly  Videotapes  taken of p a r t i c i p a n t s  recorder playback unit.  o f cardboard  employ.  o f t h e 10 v i d e o t a p e s  mounted  the r a t i n g c a t e g o r i e s t h a t s u b j e c t s were t o directly  onto F o r t r a n coding  forms.  from each o f the 3 groups o f s u b j e c t s i n t h e  s t u d y were s e l e c t e d f o r v i e w i n g .  each o f t h e T o l e r a n t and I n t o l e r a n t s e n t a t i o n i n t h i s part of the study. one s u b j e c t i n t h e c o n t r o l g r o u p who tection series.  first  s e t v i a a S o n y AV3400  A b o v e t h e t e l e v i s i o n s c r e e n was  S u b j e c t s coded t h e i r responses  Nine first  displaying  undergoing  (influenced) s e s s i o n of the  s t u d y w e r e shown t o s u b j e c t s o n a 23 i n c h t e l e v i s i o n  a sheet  assigned  each.  the s i g n a l d e t e c t i o n phase o f the second  videotape  the under-  The v i d e o t a p e s  o f one s u b j e c t  groups were randomly e x c l u d e d Excluded  a s w e l l was  d i d n o t complete  Each s e t o f nine tapes  s o f o r m e d was  from  the tape  from pre-  of the  t h e e n t i r e s i g n a l derandomly d i v i d e d  into  three groups o f t h r e e s u b j e c t s . Procedure. laboratory who  When a l l f i v e o b s e r v i n g s u b j e c t s i n a g r o u p a r r i v e d a t t h e  f o r the f i r s t  s e s s i o n , they were g r e e t e d by a female  read a standard s e t of i n s t r u c t i o n s .  being concerned o t h e r p e o p l e who  The e x p e r i m e n t  was  experimenter  d e s c r i b e d as  w i t h t h e way p e o p l e " . . . d i f f e r e n t i a t e t h e b e h a v i o u r . . . . o f are experimenting various l e v e l s of pain."  t h e v i d e o t a p e s was  t h e n e x p l a i n e d as  follows:  The p e o p l e t h a t y o u w i l l be w a t c h i n g t o o k p a r t i n an e x p e r i m e n t on t h e p e r c e p t i o n o f p a i n . They were s e a t e d i n t h e l a b o r a t o r y and had an e l e c t r o d e a t t a c h e d t o t h e i r arm. Then t h e y w e r e e x p o s e d t o  The c o n t e n t o f  75  a s e r i e s of e l e c t r i c shocks, s t a r t i n g at undetectable levels, that gradually increased i n intensity u n t i l they got p a i n f u l . The s h o c k s i n c r e a s e d some more u n t i l t h e s u b j e c t s t o l d us t h e y w e r e p a i n f u l e n o u g h t h a t t h e y w o u l d t o l e r a t e no more. After d o i n g t h i s a few t i m e s , t h r e e d i f f e r e n t p a i r s o f c u r r e n t s were determined. The f i r s t p a i r was a t an i n t e n s i t y t h a t t h e p e o p l e r e p o r t e d as j u s t b a r e l y detectable. The s e c o n d p a i r was a t a s t r o n g e r i n t e n s i t y a n d t h e t h i r d p a i r was a t an i n t e n s i t y b e y o n d w h a t t h e y s a i d was p a i n f u l . So t h e r e w e r e t h r e e l e v e l s of p a i r s of shocks: l o w , medium, a n d h i g h . These t h r e e l e v e l s w e r e t h e n p r e s e n t e d ... t o t h e s u b j e c t s many t i m e s . . . i n a r a n d o m o r d e r , a n d e a c h o c c u r r e d an e q u a l number of times. No  m e n t i o n was  made o f  the  i n f l u e n c e conditions that observed subjects  under-  went. After this task. that  d e s c r i p t i o n of the  task, observers  F o l l o w i n g each t r i a l observers the shock l e v e l e x p e r i e n c e d  intensity.  The  on  i n s t r u c t i o n s then  were i n s t r u c t e d i n  were t o i n d i c a t e whether they  t h e t r i a l was  their  thought  of h i g h , moderate, or  low  continued:  . . . b e f o r e we s t a r t w i t h t h e e x p e r i m e n t i t s e l f , we u s u a l l y f i n d i t b e s t t o p r o v i d e y o u w i t h a l i t t l e b i t of p r a c t i c e beforehand. So w h a t I ' l l do i s show y o u a c o u p l e o f p r a c t i c e t a p e s . As we go t h r o u g h , pay c l o s e a t t e n t i o n t o t h e b e h a v i o u r of the person you are watching. L o o k f o r any s i g n s i n t h e i r b e h a v i o u r t h a t w i l l g i v e you a c l u e as t o t h e l e v e l o f s h o c k t h e y ' r e r e c e i v i n g a n d how much p a i n t h e y ' r e f e e l i n g . Before  the  s e s s i o n began, observers  responses w e l l ,  and  make u s e  Following instructions, s u b j e c t s o b s e r v e d two  of  were a l s o i n s t r u c t e d to d i s t r i b u t e  o f a l l the  categories.  the p r a c t i c e t r i a l s  the t h r e e  which of the  three  the experimenter p r o v i d e d  current levels  began.  t a p e s w h i c h had  from p r e s e n t a t i o n i n the major p a r t of the study. the p r a c t i c e s e r i e s ,  the  their  During  been randomly  trials,  excluded  F o l l o w i n g each t r i a l  f e e d b a c k by  s u b j e c t had  these  received.  telling  the  in raters  76 When t h e p r a c t i c e t r i a l s h a d b e e n c o m p l e t e d , gan.  E a c h s a m p l e o f f i v e o b s e r v e r s r a t e d a l l t a p e s i n one  "squads"  o f t h r e e r a n d o m l y - s e l e c t e d s u b j e c t s from each  conditions of the f i r s t ability,  study.  a l l o b s e r v e r s i n each  s u b j e c t was  comprised  o f 18 e x a m p l e s e a c h  level  the p o s s i b i l i t y  of performance  questionnaire  c o n s i s t i n g o f two  7-point L i k e r t  t h e amount o f d i s t r e s s e x h i b i t e d b y of  rating Four  at  re-  observed low, for  2:1. continuously informed  However, i n o r d e r t o guard the o b s e r v e r s , the 33% o f t r i a l s .  t h e i r r a t i n g s of each  reli-  from t h e i r  mean c u r r e n t i n t e n s i t i e s  on a r a n d o m l y s e l e c t e d  completely finished  three  o f b e h a v i o u r e l i c i t e d by  d e t e r i o r a t i o n by  against experi-  When o b s e r -  tape, they completed  s c a l e s a s k i n g them t o  t h e s u b j e c t and  be-  influence  tape of each  o b s e r v e r s were not  the subject received.  menter p r o v i d e d feedback v e r s had  The  The  s u b j e c t s are presented i n Table  F o l l o w i n g the p r a c t i c e t r i a l s , what s h o c k  of the  of the  s a m p l e r a t e d t h e same t a p e s  medium, a n d h i g h c u r r e n t i n t e n s i t i e s . group o f observed  proper  I n o r d e r to assess r e p e a t e d measures  s p e c t i v e "squad" t w i c e i n d i f f e r e n t s e s s i o n s .  each  the experiment  the ease o r  a  rate  difficulty  the s u b j e c t . t e s t i n g s e s s i o n s o f a p p r o x i m a t e l y two h o u r s  one week i n t e r v a l s w e r e r e q u i r e d t o c o m p l e t e  data  i n l e n g t h and collection.  spaced  •  77  Table  2:1  Means o f Low, M e d i u m , a n d H i g h C u r r e n t Administered  Group  Low  t o Observed  Current  Intensities  Subjects.  Intensity  Medium  High  Tolerant  0.88  3.73  6.95  Control  1.13  4.00  7.28  Intolerant  1.19  3.97  6.33  Note:  Means a r e i n m i l l i a m p e r e s at  and r e p r e s e n t  e a c h o f t h e l o w , medium, a n d h i g h  t h e mean o f two  levels.  intensities  78  RESULTS  For  t h e p u r p o s e s o f SDT a n a l y s e s , c o n d i t i o n a l p r o b a b i l i t i e s o f  occurr-  ence o f each r e s p o n s e g i v e n t h e o c c u r r e n c e o f an example o f s u b j e c t following presentation calculated.  o f each o f t h e t h r e e p a i r s o f shock i n t e n s i t i e s were  These p r o b a b i l i t i e s were t h e n c u m u l a t e d f r o m t h e l o w t o t h e h i g h  response category f o r each stimulus Clark  behaviour  (1974).  Following  i n t e n s i t y l e v e l i n t h e manner o u t l i n e d by  the generation of cumulative p r o b a b i l i t y  tables  e s t i m a t e s o f d.' a n d L ^ w e r e c a l c u l a t e d a t t h e "medium" a n d t h e " l o w " r e s p o n s e c a t e g o r y f o r t h e h i g h v s . medium a n d medium v s . l o w d i s c r i m i n a t i o n s . data so derived  were i n v e s t i g a t e d by a n a l y s i s  of variance.  e f f e c t s were o f p r i n c i p a l i n t e r e s t i n these a n a l y s e s : parameters v a r i e d  systematically  o b s e r v e r s were r e q u i r e d  as a f u n c t i o n  to perform  (i.e.,  Two  The  potential  ( 1 ) w h e t h e r t h e SDT  of the discrimination  d i d d' a n d / o r L d i f f e r — —x  that  between  t h e medium v s . l o w (ML) a n d t h e h i g h v s . medium (HM) d i s c r i m i n a t i o n ) , a n d (2) w h e t h e r t h e p a r a m e t e r s v a r i e d s y s t e m a t i c a l l y tions  that  observed subjects  expected that  t h e HM d i s c r i m i n a t i o n w o u l d b e a s s o c i a t e d  i t was e x p e c t e d t h a t  i n ability  from the three d i f f e r e n t stimulus  For  d' effects,  models  behaviours r e s u l t i n g  i n t e n s i t i e s (a reduction  observers r a t i n g subjects  e x h i b i t enhanced  greater  exposed t o t o l e r a n t  to discriminate  same o b s e r v e r s r a t i n g c o n t r o l s u b j e c t s .  pected that  with  I t was  With respect to s o c i a l influence  observers r a t i n g subjects  would e x h i b i t reductions  of the condi-  h a d b e e n e x p o s e d t o i n E x p e r i m e n t 1.  v a l u e s t h a n t h e ML d i s c r i m i n a t i o n .  the  as a f u n c t i o n  i n d.') r e l a t i v e t o  Cn t h e o t h e r h a n d , i t was e x -  exposed t o an i n t o l e r a n t model w o u l d  discrimination.  t h e ANOVAs v a l u e s o f d_' a n d L_^ a t e a c h c r i t e r i o n a l o n g t h e r a t i n g  s c a l e were averaged.  T h e s e a v e r a g e d.' a n d _L  v a l u e s were then  averaged  79  a c r o s s t h e t h r e e s u b j e c t s p e r i n f l u e n c e c o n d i t i o n t h a t were p r e s e n t e d t o each o b s e r v e r sample.  I n order t o e x t r a c t the v a r i a n c e a s s o c i a t e d w i t h each  observer sample-videotape  squad p a i r i n g , v i d e o t a p e squads were i n c l u d e d as  a b e t w e e n - g r o u p s f a c t o r i n t h e ANOVA.  The o v e r a l l  d e s i g n , t h e n , was a 3  (Squads) X 2 ( R e p l i c a t i o n s ) X 3 ( M o d e l i n g C o n d i t i o n s ) X 2 ( D i s c r i m i n a t i o n s ) ANOVA, w i t h r e p e a t e d m e a s u r e m e n t s on t h e l a s t  three  factors.  R e s u l t s o f t h e a n a l y s i s o f v a l u e s o f L_ w e r e l a r g e l y n e g a t i v e . x  only effect  t h a t a p p r o a c h e d s i g n i f i c a n c e was t h a t f o r R e p l i c a t i o n s , _F(1,12)  = 4 . 0 7 , p_ = . 0 6 7 . T h i s r e f l e c t e d o b s e r v e r s ' t e n d e n c y vative  criteria  the second  The  f o r r e p o r t i n g the occurrence  time t h a t they viewed  t o a d o p t more  o f h i g h e r shock  each video-tape  conser-  intensities  (M R e p l i c a t i o n  1 = 0.9 7;  " R e p l i c a t i o n 2 = 1.18). A number o f s i g n i f i c a n t The  f i n d i n g s emerged f r o m  most i m p o r t a n t w e r e a s i g n i f i c a n t  p_ < -.01, a n d a s i g n i f i c a n t M o d e l i n g .01.  Examination  responses  D i s c r i m i n a t i o n s e f f e c t , _F(1,12) = 4 9 . 6 0 ,  C o n d i t i o n s e f f e c t , _F(1,12) = 2 2 . 5 9 , p_<  o f means r e v e a l e d t h a t d.' v a l u e s f o r t h e HM  were g r e a t e r than those respectively).  t h e a n a l y s i s o f d_' v a l u e s .  f o r t h e ML d i s c r i m i n a t i o n  Thus, t h e a b i l i t y  was c l o s e l y  discrimination  (M d' = 0.65 a n d 0 . 2 1 ,  to discriminate shock-elicited  expressive  r e l a t e d t o t h e magnitude o f c u r r e n t t h e observed  sub-  j e c t was e x p o s e d t o . Mean d.' v a l u e s  f o r the s i g n i f i c a n t Modeling  g r o u p s m a i n e f f e c t w e r e 0.31  for  g r o u p T, 0.42 f o r g r o u p I , a n d 0.5 7 f o r g r o u p C.  all  t h r e e means e x c e e d e d t h e c r i t i c a l v a l u e f o r Dunn's m u l t i p l e  procedure  (_t* D .05/2;3,24 = 0 . 1 0 ) .  comparison  Thus o b s e r v e r s e x h i b i t e d r e l i a b l y  d_' v a l u e s when o b s e r v i n g t h e b e h a v i o u r model r e l a t i v e  The d i f f e r e n c e s b e t w e e n  lower  o f s u b j e c t s e x p o s e d t o an i n t o l e r a n t  t o when t h e y w e r e o b s e r v i n g t h e b e h a v i o u r  o f " c o n t r o l s , and they  e x h i b i t e d e v e n l o w e r _d' v a l u e s when o b s e r v i n g t h e b e h a v i o u r  of subjects ex-  80 posed t o a t o l e r a n t or  control  m o d e l r e l a t i v e t o when t h e y o b s e r v e d e i t h e r  subjects.  Other s i g n i f i c a n t e f f e c t s less  intolerant  readily interpretable  w h i c h was i n c l u d e d  emerged f r o m t h e a n a l y s i s ;  since  they involved  i n the analysis  however, they were  the o b s e r v e r samples  simply to extract  the variance  from p a r t i c u l a r o b s e r v e r sample-videotapes squad p a i r i n g s .  resulting  The o v e r a l l  S q u a d s e f f e c t was s i g n i f i c a n t , F ( l , 1 2 ) = 7.12, £ < . 0 1 , i n d i c a t i n g :  t h r e e o b s e r v e r sample-videotape squad p a i r i n g s o v e r a l l d_' v a l u e s  (means:  p_  were a s s o c i a t e d w i t h  S a m p l e 1 = 0 . 5 0 ; S a m p l e 2 = 0.5 7;  T h e r e was a s i g n i f i c a n t S q u a d s x R e p l i c a t i o n s  that the different  Sample 3 = 0 . 2 3 ) .  i n t e r a c t i o n , F_(2,12) = 5 . 8 5 ,  a;-t05, r e f l e c t i n g d i f f e r e n t i a l p a t t e r n s o f r e s p o n s e a c r o s s b o t h r e p l i c a -  tions can  f o r a l l three samples.  be seen that  discrimination  3 exhibited  The means a r e p r e s e n t e d i n T a b l e 2:2 w h e r e i t  o b s e r v e r s j u d g i n g s u b j e c t s i n Squad 1 e x h i b i t e d  from R e p l i c a t i o n  w i t h reduced d i s c r i m i n a t i o n minimal  1 to Replication  from R e p l i c a t i o n  tions  1 to Replication  attributable  i n t e r a c t i o n , F (2,12) = 10.79, p < .01.  associated  2, a n d S q u a d  t o t h e Squads X  Discrimina-  The means f o r t h i s e f f e c t a r e  p r e s e n t e d i n T a b l e 2:3 w h e r e i t c a n b e s e e n t h a t d.' b e t w e e n t h e HM a n d t h e ML d i s c r i m i n a t i o n s  Squads.  2, S q u a d 2 was  improved  change.  A s i g n i f i c a n t e f f e c t was a l s o  in  variable  the magnitude o f r e d u c t i o n varied  across the three  S q u a d 1 was a s s o c i a t e d w i t h t h e g r e a t e s t HM t o ML d e c r e a s e i n d.' ,  S q u a d 2 an i n t e r m e d i a t e d e c r e a s e , a n d S q u a d 3 t h e l e a s t  decrease.  c a s e , h o w e v e r , d i d t h e o v e r a l l d i r e c t i o n o f c h a n g e i n d.' d i f f e r  I n no  between  squads. Two f u r t h e r the .01;  significant interaction effects  modeling v a r i a b l e :  occurred, both  involving  S q u a d s X M o d e l i n g C o n d i t i o n s , F_ ( 2 , 2 4 ) = 1 0 . 3 9 , p <  and Squads X M o d e l i n g C o n d i t i o n s X D i s c r i m i n a t i o n s ,  ]? ( 2 , 2 4 ) = 4 . 5 2 , p- <  81  Table  2:2  Mean d.' V a l u e s f o r t h e S q u a d s x Replications  Replication  Squad 1  Interaction  Squad 2  Squad 3  1  0.40  0.76  0.20  2  0.61  0.37  0.25  82  .01.  Means f o r t h e 3 - f a c t o r i n t e r a c t i o n a r e p r e s e n t e d  can be seen t h a t w h i l e  t h e r e was a g e n e r a l  ML d i s c r i m i n a t i o n , o b s e r v e r s ately  l o w mean d_' v a l u e s  disordinal with respect the  data  i n T a b l e 2:4 w h e r e i t  r e d u c t i o n i n d_' f r o m t h e HM t o t h e  j u d g i n g s u b j e c t s i n Squad 3 e x h i b i t e d i n o r d i n -  a t t h e HM d i s c r i m i n a t i o n .  The i n t e r a c t i o n i s n o t  to the e f f e c t s of Modeling Conditions.  Therefore,  do n o t s u g g e s t t h a t t h e o v e r a l l c o n c l u s i o n t h a t o b s e r v e r s  s u b j e c t s exposed t o a t o l e r a n t model e x h i b i t e d reduced a b i l i t y a t e needs t o be q u a l i f i e d  rating  to d i s c r i m i n -  significantly.  G l o b a l r a t i n g s o f d i s t r e s s and d i f f i c u l t y . Observers' overall the  r a t i n g s on t h e p o s t  experimental  questionnaire e v a l u a t i n g the  l e v e l o f d i s t r e s s e x h i b i t e d by o b s e r v e d s u b j e c t s were e n t e r e d  same ANOVA d e s i g n  levels of s t a t i s t i c a l  .  The M o d e l i n g C o n d i t i o n s  reliability,  term approached  F_(2,24) = 3 . 3 3 , p_ = .05.  into  conventional  However, m u l t i p l e  c o m p a r i s o n s w i t h Dunn's p r o c e d u r e f a i l e d t o d e m o n s t r a t e t h a t a n y p a i r o f modeling conditions d i f f e r e d r e l i a b l y ratings:  (t_'D . 0 5 / 2 , 3, 24 = 0.68; Mean d i s t r e s s  Group T = 2.96, Group I = 2.79, Group C = 3.44).  The same m o d e l o f a n a l y s i s was e m p l o y e d i n e v a l u a t i n g o b s e r v e r s ' o f how d i f f i c u l t e a c h o b s e r v e d s u b j e c t was t o j u d g e . Conditions tiple  A reliable  e f f e c t e m e r g e d f r o m t h i s a n a l y s i s , _F(2,24) = 1 1 . 7 5 , £  ratings  Modeling < .01.  Mul-  c o m p a r i s o n s b y means o f Dunn's p r o c e d u r e i n d i c a t e d t h a t t h i s e f f e c t  e x c l u s i v e l y accounted f o r by the i n c r e a s e d d i f f i c u l t y when j u d g i n g intolerant  that observers  s u b j e c t s exposed t o a t o l e r a n t model r e l a t i v e  and c o n t r o l s u b j e c t s .  t o l e r a n t and c o n t r o l s u b j e c t s  Ratings  (_t' D. 0 5 / 2 , 3 , 2 4  G r o u p T = 5 . 2 8 , G r o u p I = 4.89, G r o u p C = 4 . 7 4 ) .  reported  t o judgements o f  of the d i f f i c u l t y  d i dnot differ  was  of judging i n = 0.29; Means:  83  Table Mean d.' V a l u e s  f o r t h e Squads x  Discriminations  Discrimination  Note:  2:3  Interaction  Squad 1  Squad 2  Squad 3  HM  0.92  0.72  0.31  ML  0.09  0.42  0.14  HM = H i g h v s . M e d i u m ML = M e d i u m v s . Low  discrimination discrimination  84  Table Mean _d' V a l u e s  2:4  f o r t h e Squads x M o d e l i n g  x Discriminations  Groups  Interaction  M o d e l i n g Group  Discrimination  1  HM  0.65  0.78  -0.06  ML  -0.19  0.44  0.23  HM  0.78  0.63  0.51  ML  0.20  0.42  -0.01  HM  1.33  0.75  0.48  ML  0.25  0.39  0.20  2  3  Squad 1  Squad 2  Squad  3  85  A significant  Squads x M o d e l i n g C o n d i t i o n s  J ? ( 2 , 2 4 ) = 1 7 . 7 0 , p_ < , . 0 1 .  i n t e r a c t i o n was a l s o  I n s p e c t i o n o f t h e means f o r t h i s  obtained,  interaction  ( T a b l e 2 : 5 ) i n d i c a t e d t h a t when o b s e r v e r s r a t e d s u b j e c t s f r o m S q u a d s 1 a n d 3 the  general  in  group T r e l a t i v e  Ratings  trend toward e l e v a t e d d i f f i c u l t y  of subjects  modeling conditions.  ratings associated with  subjects  t o those a s s o c i a t e d w i t h s u b j e c t s i n groups I and C h e l d . f r o m Squad 2 d i d n o t a p p e a r t o d i f f e r a c r o s s  the 3  86  T a b l e 2:5 Mean D i f f i c u l t y  Ratings  A s s o c i a t e d w i t h e a c h S q u a d when O b s e r v e r s  Made J u d g e m e n t s o f S u b j e c t s  from the Three  Influence  o f Study 1  Conditions  Social  Squad  Tolerant  Modeling Condition Intolerant  Control  1  5.70  4.73  4.73  2  4.97  5.59  5.67  3  5.17  4.33  3.83  Note:  M i n i m u m r a t i n g = 1 ( v e r y e a s y ) ; Maximum r a t i n g = 7 ( v e r y  difficult).  87 Discussion  A number o f i n t e r e s t i n g f i n d i n g s e m e r g e d f r o m t h i s may  be  s u m m a r i z e d as  follows.  Observers, i n general  d e c i s i o n c r i t e r i a when m a k i n g j u d g e m e n t s o f served subjects  were exposed t o .  t h e ANOVA p e r f o r m e d on v a r i a t i o n as  v a l u e s o f L_  a f u n c t i o n of  s h o c k l e v e l s as  greater  than zero.  were r e q u i r e d  by  and  high  the  r e v e a l any  fact that  results stable  that  the  ob-  fact  statistically  reliable  Observers were by  low,  that  capable  medium  and  d.' v a l u e s w e r e  generally  d i s c r i m i n a b i l i t y of observed s u b j e c t s '  behaviour  v a r i e d s y s t e m a t i c a l l y as servers  i s b a s e d on  i n the b e h a v i o u r e l i c i t e d  e v i d e n c e d by The  l e v e l of c u r r e n t  conclusion  did not  x  The  adopted f a i r l y  the m a n i p u l a t e d v a r i a b l e s .  of d i s c r i m i n a t i n g differences high  This  the  study.  a f u n c t i o n of the  t o make.  medium c u r r e n t  The  type of  d i s c r i m i n a t i o n that  ob-  d i f f e r e n c e between b e h a v i o u r c o n t r o l l e d  l e v e l s was  more r e a d i l y d i s c r i m i n a t e d  d i f f e r e n c e between b e h a v i o u r c o n t r o l l e d by  The  d i s c r i m i n a b i l i t y of s h o c k - e l i c i t e d e x p r e s s i o n s v a r i e d s y s t e m a t i c a l l y  h a v i o u r of s u b j e c t s v a l u e s o f d_' , and  the behaviour of subjects  o c c u r r e d across the not  s u c h as  values with of  the  that  of the  i n the  amount o f  highest  to c a l l i n t o question i n the  difficulty  they found subjects  subjects  the  d.' v a l u e s .  the  t h e y had  i n the  i n making the  the  the  Finally,  inactive  observed  coeffect  r e d u c e d d_'  Observers'  discriminations  ratings  indicated  observers' post observation  subject.  be-  this variation  a s s o c i a t i o n of  observed subjects  as  lowest  t o l e r a n t g r o u p more d i f f i c u l t t o j u d g e  d i s t r e s s e x h i b i t e d by o f the  general  levels.  Variation in this  t o l e r a n t modeling condition.  other groups.  modeling condition  e x p o s e d t o an  with  3 v i d e o t a p e squads, however, the n a t u r e of  subjects  amount o f  with  current  observed subject, with  exposed to a t o l e r a n t model a s s o c i a t e d  participant associated  was  of the  low  was  the  a f u n c t i o n of the modeling c o n d i t i o n  medium a n d  than  varied with  than  ratings the  88 > .  While  processes  t h e r e have been s e v e r a l attempts (Grossberg & Grant, 1976),  procedures 1978).  t o a p p l y SDT m e t h o d s t o s o c i a l  o n l y one o t h e r s t u d y h a s e x t e n d e d  t o t h e a n a l y s i s o f o v e r t s o c i a l b e h a v i o u r i n humans  (Thompson,  T h e r e f o r e , b o t h m e t h o d o l o g i c a l and s u b s t a n t i v e i s s u e s r e q u i r e d i s -  cussion.  The f a c t  t h a t t h e HM d i s c r i m i n a t i o n was a s s o c i a t e d w i t h g r e a t e r  v a l u e s o f _d' t h a n t h e ML d i s c r i m i n a t i o n s o l i d l y SDT p r o c e d u r e s Clearly,  supports the u t i l i t y  of  i n investigations of p a i n - e l i c i t e d expressive behaviour.  s u b s t a n t i a l q u a n t i t a t i v e and/or q u a l i t a t i v e d i f f e r e n c e s i n expres-  sive behaviour sity  SDT  levels.  a r e produced  by e l e c t r i c shocks  varying across global  T h i s o c c u r r e d even i n a r e l a t i v e l y  inten-  impoverished laboratory  environment where d i r e c t v i s u a l c o n t a c t between s u b j e c t , c o - p a r t i c i p a n t , and e x p e r i m e n t e r was e l i m i n a t e d . and  The f a c t  t h a t t h e v i d e o t a p e c a m e r a was p r e s e n t  i n s u b j e c t s ' c l e a r view i n the s e s s i o n during which  t h e i r b e h a v i o u r was  t a p e d was o f some c o n c e r n , s i n c e p r e v i o u s i n v e s t i g a t o r s h a v e i n t i m a t e d t h a t subjects w i l l  a c t i v e l y monitor and minimize  t h e y know t h a t i t i s b e i n g r e c o r d e d 1976).  t h e i r expressive behaviour  (Lanzetta et a l . ,  when  1976; K l e c k e t a l . ,  S i n c e p o s i t i v e n o n z e r o d_' v a l u e s w e r e t h e r u l e i n t h i s s t u d y , a n d  s i n c e v a l u e s o f d_' v a r i e d s y s t e m a t i c a l l y w i t h t h e t y p e o f d i s c r i m i n a t i o n t h a t o b s e r v e r s w e r e r e q u i r e d t o make, i t a p p e a r s t h a t s u c h a phenomenon e i t h e r d i d n o t o c c u r o r was o f m i n i m a l Other, ing  unsystematic data support  importance. this  contention.  t h a t f o l l o w e d E x p e r i m e n t . 1, m o s t s u b j e c t s e x h i b i t e d  During  the d e b r i e f -  considerable surprise  when i n f o r m e d t h a t p a r t o f t h e p u r p o s e o f t h e s t u d y was t o a n a l y s e t h e r e cordings of t h e i r expressive behaviour. forgotten  t h a t they were b e i n g r e c o r d e d .  were t e s t e d and had t h e i r b e h a v i o u r it  seems u n l i k e l y  Almost a l l s u b j e c t s reported having Furthermore,  since these subjects  r e c o r d e d o v e r an e x t e n d e d  p e r i o d of time,  t h a t they would have maintained such a " c e n s o r s h i p " o f  t h e i r expressive behaviour.  89  The requires  m e a n i n g o f t h e m e a s u r e , d.' as further elaboration.  o f 2 o r more c l a s s e s were the  overt  3 stimulus  d/  of events.  expressive  l e v e l s that  a p p l i e d to the  provides  an  data from t h i s  index of the  In the present case, the  behaviours of subjects,  they were exposed t o .  discriminability events of i n t e r e s t  e l i c i t e d by  The  study  current  each of  the  intensities  pre-  sented to observed s u b j e c t s were s e l e c t e d , p r i o r to t h e i r undergoing  pain-  modulating manipulations,  sensa-  tion threshold,  (2)  s l i g h t l y below pain  m i d p o i n t between p a i n l e v e l w o u l d be  and  Since  the  p e r f o r m a n c e was  part  of the  Thus, i n the  tolerance.  d_' v a l u e s  increased  the  clearly painful  Only the  latter  stimulus  responses c l e a r l y i n -  m a r k e d l y f r o m t h e ML  to  resulted This liable  observed subject  t h a t met  a consensual d e f i n i t i o n of  be  context, the  i t appears that observers'  argued that  the  observed subject.  The  of the  p r e s e n c e o f any  observed subject's  a reliable  behaviour. greater  behaviour.  i n t o l e r a n t m o d e l i n g c o n d i t i o n w o u l d be  discriminability  f i n d i n g of  re-  condi-  concurrently-verbalizing  associated with  a reliably  in  pain.  a f u n c t i o n of the modeling  observed subject's  t o l e r a n t , t h e r e was  discriminability t h a t the  o f an  and  discrimination  f u r t h e r importance to the  d i f f e r e n c e s i n d i s c r i m i n a b i l i t y as  discriminability  d_' f o r t h e HM  behaviour i n d i c a t i v e of  m o d e l , t o l e r a n t , o r i n t o l e r a n t , was  the  greater  pain.  d i s c r i m i n a t i o n s were  occurrence of behaviours i n d i c a t i v e of p a i n ,  i n t e r p r e t a t i o n o f d.' l e n d s  t h e m o d e l was  ob-  occurrence of s a l i e n t behaviours  from expressive  t i o n of the  the  upon the  present  t h i s sense i t can  in  pain  (3)  contingent  c o n t r o l l e d l a r g e l y by  the  threshold,  the n o n a v e r s i v e  d i s c r i m i n a t i o n , i t i s r e a s o n a b l e to i n f e r t h a t t h i s improvement i n  servers' on  threshold  (1)  expected to r e l i a b l y provoke expressive  d i c a t i v e of "pain". HM  from 3 g l o b a l l e v e l s :  reduction  Furthermore, i f  decrement i n I t had  been  associated with  of the behaviour of s u b j e c t s  in  in this  an  the expected increment  condition.  90 T h i s outcome p r e s e n t s these  some i n t e r p r e t i v e p r o b l e m s .  s u b j e c t s gave e v i d e n c e o f e x p e r i e n c i n g  did not manifest readily  g r e a t e r amounts o f p a i n ,  nonvocal expressive behaviour  discriminate the actual i n t e n s i t y  e n c e d o r t h e amount o f d i s t r e s s t h e y  While i n Experiment  that allowed  observers  of noxious s t i m u l a t i o n they  reported.  1 they to experi-  One i m p l i c a t i o n o f t h i s  f i n d i n g might be t h a t t h e i m p a c t o f s o c i a l m o d e l i n g i n f l u e n c e s on p a i n b e h a v i o u r was n o t c o n s i s t e n t a c r o s s not  seem t o f u l l y  hypothesized  differential  model d i d occur. large  capture  measures.  However, t h i s  conclusion  t h e o b s e r v e d outcomes o f t h e e x p e r i m e n t .  The  r e d u c t i o n i n d.' among s u b j e c t s e x p o s e d t o a t o l e r a n t  F u r t h e r m o r e , t h e m a g n i t u d e o f t h e e f f e c t was  t h a t d.' v a l u e s w e r e l o w e r  t o an i n t o l e r a n t m o d e l .  does  than those  Therefore,  sufficiently  o b s e r v e d among s u b j e c t s  exposed  a l t e r n a t i v e a c c o u n t s might be e q u a l l y  plausible. Two f u r t h e r c o n s i d e r a t i o n s m i g h t a c c o u n t f o r t h e f i n d i n g . jects  i n t h e i n t o l e r a n t group were exposed n o t o n l y  First,  to the formal  sub-  content  of the confederate's  r a t i n g s , b u t a l s o t o t h e model's e x p r e s s i v e  making the r a t i n g s .  W h i l e t h e a c t u a l r a t i n g s made b y t h e m o d e l i n d i c a t e d  the  experience  style  o f g r e a t e r a m o u n t s o f p a i n t h a n t h e s u b j e c t was r e p o r t i n g ,  t h e m a n n e r i n w h i c h t h e m o d e l made h e r r a t i n g s w a s , i n f a c t , q u i t e passionate.  while  As E p l e y  ( 1 9 7 4 , p. 2 7 3 ) , i n a r e v i e w  dis-  o f t h e e f f e c t s on r e a c t i o n s  t o a v e r s i v e s t i m u l a t i o n o f t h e p r e s e n c e o f c o m p a n i o n s h a s n o t e d , "A c o m p a n i o n that emits haviours  c a l m r e s p o n s e s i n a t h r e a t e n i n g s i t u a t i o n may e l i c i t  from t h e observing  discriminability  subject."  of the behaviour  was c o n t r o l l e d b y t h e r e l a t i v e l y  I t seems l i k e l y  s i m i l a r be-  that the reduced  o f s u b j e c t s exposed t o an i n t o l e r a n t model calm e x p r e s s i v e  style  o f t h e model.  Sub-  j e c t s exposed t o an i n a c t i v e c o - p a r t i c i p a n t were n o t exposed t o e x p r e s s i v e communication from t h e i r  c o m p a n i o n ; h e n c e , t h e i r own e x p r e s s i v e  behaviour  was  likely  relatively  uninfluenced.  c o u l d r e a d i l y be. a s s e s s e d aspects  of the model's  An  by  rate of subjects i n t h i s  terminated this who  of formal  g r o u p i n E x p e r i m e n t 1.  I t may  Thus, the  h a v e b e e n an a r t i f a c t  of s u b s t a n t i a l i n t e r e s t  the procedures that  resulting  consistent with  In a d d i t i o n to reducing  reduce.the emission This  explanations  i s correct,  finding i s particularly  t h e i r v e r b a l report of  r e p o r t s o f p a i n and  important  avoidance  accounts of the  First,  i t identifies  that c o n t r o l overt  a specific  d i s p l a y s of p a i n .  set of s o c i a l antecedent Second, the e f f e c t of t h i s  a n t e c e d e n t s — r e m o v a l o r r e d u c t i o n o f p a i n d i s p l a y s — c a n be minimizing may in  the  occurrence  s e t the o c c a s i o n the  shaping  The  on  or maintenance of p a i n  various interaction  clearly  the p a r t of others  pain.  two  rea-  conditions set  of  conceived  of  of a set of s o c i a l d i s c r i m i n a t i v e s t i m u l i  f o r behaviours  of  o r i g i n s of  v a r i a t i o n s i n s t y l e s of response to p a i n f u l s t i m u l a t i o n f o r at l e a s t sons.  was  pain  i n d i c a t i v e of the presence of  for social  the  less  groups  t o l e r a n t m o d e l i n g seemed t o q u i t e  of nonvocal behaviours  in  procedures.  of s u b j e c t s i n both of the other  s t i m u l a t i o n at greater i n t e n s i t i e s ,  they  from s e l e c t i o n f o r s u b j e c t s  o f s u b j e c t s e x p o s e d t o a t o l e r a n t m o d e l was  a n d was  ex-  f i n d i n g of reduced d i s c r i m i n a b i l i t y  of whether e i t h e r of these  than the behaviour  i n E x p e r i m e n t 1.  those  t o e x h i b i t e n h a n c e d p a i n d i s p l a y s as a f u n c t i o n o f  t h a t the b e h a v i o u r  discriminable  dropout  have been t h a t  w o u l d e x h i b i t m i n i m a l d i s t r e s s upon e x p o s u r e t o the  finding  behaviour  i n t o l e r a n t model r e l a t e s to the e x c e s s i v e  the experiment.  Regardless  expressive  f o r reduced d i s c r i m i n a b i l i t y of the  i n t o l e r a n t m o d e l w e r e so d i s t r e s s e d by  g r o u p may  and  communications.  o f s u b j e c t s e x p o s e d t o an  p o s u r e t o an  adequacy of t h i s i n t e r p r e t a t i o n  direct manipulation  alternative explanation  s u b j e c t s most l i k e l y  The  that are  as  that implicated  behaviour.  terms which a t t a i n e d s t a t i s t i c a l s i g n i f i c a n c e  92  in  t h e ANOVA o f d_' v a l u e s w e r e o f l i t t l e  interest,  s i n c e i n no  i n d i c a t e d t h a t the o v e r a l l c o n c l u s i o n s w i t h r e s p e c t m o d e l i n g c o n d i t i o n s n e e d e d t o be  qualified.  the 3 observer  tape squad p a i r i n g s ; however, the magnitude of The  i n t e r a c t i o n s seem q u i t e c l e a r l y  response s t y l e s of the  specific  i t  to the main e f f e c t  Similar overall patterns  f o r the e f f e c t s of modeling c o n d i t i o n s a c r o s s  what.  c a s e was  these  to r e s u l t  of held  sample-video-  e f f e c t s v a r i e d somefrom  idiosyncratic  s u b j e c t s whose t a p e s were a s s i g n e d  to a  given  squad. Results corroborate  of the the  s e v e r i t y o f d i s t r e s s and  findings with regard  s i g n i f i c a n t modeling groups e f f e c t comparisons revealed  t h a t no  difficulty  of judgement r a t i n g s  to d i s c r i m i n a b i l i t y .  i n the  T h e r e was  a  distress rating analysis.  p a i r of groups d i f f e r e d  Multiple  from each other.  This  s u g g e s t s t h a t r a t i n g s w e r e r e l a t i v e l y homogeneous w i t h i n some p a i r o f groups, r e l a t i v e  to a t h i r d  l o w e r when j u d g i n g b o t h suggesting Since  that these  d' was  Observers'  t o l e r a n t and  r a t i n g s of d i s t r e s s were  intolerant subjects relative  groups combined accounted f o r the m a r g i n a l  reduced i n both groups, t h i s marginal  of differences with  respect  i n t e r p r e t a t i o n o f d_' as difficulty  group.  Analyses  t o judge than were s u b j e c t s i n the o t h e r  that observers  r e l i e d upon t h e o c c u r r e n c e  of  groups.  cues tended to occur  quently  among t o l e r a n t s u b j e c t s .  of pain  c u e s among t o l e r a n t s u b j e c t s i n a d d i t i o n t o m i r r o r i n g t h e  reductions  i n the  Experimental  discriminability  pattern the  observers' reliably  Assuming  of a p a r t i c u l a r s e t of cues t o base  r a t i n g s u p o n , i t w o u l d seem t h a t t h e s e This  the  t o l e r a n t group were  more d i f f i c u l t  their  effect.  f u r t h e r supports  pain.  r a t i n g s r e v e a l e d t h a t s u b j e c t s i n the  to c o n t r o l s ,  finding mirrors  t o d i s c r i m i n a b i l i t y , and  a measure o f e x p r e s s e d  the  f i n d i n g may  of t h e i r  less  fre-  r e f l e c t a f u r t h e r absence marked  behaviour.  s t u d i e s of the e f f e c t s of p a i n modulation procedures  humans h a v e r e l i e d a l m o s t e x c l u s i v e l y u p o n v e r b a l c h a r a c t e r i z a t i o n s  on  93 of the experience reflects Hilgard's ating,  o f p a i n as a dependent v a r i a b l e .  (1969) c o n c l u s i o n t h a t s u c h measures a r e h i g h l y d i s c r i m i n -  r e p l i c a b l e , and: l a w f u l .  processes  However, i n v e s t i g a t o r s i n t e r e s t e d i n s o c i a l  r e l a t e d t o p a i n r e q u i r e s o m e t h i n g more, i n t h a t t h e i r c o n c e r n i s  with the s o c i a l behaviours  i n d i c a t i v e o f p a i n , and t h e s o c i a l m i l i e u i n  w h i c h p a i n and i t s i n d i c a n t s o c c u r . utility  relevant pain behaviour experimental  clusively types  The p r e s e n t  o f a methodology that i s based d i r e c t l y  The  This trend i n the research  study  has demonstrated the  upon t h e o v e r t ,  o f t h e i n d i v i d u a l , and i s r e a d i l y adaptable  impact o f t h e v a r i a b l e s manipulated upon d i s c r i m i n a b i l i t y .  i n this  I t i s of interest  s t u d y was a l m o s t e x to speculate  about t h e  o f v a r i a b l e t h a t might be a s s o c i a t e d w i t h a l t e r a t i o n s i n o b s e r v e r s o f task employed i n t h i s study.  t i o n s o f t h e amount o f p a i n a n i n d i v i d u a l i s e x p e r i e n c i n g clinical  settings.  evidence that pain i s being  of the d i a g n o s t i c i a n .  regard  experienced,  a r e commonplace i n  b u t a l s o upon a v a i l a b l e b a c k -  to the i n d i v i d u a l ,  C e r t a i n types  amount o f p a i n i s p r e s e n t .  of background information l i k e l y  and t h e p r i o r  experience  o f background information are very  t o i n f l u e n c e the d i a g n o s t i c i a n ' s c r i t e r i o n  that a significant  Evalua-  Such e v a l u a t i o n s a r e b a s e d n o t o n l y upon t h e p r e s e n c e o f  ground i n f o r m a t i o n w i t h  likely  t o many  settings.  d e c i s i o n r u l e s ( c r i t e r i a ) i n the type  direct  socially-  for accepting  evidence  Some e x a m p l e s o f t h e t y p e s  t o i n f l u e n c e judgements o f p a i n  include:  the p a t i e n t ' s e t h n i c background, t h e h i s t o r y and c h r o n i c i t y o f t h e problem, the emotional  o r p s y c h i a t r i c s t a t u s o f the p a t i e n t  or " s t o i c a l " ? ) ,  " p a y o f f s " a s s o c i a t e d w i t h e v i d e n c e o f p a i n s u c h as compensa-  t i o n , "secondary gains", e t c . ence w i t h p a i n e x p r e s s i o n s conceivable,  ( e . g . , i s s/he " n e u r o t i c "  Other v a r i a b l e s l i k e  are l i k e l y  the observer's  experi-  t o contribute to this process.  f o r e x a m p l e , t h a t i n d i v i d u a l s who l i v e  I t i s  i n a f a m i l y w h e r e one  94  member has a chronic pain problem may come to exhibit different criteria for evaluating pain as a function of their increased exposure to evidence of i t s presence.  Indeed, i n the present study, the finding that observers tended  to employ more conservative criteria for reporting higher magnitudes of shock during their second viewing of each subject suggests that greater experience with expressions of pain alters evaluators' decision rules for reporting i t s presence in others.  Determining the contribution of such vari-  ables to decisions regarding the presence or magnitude of pain is a c r i t i c a l step in understanding nosis.  the complex phenomena of clinical pain and its diag-  The methodology employed in the present study seems a particularly  appropriate one for examining these issues.  95  E x p e r i m e n t 3.  An  i n v e s t i g a t i o n of v i c a r i o u s i n f l u e n c e s  communications employing n a t u r a l l y - o c c u r r i n g  R e s e a r c h on  social  pain  groups.  i n f l u e n c e v i a m o d e l i n g p r o c e d u r e s has  important consequences i n three has  on  respects.  First,  such  uncovered a major s o u r c e of v a r i a t i o n i n s o c i a l  Second, m o d e l i n g r e s e a r c h  has  led directly  to the  had  research  behaviour.  development of  procedures  e f f e c t i v e i n a l t e r i n g problematic behaviours, p a r t i c u l a r l y those characterized  by  avoidance.  have been employed w i t h i n the  o r i g i n s of various  one  example of  the  Third,  the  c o n t e x t of  latter,  the  acquisition ~of :  the  n a t u r a l e n v i r o n m e n t has  of  f e a r f u l b e h a v i o u r e x h i b i t e d by (Rachman, 1972;  Bandura, 1969,1976).  and  o t h e r s have argued t h a t d i f f e r e n c e s  (1976a), C r a i g  l a r g e l y be  the  product of  tolerance  or  stylistic  differences  emitted  As  avoidance to the  modeling  M o r e germane ( N o t e 1,  in pain-related  to  1978b), behaviour  r e f l e c t variations i n s o c i a l i z a t i o n experiences.  In p a r t i c u l a r , r e l a t i v e t o l e r a n c e may  fearful  of  others i n s p e c i f i c s i t u a t i o n a l  present d i s c u s s i o n , Fordyce  i n part,  behaviour.  been a t t r i b u t e d i n p a r t  the  can,  research  t h e o r e t i c a l accounts  forms of s o c i a l / e m o t i o n a l  in  contexts  f i n d i n g s from modeling  intolerance  of  i n the  i n such contexts  may  or  intolerance  for noxious  stimulation  exposure to others d i s p l a y i n g r e l a t i v e  the  same s t i m u l a t i o n .  Similarly,  p a r t i c u l a r forms of p a i n be  m e d i a t e d by  behaviour  the modeling  process.  96  Previous  laboratory  i n v e s t i g a t i o n s have been concerned  demonstrating the occurrence of a modeling impact  of modeling  of pain,  and  of modeling.  effect, evaluating  on a v a r i e t y o f d i m e n s i o n s  examining  other influences  T h e s e i n v e s t i g a t i o n s and  the p r e s e n t s e r i e s have demonstrated  I t has  been suggested  modulate the e f f e c t s  the preceding s t u d i e s  that  that  been p a i d  in  the e f f e c t s are r o b u s t of response  to p a i n f u l  these f i n d i n g s are d e s c r i p t i v e  of n a t u r a l l y o c c u r r i n g v a r i a t i o n s i n p a i n behaviour. l e s s a t t e n t i o n has  the  of the experience  t h a t may  and o b s e r v a b l e a c r o s s a v a r i e t y o f p a r a m e t e r s stimulation.  with  to examining  this  However,  relatively  "etiological"  implication. T h e r e i s a number o f e m p i r i c a l l a c u n a e i n a c c o u n t s of d i f f e r e n c e s on m o d e l i n g  research.  over v a r i a b l e s the c o n t r o l s in  i n s t y l e of response  to p a i n f u l events  Laboratory research allows  of the o r i g i n s  that are  stringent  the n a t u r a l  control  t h a t h a v e p o t e n t i a l o r known e f f e c t s o n p a i n .  c a n e l i m i n a t e s o u r c e s o f i n f l u e n c e t h a t may  be  based  However, important  environment.  S o c i a l i n t e r a c t i o n provides f o r r e c i p r o c a l influence i n that individuals to a l t e r  t h e b e h a v i o u r o f one  K a n f e r and modeling  r e s p o n d i n g i n t h e same s i t u a t i o n a l  Grimm, 1976;  (Skinner,  Bandura, 1978).  c o n s t r a i n t may  The  limit  possibility  1953;  exists that  i n which mutual  r e v e a l n o v e l o r u n u s u a l phenomena.  1968;  examinations of u n i d i r e c this  experimental  t h e r a n g e o f phenomena o b s e r v e d .  an e x p e r i m e n t a l paradigm  Bell,  come  T r a d i t i o n a l l y , however,  r e s e a r c h has been d i r e c t e d toward  tional influence.  may  another  c o n t e x t may  That i s ,  influence i s provided f o r  A second t h e o r e t i c a l used p r e v i o u s l y  i s that  of v a r y i n g s t y l e s two  individuals  l i m i t a t i o n of modeling research with  i tfails  of pain behaviour.  exhibiting  the  forpredicting  previously  whose b e h a v i o u r w i l l change more.  S u b j e c t s who  matched i n p a i r s  that  These s u b j e c t s  then p a r t i c i p a t e d  session,  pairs  that  similar pairs  would be  ascertained pain  s u b j e c t s w o u l d become more t o l e r a n t ) .  reciprocal.  behaviour.  In contrast,  and t h a t  i t was  (i.e., tolerant  hypothesized  that  i n dissimilar pairs, subjects  f r o m e a c h g r o u p w o u l d become more  like  subjects  (i.e.,  become more t o l e r a n t , This paradigm a l s o  and t o l e r a n t  session  w o u l d e x h i b i t more p r o n o u n c e d  s u b j e c t s w o u l d become more i n t o l e r a n t ,  from t h e o t h e r group  intolerance  similar  i n the d i r e c t i o n of t h e i r o r i g i n a l s t y l e of response  intolerant  uninfluenced  i n a second  o f s u b j e c t s were e i t h e r  study,  selecting  r e l a t i v e tolerance or r e l a t i v e  i n terms o f t h e i r p r e v i o u s l y  I t was e x p e c t e d tendencies  exhibited  empirical  In the present  o f p a i n b e h a v i o u r under  i n o r d e r t o examine whether i n f l u e n c e  During the influence different  i n styles  pain  o n e a n o t h e r , t h e r e i s no  e m p l o y e d m o d e l i n g p a r a d i g m was m o d i f i e d b y  f o r p a i n were chosen.  or  LThat i s , given a s i t u a t i o n i n which  to influence  g r o u p s o f s u b j e c t s who d i f f e r e d conditions.  t h e r e l a t i v e power  d i f f e r i n g levels of naturally-occurring  t o l e r a n c e have t h e p o t e n t i a l basis  to adequately predict  the paradigm  intolerant  subjects  would  s u b j e c t s w o u l d become more i n t o l e r a n t ) .  a l l o w e d an e x a m i n a t i o n o f t h e r e l a t i v e  power o f t h e two f o r m s o f b e h a v i o u r .  influencing  98  METHOD  Subjects.  One h u n d r e d t w e n t y - s e v e n f e m a l e s  from undergraduate Psychology  were r e c r u i t e d by  c l a s s e s at the U n i v e r s i t y of B r i t i s h  and w e r e p a i d f o r t h e i r p a r t i c i p a t i o n i n a t w o - p a r t of perception". Apparatus.  Mean age o f t h e s u b j e c t s was  Columbia  "on t h e t o p i c  1 9 . 1 (SD = 1 . 7 ) .  The e q u i p m e n t e m p l o y e d was s i m i l a r t o t h a t u s e d i n t h e  f i r s t study except current  experiment  telephone  t h a t i t was m o d i f i e d t o p r o v i d e t h e c a p a c i t y t o a d m i n i s t e r  t o two s u b j e c t s s i m u l t a n e o u s l y .  Procedure. S e s s i o n 1. in  U p o n h e r a r r i v a l a t t h e l a b o r a t o r y , t h e s u b j e c t was  a room a d j a c e n t  to the experimental  her a standard set of instructions and  provided assurance  chamber and t h e e x p e r i m e n t e r  d e s c r i b i n g the nature  of the  regarding the s a f e t y of the techniques.  seated read t o  experiment After  a s s u r i n g t h e s u b j e c t t h a t h e r p a r t i c i p a t i o n was e n t i r e l y v o l u n t a r y , a n d that the study  c o u l d be t e r m i n a t e d  was p r o v i d e d .  Three s u b j e c t s i n d i c a t e d t h e i r u n w i l l i n g n e s s t o c o n t i n u e a t  this point.  a t any t i m e , o p p o r t u n i t y t o w i t h d r a w  A f u r t h e r 4 s u b j e c t s were e x c l u d e d because they h a d n o t h a d a  p h y s i c a l examination  w i t h i n the past year.  Subjects w i l l i n g  gave w r i t t e n c o n s e n t  a t t h i s p o i n t , and were t h e n e s c o r t e d t o t h e e x p e r i -  m e n t a l chamber where t h e f o l l o w i n g i n s t r u c t i o n s were  read:  I am g o i n g t o p r e s e n t y o u w i t h a s e r i e s o f c u r r e n t s that w i l l s t a r t a t u n d e t e c t a b l e l e v e l s and w i l l g r a d u a l l y i n c r e a s e . Your t a s k w i l l be t o i n d i c a t e how u n c o m f o r t a b l e e a c h one f e e l s b y a s s i g n i n g i t a number r a n g i n g f r o m z e r o up t o 10 o r a b o v e . I n i t i a l l y , t h e c u r r e n t s w i l l be so low t h a t y o u w i l l probably f e e l nothing. I f t h i s i s the case, the r a t i n g "0" f o r " u n d e t e c t a b l e " i s a p p r o p r i a t e .  t o take  part  99 Thereafter, they w i l l g r a d u a l l y increase i ni n t e n s i t y and d i s c o m f o r t . I want y o u t o a s s i g n e a c h one a number t h a t c o r r e s p o n d s t o t h e amount o f discomfort that you f e e l . F o r example, i f y o u g i v e one c u r r e n t a r a t i n g o f " 2 " and t h e n a l a t e r one f e e l s t w i c e a s u n c o m f o r t a b l e , a s s i g n t h e l a t e r one a r a t i n g o f " 4 " .... The c u r r e n t w i l l e v e n t u a l l y reach a l e v e l t h a t y o u would d e s c r i b e as g i v i n g y o u a sensation of pain. We w o u l d l i k e y o u t o g i v e t h a t c u r r e n t a r a t i n g o f 10 o r a b o v e . When y o u j u d g e a c u r r e n t t o be p a i n f u l , and g i v e a r a t i n g o f 10 o r a b o v e , n o more w i l l b e g i v e n y o u . Subjects were then p r o v i d e d w i t h t h e o p p o r t u n i t y i t was c l e a r  that the subject understood the nature  was  to her left  attached  forearm  behind  the partition  Two a s c e n d i n g  strength.  Following this,  the electrode  t o provide  the experimenter retreated  a n d commenced t h e e x p e r i m e n t .  shock s e r i e s were a d m i n i s t e r e d ,  s t a r t i n g a t 0.0 mA a n d g a v e a r a t i n g o f 10 o r  A t t h e e n d o f t h e s e c o n d s e r i e s , t h e e x p e r i m e n t e r removed t h e  e l e c t r o d e and e s c o r t e d  the subject  t o t h e a d j o i n i n g room.  thanked f o r h e r p a r t i c i p a t i o n and informed a second s e s s i o n .  She was t h e n  t h a t she might be c o n t a c t e d f o r  The s e c o n d s e s s i o n was d e s c r i b e d a s b e i n g  basically  s i m i l a r " e x c e p t t h a t w e ' l l b e t a k i n g some p h y s i o l o g i c a l r e c o r d i n g s Prior her  When  t o reduce the  t o 5,000 ohms i n o r d e r  i n c r e a s i n g i n 0.5 mA i n c r e m e n t s u n t i l t h e s u b j e c t greater.  of her task,  and p o s i t i o n e d as n e c e s s a r y  resistance i n the skin-electrode circuit uniformity of stimulus  to ask questions.  as w e l l " .  t o l e a v i n g , t h e s u b j e c t was a s k e d n o t t o t a l k a b o u t t h e e x p e r i m e n t t o classmates. Between t h e f i r s t  threshold scores t h i s measure. greater  and t h e second s e s s i o n o f t h e experiment, average  f o r the f i r s t  Subjects  s e s s i o n were d e t e r m i n e d and s u b j e c t s r a n k e d on  e x h i b i t i n g a range o f p a i n t h r e s h o l d scores o f  t h a n 3.0 mA b e t w e e n t h e f i r s t  from the study. the e n t i r e  pain  and second s e r i e s were e l i m i n a t e d  Three s u b j e c t s were e l i m i n a t e d f o r t h i s  reason.  Thereafter,  g r o u p was d i v i d e d i n t o h i g h a n d l o w t h r e s h o l d g r o u p s b y t a k i n g  100 the  t o p 42 a n d t h e b o t t o m 40 s u b j e c t s o f t h e d i s t r i b u t i o n " ' " . Session  2.  I n t h e second s e s s i o n , s u b j e c t s were e i t h e r r u n i n p a i r s  c o n s i s t i n g of combinations o f subjects e x h i b i t i n g high holds, or participated individually. high  ( H H ) , c o n s i s t i n g o f 22 s u b j e c t s  (HL), in  Three types  HL-H,  (11 p a i r s ) from the h i g h  sisting  from t h e l o w group were d e s i g n a t e d  o f 20 s u b j e c t s  from the l o w group.  a p a i r d i d n o t return f o r a scheduled o f t h e p a i r was a u t o m a t i c a l l y a s s i g n e d g r o u p , a n d was r u n i n d i v i d u a l l y . important  i n order  t o estimate  group;  and low groups  g r o u p who h a d h i g h p r e t e s t t h r e s h o l d s w e r e g i v e n  those  thres-  o f dyad were formed:  c o n s i s t i n g o f 10 s u b j e c t s e a c h f r o m t h e h i g h  this  o r low p r e t e s t  high-  high-low  (subjects  the designation  HL-L) ; and l o w - l o w  ( L L ) , con-  I n t h e e v e n t t h a t one s u b j e c t o f  appointment, the corresponding to a high  member  (HC) o r l o w ( L C ) c o n t r o l  These groups were c o n s i d e r e d e s p e c i a l l y  regression-toward-the-mean.  Upon t h e i r r e t u r n f o r t h e s e c o n d s e s s i o n , s u b j e c t s w e r e c a s u a l l y i n formed t h a t they were g o i n g e x p e r i m e n t more q u i c k l y . had  t o be r u n i n p a i r s i n o r d e r  They w e r e s e a t e d  t h e f o l l o w i n g i n s t r u c t i o n s read  to finish the  i n the experimental  chamber and  t o them:  Today's s e s s i o n w i l l be v e r y s i m i l a r t o t h e f i r s t session. I w i l l again present you with a s e r i e s of currents that w i l l s t a r t a t undetectable levels and w i l l g r a d u a l l y i n c r e a s e . Once a g a i n , I w o u l d l i k e y o u t o make p r o p o r t i o n a t e r a t i n g s o f t h e amount of discomfort that you f e e l , s t a r t i n g a t "zero" f o r u n d e t e c t a b l e and i n c r e a s i n g t h e r e a f t e r . You w i l l e v e n t u a l l y reach a l e v e l t h a t y o u would d e s c r i b e as giving you a sensation of pain. Assign that current a r a t i n g o f 10 o r g r e a t e r . A f t e r you give a r a t i n g o f 10 o r a b o v e , we w o u l d l i k e .you t o c o n t i n u e t a k i n g c u r r e n t f o r as l o n g as p o s s i b l e , b u t t h e d e c i s i o n i s y o u r s t o s t o p a t any t i m e . F o r those c u r r e n t s that occur a f t e r you give a r a t i n g o f 10, continue t o make p r o p o r t i o n a t e r a t i n g s u s i n g a n y w h o l e n u m b e r s  1.  O w i n g t o a n i n a d v e r t e n t s c h e d u l i n g e r r o r on t h e p a r t o f t h e e x p e r i m e n t e r t h e r e w e r e two e x t r a s u b j e c t s f r o m t h e h i g h g r o u p .  101 that you l i k e . When y o u r e a c h t h e p o i n t w h e r e y o u don't w i s h t o a c c e p t any f u r t h e r s t i m u l i , g i v e t h a t current your f i n a l r a t i n g , p u l l the switch i n front o f y o u t o t h e o f f p o s i t i o n a n d n o more w i l l be g i v e n to you. Each ascending first  series  reported pain.  accept  i n the f i r s t  s e s s i o n was  terminated  when t h e s u b j e c t  I n the second s e s s i o n s u b j e c t s were encouraged to  c u r r e n t s b e y o n d p a i n t h r e s h o l d up t o t h e p o i n t w h e r e t h e y w e r e u n -  willing  to  continue.  Prior to testing, rating  first.  For h a l f  threshold score  t h e e x p e r i m e n t e r a s k e d one s u b j e c t t o make h e r  of the dyads, the s u b j e c t having  gave h e r r a t i n g  f i r s t , while  member o f t h e p a i r g a v e h e r r a t i n g In order  to maintain  the higher  f o r the other h a l f ,  the  each s u b j e c t ' s  Prior  right  index  the ruse  index  that i n this  s e s s i o n the concern  f i n g e r a n d i t s o p e r a t i o n was  t o commencing t h e s h o c k s e r i e s ,  " s e t a f e w t h i n g s up on t h e p o l y g r a p h " , 30 s e c . the  and l e f t  At  approximately  shocks were a d m i n i s t e r e d (  mA  steps  to  until  t h e e n d o f t h e s e s s i o n , t h e e l e c t r o d e s a n d pleth'ys'niogfaphs ' w e f e T -  post-experimental  study were  described.  termination of the s e r i e s .  removed, and s u b j e c t s were e s c o r t e d  tionnaires,  t h e room f o r  E a c h s t a r t e d a t 0.0 mA a n d i n c r e a s e d i n 0.'5  both subjects had requested  attached;^  the experimenter excused h i m s e l f t o  Upon r e t u r n i n g , 4 s e r i e s o f e l e c t r i c  subjects.  lower  first.  was w i t h p h y s i o l o g i c a l m e a s u r e s , a "dummy" p h o t o p l e t / h y j s m o g r a p h was to  pretest  questionnaires.  they were f u l l y answered.  t o t h e a d j o i n i n g room w h e r e t h e y  completed  When b o t h s u b j e c t s h a d f i n i s h e d t h e q u e s -  d e b r i e f e d and a l l q u e s t i o n s  they  had about the  102 RESULTS  Pairi threshold.  P a i n t h r e s h o l d d a t a were a n a l y s e d a c c o r d i n g t o a 6  (Groups) x 6 (Shock S e r i e s ) ANOVA d e s i g n w i t h r e p e a t e d measurements on t h e Series variable.  The f i r s t  two l e v e l s o f t h e S e r i e s f a c t o r r e p r e s e n t e d p e r -  formance d u r i n g t h e p r e t e s t s e s s i o n , w h i l e t h e f o l l o w i n g 4 l e v e l s r e p r e s e n t e d performance under i n f l u e n c e c o n d i t i o n s f o r s u b j e c t s i n groups HH, HLH, HLL, and LL o r d u r i n g re-assessment f o r s u b j e c t s i n groups HC and LC. R e s u l t s o f t h e ANOVA i n d i c a t e d a s i g n i f i c a n t o v e r a l l  between  groups main e f f e c t , _F(5,76) = 27.67, p_ < .01, and a s i g n i f i c a n t Groups x S e r i e s i n t e r a c t i o n , F(25,380) = 3.81, £ < .01. The main e f f e c t f o r Groups was o f l i t t l e i n t e r e s t s i n c e group assignment h a d been conducted by s e l e c t i n g s u b j e c t s from extremes o f the d i s t r i b u t i o n .  Of more i n t e r e s t was t h e p r e -  d i c t e d i n t e r a c t i o n ( r e p r e s e n t e d i n F i g u r e 3:1) o f Groups x Shock S e r i e s w h i c h was f u r t h e r i n v e s t i g a t e d v i a a s e r i e s o f p l a n n e d o r t h o g o n a l j t - t e s t s .  Sub-  sequent a n a l y s e s were performed i n o r d e r t o determine which groups e x h i b i t e d changes from S e s s i o n 1 t o S e s s i o n 2, and t o compare t h r e s h o l d l e v e l s influence conditions.  These l a t t e r between-group  t i o n on w h i c h groups e x h i b i t e d d i f f e r e n t i a l  under  analyses provided informa-  changes.  The f i r s t s e t o f comparisons examined change from S e r i e s 1 and 2 (preassessment s e s s i o n ) t o S e r i e s 3 through 6 ( i n f l u e n c e s e s s i o n ) a t each l e v e l o f t h e groups v a r i a b l e .  The o v e r a l l t> v a l u e s f o r each o f t h e s e com-  p a r i s o n s a r e p r e s e n t e d i n Table 3:1. The r e s u l t s o f t h e s e a n a l y s e s c o n f i r m t h a t the decrease i n p a i n t h r e s h o l d v a l u e observed i n groups HL-H from t h e preassessment t o t h e i n f l u e n c e s e s s i o n and t h e i n c r e a s e s o b s e r v e d i n groups HL-L, L L , and LC were s t a t i s t i c a l l y  reliable.  103  Figure 3: 1. Mean intensity of current provoking a rating of "10" (pain threshold) overall shock series in Session 1 (pretest) and Session 2 (tn<fluence session) for subjects in a l l groups,  104  Table Results  3:1  o f Planned Orthogonal Comparisons f o r P a i n Threshold  Error Estimate  Comparison  S  S  1' 2 " Group 1  (HC)  V 2 S  S  S  S  " 3' 4' 5' 6 G r o u p 3 (HL-H)  V 2 S  S  S  S  S  " 3' 4' 5' 6 Group 4 (HL-L)  S  S  S  S  S  1' 2 " S 3 ' W Group 5 ( L L ) S  S  S  6  a  1' 2 " 3 ' 4 ! 4 ' 6 Group 6 (LC) S  S  t Value  S  1.23  0.33  >  .10  1.25  0.83  1.35  >  .10  1.25  1.23  6.52  <  .01  1.25  1.23  -4.93  <  .01  1.25  0.87  -3.66  <  .01  1.25  1.23  -2.12  <  .05  1.20  2.35  <  .05  .05  (SxS w i t h i n groups)  1' 2 " 3 ' 4 ' 5 ' 6 G r o u p 2 (HH) S  t - Ratio Denominator  1.25  S  S  Data  S  S  a t  a t  a t  t  a t  HC, HH v s HL-H  at Series 3  HC, HH v s HL-H  at  Series 4  2.62  1.20  1.56  <  HC, HH v s HL-H  at  Series 5  2.62  1.20  2.22  <  .05  HC, HH v s HL-H  at Series 6  2.62  1.20  2.45  <  .05  2.62 (Ss w i t h i n G S x S s w i t h i n G, pooled)  continued  105 T a b l e 3:1  Error Estimate  Comparison  continued  _t- Ratio Denominator  t Value  HC v s HH a t S e r i e s  3  2.62  0.62  0.14  >  .10  HC v s HH a t S e r i e s  4  2.62  0.62  0.05  >  .10  HC v s HH a t S e r i e s 5  2.62  0.62  1.52  >  .05  HC v  2.62  0.62  1.42  >  .05  0.25  >  .10  HH a t S e r i e s 6  LC,  L L v s HL-L a t S e r i e s 3  2.62  0.62  LC,  L L v s HL-L a t S e r i e s 4  2.62  0.62  -1.16  >  .10  LC,  L L v s HL-L a t S e r i e s 5  2.62  0.62  -0.85  >  .10  LC,  L L v s HL-L a t S e r i e s 6  2.62  0.62  -0.62  >  .10  LC  vs LL a t S e r i e s  3  2.62  0.62  0.96  >•  .10  LC  vs LL a t Series  4  2.62  0.62  0.32  >  .10  LC  vs LL at Series 5  2.62  0.62  0.04  >  .10  LC  vs. L L a t S e r i e s 6  2.62  0.62  0.24  >  .10  Note:  HC = H i g h C o n t r o l , HH = H i g h - H i g h , HL-H = H i g h - L o w ( H i g h ) , HH-L = H i g h - L o w ( L o w ) , L L = Low-Low, L C = Low C o n t r o l . D e n o m i n a t o r s o f t - r a t i o s v a r y when c o m p a r i s o n s a r e b a s e d u p o n d i f f e r e n t n ' s . F o r c o n s e r v a t i v e _ t - t e s t o f b e t w e e n g r o u p comp a r i s o n s , t h e c r i t i c a l v a l u e o f t ' ,„ = 1.98. —a/ 2  106  The Series  factor during.the  each l e v e l : (3)  s e c o n d s e t o f c o m p a r i s o n s was influence session.  (1) Groups  HC  a n d HH  w i t h i n e r r o r t e r m recommended b y K i r k  differences. cated  subjects  i n g r o u p s HC  3, 5, a n d 6. tical  employed  (1968).  to evaluate  i n g r o u p HL-H  a n d HH  These  data.  to a subject  conservative  (Table  3:1)  indi-  differences  differences occurred  at  from  Series  comparisons approached  statis-  Among h i g h  pain  threshold  to the i n f l u e n c e s e s s i o n .  crease i n pain ment p a i n  t h e f o l l o w i n g p a t t e r n was  observed i n the analyses groups, only  threshold.  This  A l l g r o u p s o f s u b j e c t s who  threshold values  g r o u p HL-H  exhibited increases  e x h i b i t e d low  i n reported  pain  exposed  de-  preassess-  threshold  Only t h e changes  r e s u l t e d i n s i g n i f i c a n t between-group  observed  differences during  the  session. Pain  threshold  those subjects  pain  c h a n g e i n v o l v e d an o v e r a l l  from the preassessment t o the i n f l u e n c e s e s s i o n .  influence  of  h a v i n g a low p r e a s s e s s m e n t t h r e s h o l d e x h i b i t e d change f r o m t h e  preassessment  tolerance.  levels  to pain  In Session tolerance.  2, s u b j e c t s These  ( G r o u p s ) x 4 ( S h o c k S e r i e s ) ANOVA w i t h  Groups  subject-  between-group  exhibited significant  combined.  HH,  reliability.  threshold  factor.  of  at  Denominators  C o c h r a n and Cox's  of these analyses  None o f t h e o t h e r b e t w e e n - g r o u p  I n sum,  in  v s Group  the p o o l e d between  the r e l i a b i l i t y  Examination of the r e s u l t s  that only  subjects  employed  ( 2 ) G r o u p HC  ( 4 ) g r o u p s LC v s g r o u p L L .  of _ t - r a t i o s f o r each of these c o n t r a s t s  1968) was  Four c o n t r a s t s were examined  v s G r o u p HL-H,  g r o u p s LC a n d L L v s G r o u p HL-L,  _t ( K i r k ,  performed at each l e v e l of the  The  r a t e d s t i m u l i beyond  d a t a were a n a l y z e d  e f f e c t , j?(5,76)  S e r i e s , F_(15,228)  = 7.75, p_ <  = 1.81, £  < .05.  via a 6  r e p e a t e d m e a s u r e s on t h e S h o c k  o u t c o m e o f t h i s a n a l y s i s i n d i c a t e d t h a t t h e r e was .01, and a s i g n i f i c a n t Mean p a i n  tolerance  a  Groups  values  pain  Series  significant x  Shock  f o r each  group  107 a t e a c h l e v e l o f t h e S h o c k S e r i e s v a r i a b l e a r e shown i n F i g u r e pain  threshold data,  i t would l a r g e l y have  t h e o v e r a l l Groups  e f f e c t was o f l i t t l e  3:2.  interest,  r e f l e c t e d the process of s e l e c t i n g subjects  tremes o f t h e d i s t r i b u t i o n o f p a i n t h r e s h o l d s c o r e s . comparisons w i t h i n t h e h i g h  and low p a i n t h r e s h o l d  As w i t h since  from ex-  Of more i n t e r e s t were  groups.  Orthogonal jt-tests  were c o n d u c t e d a t each l e v e l o f t h e Shock S e r i e s v a r i a b l e f o r t h e f o l l o w i n g between  group c o m p a r i s o n s :  L L v s HL-L, (4) LC v s L L .  ( 1 ) HC a n d HH v s HL-H, ( 2 ) HC v s HH, As w i t h  the previous  s u b j e c t - w i t h i n - s u b j e c t e r r o r t e r m was e m p l o y e d was a s s e s s e d  at a conservative  comparisons exceeded t h i s the  significant  _t'.05/2 v a l u e  c r i t i c a l _t-value.  i n t e r a c t i o n derived  o r i g i n a l set of orthogonal  analyses,  evaluate the  responsible  occurred  f o r the s i g n i f i c a n t  interaction effect.  at a conservative  The o n l y d i f f e r e n c e b e t w e e n  To  a t each l e v e l o f  The e r r o r t e r m f o r t h e s e c o n -  value  error variance, f o r Tukey's  and s i g n i -  t e s t o f 2.82  groups t h a t exceeded t h i s  l o w e r t h a n t h a t f o r g r o u p HC  ( 1 0 . 8 0 mA).  value  Inspection of the  g r o u p means a l s o s u g g e s t e d t h a t a t S h o c k S e r i e s 4 t h e d i f f e r e n c e g r o u p LC a n d g r o u p H L - L may h a v e b e e n i t y by Tukey's  for  have  a t S h o c k S e r i e s 6 (q_ = 3 . 1 0 ) , w h e r e t h e mean f o r g r o u p HL-H ( 8 . 6 0 mA)  was r e l i a b l y  c[ v a l u e  that  Inspection  g r o u p s HC a n d HL-H may  b e t w e e n - s u b j e c t and w i t h i n s u b j e c t  ( K i r k , 1968).  orthogonal  therefore,  comparisons s e l e c t e d f o r a n a l y s i s .  s e r i e s v a r i a b l e u s i n g Tukey's p r o c e d u r e .  f i c a n c e was e v a l u a t e d  reliability  from a c o n t r a s t not i n c l u d e d i n the  t h i s , means f o r g r o u p s HC a n d HL-H w e r e c o m p a r e d  t r a s t s pooled  between-  None o f t h e  I t was l i k e l y ,  o f t h e means s u g g e s t e d t h a t d i f f e r e n c e s b e t w e e n been p a r t i a l l y  a pooled  and s t a t i s t i c a l  o f 1.99.  (3) LC and  reliable.  between  Evaluation of this  possibil-  t e s t i n d i c a t e d . t h a t t h i s was n o t t h e c a s e s i n c e t h e o b t a i n e d  f o rthis  c o m p a r i s o n ( 1.61) f a i l e d  r e j e c t i o n of the n u l l  hypothesis.  to exceed the c r i t i c a l  value  108  Figure 3: 2, Mean intensity of current at the point where subjects terminated each shock series (pain tolerance) during Session 2 for a l l groups.  109 Results o f pain tolerance analyses between group d i f f e r e n c e s were o b t a i n e d groups.  may be summarized  as f o l l o w s .  No  f o r any o f the low p a i n t h r e s h o l d  Among h i g h p a i n t h r e s h o l d groups, the only s i g n i f i c a n t  effect  appeared to d e r i v e from s u b j e c t s i n group HL-H e x h i b i t i n g a p r o g r e s s i v e decline i n pain tolerance values session.  over the 4 shock s e r i e s o f the i n f l u e n c e  T h i s r e s u l t e d i n the mean p a i n t h r e s h o l d v a l u e  being s i g n i f i c a n t l y shock s e r i e s .  f o r group HL-L  lower than t h a t f o r s u b j e c t s i n group HC a t the l e a s t  However, s u b j e c t s i n group HL-H c o u l d not be d i f f e r e n t i a t e d  from s u b j e c t s i n group HH on t h e i r p a i n t o l e r a n c e v a l u e s .  Thus there was  evidence t h a t exposure to s u b j e c t s h a v i n g a low-preassessment  threshold  r e s u l t e d i n a decrease i n p a i n t o l e r a n c e f o r s u b j e c t s e x h i b i t i n g high pain threshold values.  initially  The e f f e c t , however, was not p a r t i c u l a r l y  s t r o n g , i n t h a t i t c o u l d only be observed d u r i n g the l a s t shock s e r i e s .  110 DISCUSSION  The  major impact o f the e x p e r i m e n t a l group p a i r i n g s was e v i d e n t  on the  p a i n t h r e s h o l d measure t h a t the groups were o r i g i n a l l y d i f f e r e n t i a t e d on. Low t h r e s h o l d s u b j e c t s l e v e l s to increase,  e x h i b i t e d a general  regardless  they were p a i r e d w i t h ,  tendency f o r t h e i r p a i n  threshold  o f the t h r e s h o l d l e v e l o f the s u b j e c t  that  o r whether, i n f a c t , they had a companion a t a l l .  High t h r e s h o l d s u b j e c t s , however, e x h i b i t e d d i f f e r e n t i a l changes depending on group assignment.  When s u b j e c t s w i t h h i g h p r e t e s t t h r e s h o l d s  were run  i n d i v i d u a l l y , o r w i t h a companion who a l s o e x h i b i t e d a h i g h p r e t e s t hold,  their pain threshold levels  remained s t a b l e .  not be d i f f e r e n t i a t e d from each other s e s s i o n 2.  However, when a s u b j e c t  p a r t i c i p a t e d concurrently high  subjects  hold values. creases  e x h i b i t i n g a high pretest pain  w i t h a s u b j e c t h a v i n g a low p r e t e s t reductions  Low p r e t e s t p a i n t h r e s h o l d s u b j e c t s levels.  f o r t h i s change.  exposed t o a h i g h  c a l l y responsible The  during  threshold  threshold,  i n t h e i r pain  thres-  i n t h i s group showed i n -  to increase  represents  strong  t h r e s h o l d companion was n o t r e s p o n s i b l e  C o n v e r s e l y , t h e d i f f e r e n t i a l p a t t e r n o f change among h i g h  pretest threshold subjects provides threshold subjects  could  However, the tendency f o r p a i n t h r e s h o l d s  o f a l l s u b j e c t s h a v i n g a low p r e t e s t t h r e s h o l d evidence t h a t b e i n g  These two groups  i n terms o f p a i n t h r e s h o l d l e v e l s  showed marked and s i g n i f i c a n t  i n pain threshold  thres-  s t r o n g e v i d e n c e t h a t exposure o f h i g h  t o the b e h a v i o u r o f low t h r e s h o l d s u b j e c t s was s p e c i f i f o r the t h r e s h o l d  reduction  observed among h i g h  subjects.  o v e r a l l outcome o f t h i s study was n o t c o n s i s t e n t w i t h the h y p o t h e s i s  of r e c i p r o c a l i n f l u e n c e .  Rather, s o c i a l i n f l u e n c e i n t h i s s e t t i n g seemed  q u i t e c l e a r l y t o be u n i d i r e c t i o n a l . threshold subjects  Low t h r e s h o l d  subjects  influenced  t o r e p o r t p a i n sooner than, i t seems, they  high  ordinarily  Ill  would have. had  no  The  behaviour  of h i g h  d e m o n s t r a b l e i m p a c t on  s u l t s of the  fact  c o n s i d e r a b l y w e a k e r and  subjects to high  troublesome, e s p e c i a l l y  and  Ritter,  M e n l o v e , 1968;  Geer and  B a n d u r a , G r u s e c and  discrepancy  d i f f e r e n t ways.  F o r one,  t h r e s h o l d s u b j e c t s was. simply  a high  The  t h r e s h o l d s u b j e c t and  among l o w  process  may  t h a n any  be  explanation h i g h l i g h t s another issue. subjects exhibited a general  threshold  so  groups to the  W h i l e many p r e v i o u s tively  not  as  same l e v e l  haviours  Wright,  1974;  general  a c t i v a t e d by  effect  of the  f o r the  e l a b o r a t e d below. In s p i t e of the  differento  change exposure  latter.  general  fact that  increment  of the  treatments  are s u f f i c i e n t l y powerful  approach normative l e v e l s .  groups. effec-  always c l e a r that  t h a t the  T h u s , m o d e l i n g may  of  low-  s t u d i e s have demonstrated t h a t modeling treatments i t i s not  this  low-threshold  the magnitude  o f the h i g h - t h r e s h o l d  be  to  Some  While p l a u s i b l e ,  t o e l e v a t e t h e mean o f any  reduce a v e r s i v e l y - m o t i v a t e d behavior,  e f f e c t of the  process  responsible  as any  and  i n c r e m e n t among a l l l o w -  increment i n pain thresholds  great  and  Bandura  subjects exposed  responsible for this  the p r o c e s s ( e s )  of  (Bandura,  to emphasize t h a t w h i l e a  h a v e m a s k e d any  threshold subjects w i l l  i n c r e m e n t was  demonstrated i s  a c c o u n t e d f o r i n a number o f  observed, a general  h a v e b e e n more p o w e r f u l  speculations regarding  not  from exposure  M e n l o v e , 1967;  i n c r e m e n t i n p a i n t h r e s h o l d among l o w - t h r e s h o l d not  regard;  cut.  Bandura, J e f f r e y  m i g h t be  i t i s important  h i g h - t h r e s h o l d s u b j e c t s was  Re-  consistently-reported efficacy  T u r t l e t a u b , 1967;  This  this  less clear  r e d u c t i o n of avoidance behaviour  1969;  Rachman, 1 9 7 2 ) .  may  hand,  threshold subjects.  t h r e s h o l d s u b j e c t s was  i n l i g h t of the  modeling procedures i n the  tial  of low  that a c l e a r pain-threshold increment r e s u l t i n g  of low-threshold  Blanchard  the behaviour  the other  a n a l y s i s of p a i n t o l e r a n c e data were c o n s i s t e n t i n t h i s  h o w e v e r , t h e e f f e c t was The  t h r e s h o l d s u b j e c t s , on  subjects' effective  bein  the  112 reducing  avoidance b e h a v i o u r s , but  The  plausibility  of the  the  eliminate  of the  of the  of the  relative  outcome o f  remarkably powerful i n f l u e n c e of groups of s u b j e c t s .  p r e s e n t study s e l e c t e d groups were employed p o i n t s  explanation  them.  The  may  have u n c h a r a c t e r i s t i c a l l y s t a b l e response s t y l e s t h a t  discussing trait  concepts pointed  situational specifity  r e a c t i v e to noxious  and  notably  those characterized s t y l e s are  of such concepts.  pain threshold Yet from the  relatively  into question  general  present  subjects,  rather  Thus, b e h a v i o u r of " h i g h s "  adopted a f i x e d r o l e been employed.  seems t o m a t c h t h e  d a t a m o s t c l o s e l y , and  cases,  the n o t i o n  that  This may  have  e x h i b i t i n g normative  finding springs  tolerance.  directly  c l e a r l y a more  High threshold r a p i d l y came t o  subjects, approxi-  became l e s s d i s c r e p a n t  the b e h a v i o u r of " l o w s " than i t would have been had, m o d e l who  general  thresholds  r e l a t i v e l y p a i n - i n t o l e r a n t b e h a v i o u r was  mate t h e i r b e h a v i o u r .  the  and  study.  f o r the  powerful source of i n f l u e n c e than r e l a t i v e  capable  (1973) i n  ( M i s c h e l , 1973).  a midrange group, comprised of s u b j e c t s  exposed to low-threshold  are  demonstrable p l a s t i c i t y  suggests t h a t enhanced p a i n  l e v e l s , been i n c l u d e d i n the  fact that  stimulation  However i n c e r t a i n extreme  s t a b l e and  another possible explanation  upon b e i n g  the  Mischel  as p a t h o l o g i c a l , e v i d e n c e f a v o r s  extreme-case s t a b i l i t y notion been o b s e r v e d had  that  o f human b e h a v i o u r c a l l s  utility  behavioral  validity  out  in  threshold  I n d i v i d u a l s who  o f e x h i b i t i n g change w i t h i n r e l a t i v e l y n a r r o w bounds.  exposure  to another p o t e n t i a l  i n e f f e c t i v e n e s s of exposure to high are p a r t i c u l a r l y  studies  fact that  subjects. simply  the  repeated demonstration i n previous  t o a t o l e r a n t m o d e l among u n s e l e c t e d the  not  "masking" e x p l a n a t i o n  p r e s e n t s t u d y i s u n d e r m i n e d by o f m o d e l i n g e f f e c t s on p a i n  i t may  This  from  f o r example, a t o l e r a n t r e l a t i v e power a c c o u n t  i s therefore  favorable.  113 The values  problem of accounting  among a l l l o w - t h r e s h o l d  differential low  f o r the  groups s t i l l  anxiety-reduction hypothesis  threshold subjects  Session  1.  effects  of anxiety  reducing  general  experienced  increment i n pain  remains.  c o u l d be  less anxiety  As  one  possibility,  advanced, suggesting  during  Session  2 than  A l a r g e number o f s t u d i e s h a v e documented the p a i n and  the n o t i o n  a  that during  enhancing  t h a t a n x i e t y - r e d u c t i o n m e d i a t e s many p a i n -  i n t e r v e n t i o n s i s w e l l i n g r a i n e d i n the  J o h n s o n , 1973;  Johnson & L e v e n t h a l ,  Kellett,  S t e r n b a c h , 1968,  1972;  threshold  1973;  1974).  literature  (Averill,  M a r t i n e z - U r r u t i a , 1975;  1973;  Staub  H o w e v e r , s u c h an h y p o t h e s i s  &  seems  cumbersome. Alternatively, cal  a p p e a l can  be  (1975) a c c o u n t o f the  f a c t o r s involved i n fear-reduction techniques.  formulation  suggesting  of techniques situation.  that  effective The  subjects  seems p o s s i b l e t h a t crease  i n pain  t h i s simple  at the  2.  Since  wide:variety  exposure t o the  feared  the b e n e f i t of p r i o r for Session  ex-  2.  It  have accounted f o r the i n subjects  upper extreme of the  a  pain  h a v e b e e n e l i m i n a t e d due  i n the h i g h  threshold to the  threshold  distribution,  operation  of  a  effect.  concurrently with their pain  another high  threshold levels.  findings i n that  explanation not  had  p r e - e x p o s u r e may  i n Session  H i g h t h r e s h o l d s u b j e c t s who  positive  study  criti-  provided  v a r i a b l e common t o t h e  s i t u a t i o n when t h e y r e t u r n e d  s u c h an e x p o s u r e e f f e c t may ceiling  critical  i n the present  thresholds  groups were a l r e a d y  the  Marks has  for fear-reduction i s simple  posure to the e x p e r i m e n t a l  did  made t o M a r k s '  for other  e x h i b i t an  p a r t i c i p a t e d alone i n the  second s e s s i o n  t h r e s h o l d s u b j e c t , e x h i b i t e d no I t i s important  they r u l e out  f i n d i n g s i n the  elevation i n pain  study.  changes i n  to note that these are, i n  regression The  t o w a r d t h e mean as fact  that high-high  threshold or tolerance  or  is likely  fact,  an pairs attri-  114 butable  to a c e i l i n g  The  present  l e a s t two  effect.  f i n d i n g s have s i g n i f i c a n t  respects.  First,  they  t h e o r e t i c a l i m p l i c a t i o n s i n at  extend the  g e n e r a l i t y of previous  t i o n s o f s o c i a l m o d e l i n g i n f l u e n c e s on p a i n b e h a v i o u r occurring v a r i a t i o n s i n pain behaviour i n f l u e n c e over the p a i n behaviour  t h e p r e s e n c e o f an e f f e c t ,  were s u f f i c i e n t l y  artificial  s o c i a l i n f l u e n c e processes pain behaviour  s t u d i e s was  s i g n i f i c a n t sources  the  required i n order  applicability  of the  to speculate  the behaviour  that s i m i l a r processes  f i n d i n g s to  \  "  ./s  :  ',-. f i n d i n g of a d i f f e r e n t i a l t o l e r a n t behaviour  impact of r e l a t i v e l y pain i n t o l e r a n t support  for  role i n  the  of r e l a t i v e  i n t o l e r a n c e f o r p a i n i n the n a t u r a l environment,  and  Fordyce, 1976b).  This  that modeling v a r i a b l e s are  provides  particular  f e r e n t i a l l y powerful  critical The  finding  a l s o r a i s e s the  pain tolerance values  reported high  study  o f t h e p a i n t o l e r a n c e a n a l y s i s was  speculations  that i n t o l e r a n t behaviour  i n t e r e s t i n g prospect ( c f . H i n d e and  deviant is  identical  ( P r i c e and  dif-  that modeling,  Stevenson-Hinde,  c o r r e l a t i o n between p a i n t h r e s h o l d  using v i r t u a l l y  employed i n the present  1975,  agents i n the e t i o l o g y of other  forms of l e a r n i n g , i s c o n s t r a i n e d In s p i t e of the  (Craig,  finding i s also consistent with  forms of a v o i d a n c e b e h a v i o r .  those  procedures  might 'operate. i n  q u i t e possibly^ i n the o r i g i n of p a t h o l o g i c a l pain behaviour  other  t o demon-  of o t h e r s , ' i t  speculations that s o c i a l modeling influences play a s i g n i f i c a n t  1978,  the  i n the n a t u r a l environment. Since n a t u r a l l y - o c c u r r i n g  -  upon r e l a t i v e l y  generation  of  c o n t r o l over  i t c o u l d have been argued t h a t the  to question  natural settings. Second, the  showing t h a t n a t u r a l l y -  While rigorous  had' a " s i g n i f i c a n t i n f l u e n c e ' o n  seems r e a s o n a b l e  behavior  provide  of others.  r o l e s e n a c t e d by models i n p r e v i o u s strate  can  by  demonstra-  s t i m u l a t i o n techniques Tursky, 1975), the  n o t n e a r l y as i m p r e s s i v e  as  the  like 1973).  and to  outcome outcome  of  115 the  pain  hold  threshold  subjects  jects,  this  analysis.  High threshold  e x h i b i t e d reduced pain  d i f f e r e n c e was o n l y  While t h i s  threshold  a n a l y s i s , and suggests t h a t  are  generalizable  tolerance  evident  session.  subjects  tolerance,  relative  to high  on t h e l a s t t r i a l  finding i s consistent with  to pain  exposed to low t h r e s c o n t r o l sub-  of the influence  t h e outcome o f t h e p a i n  the conclusions  derived  from the l a t t e r  t h e e f f e c t was e v i d e n t l y q u i t e weak.  Two p o i n t s m u s t b e t a k e n i n t o a c c o u n t i n r e l a t i o n t o t h i s p r o b l e m . while and  P r i c e and T u r s k y  tolerance  (1975) r e p o r t e d  a strong  r e l a t i o n s h i p between  measures, t h e r e l a t i o n s h i p was, o f c o u r s e , n o t p e r f e c t .  might be e x p e c t e d t h a t  the e r r o r involved  threshold It  i n t h e r e l a t i o n s h i p m i g h t be magni-  f i e d when v a r i a b l e s a r e m a n i p u l a t e d i n o r d e r the measures.  First,  to investigate modulation of  Second measures o f t h e s t r e n g t h  of a r e l a t i o n s h i p tend t o  t a k e on l o w e r v a l u e s  when e x t r e m e g r o u p s a r e e m p l o y e d , a s i n t h e p r e s e n t  It i s possible, that  t h e o b s e r v e d outcome r e f l e c t s ,  of extreme  groups.  study.  i n some way, t h e e m p l o y m e n t  116  GENERAL DISCUSSION  The  f o r e g o i n g s t u d i e s have attempted  responses  t o p a i n t h a t may  be  t o map  more b r o a d l y t h e v a r i e t y  a l t e r e d as a f u n c t i o n o f s o c i a l m o d e l i n g  f l u e n c e s , and  to extend  k n o w l e d g e and  theory of s o c i a l i n f l u e n c e processes.  evidence  supportive of previous  model enhances sensory suggesting to  the g e n e r a l i t y of accounts  that previous  ent v a r i a b l e — evidence  was  alterations  restricted.  suggesting that s o c i a l  i n behaviour  intolerant  was  a novel  i n v e s t i g a t e d , and  i n f l u e n c e s are  that are c r i t i c a l  capable  social discriminative  Experiment 3 demonstrated that modeling  effects  j e c t s e x h i b i t i n g p r e d i s p o s i t i o n s toward  p a r t i c u l a r k i n d s of p a i n  are observable  r a t h e r t h a n p r o g r a m m e d c o n f e d e r a t e s , a r e e m p l o y e d as m o d e l s . appeared t h a t i n the impact i n f l u e n c e , r a t h e r than b e i n g ant behaviour studies,  was  r e c i p r o c a l , was  c o n s i d e r a b l y more p o w e r f u l  than  Experimental p a s t decade.  p a i n r e s e a r c h has  In the process  e m e r g e d t h a t c a n be  of t h i s expansion,  d i f f e r e n t i a t e d on  of dependent v a r i a b l e  s u b j e c t s t e n d t o be  experienced  provocative of  producing  stimuli.  e v e n when s u b behaviour,  Further, i t  and  that  intolerThe events  Simultaneously,  the  further discussion.  an e n o r m o u s g r o w t h w i t h i n t h e two  groups o f r e s e a r c h e r s have  Researchers  i n t e r e s t e d i n the anatomical  depend-  claim that s o c i a l  the b a s i s of the types  they employ.  exposure  tolerant behaviour.  of pain.  a number o f i s s u e s t h a t w a r r a n t  time  styles, interpersonal  unidirectional,  i m p l i c a t e d i n fundamental aspects  studies highlight  the type  of c o n f l i c t i n g response  t a k e n as a w h o l e , g i v e a d d e d i m p e t u s t o t h e  are c r i t i c a l l y  social  e f f e c t s of  I n E x p e r i m e n t 2,  on  provided  t o p a i n f u l s t i m u l i , w h i l e a t t h e same  overt expression of pain —  found  Experiment 1  c o n c l u s i o n s r e g a r d i n g the sensory  a t o l e r a n t m o d e l n e e d t o be  in-  o f p a i n phenomena b a s e d  c l a i m s t h a t e x p o s u r e t o an  sensitivity  of  who  of s u b j e c t  and  e m p l o y nonhuman  s t r u c t u r e s and  physiological  117 processes  subserving  p a i n , and  behaviour  of the organism.  R e s e a r c h e r s who  w i d e r range of i n f l u e n c e s , but fluences  on p a i n .  they  tend  t o be  the  B o t h g r o u p s make e q u i v a l e n t  The  claims  The  technique  s t u d i e s and  appears to o f f e r a great  modulation  procedures.  Another important  can  s e r i e s was  r e a d i l y be  c l i n i c i a n who  overwhelming degree of r e s p e c t  p a i n been reduced?"  a d a p t e d t o most  ployed  complicated  sensory  and  m o d u l a t i o n s u g g e s t e d t h a t e x p o s u r e t o an source  of i n f l u e n c e .  of expressive behaviour  At  answer t o the q u e s t i o n ,  as a s o u r c e  s u g g e s t e d t h a t an  data  be-  does  "Has that  of i n f o r m a t i o n about  i n t o l e r a n t m o d e l was  t h e same t i m e ,  The  (1977) c a r i c a t u r e o f  s e r i e s of i n v e s t i g a t i o n s , those  the subject's v e r b a l behaviour  powerful  pain  s t u d i e s i s t h a t of the i n -  f o r Rollman's  definitive  In the present  of  d i f f e r e n t measures o f p a i n .  of exceedingly  wishes a simple  and  unusual  h a v i o u r a l phenomena t h a t d e f y o v e r s i m p l i f i e d i n t e r p r e t a t i o n s . N a t u r e  the  their  b a s e d upon o b s e r v a t i o n s  the present  c o n s i s t e n t i n t e r r e l a t i o n s h i p s e x h i b i t e d by  show an  a  d e a l of promise f o r e v a l u a t i n g p a i n -  i s s u e r a i s e d by  w o r d " p a i n " subsumes a d i v e r s i t y  regarding  u n d e r l y i n g pain responses  second experiment i n the present  overt behaviour.  not  overt  i n t e r e s t e d i n exogenous i n -  among s t u d i e s o f p a i n i n humans i n t h a t i t was subjects'  on  e m p l o y human s u b j e c t s e x a m i n e  t o draw i n f e r e n c e s about the p r o c e s s e s  pain modulation.  conclusions  T h e i r dependent v a r i a b l e s a r e almost e x c l u s i v e l y d e r i v e d  from s u b j e c t s ' r e p o r t s . ability  n a t u r a l l y base t h e i r  a  em-  pain  particularly  derived from  observations  impact of g r e a t e r magnitude  was  a s s o c i a t e d w i t h exposure to a t o l e r a n t model. An  important,  related question  p o r t concerns the n a t u r e behaviour  and  the  sensory  of the  r a i s e d by  the d a t a p r e s e n t e d  re-  r e l a t i o n s h i p between t h e o b s e r v e d changes i n  e v e n t s t h a t c o n t r i b u t e t o them.  tion that vocal reports provide,  in this  under a p p r o p r i a t e  The  common a s s u m p -  circumstances,  fairly  direct  118  access to p r i v a t e experiences i s apparent t h e r e a s o n s why  vocal behaviour  i n much p a i n r e s e a r c h .  However,  s h o u l d p r o v i d e any more a d e q u a t e a c c e s s  such e x p e r i e n c e s than o t h e r types of b e h a v i o u r are not apparent. to  be no p a r t i c u l a r  reason t h a t ,  be  assumed t o p r o v i d e e q u a l l y a d e q u a t e a c c e s s  comes o f E x p e r i m e n t s evidence based  1 and  of for  2,  a number o f r e a s o n s  t o l e r a n t m o d e l i n g was sensitivity  is difficult  that are presumably  ted  toward  al..  out-  the  examining and  impact  on s e n s i t i v i t y .  to the s t i m u l a t i o n .  to accept mediated  While  by  modeling  2 was  indicative  that of  Which source of i n f o r m a t i o n —  vocal  p r o v i d e s the most a p p r o p r i a t e b a s i s f o r sensitivity?  the n o t i o n t h a t data from d i f f e r e n t s i m i l a r processes  relationships  Lately,  c a n u n d e r many  some I n t e r e s t h a s  measures  circumstances been  direc-  among p r i v a t e e x p e r i e n c e s , e x p r e s s i v e  p h y s i o l o g i c a l processes an a c c o u n t ,  and  ( C r a i g & P r k a c h i n , 1978") - K l e c k  a n d m a r s h a l l e d some s u p p o r t i v e e v i -  d e n c e s u g g e s t i n g t h a t p r i v a t e e x p e r i e n c e s , o f p a i n may i n expressive behaviour.  In  quite different conclusions.  associated with expressive behaviour  (1976) h a v e p r o p o s e d  provided evidence  stimulation, while  the i m p l i c a t i o n of Experiment  a l a c k of correspondence.  vocal behaviour et.  1,  i n f e r e n c e s about the i n f l u e n c e of i n t o l e r a n t  i n f e r e n c e s about sensory  e x h i b i t such  f o r the  In Experiment  to p a i n f u l  apparent  1 provoked  report or e x p r e s s i v e behaviour —  It  These  on o b s e r v a t i o n o f t h e e x p r e s s i v e b e h a v i o u r  present i n t e r p r e t i v e d i f f i c u l t i e s ,  drawing  i n attempting to account  sensitivity  the evidence, based  the s u b j e c t s i n Experiment  reduced  not  on s u b j e c t s ' v o c a l r e p o r t s , i n d i c a t e d t h a t e x p o s u r e ^ t o a n i n -  t o a t o l e r a n t m o d e l h a d no  Experiment  can  to p r i v a t e experiences.  2 i n the p r e s e n t s e r i e s .  t o l e r a n t model i n c r e a s e d sensory exposure  T h e r e seems  f o r example, e x p r e s s i v e behaviour  questions are of s u b s t a n t i a l importance  to  be m e d i a t e d  S i m i l a r l y , B a n d l e r , M a d a r a s , and  t h a t p a i n p e r c e p t i o n may  largely  reflect  by  changes  Bern ( 1 9 6 8 ) h a v e the o p e r a t i o n of  119 processes specific  that f i r s t details  to speculate  affect  the i n d i v i d u a l ' s overt behaviour.  o f t h e i r model n e e d n o t be a d h e r e d t o , i t i s i n t e r e s t i n g  that s o c i a l influence procedures exert  m o s t i m m e d i a t e i m p a c t on o v e r t experiences gest  may f o l l o w t h e s e  s o c i a l behaviour  primary  their  fundamental and  and t h a t changes i n s e n s o r y  c h a n g e s a t some d e l a y .  This would  sug-  t h a t t h e t e m p o r a l c o n s t r a i n t s i n v o l v e d i n Experiment 1 and p r e v i o u s  analyses  o f m o d e l i n g e f f e c t s on p a i n , p r o v i d e d  observe the u l t i m a t e sensory while  effects  are quite l i k e l y  cumulative  remediation  The  (Fordyce,  pro-  programs f o r periods  operative i n  1976b).  i s a l s o c o n s i s t e n t w i t h some o f S k i n n e r ' s  p l a i n how e n v i r o n m e n t a l  forthis  over extended  of contingencies  the n a t u r a l f a m i l i a l environments o f p a t i e n t s  experiences  Other support  o f chronic p a i n problems which operate  This proposal  socialization  of behaviourally-based  and emphasize l o n g term a l t e r a t i o n  proposal  o v e r a l o n g t e r m , and t h e i r  over time.  from the apparent success  SDT  opportunity to  This  makes s e n s e i n t h a t n a t u r a l  i m p l i c a t e d i n pain modulation operate  posal derives  of time,  an i n s u f f i c i e n t  effects of social influences.  l a c k i n g e m p i r i c a l support,  processes  the  While the  attempts to ex-  e v e n t s c a n come t o e x e r t a n i n f l u e n c e u p o n p r i v a t e  ( S k i n n e r , 1945; 1957).  l a c k o f a s i g n i f i c a n t p a i n t h r e s h o l d d e c r e m e n t among s u b j e c t s  exposed  t o an i n t o l e r a n t model i n E x p e r i m e n t 1 m i g h t be a c c o u n t e d f o r b y r e f e r e n c e t o t h e o u t c o m e o f E x p e r i m e n t 3. thresholds  Both experiments i n v o l v e d assessment o f p a i n  i n a p r e t e s t and an i n f l u e n c e s e s s i o n , and i n E x p e r i m e n t  observed that subjects e x h i b i t i n g n a t u r a l l y low pain thresholds r e a s s e s s m e n t t o show a n e l e v a t i o n i n t h r e s h o l d s . unselected  3 i t was  t e n d e d , upon  While Experiment 1 employed  groups, i ti s p o s s i b l e t h a t a s i g n i f i c a n t p r o p o r t i o n of s u b j e c t s  i n t h e i n t o l e r a n t g r o u p may h a v e e x h i b i t e d t h e same t e n d e n c y a s t h a t among l o w t h r e s h o l d s u b j e c t s i n E x p e r i m e n t 3.  This  outcome w o u l d , o f  observed course,  120  have masked any m o d u l a t i n g e f f e c t s T h i s o u t c o m e among i n t o l e r a n t  attributable  to the intolerant  group s u b j e c t s i n Experiment  modeling.  1 may h a v e b e e n  a by product o f the use o f a repeated s e s s i o n s procedure. A f i n a l p o i n t i s i n order concerning the apparent 3.  While  unidirectionality  of  i n f l u e n c e i n Experiment  of  t h e e x p e r i m e n t a l p r o c e d u r e s , r e l a t i v e p a i n i n t o l e r a n c e was t h e more p o w e r -  f u l source of i n f l u e n c e , i t i s l i k e l y  i t was c l e a r t h a t , w i t h i n t h e c o n s t r a i n t s  that an exact analog o f n a t u r a l l y -  o c c u r r i n g s o c i a l i n f l u e n c e p r o c e s s e s was n o t c r e a t e d . communications t o the e f f e c t tive social stimuli.  T h e i r e f f e c t s on t h e b e h a v i o r o f o t h e r s q u i t e  on t h e o t h e r h a n d , i s l i k e l y t h i s experiment,  Relatively  t h e n , may r e f l e c t  reasonably  behaviour, The o u t c o m e  t e m p o r a l c o n s t r a i n t s on t h e i n t e r p e r -  t h e n , t o s p e c u l a t e t h a t a more e x t e n d e d  I t i s not unreasonable,  p e r i o d o f concurrent exposure  another of s u b j e c t s e x h i b i t i n g c o n f l i c t i n g response s t r a t e d a g r e a t e r degree o f i n f l u e n c e r e s u l t i n g behaviour.  tolerant  t o b e more d e l a y e d i n i t s i m p a c t .  s o n a l e f f e c t s o f t o l e r a n t and i n t o l e r a n t b e h a v i o u r .  pain tolerant  earlier,  that p a i n i s being experienced represent impera-  w o u l d be e x p e c t e d t o be r a p i d and p o w e r f u l .  of  A s was n o t e d  t o one  s t y l e s m i g h t h a v e demon-  from exposure  to relatively  121  REFERENCE NOTES  1. 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Psychological Bulletin,  San F r a n c i s c o :  leak-  St. Louis:  1977, 84,  J o s s e y - B a s s , 1969.  130  A p p e n d i x A:  This  appendix presents  administered and  analyses  The  was  (197'2) t a b l e , a n d p r e - and  t o emerge f r o m t h i s  MPQ  was  t h a t c o n t a i n s 20 o f p a i n , and  and  presented  a f t e r each s e s s i o n i n Study  i n t o a 3 (Groups) X 2 The  administered two  Thus, s u b j e c t s r e p o r t e d lower  a t t h e end  components:  they  M e l z a c k and  as  ( 1 9 7 1 ) and  a n a l y s i s o f t h e MPQ  Melzack  1.  respondent  scale ranging  the h i g h e s t  to each  question. subdivid-  termed Sensory, A f f e c -  C r a i g (1977) c o n d u c t e d a f a c t o r  They e x t r a c t e d 5 f a c t o r s f r o m  ( I ) Immediate A n x i e t y ,  from  current  a d j e c t i v e s i n g r o u p s o f l o w b a c k p a i n p a t i e n t s and pain.  1.  qualities  (1975) have r a t i o n a l l y  3 dimensions:  C r o c k e t t , P r k a c h i n , and  t e e r s exposed to experimental a n a l y s i s , named:  a 5-point  f o r responding  adjective checklist portion into Evaluative.  of  (1) a n a d j e c t i v e c h e c k l i s t p o r t i o n  o f h i s o r h e r p a i n on  their reference  1  levels  of each s e s s i o n i n Experiment  S u b j e c t s were i n s t r u c t e d t o use  Torgerson  effect  did during Session  (2) a P a i n I n t e n s i t y R a t i n g p o r t i o n t h a t r e q u i r e s t h e  accepted  2  during Session  c a t e g o r i e s of 2 to 6 words d e s c r i p t i v e of v a r i o u s  mild to excruciating.  1.  and  (Sessions) X  only s i g n i f i c a n t  d e c l i n e d f r o m a mean o f 1.14  s t r e s s d u r i n g Session 2 than  to i n d i c a t e the i n t e n s i t y  t i v e , and  These q u e s t i o n n a i r e s are  (SSS),  t h a t f o r S e s s i o n s , _F ( 1 , 3 2 ) = 1 5 . 4 5 , p_ <  d u r i n g S e s s i o n 2.  T h i s q u e s t i o n n a i r e has  the  the S u b j e c t i v e S t r e s s Scale  p o s t ) ANOVA d e s i g n .  a n a l y s i s was  subjectively appraised  they had  entered  scale-score values  t o a mean o f 0.62  The  (MPQ).  questionnaires  f o r each a d m i n i s t r a t i o n were determined from N e u f e l d  (Administrations:  SSS  1.  o f d a t a d e r i v e d f r o m two  administered both before  Scale score values  .01.  from Experiment  C.  SSS  Davidson's  data  t o s u b j e c t s i n E x p e r i m e n t 1:  the M c G i l l P a i n Q u e s t i o n n a i r e  i n Appendix  ed  Psychometric  volun-  their  ( I I ) P e r c e p t i o n o f Harm, ( I I I ) Somes-  131 thetic Pressure, Analyses rank  scores  ( I V ) Cutaneous. , S e n s i t i v i t y ,  were conducted  f o r Melzack's  a n d (V) S e n s o r y  Information.  on t h e s c a l e v a l u e o f t h e P a i n I n t e n s i t y  rationally-defined  dimensions,  for Crockett et. al.'s empirically-derivedfactors.  and f a c t o r  A l l analyses  Rating,  scores  used a 3  ( G r o u p s ) X 2 ( S e s s i o n ) ANOVA. d e s i g n . No s i g n i f i c a n t  d i f f e r e n c e s emerged on P a i n I n t e n s i t y  of the r a t i o n a l l y - d e r i v e d sory and A f f e c t i v e  f a c t o r s r e v e a l e d no s i g n i f i c a n t  dimensions.  ratings.  a f f e c t s on t h e Sen-  On t h e E v a l u a t i v e d i m e n s i o n ,  S e s s i o n s e f f e c t e m e r g e d , F_ ( 1 , 3 2 ) = 1 0 . 6 3 , p  < .01.  Analyses  a significant  The mean r a n k  t h i s m e a s u r e i n c r e a s e d f r o m 1.06 i n S e s s i o n 1 t o 1.89 i n S e s s i o n 2. to Melzack  and Torgerson  (19 7 1 , p . 5 1 ) t h i s d i m e n s i o n  subjective o v e r a l l experience unreasonable  of the t o t a l experience  s c o r e on According  i s descriptive "of the of pain."  I t i s not  t h a t t h i s m e a s u r e s h o u l d h a v e i n c r e a s e d i n S e s s i o n 2, s i n c e t h e  s e s s i o n was v e r y l o n g a n d i n v o l v e d e x t e n d e d e x p e r i e n c e w i t h h i g h  intensity  shocks. I n t h e a n a l y s i s o f C r o c k e t t e_t. a l ' s (19 77) effect  occurred  on F a c t o r I I I ( S o m e s t h e t i c  factors a significant  Sessions  P r e s s u r e ) , F_ ( 1 , 3 2 ) = 7.29, p_ < . 0 1 .  F a c t o r s c o r e s i n c r e a s e d f r o m a mean o f 1.36 i n S e s s i o n 1 t o 1.97 i n S e s s i o n 2.  Appendix B:  Consent forms.  133  CONSENT FORM:  EXPERIMENT 1  Experimental P a r t i c i p a t i o n Consent Form Name of the Subject:  I hereby consent to p a r t i c i p a t e i n the study as described by to me a t t h i s time.  I  understand that the r i s k s to me as a subject are minimal. I f u r t h e r acknowledge that I have been advised that I can withdraw from p a r t i c i p a t i o n i n the project a t any time. Signature: Date:  Experimental P a r t i c i p a t i o n Consent Form, Name of the Subject: I hereby consent t o p a r t i c i p a t e i n the study as described by to me a t t h i s time.  I  understand that the r i s k s to me as a subject are minimal. I f u r t h e r acknowledge that I have been advised that I can withdraw from p a r t i c i p a t i o n i n the p r o j e c t a t any time. Signature: Date:  134  VIDEOTAPE PLAYBACK CONSENT FORM  I,  , do h e r e b y for  o f m y s e l f d u r i n g my p a r t i c i p a t i o n modeling  g i v e my c o n s e n t t o  t h e showing o f v i d e o t a p e s taken  i n the experiment  entitled,"Social  i n f l u e n c e s on e x p r e s s i v e and p s y c h o p h y s i c a l components o f  pain response," t o : 1. 2. 3.  o t h e r p e o p l e p a r t i c i p a t i n g as s u b j e c t s i n t h e a f o r e m e n t i o n e d experiment, people involved i n the analysis of data c o l l e c t e d during the experiment, p r o f e s s i o n a l audiences i n t h e context of research c o l l o q u i a o r s i m i l a r s c i e n t i f i c purposes.  I u n d e r s t a n d t h a t t h e above t h r e e items a r e a l l t h a t I have given consent  t o , and t h a t , o u t s i d e o f t h e s e c o n s t r a i n t s , t h e  r e c o r d s t a k e n o f me w i l l b e k e p t s t r i c t l y  confidential.  Signature of  participant  Signature of experimenter  Date  135  CONSENT FORM:  EXPERIMENT 3  EXPERIMENTAL P A R T I C I P A T I O N CONSENT FORM  Name o f t h e s u b j e c t : I hereby consent t o p a r t i c i p a t e i n t h e study as d e s c r i b e d ,  t o me a t t h i s  understand that  the risks  I f u r t h e r acknowledge that participation  by  t o me a s a s u b j e c t  s e e n my p h y s i c i a n w i t h i n t h e p a s t  that  I can withdraw  from  I a l s o acknowledge t h a t I have  year. Signature: Date:  I  are minimal.  I have been a d v i s e d  i n t h e p r o j e c t a t any time.  time.  136 Appendix C:  Questionnaires administered in Experiment 1. 1.  Subjective Stress Scale  2.  McGill Pain Questionnaire  137  S U B J E C T I V E STRESS  SCALE  P i c k o n l y one w o r d o f t h e f o l l o w i n g d e s c r i b e s how y o u f e e l a t t h i s  l i s t which  moment.  Wonderful Steady Comfortable Fine Indifferent Didn't  Bother  Timid Unsteady Unsafe Nervous Worried Frightened Panicky Scared  Stiff  Me  best  ,1-38 MCGILL PAIN QUESTIONNAIRE Please answer the following two questions: 1.  What d i d your pain f e e l l i k e when you received the most intense shock?  Some of the words below describe the pain you experienced. C i r c l e ONLY those words that best describe i t . Leave out any category that i s not s u i t a b l e . Use only a single word i n each appropriate category — the one that applied best.  Flickering Quivering Pulsing Throbbing Beating Pounding  Jumping Flashing Shooting  Pricking Boring Drilling Stabbing Lancinating  12  11 Tiring Exhausting  Sickening Suffocating  10  Tingling Itchy Smarting Stinging  Dull Sore Hurting Aching Heavy  Tender Taut Rasping Splitting  13  14  15  Annoying Troublesome Miserable Intense Unbearable  Fearful Frightful Terrifying  18  17  16  2.  Hot Burning Scalding Searing  Spreading Radiating Penetrating Piercing  Pinching Pressing Gnawing Cramping Crushing  9  8 Tugging Pulling Wrenching  Sharp Cutting Lacerating  Tight Numb Drawing Squeezing Tearing  Punishing Gruelling Cruel Vicious Killing  Wretched Blinding  20  19 Cool Cold Freezing  Nagging Nauseating Agonizing Dreadful Torturing  How strong was the most intense pain? The following 5 words represent pain of increasing i n t e n s i t y . 1 Mild  2 Discomforting  3 Distressing  4 Horrible  5 Excruciating  Write the number of the most appropriate word i n the space beside the question. Which word describes the shock at i t s worst?  

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