UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Attention demands of movements of varying complexity Tennant, James Mark 1973

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1973_A7_5 T45_5.pdf [ 4.4MB ]
Metadata
JSON: 831-1.0077323.json
JSON-LD: 831-1.0077323-ld.json
RDF/XML (Pretty): 831-1.0077323-rdf.xml
RDF/JSON: 831-1.0077323-rdf.json
Turtle: 831-1.0077323-turtle.txt
N-Triples: 831-1.0077323-rdf-ntriples.txt
Original Record: 831-1.0077323-source.json
Full Text
831-1.0077323-fulltext.txt
Citation
831-1.0077323.ris

Full Text

THE ATTENTION DEMANDS OF MOVEMENTS OF VARYING COMPLEXITY  BY JAMES MARK TENNANT B.P.E., U n i v e r s i t y o f M a n i t o b a ,  1969  A THESIS SUBMITTED I N PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF PHYSICAL EDUCATION i n the School of P h y s i c a l Education and Recreation  We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e required standard  THE UNIVERSITY OF BRITISH COLUMBIA July,  1973  In p r e s e n t i n g an the  this  thesis in partial  advanced degree at the Library  f u l f i l m e n t of the  U n i v e r s i t y of B r i t i s h Columbia, I agree  s h a l l make I t f r e e l y  a v a i l a b l e f o r r e f e r e n c e and  I f u r t h e r agree t h a t p e r m i s s i o n f o r extensive for  s c h o l a r l y p u r p o s e s may  by h i s r e p r e s e n t a t i v e s .  be  g r a n t e d by  thesis for financial  written  permission.  gain  of  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, C a n a d a  the  Head o f my  Columbia  s h a l l not  be  that  thesis  Department  copying or  for  study.  copying of t h i s  I t i s understood that  of t h i s  Department  requirements  or  publication  allowed without  my  ABSTRACT  The  experiment was d e s i g n e d  t o d i v i d e t h e a t t e n t i o n demands o f a t o t a l  motor r e s p o n s e t i m e i n t o two components, t h e i n i t i a t i o n o f a r e s p o n s e and t h e e x e c u t i o n o f a movement.  The purpose was t o d e t e r m i n e t h e e f f e c t s o f  movement c o m p l e x i t y on t h e r e l a t i v e degree o f a t t e n t i o n r e q u i r e d d u r i n g t h e s e component p r o c e s s e s .  S i x male r i g h t handed S's were t e s t e d i n a  s i t u a t i o n i n v o l v i n g two d i s c r e t e r e a c t i o n s t o two s t i m u l i s e p a r a t e d by a s h o r t t i m e i n t e r v a l . j.The f i r s t s t i m u l u s was a s s o c i a t e d w i t h t h e performance o f a p r i m a r y motor t a s k t h a t was v a r i e d i n c o m p l e x i t y and t h a t was performed w i t h t h e S's r i g h t hand.  The second o r probe s t i m u l u s was a s s o c i a t e d w i t h  a s i m p l e r e a c t i o n t i m e performed w i t h t h e l e f t hand. was p r e s e n t e d  The probe s t i m u l u s  d u r i n g t h e S's performance o f t h e p r i m a r y t a s k and t h e r e a c t i o n  t o t h i s s t i m u l u s was u s e d as an i n d e x o f t h e a t t e n t i o n a l demands o f t h e primaryy  task.  The r e s u l t s o f t h e p r i m a r y t a s k i n d i c a t e t h a t t h e r e a c t i o n t i m e (RT) component o f t h e r e s p o n s e was n o t a f u n c t i o n o f movement c o m p l e x i t y , a l though t h e r e was an apparent d i f f e r e n c e between t h e s i m p l e s t r e s p o n s e and responses o f greater complexity.  Movement c o m p l e x i t y a f f e c t e d t h e movement  t i m e (MT) component o f t h e r e s p o n s e i n t h a t MT i n c r e a s e d as c o m p l e x i t y increased. The  second o r probe r e a c t i o n t i m e (PRT) was d e l a y e d when t h e probe  o c c u r r e d d u r i n g t h e i n i t i a t i o n o f t h e r e s p o n s e and d u r i n g t h e e x e c u t i o n o f the response.  When t h e probe was p r e s e n t e d  during the i n i t i a t i o n of the  r e s p o n s e , t h e PRT was r e l a t e d d i r e c t l y t o t h e RT, and when p r e s e n t e d  during  t h e e x e c u t i o n o f t h e r e s p o n s e , t h e PRT r e l a t e d d i r e c t l y t o MT. seen t o v a r y t h r o u g h o u t  PRT was a l s o  t h e r a n g e o f movement w i t h t h e l o n g e s t PRTs o c c u r r i n g  a t t h e b e g i n n i n g and end o f a movement t e r m i n a t e d a t a t a r g e t . These r e s u l t s p r o v i d e e v i d e n c e f o r a model o f human performance t h a t suggests component p r o c e s s e s o f l i m i t e d c a p a c i t y i n t h a t t h e a t t e n t i o n demands o f i n i t i a t i n g and e x e c u t i n g a motor t a s k t e n d t o v a r y w i t h t a s k comp l e x i t y and p o s i t i o n o f t h e r e s p o n d i n g l i m b i n moving t o a t a r g e t .  Further,  t h e r e s u l t s i n d i c a t e d t h a t i n g e n e r a l RT and MT c a n be u s e d t o a s s e s s t h e a t t e n t i o n demands o f a p a r t i c u l a r motor  ii  response.  TABLE OF CONTENTS  CHAPTER I  PAGE 1  Statement o f t h e problem Introduction  1  Purpose o f t h e S t u d y  3  S i g n i f i c a n c e o f t h e Study  II  .  3  Hypotheses  4  Limitations  4  Delimitations  4  D e f i n i t i o n o f Terms  5  Review o f L i t e r a t u r e  6  A Model o f a Motor Response  6  Time C h a r a c t e r i s t i c s o f Human . . * * - « • 10  Performance Attention Characteristics of  11  Human Performance III  17  Method and P r o c e d u r e s Subjects  17  Apparatus  17  Experimental Conditions  20  Experimental Design  23  A n a l y s i s o f Data  24  RT t o P r i m a r y Task  24  MT t o P r i m a r y Task  24  RT t o Secondary Task (PRT)  25  i n  IV  R e s u l t s and D i s c u s s i o n  26  Results  26  RT - C o n t r o l , Phase I , and Phase I I  26  PRT - Phase I  32  MT - C o n t r o l , Phase I and Phase I I  38  PRT - Phase I I  43  Discussion  49  RT - C o n t r o l , Phase I and Phase I I  49  PRT - Phase I . . . .  52  MT - C o n t r o l , Phase I and Phase I I  53  PRT - Phase I I  54  Comparison o f A t t e n t i o n D u r i n g Phase I and Phase I I  V  56  Summary and C o n c l u s i o n s  58  References  6l  Appendices A.  P i l o t Study  65  B.  I n d i v i d u a l Men S c o r e s  iv  . . . .  67  LIST OF TABLES PAGE I II III IV V  VI VII VIII IX X XI XII  A n a l y s i s o f V a r i a n c e o f C o n t r o l RT  .  A n a l y s i s o f V a r i a n c e o f RT D u r i n g Phase I  26 ...  28  A n a l y s i s o f V a r i a n c e o f RT D u r i n g Phase I I . . .  30  A n a l y s i s o f V a r i a n c e o f RT D u r i n g C o n t r o l , Phase I , and Phase I I  32  A n a l y s i s o f V a r i a n c e o f PRT D u r i n g  Control  and Phase I  33  A n a l y s i s o f V a r i a n c e o f P r t D u r i n g Phase I . . .  35  A n a l y s i s o f V a r i a n c e o f C o n t r o l MT  38  A n a l y s i s o f V a r i a n c e o f Phase I I MT  40  A n a l y s i s o f V a r i a n c e o f Phase I MT  42  A n a l y s i s o f V a r i a n c e o f MT D u r i n g C o n t r o l , Phase I , and Phase I I A n a l y s i s o f V a r i a n c e o f PRT D u r i n g C o n t r o l and Phase I I A n a l y s i s o f V a r i a n c e o f Phase I I PRT  v  43 45 47  LIST OF FIGURES FIGURE 1.  PAGE B e h a v i o r a l model o f t h e human nervous system ( W e l f o r d , 196 5)  6  2.  P o s i t i o n o f subject a t apparatus  18  3.  The a p p a r a t u s  19  4.  Mean RT d u r i n g c o n t r o l , Phase I , and Phase I I as a f u n c t i o n o f movement c o m p l e x i t y  27  5.  Mean phase I RT as a f u n c t i o n o f I S I  29  6.  Mean phase I RT f o r each c o n d i t i o n as a function of I S I Mean phase I PRT as a f u n c t i o n o f movement c o m p l e x i t y and mean c o n t r o l PRT  7. 8.  31 34  Mean PRT d u r i n g phase I f o r a l l c o n d i t i o n s as a f u n c t i o n o f I S I  36  Mean PRT d u r i n g Phase I f o r each c o n d i t i o n as a f u n c t i o n o f I S I and mean c o n t r o l PRT  37  Mean MT d u r i n g c o n t r o l , phase I , , and phase I I as a f u n c t i o n o f movement c o m p l e x i t y  39  11.  Mean phase I I MT as a f u n c t i o n o f I S I  41  12.  Mean phase I I PRT a s a f u n c t i o n o f movement c o m p l e x i t y and mean c o n t r o l PRT  44  13.  Mean phase I I PRT as a f u n c t i o n o f I S I  4°  14.  Mean phase I I PRT f o r each c o n d i t i o n as a f u n c t i o n o f I S I and mean c o n t r o l PRT  48  9. 10.  vi  CHAPTER I STATEMENT OF THE PROBLEM Introduction I n o r d e r t o u n d e r s t a n d motor s k i l l s , models o f human performance have been f o r m u l a t e d t o s p e c i f y t h e component p r o c e s s e s i n t e r v e n i n g between t h e o n s e t o f a s t i m u l u s and t h e t e r m i n a t i o n o f i t s r e s p o n s e . 1969;  F i t t s and P e t e r s o n , 1964;  I t has been shown ( E l l s ,  F i t t s and R a d f o r d , 1966;  Henry, 196l; Henry and  i960) t h a t a complete motor r e s p o n s e i s composed o f a t l e a s t two i n d e -  Rodgers,  pendent components, t h e i n i t i a t i o n o f t h e r e s p o n s e and t h e e x e c u t i o n o f t h e movement.  E a c h o f t h e s e components has been f u r t h e r s u b d i v i d e d i n t o more s p e c i f i c  processes.  Welford  (1965» 19°&) has suggested a model f o r t h e initiafciony6f>,a  r e s p o n s e c o n s i s t i n g o f t h r e e c e n t r a l mechanisms:  a p e r c e p t u a l mechanism w h i c h  p e r c e i v e s and encodes s t i m u l i from t h e environment; a d e c i s i o n mechanism w h i c h d e s i g n a t e s t h e a p p r o p r i a t e r e s p o n s e and t h e n r e t r i e v e s t h e motor program t o g o v e r n t h e motor b e h a v i o r from a motor memory; and an e f f e c t o r mechanism w h i c h c o n t r o l s the response.  Keele  by means o f t h r e e p r o c e s s e s :  (1968) has suggested t h a t movement i s c o n t r o l l e d a motor program; k i n e s t h e t i c f e e d b a c k ; and,  v i s u a l feedback. A c h a r a c t e r i s t i c o f t h e human organism i s t h a t t h e r e always i s a f i n i t e p e r i o d o f t i m e between t h e p r e s e n t a t i o n o f a s t i m u l u s and t h e i n i t i a t i o n o f a response.  T h i s d e l a y , known as r e a c t i o n t i m e ( R T ) , i s due t o p r o c e s s i n g i n f o r -  m a t i o n r e l a t e d t o t h e s e l e c t i o n and o r g a n i z a t i o n o f t h e r e s p o n s e .  I n terms o f  RT r e s e a r c h e r s have f o u n d t h a t a number o f f a c t o r s l e a d t o a decrement i n p e r formance.  One such f a c t o r i s t h e c o m p l e x i t y o f movement p a t t e r n s r e q u i r e d  during the response. (Henry,  A number o f i n v e s t i g a t o r s have o b t a i n e d e m p i r i c a l e v i d e n c e  196l; Henry and Rodgers, I960; N o r r i e , 1967; O ' B r i e n , 1959; S i d o w s k i ,  Morgan and E c k s t r a n d , 1958)  i n d i c a t i n g an i n c r e a s e i n RT t o a s t i m u l u s when t h e  2.  r e s p o n s e t o t h a t s t i m u l u s i n v o l v e s a more complex movement.  These r e s u l t s  suggest t h a t i n c r e a s e d movement c o m p l e x i t y r e f l e c t s i n c r e a s e d demands w i t h i n t h e organism i n o r d e r t o m a i n t a i n g r e a t e r c o n t r o l over l i m b movements.  B u t where  w i t h i n t h e o r g a n i s m t h e s e d e l a y s a c t u a l l y occur i s n o t known. Some r e c e n t e x p e r i m e n t a l work has p r o v i d e d a b a s i s f o r d i s t i n g u i s h i n g whether t h e s e d e l a y s a r e due t o c e n t r a l p r o c e s s e s ,  o r a r e caused b y p e r i p h e r a l  f a c t o r s such as number o f motor u n i t s i n v o l v e d , a c t i o n o f a n t a g o n i s t i c m u s c l e s , muscular w e a k n e s s o r , v i s c o s i t y o f t h e m u s c l e s .  T h i s i s based on a number o f  s t u d i e s w h i c h have shown t h a t t h e c e n t r a l mechanisms have a l i m i t e d c a p a c i t y i n t h a t two t a s k s r e q u i r i n g t h e s i m u l t a n e o u s mechanisms c a n i n t e r f e r e w i t h each o t h e r .  processing  attention of the central  These s t u d i e s have been r e p o r t e d  i n r e c e n t r e v i e w s o f t h e p s y c h o l o g i c a l r e f r a c t o r y p e r i o d (PRP) t h e o r y ( B e r t e l s o n ,  1966; S m i t h , 1967). I n h e r r e v i e w S m i t h concluded t h a t t h e s i n g l e c h a n n e l t h e o r y a s suggested by W e l f o r d  (1959; 1967) was t h e b e s t s u p p o r t e d  explanation  o f PRP. T h i s t h e o r y p o s t u l a t e s t h a t i f a second s t i m u l u s a r r i v e d d u r i n g t h e r e s p o n s e p r o c e s s i n g a s s o c i a t e d w i t h a f i r s t s t i m u l u s , t h e second s t i m u l u s would have t o be " h e l d i n s t o r e " ( W e l f o r d , 1959) u n t i l p r o c e s s i n g o f t h e f i r s t  stimulus  was completed. I n r e c e n t work (Posner, 1969) i t has been suggested t h a t one way o f i n v e s t i g a t i n g t h e a t t e n t i o n a l demands o f t h e f i r s t s t i m u l u s i n a PRP e x p e r i ment i s b y u s i n g t h e p r o b e t e c h n i q u e . or probe t h a t must be p r o c e s s e d  T h i s i n v o l v e s p r e s e n t i n g a second s t i m u l u s  d u r i n g t h e RT i n t e r v a l o f t h e f i r s t  stimulus.  Thus, i f c o n t r o l i s t a k e n t o ensure t h a t t h e s i g n a l s do n o t r e q u i r e c o n f l i c t i n g sensory or e f f e c t o r processes, c e n t r a l processes.  t h e d e l a y t o t h e probe may be a t t r i b u t e d t o t h e  I n t h i s way i t has been f o u n d t h a t i f t h e a t t e n t i o n a l  demands o f t h e p r i m a r y t a s k a r e i n c r e a s e d , o r i f t h e p r i m a r y t a s k i s made more d i f f i c u l t , t h e c a p a c i t y a v a i l a b l e f o r a t t e n d i n g t o t h e second s t i m u l u s  will  3. d e c l i n e , r e s u l t i n g i n a p r o g r e s s i v e l y l o n g e r second RT (PRT). The  probe t e c h n i q u e has a l s o been used t o measure a t t e n t i o n d u r i n g  t h e e x e c u t i o n o f movement.  T h i s i n v o l v e s t h e p r e s e n t a t i o n o f a second s t i m u l u s  or probe t h a t must be p r o c e s s e d primary task.  d u r i n g t h e movement t i m e i n t e r v a l o f t h e  R e s u l t s o f these experiments i n d i c a t e t h a t t h e d e l a y i n t h e  probe t a s k was r e l a t e d t o t h e p r e c i s i o n o f t h e movement as PRT's d u r i n g t h e movement t o a s m a l l t a r g e t were g r e a t e r t h a n t h e PRT's when moving t o a l a r g e r target ( E l l s ,  1969; Posner and K e e l e , 1969, 1970). A l s o , i t was f o u n d t h a t  a t t e n t i o n a l demands o f a movement were a s s o c i a t e d w i t h t h e p o s i t i o n i n t h e movement where t h e p r o b e s i g n a l o c c u r r e d Keele,  ( E l l s , 1969;  P o s n e r , 1969;  Posner and  1969, 1970). G e n e r a l l y i t was f o u n d t h a t a t t e n t i o n f o l l o w e d a "U"  shaped t r e n d .  PRT's were g r e a t e r a t t h e b e g i n n i n g o f movement, d e c r e a s e d t o  a r e l a t i v e l y l o w v a l u e i n t h e m i d d l e , and showed a s l i g h t i n c r e a s e near t h e end. The  present  s t u d y was d e s i g n e d  t o u s e t h e above p r i n c i p l e s i n d e t e r -  m i n i n g t h e e f f e c t s t h a t t a s k c o m p l e x i t y had on t h e a t t e n t i o n demands o f t h e c e n t r a l processes  d u r i n g t h e initiation-it'.©;, and e x e c u t i o n o f , a motor t a s k .  Purpose o f t h e S t u d y The purpose o f t h i s i n v e s t i g a t i o n was t o a n a l y z e t h e e f f e c t s o f movement c o m p l e x i t y on t h e a t t e n t i o n r e q u i r e d d u r i n g t h e i n i t i a t i o n  o f a response  and t h e e x e c u t i o n o f a movement. S i g n i f i c a n c e o f t h e Study R e s e a r c h e r s commonly u s e t h e l e n g t h o f r e a c t i o n t i m e as an i n d e x f o r measuring p r o c e s s i n g demands on man's c e n t r a l o p e r a t i o n s .  Subsequently,  i n v e s t i g a t o r s t h a t have f o u n d movement c o m p l e x i t y d u r i n g a r e s p o n s e t o cause an i n c r e a s e d d e l a y i n r e a c t i o n t i m e have assumed t h i s decrement i n performance  4. t o be o f a c e n t r a l n a t u r e .  But t h e p o s s i b i l i t y e x i s t s t h a t t h i s decrement i n  performance c o u l d a l s o be t h e r e s u l t o f p e r i p h e r a l f a c t o r s , such as number o f motor u n i t s i n v o l v e d , a c t i o n o f a n t a g o n i s t i c m u s c l e s , muscular weakness, or v i s c o s i t y o f t h e muscles.  T h e r e f o r e , i t i s d e s i r a b l e t o d e t e r m i n e a t what  s t a g e w i t h i n t h e human organism's r e s p o n s e t h i s t i m e decrement o c c u r s .  Hypotheses 1.  The t i m e t a k e n t o i n i t i a t e a p r i m a r y r e s p o n s e (RT) i s i n c r e a s e d  as a f u n c t i o n o f t h e c o m p l e x i t y o f t h e movement r e q u i r e d d u r i n g t h e e x e c u t i o n of t h a t r e s p o n s e . 2.  The t i m e t a k e n t o i n i t i a t e a r e s p o n s e t o a second s t i m u l u s (PRT)  p r e s e n t e d d u r i n g t h e i n i t i a t i o n o f a p r i m a r y r e s p o n s e i s i n c r e a s e d as a f u n c t i o n o f t h e c o m p l e x i t y o f movement r e q u i r e d d u r i n g t h e p r i m a r y r e s p o n s e . 3.  The t i m e t a k e n t o i n i t i a t e a r e s p o n s e t o a second s t i m u l u s (PRT)  p r e s e n t e d d u r i n g t h e e x e c u t i o n ( i . e . , movement) o f a p r i m a r y r e s p o n s e i s i n c r e a s e d as a f u n c t i o n o f t h e c o m p l e x i t y o f movement r e q u i r e d d u r i n g t h e primary response. Limitations The s t u d y w i l l be l i m i t e d by t h e f o l l o w i n g f a c t o r s : 1.  The sample s i z e o f s i x s u b j e c t s .  2.  The methods and p r o c e d u r e s used i n i n v e s t i g a t i n g t h e problem.  Delimitations T h i s s t u d y w i l l be r e s t r i c t e d t o : 1.  The s p e c i f i c t y p e s o f movements used i n t h e e x p e r i m e n t a l t a s k s .  2.  A d e s c r i p t i o n o f performance as h y p o t h e s i z e d b y W e l f o r d ' s model  o f behaviour '(1965, 1 9 6 8 ) .  5. 3.  An a n a l y s i s o f f u n c t i o n a l b e h a v i o u r a c c o r d i n g t o P o s n e r ' s concept  o f a t t e n t i o n ( P o s n e r , 1969; Posner and B o i e s , 1970; Posner and K e e l e , 1969, 1970). D e f i n i t i o n o f Terms Attention.  The m e n t a l o p e r a t i o n s t h a t r e q u i r e a c c e s s t o man's l i m i t e d  c a p a c i t y c e n t r a l p r o c e s s i n g system i n t h e sense t h a t t h e y w i l l i n t e r f e r e w i t h any o t h e r t a s k w h i c h i s t o be performed s i m u l t a n e o u s l y (Posner and K e e l e , 1970). Movement C o m p l e x i t y .  The r e l a t i v e degree o f a t t e n t i o n n e c e s s a r y t o  i n i t i a t e and c o n t r o l a motor r e s p o n s e .  CHAPTER I I REVIEW OF LITERATURE  A M o d e l o f a Motor Response.  Performance o f a r a p i d d i s c r e t e motor  a c t c o n s i s t s o f two b a s i c components, t h e i n i t i a t i o n o f t h e r e s p o n s e and t h e e x e c u t i o n o f t h e movement.  Each o f t h e s e components r e q u i r e s t h a t  information  be p r o c e s s e d i n o r d e r t h a t t h e a p p r o p r i a t e r e s p o n s e i s p e r f o r m e d s a t i s f a c t o r i l y . As an a i d i n u n d e r s t a n d i n g motor s k i l l s , h y p o t h e t i c a l models o f human p e r formance a r e d e v e l o p e d t o diagram t h e f l o w o f such i n f o r m a t i o n between t h e environment and an i n d i v i d u a l ' s behaviour.  These models attempt t o s p e c i f y t h e  number o f f u n c t i o n a l ' components r e q u i r e d t o produce o b s e r v e d performance, and, t o d e s c r i b e t h e p r o p e r t i e s o f t h e s e components, W e l f o r d (1965) has suggested such a model o f t h e human sensory-motor system ( F i g u r e l ) . T h i s model v i e w s s k i l l s p e r f o r m a n c e i n terms o f a c h a i n o f mechanisms i n t e r v e n i n g between s e n s o r y i n p u t and motor o u t p u t .  s  0  e  r  n  g  s  a  e  n s  M Perceptual  Decision  Effector  u s  Mechanism  Mechanism  Mechanism  c  1 PM  DM  EM  e s  F i g u r e 1:  B e h a v i o r a l model o f t h e human n e r v o u s system ( W e l f o r d ,  1965)  7. The p e r c e p t u a l mechanism (PM) r e f e r s t o t h o s e p r o c e s s e s d e a l i n g w i t h t h e . p e r c e p t i o n o f e x t e r n a l s t i m u l i from t h e environment and t h e encoding o f t h i s sensory i n p u t .  T h i s mechanism r e c e i v e s much more i n f o r m a t i o n t h a n can  be t r a n s m i t t e d and, t h e r e f o r e , some form o f i n f o r m a t i o n c o m p r e s s i o n must t a k e place.  I t has been s u g g e s t e d (Crossman, 1964)  t h a t t h i s compression i s achieved  f i r s t by p e r i p h e r a l f i l t e r s w h i c h o n l y a c c e p t d i s c r e t e samples o f t h e i n c o m i n g sensory i n f o r m a t i o n .  I n t h i s way a l l b u t t h e dominant and i m p o r t a n t f e a t u r e s  o f t h e environment i n t h e i n c o m i n g d a t a a r e r e j e c t e d .  Second, t h e a c t u a l s e n s o r y  c a p a c i t y i s l i m i t e d by a b s o l u t e s e n s o r y t h r e s h o l d s , j u s t n o t i c e a b l e d i f f e r e n c e s , and a b s o l u t e  judgements.  Once t h e e n v i r o n m e n t a l i n f o r m a t i o n i s encoded, i t i s p a s s e d t o t h e d e c i s i o n mechanism (DM) as an i n f o r m a t i o n s i g n a l t o w h i c h a r e s p o n s e i s r e q u i r e d . W i t h i n t h e DM t h e r e a r e two component p r o c e s s e s n e c e s s a r y f o r t h e i n i t i a i o n o f the r e q u i r e d response, w i t h the f i r s t being response s e l e c t i o n or the d e s i g n a t i o n of the appropriate response.  U s i n g a computer a n a l o g y Henry and  Rodgers  (i960) have s u g g e s t e d t h a t t h e second component would be t h e r e t r i e v a l o f motor programs from motor memory w h i c h a r e used t o govern t h e d e s i r e d motor behaviour.  I t i s p o s t u l a t e d (Henry and Rodgers,  i960; S c h u t z ; 1970)  t h i s r e s p o n s e program i s c o m p i l e d o f a number o f subprograms, governs one element o f t h e motor t a s k .  that  each o f w h i c h  C o n s e q u e n t l y , t h e g r e a t e r t h e number  o f movement elements i n v o l v e d i n t h e r e s p o n s e t h e g r e a t e r w i l l be t h e number o f subprograms i n c o r p o r a t e d i n t o t h e motor  program.  A f t e r r e t r i e v a l t h e motor program i s made a v a i l a b l e t o t h e e f f e c t o r mechanism (EM).  The EM c o n t r o l s t h e r e s p o n s e and i n t h i s way i s d i s t i n c t from  t h e d e c i s i o n s t o i n i t i a t e them.  Marteniuk  (1970:2) has proposed a k i n e s t h e t i c  model w h i c h e x p l a i n s t h e methods o f c o n t r o l w h i c h g u i d e t h e r e s p o n s e  execution  8. o f d i s c r e t e motor a c t s .  F o r t h i s model M a r t e n i u k d e s c r i b e s k i n e s t h e s i s as  "those s e n s a t i o n s d e r i v e d f r o m motor i n n e r v a t i o n o r e f f e r e n t o u t f l o w and from r e c e p t o r s w i t h i n t h e j o i n t c a p s u l e s and l i g a m e n t s . " From t h i s d e f i n i t i o n i t i s apparent  t h a t t h e r e a r e two s o u r c e s o f sensory-  s t i m u l a t i o n , c e n t r a l and p e r i p h e r a l . T h i s l e a d s t o two s e p a r a t e models o f 1.  control:  1.  E f f e r e n c e , 2. Efference.  a motor r e s p o n s e  C l o s e d Loop.  B a s i c a l l y the i n t e r p r e t a t i o n o f t h i s theory i s that  c a n be p e r f o r m e d s o l e l y on t h e b a s i s o f c e n t r a l c o n t r o l .  R e c e n t l y t h i s form o f motor r e s p o n s e  c o n t r o l has r e c e i v e d a g r e a t d e a l o f  a t t e n t i o n by a number o f n o t a b l e r e s e a r c h e r s who have u t i l i z e d two s e p a r a t e approaches f o r i n v e s t i g a t i o n .  One approach has been t o d e p r i v e o r d i s t o r t  p e r i p h e r a l k i n e s t h e t i c a f f e r e n c e i n o r d e r t o g a i n support t h a t p e r i p h e r a l k i n e s t h e t i c feedback response.  i s n o t n e c e s s a r y f o r e x e c u t i o n and c o n t r o l o f a motor  A number o f e x c e l l e n t r e v i e w s o f work done i n t h i s a r e a have been  p u b l i s h e d r e c e n t l y (Greenwald, 1970).  1970; K i m b l e and P e r l m u t e r , 1970;  Marteniuk,  The second approach has been t o compare measurements o f e r r o r d e t e c -  t i o n w i t h e r r o r c o r r e c t i o n i n a d i s c r e t e motor r e s p o n s e .  I t has been found  t h a t e r r o r s c a n be c o r r e c t e d more r a p i d l y ' t h a n s e n s o r y feedback d e t e c t e d ( H i g g i n s and A n g e l , 1970; R a b b i t t , 1966a, 1966b, 1967).  c a n be These r e s u l t s  have been i n t e r p r e t e d b y t h e s e a u t h o r s as evidence o f a c e n t r a l mechanism which operates t o c o n t r o l t h e response. B a s i c a l l y , t h e s e two approaches d i f f e r as t o t h e s o u r c e o f s t i m u l a t i o n t h a t i n i t i a t e s t h e response  execution.  The v i e w i n t h i s s t u d y i s t h a t t h e  motor program s e l e c t e d from t h e memory s t o r a g e i s " r e a d o u t " t o t h e EM p r o v i d i n g t h e EM w i t h an image o f t h e d e s i r e d outcomes. fold:  The r o l e o f t h i s image i s two  9. a)  As soon as t h e motor program has been r e a d out and t h e image  f u l l y d e v e l o p e d , n e u r a l i n s t r u c t i o n s i n t h e form o f e f f e r e n t o u t p u t a r e r e l e a s e d b y t h e EM t o t h e m u s c l e s .  I f i t i s assumed t h a t each r e s p o n s e com-  ponent, o r subprogram, has a c o r r e s p o n d i n g image, i t would f o l l o w t h a t movements i n v o l v i n g s e v e r a l subprograms would r e q u i r e a g r e a t e r p e r i o d o f t i m e t o f o r m u l a t e a complete b)  image.  The image s e r v e s as a s t o r e d r e p r e s e n t a t i o n o f what t h e c o r r e c t  performance s h o u l d be.  I n t h i s way t h e r e s p o n s e program i n t h e form o f an  image i s used as a s o u r c e o f r e f e r e n c e w i t h i n t h e c l o s e d l o o p form o f c o n t r o l . 2.  C l o s e d Loop.  The second method o f c o n t r o l w i t h w h i c h t h e motor  program i s e x e c u t e d c o n c e i v e s man as b e i n g analogous t o a computer machine i n w h i c h t h e o p e r a t i o n s pass s u c c e s s i v e l y from one n e u r a l i n s t r u c t i o n t o a n o t h e r as t h e machine proceeds t o e x e c u t e t h e l i s t o f i n s t r u c t i o n s t h a t c o m p r i s e a motor program.  I t i s t h e o r i z e d t h a t a f t e r some minimum p e r i o d o f t i m e t h i s  form o f c o n t r o l would augment t h e i n i t i a l  e f f e r e n t c o n t r o l o f movement.  G a l a n t e r , and P r i b r a m (i960) proposed a c l o s e d l o o p t h e o r y w h i c h would the of  method o f c o n t r o l w i t h w h i c h t h e motor program i s e x e c u t e d .  Miller, explain  I n t h i s model  e f f e c t o r c o n t r o l each n e u r a l i n s t r u c t i o n o f t h e motor program i s s u c c e s s i v e l y  t e s t e d a g a i n s t some c r i t e r i a e s t a b l i s h e d w i t h i n t h e image.  I f the t e s t deter-  mines t h a t t h e r e s p o n s e has n o t been a p p r o p r i a t e up t o t h a t p o i n t t h e EM conc e r n s i t s e l f w i t h e r r o r c o r r e c t i o n u n t i l t h e d e s i r e d outcome has b e e n r r e a c h e d . I n f o r m a t i o n t o conduct t h e s e t e s t s i n d i s c r e t e r a p i d movements i s p r o v i d e d t o t h e EM by t h e k i n e s t h e t i c r e c e p t o r s l o c a t e d w i t h i n t h e j o i n t c a p s u l e s and l i g a m e n t s ( S m i t h , 1969). The purpose o f t h i s model has been t o d i v i d e a d i s c r e t e motor r e s p o n s e i n t o component p a r t s and s u b p r o c e s s e s .  On t h i s b a s i s , t h e demands made on  t h e s e c e n t r a l p r o c e s s e s by a r e s p o n s e c a n be measured.  The b a s i c a s s u m p t i o n  10.  i s t h a t by o v e r l o a d i n g a s u b j e c t s (S's) c a p a c i t y a decrement i n performance w i l l occur a t some s t a g e i n t h e sensory-motor c h a i n .  I f t h e S's t a s k s a r e  d e s i g n e d t o i m p a i r performance i n one p a r t i c u l a r h y p o t h e t i c a l p r o c e s s ,  pro-  p e r t i e s o f t h a t p r o c e s s c a n be i n f e r r e d from t h e p a t t e r n o f r e s u l t s . Time C h a r a c t e r i s t i c s o f Human Performance.  A f e a t u r e o f t h e human  organism i s t h a t i t always t a k e s a f i n i t e , p e r i o d o f t i m e t o i n i t i a t e a r e q u i r e d response a f t e r t h e p r e s e n t a t i o n o f a c e r t a i n s t i m u l u s .  T h i s d e l a y between t h e  p r e s e n t a t i o n o f a s t i m u l u s and t h e i n i t i a i o n o f a r e s p o n s e i s c a l l e d r e a c t i o n t i m e (RT).  A g r e a t d e a l o f s t u d y has been done on t h e f a c t o r s t h a t a f f e c t RT  and r e s e a r c h e r s now u s e t h e l e n g t h o f RT as an i n d e x f o r measuring t h e demand made b y t h e r e s p o n s e on t h e c e n t r a l p r o c e s s e s . One such f a c t o r i s t h e c o m p l e x i t y o f t h e movement p a t t e r n r e q u i r e d d u r i n g t h e execution o f t h e response. et a l . , 1958;  A number o f i n v e s t i g a t i o n s ( S i d o w s k i ,  Henry and Rodgers, I 9 6 0 ; N o r r i e , 1967;  O ' B r i e n , 1967)  have  o b t a i n e d e m p i r i c a l evidence i n d i c a t i n g an i n c r e a s e i n RT t o a s i g n a l when t h e r e s p o n s e t o t h a t s i g n a l i n v o l v e s a more complex movement.  T h i s phenomena  was c o n v i n c i n g l y demonstrated i n a s t u d y by Henry and Rodgers (19&0) who r e q u i r e d S's t o r e a c t t o a s t i m u l u s and t o complete a movement as q u i c k l y as possible.  T h i s s t u d y r e v e a l e d t h a t t h e RT f o r a complex t y p e o f movement  was s i g n i f i c a n t l y slower t h a n t h e RT f o r a s i m p l e t y p e o f movement.  As w e l l ,  t h e y f o u n d t h a t t h e g r e a t e s t i n c r e a s e i n RT as a f u n c t i o n o f movement comp l e x i t y came a t l o w l e v e l s o f c o m p l e x i t y and t h a t i n c r e a s i n g c o m p l e x i t y beyond t h i s caused o n l y s m a l l i n c r e a s e s i n RT. The r e s u l t s o f t h e s e s t u d i e s suggest t h a t t h e i n c r e a s e i n RT a s s o c i a t e d w i t h i n c r e a s e d movement c o m p l e x i t y r e f l e c t i n c r e a s e d demands w i t h i n t h e organism i n o r d e r t o m a i n t a i n g r e a t e r c o n t r o l over l i m b movements.  Speci-  f i c a l l y , i t c o u l d be h y p o t h e s i z e d t h a t t h e i n c r e a s e i n RT r e f l e c t s a decrement  11. i n performance w i t h i n t h e c e n t r a l p r o c e s s o r .  However, t h e p o s s i b i l i t y  exists  t h a t t h e performance decrement c o u l d a l s o be t h e r e s u l t o f p e r i p h e r a l f a c t o r s such a s number o f motor u n i t s i n v o l v e d , a c t i o n o f a n t a g o n i s t i c m u s c l e s , m u s c u l a r weakness, o r , v i s c o s i t y o f t h e m u s c l e s . A t t e n t i o n C h a r a c t e r i s t i c s o f Human Performance.  Some  experimental  work has p r o v i d e d a b a s i s f o r d i s t i n g u i s h i n g d e l a y s due t o c e n t r a l p r o c e s s e s from t h o s e caused b y p e r i p h e r a l f a c t o r s .  T h i s work i s based on t h e t h e o r y o f  t h e p s y c h o l o g i c a l r e f r a c t o r y p e r i o d (PRP)'which c l a i m s t h a t t h e c e n t r a l p r o c e s s i n g mechanisms have l i m i t e d p r o c e s s i n g c a p a c i t y . two t a s k s r e q u i r i n g t h e ^ s i m u l t a n e o u s i n t e r f e r e w i t h each o t h e r .  I t has been found t h a t  a t t e n t i o n o f t h e c e n t r a l processor can  S e v e r a l comprehensive r e v i e w s  o f proposed t h e o r i e s  o f t h e PRP e f f e c t and e v a l u a t i o n s o f t h e i r r e l a t i v e adequacy i n h a n d l i n g PRP d a t a have been r e p o r t e d r e c e n t l y (Broadbent, 1958; R e y n o l d s , 1964; B e r t e l s o n , 1966; S m i t h , 1967(b); Herman and K a n t o w i t z , 1 9 7 0 ) .  Unfortunately, these  reviews  do n o t a l l r e a c h t h e same c o n c l u s i o n as t o w h i c h t h e o r y b e s t e x p l a i n s t h e d a t a . I t i s t h e v i e w o f t h i s p a p e r , and as concluded  by S m i t h (1967a, 1967b, 1969a,  1969b), t h a t t h e s i n g l e c h a n n e l as suggested by W e l f o r d best supported  e x p l a n a t i o n o f PRP.  Welford  (1959; 1967) was t h e  (1959) p o s t u l a t e s t h a t i f a second  stimulus a r r i v e s during t h e response processing associated w i t h a f i r s t  stimulus,  t h e second s t i m u l u s would have t o be " h e l d i n s t o r e " u n t i l t h e p r o c e s s i n g o f the f i r s t s t i m u l u s i s completed. s t i m u l u s t h a t must be p r o c e s s e d would be l e n g t h e n e d  T h i s t h e o r y would p r e d i c t t h a t a second d u r i n g t h e RT i n t e r v a l o f a f i r s t  stimulus  b y a n amount e q u a l t o t h e i n t e r v a l between t h e a r r i v a l o f  t h e s t i m u l u s and t h e end o f t h e f i r s t r e s p o n s e .  Thus, a c c o r d i n g t o t h e s i n g l e  c h a n n e l t h e o r y , i t s h o u l d be p o s s i b l e t o measure p r o c e s s i n g c a p a c i t y . t r o l i s t a k e n t o ensure t h a t t h e s i g n a l s do n o t r e q u i r e c o n f l i c t i n g  I f con-  sensory  12. and e f f e c t o r p r o c e s s e s , t h e d e l a y may be a t t r i b u t e d t o t h e c e n t r a l p r o c e s s e s ( P o s n e r , 1969).  I n t h i s way i t has been found t h a t i f t h e a t t e n t i o n a l demands  of  the primary task are increased, the capacity available f o r attending to  the  second t a s k w i l l d e c l i n e , r e s u l t i n g i n a p r o g r e s s i v e l y l o n g e r second  r e a c t i o n t i m e (PRT). The knowledge t h a t m e n t a l o p e r a t i o n s c a n be measured i n terms o f t h e i r t i m e r e q u i r e m e n t s i s n o t new, and t h e concept o f a l i m i t e d p r o c e s s i n g c a p a c i t y i s w e l l e s t a b l i s h e d ( D a v i s , 1956; W e l f o r d , 1959, 1 9 6 7 ) .  However, i t has been  suggested r e c e n t l y t h a t a l l p r o c e s s i n g performed on a g i v e n s i g n a l does n o t r e q u i r e , t h e l i m i t e d c a p a c i t y mechanism and i t i s n o t y e t c l e a r w h i c h components of  t h e human sensory-motor system r e q u i r e a c c e s s t o t h i s system ( S m i t h , 1967a,  1969a, 1969b; P o s n e r , 1969; Posner and B o i e s , 1970; Posner and K e e l e , 1969, 1970). A s e r i e s o f e x p e r i m e n t s have been r e c e n t l y conducted t o i n v e s t i g a t e t h i s problem u s i n g t h e p r i n c i p l e s o u t l i n e d above.  Posner and c o l l e a g u e s ( P o s n e r ,  1969; Posner and B o i e s , 1970; Posner and K e e l e , 1970) have used t h e s e s i n g l e c h a n n e l p r i n c i p l e s i n a n a t t e m p t t o d e t e r m i n e whether t h e m e n t a l o p e r a t i o n s which r e l a t e e x t e r n a l a f f e r e n t s t i m u l i t o s t o r e d i n f o r m a t i o n r e q u i r e c e n t r a l processing capacity. paper.  T h i s would be w i t h i n t h e PM i n t h e terms o f t h e p r e s e n t  These i n v e s t i g a t o r s v a r i e d t h e a t t e n t i o n demands w i t h i n t h e PM by  u s i n g a l e t t e r m a t c h i n g t a s k t o measure t h e t i m e f o r e n c o d i n g a l e t t e r . the  With  u s e o f t h e probe t e c h n i q u e as d e s c r i b e d above i t was shown t h a t d u r i n g t h e  f i r s t few hundred m i l l i s e c o n d s (msecs) a f t e r p r e s e n t a t i o n o f t h e f i r s t t h e r e was no s u b s t a n t i a l i n t e r f e r e n c e between t h e t a s k s .  letter  However, t h i s assumes  t h a t encoding normally takes p l a c e d u r i n g , t h i s time p e r i o d a f t e r t h e f i r s t s t i m u l u s has been p r e s e n t e d .  Posner and K e e l e (1970) t h e n conducted a second  s e r i e s o f experiments t o i n v e s t i g a t e t h i s problem.  The r e s u l t s i n d i c a t e d t h a t  13. encoding is  seems t o  complete  Work  in this  and K e e l e , of  the  a task  PRT b e g i n s  area  do n o t  require  to  this  Broadbent  the  response  selection  study both the reactions.  the  compatible  visual  opposite to tion  key i n to  spatial the  of  probability (Smith,  of  the  of  1969;  in  the  the  recent  the  sequence system  1968; to  designed to  test  DM.  the  a n i n c r e a s e i n RT d u e i n c r e a s e PRT.  In  a c h o i c e between first  one o f  s i g n a l was  key immediately  beneath  In the  depressing the  lamp.  A third  than  c o n d i t i o n and t o  the  equally the  by an i n c r e a s e i n 1968;  key  condi-  exception that  rather  two  affected  response.  and Kestenbaum,  to  this  s i g n a l and t h e  a n d 0.20  compatible  investigations  created w i t h i n the  c o n d i t i o n with the  Karlin  have  channel theory  delays  o c c u r r e n c e was r e f l e c t e d  1967,  (PM)  those processes  late  condition required  0.80  processes  single  also  to  of  correspondence with the  " T h e - i n c r e a s e d RT f o r  studies  the  depress the  incompatible  stages  and Kestenbaum,  situation,  between  Posner  1970;  initial  two  down.  human s e n s o r y - m o t o r  an experiment  incompatible  occurred with probabilities  probably. w i t h low  compatability  while the  was i d e n t i c a l  stimuli  Other  the  of  i n response latency  slowing  Karlin  and second r e s p o n s e s r e q u i r e d  c o n d i t i o n S ' s were t o  stimulus,  the  1969;  a function  successive stimulus  spatial  the  encoding  EM.  or r e s p o n s e r e t r i e v a l w i l l  first  the  1967,  principles  i n PRT a r e  An i n c r e a s e  by varying  Smith,  1967;  model o f  time  and B o i e s ,  be r e l a t i v e l y  DM a n d t h e  (1967) p e r f o r m e d  and G r e g o r y a  the  the  or  suggest that  s u p p o r t e d b y a number  has used t h e  in  seem t o  According to  delays  hypothesis that  increase,  conclude (Posner  These authors  demand c a p a c i t y  and G r e g o r y ,  demonstrate  and about  processing capacity unless the  would i n c l u d e the  I969) w h i c h  Ells,  msec,  show a s u b s t a n t i a l  These c o n c l u s i o n s are (Broadbent  300-500  those processes involved during  operation.  presented,  to  about  incompatiability.  w h i c h do a p p e a r mental  for  has l e d Posner t o that  1970)  some s p e c i f i c  of  continue  signal PRT.  Ells,'  1969)  14. w h i c h used t h e same b a s i c probe d e s i g n have demonstrated t h a t d e l a y s i n PRT a r e a f u n c t i o n o f t h e number o f a l t e r n a t i v e s f o r t h e f i r s t s i g n a l .  These  r e s u l t s have been i n t e r p r e t e d i n t h i s r e v i e w as b e i n g an i n d i c a t i o n t h a t p r o c e s s e s o f t h e DM r e q u i r e a c c e s s t o t h e l i m i t e d c a p a c i t y p r o c e s s i n g  the  system.  I t i s not q u i t e a s c l e a r whether t h e p r o c e s s e s w i t h i n t h e EM r e q u i r e processing  capacity.  To demonstrate t h i s t h e PRT would have t o be a f u n c t i o n  o f t h e a t t e n t i o n a l demands w i t h i n t h e EM t o t h e r e s p o n s e t a s k .  E l l s (1969),  u s i n g a c h o i c e r e a c t i o n t i m e p r o b e , f o u n d t h a t p r o b e s i n s e r t e d d u r i n g t h e RT t o a movement were r e l a t e d t o t h e a c c u r a c y o f t h e movement d u r i n g t h e r e s p o n s e execution.  However, t h e s e r e s u l t s were d i s m i s s e d  f u n c t i o n o f t h e movement c o n d i t i o n s .  because t h e RT's  were not a  E l l s i n t e r p r e t a t i o n o f t h i s was t h a t  t h e demands p r i o r t o r e s p o n s e i n i t i a t i o n were e q u a l f o r a l l movements t e s t e d . T h i s would be c o n s i s t e n t w i t h t h e e x p e c t e d r e s u l t s t h a t t a r g e t w i d t h and a m p l i t u d e have no s i g n i f i c a n t e f f e c t on t h e t i m e r e q u i r e d t o i n i t i a t e a r e s p o n s e ( F i t t s and P e t e r s o n ,  1964).  On t h e s e grounds E l l s c o n c l u d e d t h a t '  a t t e n t i o n d u r i n g t h e RT i n t e r v a l c o u l d not be a f u n c t i o n o f t h e c h a r a c t e r i s t i c s o f t h e movement f o l l o w i n g . The  probe t e c h n i q u e has a l s o been used t o measure a t t e n t i o n d u r i n g  the execution  o f the response.  T h i s i n v o l v e s t h e p r e s e n t a t i o n o f a second  s t i m u l u s o r probe t h a t must be p r o c e s s e d d u r i n g t h e movement t i m e i n t e r v a l of the primary task.  I t i s i n t e r p r e t e d t h a t t h e PRT w i l l r e f l e c t t h e a t t e n t i o n  needed d u r i n g t h e r e s p o n s e t o c o n t r o l t h e movement. and K e e l e (1969),- and E l l s  Posner (1969), Posner  (l9°9) have shown t h a t w h i l e feedback i s b e i n g  processed there i s a delay i n the processing  o f a probe s i g n a l .  I n t h e s t u d y b y Posner and K e e l e (l9°9) t h e t a s k s i n v o l v e d two l e v e l s o f movement d i f f i c u l t y , w r i s t r o t a t i o n o f 120° t o e i t h e r a narrow t a r g e t (2°)  o r a wide t a r g e t (30°).  The r e s u l t s showed t h a t t h e d e l a y i n  15. PRT was r e l a t e d t o t h e r e q u i r e d a c c u r a c y o f t h e movement as t h e PRT's d u r i n g t h e movement t o a s m a l l t a r g e t were g r e a t e r t h a n t h e PRT's when moving t o a larger target.  A l s o , t h e a t t e n t i o n a l demands o f t h e movement were f o u n d t o  be a s s o c i a t e d w i t h t h e p o s i t i o n i n t h e movement where t h e p r o b e s i g n a l Ells  occurred.  (1969) a l s o f o u n d t h a t probes i n s e r t e d d u r i n g t h e movement were a f u n c t i o n  o f movement a c c u r a c y . both experiments.  However, t h e r e s u l t s were n o t c o m p l e t e l y i d e n t i c a l f o r  I n t h e s t u d y b y Posner and K e e l e t h e a t t e n t i o n demands  f o l l o w e d a U shaped probe f u n c t i o n w i t h PRT's g r e a t e r a t t h e b e g i n n i n g o f movement, d e c r e a s i n g t o a r e l a t i v e l y l o w l e v e l i n t h e m i d d l e ,  and a s l i g h t  i n c r e a s e near t h e end. E l l s r e p o r t e d t h a t t h e PRT was a c o n s t a n t l y d e c r e a s i n g f u n c t i o n o f t h e p r o b e p o s i t i o n , t h e c l o s e r t o t h e t a r g e t t h e f a s t e r t h e PRT. A p o s s i b l e e x p l a n a t i o n f o r t h i s phenomena i s t h a t i n t h e Posner and K e e l e s t u d y no r e s t r i c t i o n was p l a c e d on o v e r s h o o t i n g t h e t a r g e t w h i l e E l l s d i d n o t allow overshoots.  Therefore,  i t i s c o n c e i v a b l e t h a t t h e i n c r e a s e d PRT a t  t h e end o f movement c o u l d be a f u n c t i o n o f t h e c o r r e c t i o n o f o v e r s h o o t s .  An  a l t e r n a t e e x p l a n a t i o n a t t r i b u t e s t h e i n c r e a s e i n PRT t o t e m p o r a l u n c e r t a i n t y . T h i s t h e o r y , commonly r e f e r r e d t o a s e x p e c t a n c y t h e o r y , h y p o t h e s i z e s  that  t h e S l e a r n s t h e r e l a t i v e v a l u e s o f t h e I S I and f o r m u l a t e s a mean w h i c h r e p r e s e n t s t h e v a l u e o f peak e x p e c t a n c y .  I t i s p r e d i c t e d t h a t PRT's a t t h e  mean"I'SI a r e responded t o r e l a t i v e l y f a s t e r , and s i g n a l s o c c u r r i n g b e f o r e or a f t e r t h i s mean a r e r e a c t e d t o r e l a t i v e l y more s l o w l y .  This could explain  t h e "U" shaped r e s u l t s o f Posner and K e e l e , and t h e l a c k o f such a t r e n d i n the r e s u l t s reported by E l l s .  I n t h e work by E l l s t h e e x p e c t a n c y t h e o r y  w o u l d riot a p p l y because t h i s s t u d y used a c h o i c e r e s p o n s e f o r t h e probe t a s k . Posner and K e e l e  (1969) conducted a n o t h e r i n v e s t i g a t i o n t o compare  t h e a t t e n t i o n demands o f d i f f e r e n t systems o f movement c o n t r o l . t h e s o u r c e s o f feedback i n f o r m a t i o n f o u r c o n d i t i o n s were u s e d :  To a)  separate S unable  16. t o see movement t o a s t o p , b) S u n a b l e t o see movement t o a t a r g e t w h i c h S had p r e v i o u s l y l e a r n e d and was t h e r e f o r e h o l d i n g i n memory, c ) S a b l e t o see movement t o a t a r g e t , d) S a b l e t o see movement t o a p o s i t i o n where t h e r e had been a t a r g e t .  PRT was g r e a t e r t h a n s i m p l e RT f o r a l l movement c o n d i t i o n s  except f o r t h e b l i n d movement t o a s t o p .  I t was assumed t h a t under t h i s con-  d i t i o n t h e S was n o t r e q u i r e d t o make c o r r e c t i o n s and, t h e r e f o r e , no p r o c e s s i n g c a p a c i t y f o r feedback was n e c e s s a r y . indicated that the processing  The l o n g e r PRT's f o r t h e o t h e r  conditions  o f b o t h k i n e s t h e t i c and v i s u a l feedback  i n t e r f e r e d w i t h t h e response t o t h e probe.  LThe PRT's were l o n g e s t when  t h e movement t o a t a r g e t was c o n t r o l l e d k i n e s t h e t i c a l l y .  CHAPTER I I I  METHODS AND PROCEDURES Subjects S i x male r i g h t handed u n i v e r s i t y s t u d e n t s who were u n a c q u a i n t e d t o b o t h t h e t a s k and a p p a r a t u s p a r t i c i p a t e d i n t h e experiment. Apparatus The  s u b j e c t (S) s a t a t a t w e n t y - e i g h t i n c h h i g h t a b l e d i r e c t l y i n  f r o n t o f t h e experimental apparatus  (Figure 2),  The l a t e r a l p o s i t i o n o f t h e  c h a i r was p e r m a n e n t l y f i x e d such t h a t when s e a t e d t h e S's r i g h t s h o u l d e r was a l i g n e d w i t h t h e approximate center l i n e ^ o f t h e experimental apparatus.  The  p o s i t i o n o f t h e c h a i r from t h e t a b l e was a d j u s t a b l e so t h a t t h e d i s t a n c e between t h e S and t h e t a b l e was t o t h e S's l i k i n g . The  e x p e r i m e n t a l a p p a r a t u s w h i c h was p l a c e d on t h e t a b l e was  p e r p e n d i c u l a r t o t h e t a b l e t o p f o r f o u r i n c h e s and was t h e n i n c l i n e d a t an a n g l e o f 55° from t h e v e r t i c a l away from t h e S.  The 20 i n c h b y 20 i n c h  c o n s o l e ( F i g u r e 3) f a c i n g t h e S c o n s i s t e d o f a p a n e l w h i c h c o n t a i n e d a r e c e s s e d RT k e y , a v i s u a l s t i m u l u s d i s p l a y , a r e s p o n s e t a r g e t , and g r i p t y p e PRT b u t t o n .  When d e p r e s s e d t h e RT k e y was sunk 0.31 i n c h e s below t h e s u r f a c e  o f t h e c o n s o l e i n a w e l l 0.81 i n c h e s i n d i a m e t e r .  T h i s was t o ensure t h a t  t h e i n i t i a l r e s p o n s e f o r a l l t r i a l s and a l l S's was t h e same; i . e . a l i f t i n g out o f t h e w e l l .  T h i s RT k e y was c e n t r a l l y l o c a t e d on t h e v e r t i c a l m i d l i n e  o f t h e c o n s o l e and 6 i n c h e s away from t h e near edge.  The v i s u a l s t i m u l u s  d i s p l a y was a t eye l e v e l and c o n s i s t e d o f a r e d s t i m u l u s l i g h t and an orange w a r n i n g l i g h t each 0.5 i n c h e s i n d i a m e t e r .  The m i d p o i n t o f t h e r e d s t i m u l u s  l i g h t was a l s o l o c a t e d on t h e v e r t i c a l m i d l i n e o f t h e c o n s o l e 10.5 i n c h e s  Figure 2:  P o s i t i o n of subject at apparatus  F i g u r e 3:  The a p p a r a t u s  20.  d i r e c t l y above t h e RT k e y . The m i d p o i n t o f t h e orange w a r n i n g l i g h t was  0.625 i n c h e s above and 0.31 i n c h e s t o t h e l e f t o f t h e c e n t e r o f t h e r e d light. diameter  IThe r e s p o n s e t a r g e t was a c i r c u l a r m e t a l d i s c 2.44 c o u n t e r sunk i n t o a h o l e w i t h i n t h e c o n s o l e 2.56  inches i n  i n c h e s i n diameter  w h i c h a l l o w e d f o r c l e a r a n c e between t h e t a r g e t and c o n s o l e when t h e t a r g e t was d e p r e s s e d .  LThe t o p o f t h e t a r g e t was f l u s h w i t h t h e c o n s o l e s u r f a c e .  Because t h e c e n t e r o f t h i s t a r g e t was o n l y 2 i n c h e s d i r e c t l y below t h e r e d s t i m u l u s l i g h t , t h e S was a b l e t o watch b o t h a t t h e same t i m e .  The d i s t a n c e  from t h e c e n t e r o f t h e RT k e y t o t h e n e a r edge o f t h e t a r g e t was 7.25 The g r i p t y p e PRT b u t t o n was a b u t t o n 0.31  i n c h e s i n diameter"  c e n t r a l l y l o c a t e d on t h e t o p o f a padded c y l i n d r i c a l hand g r i p . o f t h e a p p a r a t u s was connected  inches.  This piece  t o t h e bottom l e f t hand c o r n e r o f t h e  a p p a r a t u s by a f o u r f o o t w i r e w h i c h enabled t h e S t o h o l d i t wherever he felt  comfortable. The S wore earphones t h r o u g h w h i c h a u d i t o r y s t i m u l i i n t h e form  o f t a p e r e c o r d e d t o n e s were p r e s e n t e d .  D u r i n g t h e experiment  t h i s . t a p e was  c o n t i n u a l l y p l a y e d , b u t t h e sound was o n l y h e a r d b y t h e S when t h e c i r c u i t t o t h e earphones was c l o s e d a t t h e a p p r o p r i a t e t i m e s . The t i m e i n t e r v a l s between t h e orange warning l i g h t and r e d s t i m u l u s l i g h t , and between t h e r e d s t i m u l u s l i g h t and t h e a u d i t o r y s t i m u l u s were c o n t r o l l e d by a t i m i n g module. Chicago,  Illinois.  T h i s module was manufactured b y C H . S t o e l t i n g Company, The t i m e d e l a y s i n r e s p o n d i n g and moving a r e measured i n  m i l l i s e c o n d s on t h r e e Model 120 A K l o c k c o u n t e r e l e c t r o n i c m i l l i s e c o n d c l o c k s produced by Hunter M a n u f a c t u r i n g Company, I n c o r p o r a t e d . Experimental Conditions To r e a l i z e t h e purpose o f t h i s experiment  i t was n e c e s s a r y t o f i n d  21.  a p a t t e r n o f movement w h i c h c o u l d be v a r i e d t o produce t h r e e l e v e l s o f movement c o m p l e x i t y .  C h a r a c t e r i s t i c s o f these experimental  c o n d i t i o n s were  t h a t t h e movements be n a t u r a l t o t h e S so t h a t a l a r g e number o f p r a c t i c e t r i a l s were n o t r e q u i r e d , and t h a t t h e s t a r t i n g p o s i t i o n and i n i t i a l movement be t h e same f o r each r e s p o n s e .  "'The a p p r o p r i a t e movement p a t t e r n s were  d e t e r m i n e d f r o m a p i l o t s t u d y (Appendix A ) . Throughout t h e experiment t h e S g r a s p e d a r o u n d peg 3 i n c h e s l o n g and 0.40 i n c h e s wide i n h i s r i g h t hand u s i n g h i s thumb and f o u r f i n g e r s such t h a t a p p r o x i m a t e l y  0.20 i n c h e s o f t h i s peg extended beyond h i s f o r e -  f i n g e r and 1 t o 1.5 i n c h e s extended beyond h i s l i t t l e f i n g e r .  At t h e s t a r t  o f each t r i a l t h e S r o t a t e d ( p r o n a t e d ) h i s r i g h t arm and hand e n a b l i n g him to  d e p r e s s t h e r e c e s s e d RT k e y w i t h t h e peg such t h a t h i s f o r e f i n g e r r e s t e d  on t h e s u r f a c e o f t h e r e a c t i o n c o n s o l e .  I n response t o t h e p r e s e n t a t i o n o f  s t i m u l u s one, a t some random i n t e r v a l ( 2 , 3, o r 4 seconds) a f t e r t h e w a r n i n g l i g h t , t h e S r e l e a s e d t h e RT k e y by l i f t i n g  t h e peg. Movement p a t t e r n s  r e q u i r e d d u r i n g t h e r e s p o n s e v a r i e d from s i m p l e ( C l ) t o complex ( C 3 ) . Experimental  c o n d i t i o n C l represented t h e simplest response.  r e q u i r e d t h e S t o r e l e a s e t h e RT k e y by w i t h d r a w a l  o f t h e peg.  c o n d i t i o n C2 was a movement t h a t t e r m i n a t e d a t a t a r g e t . to  T h i s movement  be a movement o f r e l a t i v e i n t e r m e d i a t e c o m p l e x i t y .  Experimental  T h i s was c o n s i d e r e d  During t h i s c o n d i t i o n  t h e S was r e q u i r e d t o withdraw t h e peg from t h e RT k e y , r e a c h f o r w a r d and s t r i k e t h e t a r g e t w i t h t h e same end o f t h e peg t h a t had d e p r e s s e d t h e RT k e y . The movement f o r e x p e r i m e n t a l  c o n d i t i o n C3 was o p e r a t i o n a l l y d e f i n e d as b e i n g  o f g r e a t e r c o m p l e x i t y t h a n C l o r C2.  The S was r e q u i r e d t o w i t h d r a w t h e peg  from t h e RT k e y , r e a c h f o r w a r d r o t a t i n g ( s u p i n a t i o n ) h i s arm and hand, and s t r i k e t h e t a r g e t w i t h t h e o p p o s i t e end o f t h e peg t h a t had d e p r e s s e d t h e RT k e y .  22.  Under each o f t h e t h r e e c o n d i t i o n s o f movement c o m p l e x i t y t h e S r e q u i r e d t o perform  a s e c o n d a r y t a s k , a r e s p o n s e t o s t i m u l u s two ( a u d i t o r y ) .  At t h e s t a r t o f each t r i a l t h e PRT b u t t o n was t h e l e f t hand.  Upon o c c u r r e n c e  by r e l e a s i n g t h e PRT  depressed  w i t h t h e thumb o f  o f s t i m u l u s two, or p r o b e , t h e S responded  button.  The t i m e i n t e r v a l between t h e p r e s e n t a t i o n o f s t i m u l u s one and s t i m u l u s two  was  (visual)  ( a u d i t o r y ) was r e f e r r e d t o as t h e probe i n t e r v a l .  Presenta-  t i o n o f t h e probe o r a u d i t o r y s t i m u l u s c o u l d be governed i n t w o a s e p a r a t e ways. D u r i n g t h e f i r s t phase o f t h i s experiment t h e probe was s t i m u l u s one by some p r e d e t e r m i n e d  time ( m i l l i s e c o n d s ) .  delayed to f o l l o w T h i s method was  used  when t h e probe was  t o be i n s e r t e d d u r i n g t h e i n i t i a t i o n o f t h e p r i m a r y r e s p o n s e  or t h e RT p e r i o d .  As recommended by W e l f o r d  o f 90 m i l l i s e c o n d s (msecs.) was these responses.  (1967) a minimum probe i n t e r v a l  chosen t o c o n t r o l a g a i n s t t h e S  grouping  F u r t h e r , a number o f i n v e s t i g a t i o n s ( W e l f o r d , 1967)  have  found t h a t when probes a r e i n s e r t e d s h o r t l y b e f o r e or a f t e r t h e end o f t h e PRT  RT,  r e s u l t s a r e i n e x p l i c a b l y i n c o n s i s t e n t . For t h i s r e a s o n t h e l o n g e s t  probe i n t e r v a l s f o r each c o n d i t i o n were a t l e a s t 20 msec, l e s s t h a n t h e mean RT f o r t h a t c o n d i t i o n . RT r e s u l t s o f t h e p i l o t  T h i s s e l e c t i o n o f t h e probe i n t e r v a l s was based on study.  D u r i n g t h e second phase o f t h i s experiment t h e probe was t o f o l l o w t h e i n i t i a t i o n o f t h e movement by some p r e d e t e r m i n e d method was  t o be u s e d when t h e probe was  of the primary response,  the  time.  t o be i n s e r t e d d u r i n g t h e  o r movement t i m e (MT)  interval.  delayed  T h i s was  This  execution achieved  by h a v i n g t h e probe i n t e r v a l s t a r t e d when t h e S r e l e a s e d t h e RT b u t t o n . s e l e c t i o n o f i n t e r v a l s was  based on t h e MT r e s u l t s o f t h e p i l o t  study.  The  23. Experimental  Design  A r e p e a t e d measures d e s i g n was u s e d where a l l S's performed a l l conditions.  To c o n t r o l f o r an o r d e r e f f e c t each S was  a s s i g n e d t o one  of  s i x p o s s i b l e p r e s e n t a t i o n orderings of the three experimental c o n d i t i o n s . Each S a t t e n d e d t h r e e , t w o  9  and one h a l f - h o u r (approximate)  same d a i l y t i m e on c o n s e c u t i v e The S performed 450  sessions at the  days. t r i a l s f o r each o f t h e e x p e r i m e n t a l c o n d i t i o n s .  Under each c o n d i t i o n t h e S was  given 5 p r a c t i c e t r i a l s of the  c o n d i t i o n a l o n e ( i . e . w i t h o u t t h e presence  o f t h e secondary  experimental  t a s k ) w h i c h were  f o l l o w e d by t h e measurement o f t e n t r i a l s f o r a c o n t r o l v a l u e .  The S  was  t h e n g i v e n 5 p r a c t i c e t r i a l s r e s p o n d i n g t o t h e probe s t i m u l u s a l o n e . were t h e n f o l l o w e d by t h e measurement o f f i v e t r i a l s o f t h e PRT control data.  Next t h e s u c c e s s i v e RT phases o f t h e experiment  w h i c h meant t h a t t h e a u d i t o r y probe s t i m u l u s was v a r i e d i n t e r v a l a f t e r s t i m u l u s one. for  C l - 90,  C3 - 90,  HO,  110,  130,  130 150,  and 150 170,  190  t h e complete e x p e r i m e n t a l t a s k . s u c c e s s i v e RT's  alone f o r were  conducted  p r e s e n t e d a t some randomly  D u r i n g t h e f i r s t phase t h e probe i n t e r v a l s  each e x p e r i m e n t a l c o n d i t i o n f o l l o w e d s t i m u l u s one by some  time:  These  m s e c ; C2 - 90, msec  110,  The S was  T h i s was  130,  150  predetermined and 170  msec;  g i v e n 10 p r a c t i c e t r i a l s  f o l l o w e d by t h e measurement o f  of 240  f o r each e x p e r i m e n t a l c o n d i t i o n . For C l 60 t r i a l s a t each  o f t h e 4 probe i n t e r v a l s were t e s t e d , f o r C2 i t was 48 t r i a l s per probe i n t e r v a l , and f o r C3 i t was 40 t r i a l s per probe i n t e r v a l .  The  order of the  4 probe i n t e r v a l s f o r C l was randomly v a r i e d w i t h i n 24 t r i a l b l o c k s so t h a t a f t e r 24 t r i a l s each probe had o c c u r r e d s i x t i m e s .  The o r d e r o f t h e 5 probe  i n t e r v a l s f o r C2 was randomly v a r i e d so t h a t a f t e r 25 t r i a l s each probe had  2k.  occurred f i v e times.  The o r d e r o f t h e 6 probe i n t e r v a l s f o r C3 was randomly-  v a r i e d w i t h i n b l o c k s so t h a t a f t e r 24 t r i a l s each probe o c c u r r e d 4 t i m e s . F o r t h e second phase o f t h e experiment t h e probe i n t e r v a l s were made t o f o l l o w t h e i n i t i a t i o n  o f movement by some p r e d e t e r m i n e d t i m e .  For  C l , C2 and C3 t h e probe i n t e r v a l s were 20, 80, 140 and 200 msec, a f t e r t h e b e g i n n i n g o f t h e movement.  LThe o r d e r o f probe i n t e r v a l s f o r each e x p e r i m e n t a l  c o n d i t i o n were randomly v a r i e d so t h a t w i t h i n each b l o c k o f 24 t r i a l s  each  probe i n t e r v a l o c c u r r e d s i x t i m e s . Under each c o n d i t i o n t h e s e s s i o n was completed b y o b t a i n i n g more c o n t r o l measures, t e n t r i a l s o f t h e e x p e r i m e n t a l c o n d i t i o n a l o n e and f i v e t r i a l s o f t h e probe r e s p o n s e a l o n e .  A n a l y s i s o f Data Data a n a l y s i s was performed on t h e mean RT's, MT's, and PRT's f o r a l l t r i a l s w i t h i n each c o n d i t i o n . RT t o P r i m a r y Task. initiation  The e f f e c t s o f movement c o m p l e x i t y o n t h e  o f a r e s p o n s e was d e t e r m i n e d by a s i m p l e a n a l y s i s o f v a r i a n c e  comparing t h e mean RT's o f t h e c o n t r o l d a t a f o r each e x p e r i m e n t a l c o n d i t i o n . These means r e p r e s e n t e d 120 t r i a l s , 60 t r i a l s from p r e t e s t c o n t r o l s and 60 t r i a l s o f t h e p o s t t e s t  control.  To d e t e r m i n e whether t h e probe i n t e r f e r e d w i t h t h e i n i t i a t i o n o f t h e p r i m a r y t a s k , t h e mean RT f o r each e x p e r i m e n t a l c o n d i t i o n from t h e s u c c e s s i v e RT d a t a were compared w i t h t h e c o r r e s p o n d i n g c o n t r o l d a t a f o r each e x p e r i m e n t a l c o n d i t i o n .  A g a i n an a n a l y s i s o f v a r i a n c e was u s e d .  MT t o t h e P r i m a r y Task.  From t h e c o n t r o l d a t a t h e mean MT f o r t h e  two e x p e r i m e n t a l c o n d i t i o n s r e q u i r i n g movement t o t h e t a r g e t were a n a l y z e d by a s i m p l e a n a l y s i s o f v a r i a n c e t o d e t e r m i n e t h e e f f e c t s o f movement  25.  c o m p l e x i t y on t h e e x e c u t i o n o f t h e movement.  Each mean r e p r e s e n t e d 120  trials,  60 from t h e p r e t e s t measurements and 60 from t h e p o s t t e s t measurements. The mean MT's  from t h e s u c c e s s i v e r e s p o n s e d a t a were s i m i l a r l y compared w i t h . ;  t h e c o r r e s p o n d i n g c o n t r o l d a t a i n o r d e r t o determine whether t h e probe i n t e r f e r e d w i t h t h e MT d u r i n g t h e p r i m a r y t a s k . RT t o t h e Secondary Task (PRT). phases o f t h e experiment,  when t h e probe was p r e s e n t e d d u r i n g t h e  o f t h e r e s p o n s e , and when t h e probe was t h e movement.  A t h r e e way  The PRT's were a n a l y z e d f o r b o t h initiation  presented during the execution of  a n a l y s i s o f v a r i a n c e was  performed on t h e mean  PRTs o f t h e common probe i n t e r v a l s f o r each c o n d i t i o n t o determine  whether  t h e a t t e n t i o n needed f o r p r o c e s s e s d u r i n g t h e i n i t i a t i o n o f a r e s p o n s e t h e e x e c u t i o n o f a movement i n c r e a s e d w i t h a movement c o m p l e x i t y .  and  .The  t h r e e v a r i a b l e s t h a t c o n s t i t u t e d t h i s a n a l y s i s were S's, c o n d i t i o n s and probe i n t e r v a l s . For t h e above a n a l y s e s , where t h e o v e r a l l F i n d i c a t e d t h e S c h e f f e method ( S c h e f f e , differences occurred.  significance,  I964) was used t o determine where .the s i g n i f i c a n t  CHAPTER IV RESULTS AND DISCUSSION RESULTS RT - C o n t r o l , Phase I and Phase I I I t was h y p o t h e s i z e d t h a t t h e t i m e t a k e n t o i n i t i a t e a p r i m a r y r e s p o n s e would i n c r e a s e as a f u n c t i o n o f t h e c o m p l e x i t y o f movement r e q u i r e d during t h e execution of t h a t response.  The r e s u l t s t e s t i n g t h i s h y p o t h e s i s  a r e shown i n F i g u r e 4 w h i c h p r e s e n t s t h e mean c o n t r o l RT f o r each o f t h e t h r e e c o n d i t i o n s o f movement c o m p l e x i t y , p l u s t h e phase I RT's (probe p r e s e n t e d d u r i n g RT i n t e r v a l ) and phase I I RT's (probe p r e s e n t e d d u r i n g MT interval).  An a n a l y s i s o f v a r i a n c e f o r t h e c o n t r o l d a t a r e v e a l e d t h a t t h e  c o n d i t i o n e f f e c t was n o t s i g n i f i c a n t . i n Table  A summary o f t h i s a n a l y s i s appears  1.  TABLE 1 ANALYSIS OF VARIANCE OF CONTROL RT  Source o f Variance  df  MS  Ss  5  2739  Cond.  2  574  Error  10  Total  17  548  F  1.05  p  > .05  F i g u r e 4:  Mean RT d u r i n g c o n t r o l , Phase I , and Phase I I as a f u n c t i o n o f movement  complexity  28.  I t was a n t i c i p a t e d t h a t t h i s h y p o t h e s i s would a l s o a p p l y t o t h e s u c c e s s i v e r e s p o n s e phases o f t h e experiment.  The mean RTs f o r each o f t h e  t h r e e c o n d i t i o n s o f movement c o m p l e x i t y d u r i n g phase I o f t h e s u c c e s s i v e response task a r e a l s o presented  i n F i g u r e 4.  a c t u a l l y o p p o s i t e t o what was expected,  The t r e n d o f t h e s e d a t a a r e  however, a n a n a l y s i s o f v a r i a n c e  r e v e a l e d t h a t t h e c o n d i t i o n main e f f e c t was n o t s i g n i f i c a n t ( T a b l e I I ) .  TABLE I I ANALYSIS OF VARIANCE OF RT DURING PHASE I  Source o f Variance  df  MS  F  Ss  5  4225  Cond.  2  464  0.35  ISI  3  1366  3L77  Linear  1  4033  Quadratic  1  33  S x Cond  10  1337  S x ISI  15  43  6  72  S x Cond. x I S I  30  20  Total  71  Cond. x I S I  P  < .00: < .001  94.41  3.60  < .01  F u r t h e r r e s u l t s f r o m t h e phase I a n a l y s i s r e v e a l e d t h a t t h e l e n g t h o f t h e I S I had a s i g n i f i c a n t e f f e c t on RT ( T a b l e I I ) . The mean RT's over a l l c o n d i t i o n s f o r phase I a r e summarized i n F i g u r e 5 as a f u n c t i o n o f t h e I S I .  29.  F i g u r e 5: Mean phase I RT as a f u n c t i o n o f I S I  30.  The Scheffe procedure was used to test the main effect of ISI on RT and this test showed significant differences among a l l ISI except between the 130 and 150 msec, i n t e r v a l . Figure 6 shows the interaction between conditions and ISIs for phase I which produced a significant F (Table I I ) . Further analysis using the Scheffe test on the table of effects from this interaction disclosed that the RT for C2 at ISI 90 caused an interaction. The mean RT for each of the three conditions of movement complexity during phase I I were presented i n Figure L\. An analysis of variance revealed that the condition main effect was not significant and that the ISI main effect was significant (Table I I I ) .  TABLE I I I ANALYSIS OF VARIANCE OF RT DURING PHASE I I  Source of Variation  df  MS  Ss •  5  13614  Cond.  2  2164  0.77  ISI  3  140  5.60  S x Cond.  10  <  .01  2818  S x ISI  15  25  Cond. x ISI  6  123  S x Cond. x ISI  30  23  Total  71  5.35  <.05  31.  F i g u r e 6:  Mean phase I RT f o r each c o n d i t i o n as a f u n c t i o n o f I S I  32.  Table IV r e p o r t s an a n a l y s i s which was conducted t o determine whether the time r e q u i r e d t o i n i t i a t e a response was changed when a second stimulus was presented.  The c o n d i t i o n main e f f e c t was not s i g n i f i c a n t ,  although the contrast between c o n t r o l , phase I , and phase I I produced a s i g n i f i c a n t F. Further a n a l y s i s using the Scheffe t e s t d i s c l o s e d that the mean f o r a l l RT measurements i n phase I I was greater than the mean f o r a l l c o n t r o l and phase I RT measurements.  TABLE TV ANALYSIS OF VARIANCE OF RT DURING CONTROL, PHASE I , AND PHASE I I  Source of Variance  df  MS  F  p  <.001  Ss  5  666o  Phase  2  7928  29.25  Cond.  2  152  O.H  S x Phase  10  271  S x Cond.  10  1325  4  533  S x Phase x Cond.  20  121  Total  53  Phase x Cond.  4.40  <.025  PRT - Phase I Hypothesis two predicted that the time taken t o i n i t i a t e a response v t o a .second stimulus presented during the i n i t i a t i o n o f a primary response  33.  would vary as a f u n c t i o n of the complexity of movement required during primary response.  the  Figure 7 presents the mean PRTs f o r c o n t r o l and each  experimental c o n d i t i o n of movement complexity.  An a n a l y s i s of variance that  included the c o n t r o l as w e l l as experimental conditions revealed that the c o n d i t i o n main e f f e c t was  s i g n i f i c a n t (Table V ) .  The Scheffe procedure was  used to t e s t f o r the d i f f e r e n c e s between these means and i t was found that the PRT means f o r both C2 and C3 were s i g n i f i c a n t l y d i f f e r e n t from the c o n t r o l s PRT.  The Scheffe procedure was a l s o used to compare the probe presented  during the RT t o the task w i t h the probe when i t occurred by i t s e l f . I t was found that the grand mean f o r a l l conditions during phase I (250 msec.) was  s i g n i f i c a n t l y greater thahnthe mean f o r a l l conditions during c o n t r o l  (183  msec).  In a d d i t i o n , the trend a n a l y s i s i n d i c a t e d a l i n e a r r e l a t i o n s h i p  between the four c o n d i t i o n s .  TABLE V ANALYSIS OF VARIANCE OF PRT DURING CONTROL AND PHASE I  Source of Variance  df  MS  Ss  5  7502  Cond.  3  10643  F  p  5.05  <.025  Linear  1  26344  12.51  <.005  Quadratic  1  2646  1.26  > .05  Error  15  Total  23  2106  F i g u r e 7:  Mean phase I PRT a s a f u n c t i o n o f movement c o m p l e x i t y and mean c o n t r o l PRT  35.  The r e s u l t s r e l a t i n g e f f e c t o f t h e l e n g t h o f t h e I S I on t h e mean PRT f o r a l l c o n d i t i o n s a r e p r e s e n t e d  i n F i g u r e 8.  An a n a l y s i s o f v a r i a n c e  i n c l u d i n g o n l y t h e t h r e e movement c o n d i t i o n s showed t h a t t h e I S I main e f f e c t was s i g n i f i c a n t ( T a b l e V I ) .  The S c h e f f e p r o c e d u r e was u s e d on t h e s e d a t a  and showed s i g n i f i c a n t d i f f e r e n c e s among a l l I S I .  I n addition, the trend  a n a l y s i s showed a s i g n i f i c a n t l i n e a r t r e n d .  TABLE V I ANALYSIS OF VARIANCE OF PRT DURING PHASE I  Source o f Variance  df  MS  Ss  5  41121  Cond.  2  24030  ISI  3  1645  F  P•  31.69  <.oo:  Linear  1  4920  94.6  Quadratic  1  5  0.1  S x Cond.  10  6961  S x ISI ;  15  52  6  142  S x Cond. x I S I  30  84  Total .  71  Cond. x I S I  I.69  > .05  Figure 9 presents t h e i n t e r a c t i o n o f I S I with the three  conditions  i n terms o f PRT. An a n a l y s i s o f v a r i a n c e , T a b l e V I , r e v e a l e d t h a t t h e cond i t i o n b y I S I i n t e r a c t i o n was n o t s i g n i f i c a n t .  36.  F i g u r e 8:  Mean PRT d u r i n g - p h a s e I f o r a l l c o n d i t i o n s as a f u n c t i o n o f I S I  37  F i g u r e 9:  Mean PRT d u r i n g Phase I f o r each c o n d i t i o n as a f u n c t i o n o f I S I and mean c o n t r o l PRT  38.  MT - C o n t r o l , Phase I , and Phase I I I t was e x p e c t e d t h a t t h e e f f e c t o f movement c o m p l e x i t y on MT would be t o i n c r e a s e MT. two  Mean c o n t r o l , phase I , and phase I I MT's f o r each o f t h e  c o n d i t i o n s i n w h i c h t h e movement was t e r m i n a t e d a t a t a r g e t a r e shown  i n F i g u r e 10.  An a n a l y s i s o f v a r i a n c e  f o r t h e c o n t r o l d a t a y i e l d e d an F  r a t i o o f 16.13  r e v e a l i n g t h a t t h e c o n d i t i o n e f f e c t was s i g n i f i c a n t ( T a b l e V I I ) .  TABLE V I I ANALYSIS OF VARIANCE OF CONTROL MT  Source o f Variation  df  MS  Ss.  5  243  Cond.  1  3675  Error  5  228  F  P  16.13  €.025  11  Total  D u r i n g phase I I o f t h e s u c c e s s i v e r e s p o n s e t a s k s , when t h e probe was p r e s e n t e d d u r i n g t h e MT, i t was found t h a t t h e movement c o m p l e x i t y e f f e c t was no l o n g e r  significant.  An a n a l y s i s o f v a r i a n c e ,  f o r t h e s e d a t a y i e l d e d an F r a t i o o f  4*63 r e v e a l i n g  summarized i n T a b l e V I I I , t h a t t h e c o n d i t i o n main  e f f e c t was n o t s i g n i f i c a n t . Presentation  o f t h e probe d u r i n g t h e RT component o f t h e r e s p o n s e  d i d n o t have t h e same e f f e c t .  An a n a l y s i s o f v a r i a n c e  c l o s e d t h a t t h e c o n d i t i o n main e f f e c t was s i g n i f i c a n t .  f o r these data d i s An o u t l i n e o f t h i s  39.  F i g u r e 10:  Mean MT d u r i n g c o n t r o l , phase I , and phase I I as a f u n c t i o n o f movement  complexity  40. a n a l y s i s appears i n T a b l e I X . I t was a l s o o f i n t e r e s t a t t h i s t i m e t o d e t e r m i n e whether t h e l e n g t h o f t h e I S I , o r t h e r e l a t i v e p o s i t i o n o f t h e probe w i t h i n t h e movement, i n f l u e n c e d MT.  Figure l l  i l l u s t r a t e s t h e mean phase I I MT's as a f u n c t i o n  o f I S I . An a n a l y s i s o f v a r i a n c e f o r t h e s e d a t a showed t h a t t h e I S I main e f f e c t was s i g n i f i c a n t ( T a b l e V I I I ) .  The S c h e f f e p r o c e d u r e was used t o t e s t  t h e main e f f e c t o f I S I on MT and t h i s t e s t showed t h e I S I o f 20 t o be d i f f e r e n t from a l l  otherMSI.  TABLE V I I I ANALYSIS OF VARIANCE OF PHASE I I MT  Source o f Variation  df  MS  F  Ss  5  3635  Cond.  1  6888  4.63  ISI  3  77  15.02  5  1488  15  :5  3  7  S x Cond. x I S I  15  10  Total  47  -S x Cond. S x ISI Cond. x I S I  P  > .05 < .001  0.71  From F i g u r e 10 i t c a n be seen t h a t t h e phase I I MT d a t a show a d i f f e r e n t f u n c t i o n t h a n t h e c o n t r o l MT d a t a .  To pursue t h i s a n a n a l y s i s o f  v a r i a n c e was conducted t o d e t e r m i n e i f t h e p r e s e n t a t i o n o f t h e probe had a n  F i g u r e 11:  Mean phase I I MT as a f u n c t i o n o f I S I  42.  e f f e c t on MT ( T a b l e X ) .  The c o n t r a s t between c o n t r o l , phase I and phase I I  produced a s i g n i f i c a n t F.  Further a n a l y s i s u s i n g t h e Scheffe procedure  r e v e a l e d t h a t t h e mean f o r a l l MT measurements i n phase I I d i f f e r e d from t h e phase I mean.  TABLE I X s ANALYSIS OF VARIANCE FOR PHASE I MT  Source o f Variation  df  F  MS  Ss  5  1786  Cond.  1  9352  14.1  ISI  3  9  1.2  S x Cond.  5  665  15  8  3  3=3  S x ISI Cond. x I S I S x Cond. x I S I  15  Total  47  10  0.3  P  < .025 > .05  43.  TABLE X ANALYSIS OF VARIANCE OF"MT DURING CONTROL PHASE I , AND PHASE I I  Source o f Variation  df  MS  Ss  5  1380  Phase  2  501  Cond.  1  7540  S x Phase  10  101  S x Cond.  5  635  Phase x Cond.  2  98  S x Phase x Cond.  10  64  Total  35  F  p  PRT - Phase I I I t was h y p o t h e s i z e d t h a t t h e t i m e needed t o i n i t i a t e a secondary response t o a stimulus presented d u r i n g t h e e x e c u t i o n o f a primary response i s i n c r e a s e d a s a f u n c t i o n o f t h e c o m p l e x i t y o f movement r e q u i r e d d u r i n g t h e execution o f t h e primary response.  The r e s u l t s w h i c h r e l a t e s p e c i f i c a l l y t o  t h i s h y p o t h e s i s a r e p r e s e n t e d i n F i g u r e 12.  An a n a l y s i s o f v a r i a n c e , T a b l e X I ,  over a l l c o n d i t i o n s i n c l u d i n g c o n t r o l showed t h e c o n d i t i o n s main e f f e c t t o be significant.  The S c h e f f e p r o c e d u r e was used t o t e s t d i f f e r e n c e s among c o n d i t i o n s .  I t was f o u n d t h a t t h e r e was a d i f f e r e n c e between a l l c o n d i t i o n s except C2 and C 3 .  44.  F i g u r e 12:  Mean phase I I PRT as a f u n c t i o n o f movement c o m p l e x i t y and mean c o n t r o l PRT  45.  TABLE X I ANALYSIS OF VARIANCE OF PRT DURING CONTROL AND PHASE I I  Source o f Variation  df  Ss Cond. Error  MS  5  1861  3 15  6614 499  F  13.25  p  '  <.001  As e x p e c t e d , t h e l e n g t h o f t h e I S I s i g n i f i c a n t l y a f f e c t e d t h e PRT. F i g u r e 13 p r e s e n t s t h e mean PRT over a l l c o n d i t i o n s as a f u n c t i o n o f I S I and t h i s d e p i c t s a s i g n i f i c a n t e f f e c t (Table X I I ) . used t o t e s t d i f f e r e n c e s among t h e I S I .  The S c h e f f e p r o c e d u r e was  I t was found t h a t each I S I was  d i f f e r e n t except f o r I 4 0 msec, and 2 0 0 msec. I S I ' s , and t h e 80 msec, and 200 msec. I S I ' s .  I n a d d i t i o n , t h e t r e n d a n a l y s i s showed.both a s i g n i f i c a n t ,  l i n e a r and q u a d r a t i c  trend.  46.  F i g u r e 13:  Mean phase I I PRT as a f u n c t i o n o f I S I  47. TABLE X I I ANALYSIS OF VARIANCE OF PHASE I I PRT  Source o f Variation  df  MS  Ss  5  10465  Cond.  2  13827  10.77  <.005  ISI  3  3541  19.48  <.001  Linear  1  6525  34.0  <.001  Quadratic  1  4034  22.1  <.00l  S x Cond.  10  1283  S x ISI  15  182  6  138  S x Cond. x I S I  30  176  Total  71  Cond. x I S I  0.78  F i g u r e 14 i l l u s t r a t e s t h e mean c o n t r o l PRT, and mean phase I I PRT f o r each c o n d i t i o n as a f u n c t i o n o f I S I .  An a n a l y s i s o f v a r i a n c e  including  t h e t h r e e movement c o m p l e x i t y c o n d i t i o n s i n d i c a t e d t h a t t h e c o n d i t i o n b y I S I i n t e r a c t i o n was n o t s i g n i f i c a n t .  A summary o f t h i s a n a l y s i s appears i n T a b l e X I I .  F i n a l l y , a " t " t e s t was conducted on t h e mean PRT's o f phase I and phase I I .  No s i g n i f i c a n t d i f f e r e n c e was f o u n d .  J  20  i  i  140  80  200  ISI F i g u r e 14:  Mean phase I I PRT f o r each c o n d i t i o n as a f u n c t i o n o f I S I and mean c o n t r o l PRT  i__r  49. DISCUSSION RT - C o n t r o l , Phase I , and Phase I I S i n c e t h e mean c o n t r o l RT's,  p r e s e n t i n F i g u r e 4, were n o t s t a t i s t i -  c a l l y d i f f e r e n t from each o t h e r i t cannot be c o n c l u d e d t h a t movement comp l e x i t y a f f e c t e d RT.  This i n d i c a t e s that the time required t o i n i t i a t e a  r e s p o n s e was u n a f f e c t e d by t h e c o m p l e x i t y execution  o f t h e response.  o f movement r e q u i r e d d u r i n g t h e  On t h e b a s i s o f p r e v i o u s  d e a l i n g s p e c i f i c a l l y with t h i s experimental  emperical i n v e s t i g a t i o n s  v a r i a b l e (Henry, 196l; Henry and  R o d g e r s , i960; N o r r i e , 1967; O ' B r i e n , 1959; S i d o w s k i  e t a l , 1958) i t was  e x p e c t e d t h a t t h e RT r e s u l t s would i n c r e a s e w i t h movement c o m p l e x i t y . assessment o f t h e a n a l y s i s o f v a r i a n c e i n T a b l e I r e v e a l s t h a t no  Detailed  signifi-  cance was f o u n d because o f an u n u s u a l l y l a r g e e r r o r term and i n s p e c t i o n o f t h e raw d a t a d i s c l o s e d a l a r g e l e a r n i n g e f f e c t .  I t was f o u n d t h a t f o r each  S, r e g a r d l e s s o f t h e o r d e r i n w h i c h t h e c o n d i t i o n s were p r e s e n t e d , t h e RT's on day one were always t h e s l o w e s t .  A l s o , t h e s e RT's became p r o g r e s s i v e l y  f a s t e r on day two, and by day t h r e e t h e f a s t e s t RT's were b e i n g r e c o r d e d .  A  second f a c t o r w h i c h c o n t r i b u t e d t o t h e l a r g e e r r o r t e r m was t h e i n c o n s i s t e n t performance o f one S whose c o n t r o l RT appeared t o be much s l o w e r t h a n h i s RT d u r i n g t h e s u c c e s s i v e t a s k a s p e c t o f t h e experiment. Even though t h e r e was no s i g n i f i c a n t d i f f e r e n c e between c o n d i t i o n s i n F i g u r e 4 i t appears t h a t t h e r e was an apparent d i f f e r e n c e a s t h e c o n t r o l RT f o r C2 and C3 seem t o be g r e a t e r t h a n t h e c o n t r o l RT f o r C l .  Considering  t h e r e a s o n s f o r t h e l a c k o f s i g n i f i c a n c e t o be v i a b l e , i t i s p o s s i b l e t o c o n s i d e r t h e decrement i n RT performance t o be a r e f l e c t i o n o f movement complexity.  I n t h i s l i g h t i t c o u l d be i n t e r p r e t e d t h a t C2 and C3 i n v o l v e move-  ments o f g r e a t e r c o m p l e x i t y  than C l .  50. I t i s p o s s i b l e t h a t t h e RT a s p e c t o f t h e experiment was  component d u r i n g t h e s u c c e s s i v e  also biased.  task  From F i g u r e 4 i t i s p o s s i b l e t o  o b s e r v e t h e e f f e c t o f t h e phase I s u c c e s s i v e r e s p o n s e t a s k on t h e RT ponent o f t h e p r i m a r y r e s p o n s e . f o u n d between t h e mean RT  com-  A l t h o u g h no s i g n i f i c a n t d i f f e r e n c e s were  f o r t h e c o n t r o l c o n d i t i o n and t h e  corresponding  mean f o r phase I ( T a b l e TV), t h e g r a p h shows t h a t f o r phase I t h e means a r e a p p r o x i m a t e l y e q u a l whereas t h e t h r e e mean c o n t r o l RT's  tend,  t o be u n e q u a l .  I t seems p o s s i b l e t o c o n c e i v e t h a t d u r i n g t h e d o u b l e s t i m u l a t i o n t a s k S adopted a s t r a t e g y w h i c h d e s i g n a t e d  the  t h e probe t a s k t o be t h e p r i m a r y t a s k  d e s p i t e t h e i n s t r u c t i o n s t o t h e S on t h e i m p o r t a n c e o f t h e f i r s t t a s k .  It  i s i n t e r p r e t e d t h a t t h i s s t r a t e g y would t e n d t o e l i m i n a t e t h e i n f l u e n c e o f movement c o m p l e x i t y  on  RT.  I n a d d i t i o n , t h e f i n d i n g t h a t RT d i f f e r e d over I S I i n d i c a t e s t h a t RT was  a f f e c t e d by t h e p o s i t i o n o f t h e probe d u r i n g t h e RT  t h e b a s i s o f r e c e n t l i t e r a t u r e (Herman and McCauley, 1969) t h a t no I S I e f f e c t on RT  interval. i t was  On  expected  s h o u l d be o b s e r v e d f o r I S I g r e a t e r t h a n 50 t o  msec, or a t t h e most, i f t h e r e was  an I S I e f f e c t , i t was  f e l t that  l o n g e r t h e I S I , or t h e l a t e r t h e o c c u r r e n c e o f t h e p r o b e d u r i n g t h e i n t e r v a l , t h e l e s s would be t h e e f f e c t on t h e RT  itself.  100  the RT  However, t h i s  was  o b v i o u s l y not t h e c a s e because t h e r e s u l t s showed a t r e n d i n t h e d i r e c t i o n opposite t o t h a t p r e d i c t e d , i n t h a t the longer the I S I the slower the  RT  became. Two  i n t e r p r e t a t i o n s o f t h e s e r e s u l t s seem p o s s i b l e .  t h e model employed i n t h e p r e s e n t s t u d y , t h e e x p e r i m e n t a l  c o n d i t i o n s were  designed to overload the l a t e r stages of the c e n t r a l processor. r e g a r d , when t h e p r o b e o c c u r r e d  According  In t h i s  during these stages i t i s p o s s i b l e t h a t  to  51.  perhaps t h e r e would be a g r e a t e r performance decrement due m e r e l y t o t h e i n t e r u p t i o n , o r even t h e u s e o f some o f t h e a t t e n t i o n c a p a c i t y t o s t o r e t h e probe i n f o r m a t i o n i n s h o r t t e r m memory.  Thus, s i n c e t h e mean RT f o r a l l  t r i a l s d u r i n g phase I was 245 msec, i t i s c o n c e i v a b l e t h a t t h e l a t e r t h e p r e s e n t a t i o n o f t h e p r o b e , t h e c l o s e r would, be i t s r e l a t i v e p o s i t i o n t o those processes associated w i t h the i n i t i a t i o n o f the primary response. C o n s e q u e n t l y , i f t h i s were t o be t h e c a s e , we would expect t h e probe t o have t h e l e a s t e f f e c t on C l and g r e a t e r e f f e c t on C2 and C3 because o f t h e i r i n c r e a s e d demands. greatest for C l .  B u t , F i g u r e 4 shows t h a t t h e mean RT f o r a l l I S I was  T h i s i n d i c a t e s t h a t t h e e f f e c t o f t h e probe was n o t due t o  i t s p o s i t i o n r e l a t i v e t o those processes associated w i t h the i n i t i a t i o n of the primary response. A second i n t e r p r e t a t i o n c o u l d be t h a t t h e S's used a s t r a t e g y o f "grouping"  ( W e l f o r d , 19°7), t h a t i s , t h e S w a i t e d f o r t h e p r e s e n t a t i o n o f t h e  second s t i m u l u s b e f o r e i n i t i a t i n g h i s r e s p o n s e t o t h e f i r s t s t i m u l u s . more complex t h e f i r s t r e s p o n s e , t h e more t h e S would d e l a y .  The  I t i s suggested  t h a t t h e S adopted t h i s s t r a t e g y d u r i n g t h e s u c c e s s i v e r e s p o n s e t a s k because o f t h e i n c r e a s e d demands p l a c e d on t h e S's m e n t a l o p e r a t i o n s .  So i t would  f o l l o w t h a t an i n c r e a s e o f t h e s e demands would r e s u l t i n a more pronounced "grouping"  s t r a t e g y , o r , t h e more complex t h e f i r s t r e s p o n s e , t h e more t h e S  would d e l a y .  But t h i s was n o t t h e case as t h e mean RT f o r a l l I S I o f t h e two  more complex c o n d i t i o n s tended t o be f a s t e r ( F i g u r e 4).  Also, i f the S  w a i t e d f o r t h e second s t i m u l u s t o o c c u r , we would expect C2 and C3 t o be l o n g e r because t h e s e two c o n d i t i o n s i n c l u d e d t h e l o n g e r I S I ' s o f 170, and 170 and 190 r e s p e c t i v e l y .  Nevertheless,  there i s evidence supporting t h e  52.  c o n t e n t i o n t h a t t h e S's were g r o u p i n g .  Probes d u r i n g t h e MT i n t e r v a l o f  t h e p r i m a r y r e s p o n s e s h o u l d not i n f l u e n c e t h e RT i n t e r v a l .  However, RT's  d u r i n g phase I I o b v i o u s l y were much slower ( F i g u r e 4) t h a n f o r c o n t r o l and phase I RT's.  I f t h e S's were g r o u p i n g , t h i s would be expected a s t h e probe  would n o t be o c c u r r i n g u u n t i l much l a t e r i n phase I I .  PRT - Phase I A r e v i e w o f p r e v i o u s i n v e s t i g a t i o n s o f t h e e f f e c t s o f movement c o m p l e x i t y r e v e a l e d t h a t t h e work i n t h i s a r e a was i n c o m p l e t e . i n v e s t i g a t o r s (Henry, 1959;  Several  1961; Henry and Rodgers, I960; N o r r i e , I967; O ' B r i e n ,  S i d o w s k i e t a l , 1958)  have c l a i m e d t h a t RT was an a c c u r a t e measurement  of t h e e f f e c t s o f movement c o m p l e x i t y on t h e o p e r a t i o n s o f .'man's c e n t r a l p r o c e s s i n g system.  B u t t h e p o s s i b i l i t y e x i s t e d t h a t t h e changes i n RT c o u l d  be t h e r e s u l t o f p e r i p h e r a l f a c t o r s and n o t o f t h e o p e r a t i o n s w i t h i n t h e central processor. possibility.  The c u r r e n t experiment was d e s i g n e d t o i n v e s t i g a t e t h i s  I  I t was h y p o t h e s i z e d t h a t C3 would have t h e g r e a t e s t e f f e c t i n d e l a y i n g RT, w i t h C2 a l s o h a v i n g a l a r g e e f f e c t on RT b u t l e s s t h a n C3, and C l having the smallest e f f e c t .  F i g u r e 4 shows t h a t b a s i c a l l y t h e s e r e s u l t s  were o b t a i n e d , mean RT's f o r C2 and C3 were s l o w e r t h a n f o r C l , however, C2 had a g r e a t e r d e l a y t h a n C3.  B u t , t h e i n t e r e s t i n g p o i n t i s t h a t t h e mean  PRT's d u r i n g phase I have f o l l o w e d t h e exact same t r e n d , C2 and C3 a r e g r e a t e r t h a n C l , and C2 i s g r e a t e r t h a n C3 , a l t h o u g h n o t s i g n i f i c a n t l y i n b o t h :  instances.  T h i s s u g g e s t s t h a t i n t h i s experiment RT i s an a c c u r a t e barometer  o f t h e o p e r a t i o n s o f man's c e n t r a l p r o c e s s i n g  system.  53.  U s i n g c o n t r o l PRT  as a s t a n d a r d  n e c e s s a r y t o i n i t i a t e a r e s p o n s e , i t was a l l c o n d i t i o n s o f movement c o m p l e x i t y  o f t h e minimum o f a t t e n t i o n f o u n d t h a t t h e PRT  (Figure 7)•  increased  for  This indicated that  a t t e n t i o n p r i o r t o t h e i n i t i a t i o n o f a r e s p o n s e i n c r e a s e d as a f u n c t i o n o f t h e movement c o m p l e x i t y i n c r e a s e i n PRT  r e q u i r e d during the execution of the response.  from C l t o C2 and C3 was  l i n e a r (Table V ) .  I t was  The  interpreted  t h a t t h e i n c r e a s e from c o n t r o l t o C l c o u l d be att'r.'ibuted-Jt'o t h e e f f e c t s o f movement c o m p l e x i t y  and t h e s u c c e s s i v e  stimuli effect.  and C3 were s i g n i f i c a n t l y d i f f e r e n t from C l t h i s was t h a t t h e d i f f e r e n c e from C l t o C2, effect.  Thus i t was  However, s i n c e  i n t e r p r e t e d as  and C l t o C'3 must be due t o t h e  C2  evidence complexity  c o n c l u d e d t h a t t h e r e l a t i v e degree o f a t t e n t i o n n e c e s s a r y  t o i n i t i a t e a motor r e s p o n s e v a r i e s d i r e c t l y w i t h t h e c o m p l e x i t y  o f movement  r e q u i r e d during the execution of that response. The  s i g n i f i c a n c e o f t h e I S I main e f f e c t ( T a b l e V I ) i n d i c a t e d t h a t  t h e l o c a t i o n o f t h e probe w i t h i n t h e RT on t h e d e l a y i n PRT.  i n t e r v a l had a s i g n i f i c a n t  As e x p e c t e d , t h e l a t e r o c c u r r e n c e s o f t h e probe r e s u l t e d  i n p r o g r e s s i v e l y f a s t e r PRT's i n a l i n e a r t r e n d . c h a n n e l t h e o r y i n t h a t t h e probes t h a t o c c u r r e d c e n t r a l processor  influence  This ^supports the s i n g l e l a t e r acquired access to  sooner r e s u l t i n g i n a d e c r e a s e d  the  PRT.  The r e s u l t s o f t h e c o n d i t i o n by I S I i n t e r a c t i o n ( T a b l e V I ) were not s i g n i f i c a n t i n d i c a t i n g t h a t t h e I S I ' s had a s i m i l a r e f f e c t on a l l c o n d i t i o n s . F i g u r e 9 a l s o r e v e a l s t h a t C2 had t h e g r e a t e s t e f f e c t on PRT which i s c o n s i s t e n t w i t h the previous  for, a l l I S I ,  apparent d i f f e r e n c e s .  MT - C o n t r o l , Phase I and Phase I I I t was  e v i d e n t from F i g u r e 10 t h a t t h e MT  increased with  the  54.  c o m p l e x i t y o f movement r e q u i r e d d u r i n g t h e r e s p o n s e .  The r e s u l t s o f t h e  s t a t i s t i c a l a n a l y s i s f o r c o n t r o l c o n d i t i o n s ( T a b l e V I I ) showed a l a r g e e f f e c t o f movement  complexity.  I t was i n t e r e s t i n g t o n o t e t h a t t h e p r e s e n t a t i o n o f t h e probe d u r i n g t h e MT i n t e r v a l had a s i m i l a r e f f e c t o n MT as t h e p r e s e n t a t i o n o f t h e probe d u r i n g t h e RT i n t e r v a l .  That i s , d u r i n g c o n t r o l and phase I t h e e f f e c t o f  c o m p l e x i t y i n c r e a s e d MT t o a s i g n i f i c a n t amount, however, when t h e probe was presented  d u r i n g t h e MT t h e d i f f e r e n c e between t h e two l e v e l s o f c o m p l e x i t y  i n terms o f MT was n o t l a r g e enough t o r e a c h s i g n i f i c a n c e .  However, i f t h e  demands o f t h e t a s k were i n a c t u a l i t y i n c r e a s e d d u r i n g phase I I , i t would be e x p e c t e d t h a t t h e mean MT's f o r phase I I w o u l d be g r e a t e r t h a n t h e means f o r the c o n t r o l c o n d i t i o n s .  B u t , t h i s was n o t t h e c a s e .  Table X revealed that  t h e r e was a s i g n i f i c a n t d i f f e r e n c e due' t o t h e p r e s e n t a t i o n o f t h e p r o b e , however, t h e S c h e f f e showed t h a t t h i s d i f f e r e n c e was between phase I and phase I I .  There was no e x p l a n a t i o n why phase I MT was f a s t e r t h a n c o n t r o l  and t h u s why a d i f f e r e n c e was found between t h e p h a s e s . The  s i g n i f i c a n c e o f t h e I S I main e f f e c t ( T a b l e V I I I ) i n d i c a t e d  t h a t t h e l o c a t i o n o f t h e probe d u r i n g t h e MT i n t e r v a l i n t e r f e r e d w i t h t h e MT. However, f r o m F i g u r e 11 i t appeared t h a t t h e s e e f f e c t s were n e g l i g i b l e . PRT - Phase I I The f i n d i n g t h a t PRT i n c r e a s e d as a f u n c t i o n o f movement  complexity  i n d i c a t e s that a t t e n t i o n during the execution o f a response v a r i e s d i r e c t l y w i t h t h e r e l a t i v e degree o f c o n t r o l n e c e s s a r y  t o execute t h a t response.  It  was e v i d e n t from F i g u r e 12 t h a t a t t e n t i o n was r e q u i r e d d u r i n g t h e e x e c u t i o n o f a l l responses.  A l s o , i t was apparent t h a t movements t e r m i n a t e d a t a t a r g e t  (C2 and C3) r e q u i r e d more a t t e n t i o n d u r i n g t h e f i r s t 200 msec, o f t h e movement  55.  t h a n d i d a n o n - t e r m i n a l movement ( C l ) .  F u r t h e r , a t t e n t i o n needed d u r i n g a  r o t a t i o n a l movement t o a t a r g e t was g r e a t e r t h a n t h a t r e q u i r e d f o r movements t o a t a r g e t n o t i n v o l v i n g arm r o t a t i o n s as C3 was g r e a t e r t h a n C2. The  s i g n i f i c a n t I S I e f f e c t (Table X I I ) s u g g e s t s t h a t t h e amount o f  a t t e n t i o n r e q u i r e d by t h e S v a r i e d w i t h t h e p o s i t i o n o f t h e probe d u r i n g t h e MT i n t e r v a l .  The g r a p h i c a l r e p r e s e n t a t i o n o f t h e PRT d a t a as a f u n c t i o n o f  I S I ( F i g u r e 13) p o i n t s out t h a t movement e x e c u t i o n r e q u i r e s more a t t e n t i o n e a r l y i n t h e movement t h a n l a t e r i n t h e movement, and t h a t near t h e end o f t h e movement t h e r e was a r e l a t i v e i n c r e a s e i n PRT s u g g e s t i n g r e q u i r e m e n t s were i n c r e a s i n g .  that attention  These r e s u l t s a r e s i m i l a r t o t h o s e  reported  by Posner and K e e l e (19°8). The  I S I by c o n d i t i o n i n t e r a c t i o n was n o t s i g n i f i c a n t ( T a b l e X I I )  i n d i c a t i n g t h a t t h e I S I ' s had a s i m i l a r e f f e c t on a l l c o n d i t i o n s * .  But  F i g u r e 14 r e v e a l s t h a t t h e i n c r e a s e i n a t t e n t i o n d u r i n g t h e l a t e r s t a g e s o f t h e movement as p o i n t e d out above, a p p l i e d o n l y t o t h o s e movements t e r m i n a t e d at the t a r g e t .  The PRT a t t h e 200 msec. I S I d i d n o t i n c r e a s e f o r C l s u g g e s t i n g  t h a t t h e i n c r e a s e d a t t e n t i o n d u r i n g t h e l a t e r p e r i o d o f MT was r e l a t e d t o the S having t o s t r i k e t h e t a r g e t . and Kay  T h i s s u p p o r t s t h e work o f A n n e t t , G o l b y  (1968) who d i d a d e t a i l e d f i l m a n a l y s i s o f movement t o a t a r g e t and  found t h a t a l t h o u g h MT v a r i e d w i t h t h e s i z e o f t h e t a r g e t , t h e i n i t i a l o f t h e t o t a l d i s t a n c e was always c o n s t a n t .  15/l6  The f i n a l adjustment t i m e  d u r i n g t h e l a s t l / l 6 o f t h e d i s t a n c e i n c r e a s e d as t h e s i z e o f t h e t a r g e t decreased.  I t was i n t e r p r e t e d i n t h i s s t u d y t h a t i t was t h e s e f i n a l a d j u s t m e n t s  as t h e t a r g e t was approached t h a t caused t h e i n c r e a s e a t t e n t i o n . These r e s u l t s ( F i g u r e 14) r e j e c t t h e " e x p e c t a n c y t h e o r y " w h i c h a l s o p r e d i c t e d t h a t PRT would be a "U" shaped f u n c t i o n o f I S I , w i t h t h e minimum  56.  PRT v a l u e o c c u r r i n g a t o r about t h e mean o r ' e x p e c t e d  v a l u e s o f I S I and t h a t  as t h e d i s t a n c e o f t h e probe from t h e mean i n c r e a s e d , PRT would become progressively increased.  However, s i n c e t h i s t h e o r y i s based upon t h e S's  l e a r n i n g t h e I S I d i s t r i b u t i o n and n o t upon t h e p r o c e s s i n g r e q u i r e d f o r t h e p r i m a r y r e s p o n s e , t h i s t h e o r y would p r e d i c t t h a t d e l a y s i n PRT would be t h e same f o r t h e t h r e e c o n d i t i o n s o f movement c o m p l e x i t y because i d e n t i c a l I S I ' s were u s e d .  However, F i g u r e 14 c l e a r l y i n d i c a t e s t h a t t h e r e were d i f f e r e n c e s  i n the ordinates of the three functions.  Further evidence against  this  t h e o r y was t h e f i n d i n g t h a t t h e "U" shaped t r e n d was n o t c o n s i s t e n t t h r o u g h out a l l c o n d i t i o n s .  The i n c r e a s e d a t t e n t i o n near t h e end o f movement  o n l y i n movements t e r m i n a t e d  occurred  at a target.  Comparison o f A t t e n t i o n D u r i n g Phase I and Phase I I The  PRT r e s u l t s o f phase I and phase I I i n d i c a t e t h a t t h e a t t e n t i o n  r e q u i r e m e n t s o f t h e two component p r o c e s s e s o f a r e s p o n s e a r e i n d e p e n d e n t . I t has been e s t a b l i s h e d t h a t t h e t i m e r e q u i r e d f o r t h e i n i t i a t i o n and e x e c u t i o n o f a r e s p o n s e a r e independent (Henry and Rodgers, I960; Henry, F i t t s and P e t e r s o n ,  1964;  F i t t s and R a d f o r d , I 9 6 6 ) .  T h i s was a l s o  1961;  evident  i n t h e d a t a o f t h i s s t u d y as t h e apparent e f f e c t o f movement c o m p l e x i t y on RT was g r e a t e s t f o r C 2 , and f o l l o w e d a t r e n d o f b e i n g somewhat l e s s f o r C3 and much l e s s f o r C l ( F i g u r e 4)•  The a t t e n t i o n r e q u i r e m e n t s d u r i n g t h e  i n i t i a t i o n o f the response c l o s e l y followed t h i s p a t t e r n , r e f l e c t i n g the time r e q u i r e d t o i n i t i a t e a r e s p o n s e ( F i g u r e 7). complexity  B u t , t h e e f f e c t o f movement  on MT was r e v e r s e d as C3 had a s i g n i f i c a n t l y l a r g e r  p e r i o d t h a n C2 ( F i g u r e 10),  execution  and i n t e r e s t i n g l y enough, t h e PRT d u r i n g phase  I I f o l l o w e d t h e exact same t r e n d ( F i g u r e  12).  57.  Comparison o f t h e r e l a t i v e degree o f a t t e n t i o n needed d u r i n g each o f t h e two component p r o c e s s e s r e v e a l e d t h a t more a t t e n t i o n was needed during t h e i n i t i a t i o n o f a response.  The mean o f a l l phase I I PRT's was  237 m s e c , w h i l e t h e mean o f a l l phase I PRT's was o n l y 250 msec. f i n d i n g i s i n agreement w i t h t h e work done b y E l l s (1969).  This  CHAPTER V SUMMARY AND CONCLUSIONS  The purpose o f t h i s s t u d y was t o d e t e r m i n e t h e e f f e c t s o f movement c o m p l e x i t y on t h e r e l a t i v e degree o f a t t e n t i o n r e q u i r e d d u r i n g t h e i n i t i a t i o n o f a r e s p o n s e and t h e e x e c u t i o n o f a movement.  T h r e e movements o f v a r y i n g  c o m p l e x i t y were s e l e c t e d on t h e b a s i s o f RT measurements o b t a i n e d from a p i l o t study.  S i x male r i g h t handed u n i v e r s i t y s t u d e n t s were p a i d t o a t t e n d  t h r e e two and one h a l f hour s e s s i o n s on c o n s e c u t i v e d a y s .  A t t e n t i o n was  c o n s i d e r e d t o be t h e d e l a y i n r e a c t i o n t i m e t o a second s t i m u l u s o r probe t h a t was t o be p r o c e s s e d  d u r i n g e i t h e r t h e i n i t i a t i o n o f t h e r e s p o n s e (phase  I ) o r t h e e x e c u t i o n o f t h e r e s p o n s e (phase I I ) t o t h e f i r s t s t i m u l u s .  This  probe r e a c t i o n t i m e (PRT) was examined as a f u n c t i o n o f movement c o m p l e x i t y required during the f i r s t  response.  I t was f o u n d t h a t t h e mean c o n t r o l RT f o r each o f t h e t h r e e t a s k s d i d n o t s t a t i s t i c a l l y d i f f e r a l t h o u g h movement c o m p l e x i t y d i d appear t o have some e f f e c t on RT as t h e r e seemed t o be an apparent d i f f e r e n c e between t h e mean c o n t r o l RT's o f t h e two more complex t a s k s and t h e mean RT o f t h e simplest task. When t h e p r o b e was p r e s e n t e d d u r i n g t h e RT phase o f t h e t h r e e t a s k s i t was f o u n d t h a t t h e l o n g e r t h e i n t e r v a l between t h e s t i m u l u s t o t h e t a s k and t h e s t i m u l u s t o t h e p r o b e , t h e l o n g e r was t h e RT t o s t i m u l u s one. suggested  t h a t t h e s u b j e c t adopted a s t r a t e g y w h i c h had t h e e f f e c t o f  e l i m i n a t i n g t h e i n f l u e n c e o f movement c o m p l e x i t y .  This  59.  C o n t r o l PRT ( i . e . r e a c t i o n t o t h e probe i n t h e absence o f t h e p r i m a r y t a s k ) was u s e d as a s t a n d a r d f o r t h e minimum o f a t t e n t i o n n e c e s s a r y t o i n i t i a t e a r e s p o n s e , and i t was shown t h a t PRT d u r i n g phase I i n c r e a s e d f o r a l l c o n d i t i o n s o f movement c o m p l e x i t y , f o l l o w i n g t h e exact same t r e n d as t h e c o n t r o l RT means.  C o n c l u s i v e e v i d e n c e i n support o f t h e s i n g l e c h a n n e l  t h e o r y ( a b a s i c a s s u m p t i o n o f t h i s e x p e r i m e n t ) was t h a t t h e l o n g e r t h e i n t e r v a l between s t i m u l u s one and s t i m u l u s two, t h e s h o r t e r was t h e r e a c t i o n t i m e t o s t i m u l u s two (PRT). MT i n c r e a s e d w i t h t h e c o m p l e x i t y o f movement r e q u i r e d d u r i n g t h e execution o f t h e response.  A l s o , p r e s e n t a t i o n o f t h e probe d u r i n g t h e MT  i n t e r v a l had an e f f e c t on MT s i m i l a r t o t h e s u c c e s s i v e s t i m u l i on RT, t h e i n f l u e n c e o f movement.complexity was removed. PRT i n c r e a s e d w i t h t h e c o m p l e x i t y o f movement r e q u i r e d d u r i n g t h e e x e c u t i o n o f a r e s p o n s e , f o l l o w i n g t h e p a t t e r n o f t h e MT r e s u l t s .  Movement  t e r m i n a t e d a t a t a r g e t r e q u i r e d more a t t e n t i o n d u r i n g t h e f i r s t 200 msec, o f t h e movement t h a n d i d a n o n - t e r m i n a l movement.  R o t a t i o n a l movement t o  a t a r g e t r e q u i r e d g r e a t e r a t t e n t i o n t h a n t h a t r e q u i r e d f o r movement t o a target  n o t i n v o l v i n g arm r o t a t i o n .  Also!], t h e e v i d e n c e suggested movement  e x e c u t i o n r e q u i r e s more a t t e n t i o n e a r l y i n t h e movement t h a n l a t e r i n t h e movement.  I n a d d i t i o n , movements t e r m i n a t e d a t a t a r g e t show a n ' i n c r e a s e i n  a t t e n t i o n demands near t h e end o f movement r e l a t i v e t o t h e a t t e n t i o n demands d u r i n g t h e m i d d l e o f t h e movement. f o r t h e s i n g l e channel  theory.  These r e s u l t s p r o v i d e d a d d i t i o n a l support  60.  The c o n c l u s i o n s o f t h i s experiment 1.  were:  That f o r t h e purposes and c o n d i t i o n s o f t h i s experiment t h e  s i n g l e c h a n n e l t h e o r y s u f f i c i e n t l y d e s c r i b e s t h e o p e r a t i o n s o f man's c e n t r a l p r o c e s s i n g system. 2.  That t h e e f f e c t o r p r o c e s s e s t h a t c o n t r o l t h e i n i t i a t i o n and  e x e c u t i o n o f a r e s p o n s e demand a t t e n t i o n w i t h i n t h e l i m i t e d c a p a c i t y c e n t r a l p r o c e s s i n g mechanism. 3.  The a t t e n t i o n demands o f a motor r e s p o n s e t e n d t o v a r y w i t h  the r e l a t i v e complexity o f t h e response  as w e l l as t h e p o s i t i o n o f t h e  r e s p o n d i n g l i m b when i t i s moving t o a t a r g e t . 4.  That RT i s an a c c u r a t e i n d i c a t i o n o f t h e a t t e n t i o n demands  r e q u i r e d d u r i n g t h e i n i t i a t i o n o f a response. 5.  That MT as s t u d i e d i n t h e p r e s e n t experiment  i s an a c c u r a t e  i n d i c a t i o n o f t h e o v e r a l l a t t e n t i o n demands r e q u i r e d d u r i n g t h e e x e c u t i o n of a response.  REFERENCES  62.  REFERENCES A n n e t t , J . , G o l b y , C.W., and Kay, H. The measurement o f elements i n a n assembly t a s k - t h e i n f o r m a t i o n o u t p u t o f t h e human motor system. Q u a r t e r l y J o u r n a l o f E x p e r i m e n t a l P s y c h o l o g y , 10: 1-11, 1958." B e r t e l s o n , P. C e n t r a l i n t e r m i t t e n c y t w e n t y y e a r s l a t e r .  Quarterly  Journal  o f E x p e r i m e n t a l P s y c h o l o g y , 18: 153-163, 1966. Broadbent, D.E. P e r c e p t i o n and Communication. Mew Y o r k :  1958.  Peramon P r e s s ,  Broadbent, D.E. and Gregory, M. P s y c h o l o g i c a l r e f r a c t o r y p e r i o d and the„_ l e n g t h o f t i m e r e q u i r e d t o make a d e c i s i o n . P r o c e e d i n g s o f t h e R o y a l S o c i e t y . 168: 181-193, 1967. Crossman, E.R.F.W. I n f o r m a t i o n p r o c e s s e s i n human s k i l l . B u l l e t i n , 20 ( l ) : 32-37, 1964.  British  D a v i s , R. The l i m i t s o f t h e " p s y c h o l o g i c a l r e f r a c t o r y p e r i o d " . J o u r n a l o f E x p e r i m e n t a l P s y c h o l o g y , 8: 24-38, 1956. E l l s , J-..G. A t t e n t i o n a l r e q u i r e m e n t s o f movement c o n t r o l . D o c t o r a l D i s s e r t a t i o n , U n i v e r s i t y o f Oregon, 1969.  Medical  Quarterly  Unpublished  F i t t s , P.M. and P e t e r s o n , J.R. I n f o r m a t i o n c a p a c i t y o f d i s c r e t e motor r e s ponses. J o u r n a l o f E x p e r i m e n t a l P s y c h o l o g y , 67 (2): 103-112, 1964. F i t t s , P.M. and R a d f o r d , B.K. I n f o r m a t i o n c a p a c i t y o f d i s c r e t e motor r e s ponses under d i f f e r e n t c o g n i t i v e s e t s . J o u r n a l o f E x p e r i m e n t a l  Psychology. 71 (4): 475-482, 1966.  Greenwald, A.G. S e n s o r y feedback mechanisms i n performance c o n t r o l : W i t h s p e c i a l r e f e r e n c e t o t h e i d i o - m o t o r mechanism. P s y c h o l o g i c a l Review,  77: 73-99, 1970.  Henry, F.M. S t i m u l u s c o m p l e x i t y , movement c o m p l e x i t y , age, and s e x i n r e l a t i o n t o r e a c t i o n l a t e n c y and speed i n l i m b movements. R e s e a r c h Q u a r t e r l y ,  32: 353-366, 1961.  Henry, F.M. and R o d g e r s , D.E. "Increased r e s p o n s e l a t e n c y f o r c o m p l i c a t e d movements and a "memory drum", t h e o r y o f neuromotor r e a c t i o n . R e s e a r c h Q u a r t e r l y . 31 (3): 448-458, i960. Herman, L.M. and K a n t o w i t z , B.H. The p s y c h o l o g i c a l r e f r a c t o r y p e r i o d e f f e c t : Only h a l f t h e double s t i m u l a t i o n story? . P s y c h o l o g i c a l B u l l e t i n ,  73 (1): 74-88, 1970.  Herman, L.M. and McCauley, M.E. D e l a y i n r e s p o n d i n g t o t h e f i r s t s t i m u l u s i n t h e " P s y c h o l o g i c a l R e f r a c t o r y P e r i o d " experiment: Comparisons w i t h d e l a y produced b y a second s t i m u l u s n o t r e q u i r i n g a r e s p o n s e . Journal  o f E x p e r i m e n t a l P s y c h o l o g y , 81 (2): 344-350, 1969.  63. H i g g i n s , J.R. and A n g e l , R.W. C o r r e c t i o n o f t r a c k i n g e r r o r s w i t h o u t sensoryf e e d b a c k . J o u r n a l o f E x p e r i m e n t a l P s y c h o l o g y , 84 (3): 412-416, 1970. Karlin,  L. and Kestenbaum, R. E f f e c t s o f number o f a l t e r n a t i v e s on t h e psychological r e f r a c t o r y period. Quarterly Journal o f Experimental  P s y c h o l o g y . 20 (2): 167-178, 1968.  K e e l e , S.W. Movement c o n t r o l i n s k i l l e d motor performance. B u l l e t i n , 70 (6): 387-403, 1968. K i m b l e , G.A. and P e r l m u t e r , L.C. The problem o f v o l i t i o n .  Psychological Psychological  Review, 77 (5): 361-384, 1970. M a r t e n i u k , R.G. K i n e s t h e t i c i n f o r m a t i o n and t h e c o n t r o l o f movement. U n p u b l i s h e d paper, The U n i v e r s i t y o f B r i t i s h Columbia, 1970. M i l l e r , G.A., G a l a n t e r , E., and P r i b r a m , K.H. P l a n s and t h e S t r u c t u r e o f B e h a v i o u r . New Y o r k : H o l t , Rhinehart- and Winston, i960. N o r r i e , M.L. P r a c t i c e e f f e c t s on r e a c t i o n l a t e n c y f o r s i m p l e and complex movements. R e s e a r c h Q u a r t e r l y , 38 ( l ) : 79-85, 1967. O ' B r i e n , P.E. The r e l a t i o n between r e a c t i o n t i m e and t h e t y p e and c o m p l e x i t y of t h e s u c c e e d i n g t a s k . U n p u b l i s h e d M a s t e r s T h e s i s , The P e n n s y l v a n i a S t a t e U n i v e r s i t y , 1959. P o s n e r , M.I. The n a t u r a l h i s t o r y o f movement c o n t r o l . Paper p r e s e n t e d a t t h e f i r s t Canadian symposium on Psycho Motor L e a r n i n g and S p o r t s P s y c h o l o g y , Edmonton, A l b e r t a , 1969. P o s n e r , M.I. and B o i e s , S . J . Components o f a t t e n t i o n . P o r t i o n o f a paper p r e s e n t e d i n a n a d d r e s s t o t h e Western P s y c h o l o g i c a l A s s o c i a t i o n ,  1970.  P o s n e r , M.I. and K e e l e , S.W. A t t e n t i o n demands o f movement. P r o c e e d i n g s o f t h e S i x t e e n t h I n t e r n a t i o n a l Congress o f A p p l i e d P s y c h o l o g y . Amsterdam: Z w i t z and Z e i t l i n g e r , I969. 4  P o s n e r , M.I. and K e e l e , S.W. Time and space as measures o f m e n t a l o p e r a t i o n s . Paper p r e s e n t e d t o t h e American P s y c h o l o g i c a l A s s o c i a t i o n , 1970. R a b b i t t , P.M.A.  E r r o r c o r r e c t i o n time without e x t e r n a l error s i g n a l s .  212: 438, 1966(a).  Nature,  R a b b i t t , P.M.A. E r r o r s and e r r o r c o r r e c t i o n i n c h o i c e - r e s p o n s e t a s k s . J o u r n a l o f E x p e r i m e n t a l P s y c h o l o g y . 71 (2): 264-272, 1966(b). R a b b i t t , P. Time t o d e t e c t e r r o r s a s a f u n c t i o n o f f a c t o r s a f f e c t i n g c h o i c e r e s p o n s e t i m e . A c t a P s y c h o l o g i c a , 27: 131-142, 1967. R e y n o l d s , D. E f f e c t s o f double s t i m u l a t i o n : P s y c h o l o g i c a l B u l l e t i n . 62: 333-347,  Temporal i n h i b i t i o n  1964.  o f response.  64. S c h e f f e , H. The A n a l y s i s o f V a r i a n c e . I n c . , 1964.  New Y o r k :  John W i l e y and Sons,  S i d o w s k i , J.B., Morgan, R.,.and E c k s t r a n d , G-. I n f l u e n c e o f t a s k c o m p l e x i t y and i n s t r u c t i o n s upon s i m p l e and d i s c r i m i n a t i o n r e a c t i o n t i m e s . J o u r n a l o f E x p e r i m e n t a l P s y c h o l o g y , 55: 163-166, 1958. S c h u t z , R.W. Motor-memory r e t r i e v a l - a t h e o r y and m a t h e m a t i c a l model. Paper p r e s e n t e d a t t h e 74th A n n u a l C o n f e r e n c e o f t h e N a t i o n a l C o l l e g e P h y s i c a l E d u c a t i o n A s s o c i a t i o n f o r Men, 1970. S m i t h , J.L. K i n e s t h e s i s : A model f o r movement feedback. I n R.C.'Brown and B . J . C r a t t y ( E d s . ) . New P e r s p e c t i v e s o f Man i n A c t i o n , Englewood Cliffs: P r e n t i c e H a l l I n c . , 1969. S m i t h , M.C. E f f e c t o f v a r y i n g c h a n n e l c a p a c i t y on s t i m u l u s d e t e c t i o n and d i s c r i m i n a t i o n . J o u r n a l o f E x p e r i m e n t a l P s y c h o l o g y , 82: 520-526,  1969(a). S m i t h , M.C. The e f f e c t o f v a r y i n g i n f o r m a t i o n on t h e p s y c h o l o g i c a l r e f r a c t o r y p e r i o d . A c t a P s y c h o l o g i c a , 30: 220-231, 1969(b). S m i t h , M.C. The p s y c h o l o g i c a l r e f r a c t o r y p e r i o d a s a f u n c t i o n o f performance of a f i r s t response. Quarterly Journal o f Experimental Psychology,  19: 350-352, 1967(a).  S m i t h , M.C. T h e o r i e s o f t h e p s y c h o l o g i c a l r e f r a c t o r y p e r i o d . B u l l e t i n , 67(3): 202-213, 1967(b).  Psychological  W e l f o r d , A.T. E v i d e n c e o f a s i n g l e c h a n n e l d e c i s i o n mechanism l i m i t i n g p e r formance i n a s e r i a l r e a c t i o n t a s k . Q u a r t e r l y J o u r n a l o f E x p e r i m e n t a l  P s y c h o l o g y , 11: 193-210, 1959. W e l f o r d , A.T. Performance, b i o l o g i c a l mechanisms and age: A theoretical s k e t c h . B e h a v i o u r , A g i n g and t h e Nervous System, e d i t e d b y W e l f o r d , A.T. and B i r r e n , J . E . S p r i n g f i e l d , I l l i n o i s : C C . Thomas, 1965. Welford,  A.T.  Single-channel operation i n the brain.  27: 5-22, 1967.  Acta  Psychologica,  APPENDIX A PILOT STUDY  66.  TABLE OF RT MEANS FOR EACH CONDITION Cl  C2  C3  51  197  203  226  52  176  194  209  53  177  191  202  54  162  197  209  X  178  196  211  TABLE OF MT MEANS FOR EACH CONDITION  SI.  C2  C3  Sl  166  220  52  143  228  53  177  214  54  162  237  x  162  225  APPENDIX B INDIVIDUAL MEAN SCORES  6 8 .  TABLE OF MEANS FOR CONTROL RT BY CONDITION Cl  C2  C3  X  SI  275  347  262  295  S2  2 L 4  2 1 7  2 3 2  2 2 1  S3  2 1 4  2 3 5  256  235  S 4  206  2 1 6  2 1 2  2 1 1  S5  220  256  2 5 8  245  S6  236  .212  2 1 3  2 2 1  X  228  247  238  238  TABLE OF MEANS FOR CONTROL MT BY CONDITION X  C3  C2  SI  186  2 1 4  2 0 0  S2  1 8 7  225  206  S3  148  2 2 0  1 8 4  S4  2 0 0  2 3 4  2 1 7  S5  196  202  199  S6  1 7 9  211  195  X  183  218  200  TABLE OF MEANS FOR CONTROL PRT BY CONDITION Cl  C2  C3  X  SI  193  2 1 4  1 7 4  1 9 4  S2  189  173  1 6 4  175  S3  1 6 8  2 1 5  193  192  S 4  181  172  176  176  S5  192  1 9 4  1 7 7  188  S6  183  172  162  172  X  1 5 4  1 9 0  1 7 4  183  69. TABLE OF MEANS FOR PHASE I RT BY CONDITION  Cl  C2  C3  X  51  284  296  261  280  52  253  217  226  232  53  226  243  270  247  54  234  220  240  231  55  245  255  234  245  56  254  225  218  232  x  250  243  241  245  TABLE OF MEANS FOR PHASE I FT BY I S I I S I 90  ISI  no  I S I 130  I S I 150  X  Sl .  264  274  287  296  280  S2  220  230  239  240  232  S3  241  249  256  247  S4  239 224  227  238  236  231  S5  239  244  248  249  245  S6  219  230  236  245  232  X  234  241  250  254  245  TABLE OF MEANS FOR PHASE I RT FOR CONDITION BY I S I I S I 90  I S I 110  I S I 130  I S I 150  X  Cl  235  245  255  263  250  C2  237  239  247  248  " 243  C3  231  238  247  250  241  X  234  241  250  254  245  70.  TABLE OF MEANS FOR PHASE I MT BY CONDITION C2  C3  X  SI  1 6 9  2 0 0  1 8 4  S2  193  2 0 1  197  S3  147  2 0 9  1 7 8  S4  2 0 9  233  221  S5  183  203  193  S6  178  2 0 1  1 8 9  X  180  2 0 8  1 9 4  TABLE OF MEANS FOR PHASE I MT BY ISI ISI 90  ISI 1  1 0  ISI  1 3 0  ISI  1 5 0  X  SI  183  1 8 5  185  1 8 4  1 8 4  S2  200  1 9 6  195  197  197  S3  179  180  176  177  178  S 4  223  2 2 0  220  220  2 2 1  S5  1 9 4  1 8 9  193  197  193  S6  1 9 0  1 9 0  187  1 9 1  1 8 9  X  195  1 9 3  193  1 9 4  1 9 4  TABLE OF MEANS FOR PHASE I MT FOR CONDITION BY ISI ISI 90  ISI 1 1 0  C2  181  179  179  180  180  C3  208  208  206  208  208  X  195  1 9 3  193  1 9 4  1 9 4  ISI  1 3 0  ISI  1 5 0  X  71. TABLE OF MEANS FOR.PHASE I PRT BY CONDITION Cl  C2  C3  X  188  269  182  213  52  241  344  370  318  53  183  196  225  201  54  180  254  207  213  253  344  395  331  S6  238  232  193  221  x  214  273  262  250  51  •  •S5  TABLE OF MEANS FOR PHASE I BY I S I ISI  90  I S I 110  I S I 130  I S I 150  X  51  222  218  210  203  213  52  332  321  316  305  319  53  208  207  200  191  201  54  226  214  212  201  213  55  351  331  326  315  331  56  229  225  213  217  221  x  261  253  246  239  250  TABLE OF MEANS FOR PHASE I PRT FOR CONDITION BY I S I ISI  90  I S I 110  I S I 130  I S I 150  X  Gl  220  220  208  207  214  C2  290  271  273  259  273  C3  274  267  258  250  262  x  261  253  246  239  250  72. TABLE OF MEANS FOR PHASE I I RT BY CONDITION I S I 90  I S I 110  I S I 130  I S I 150  X  Cl  220  220  208  207  214  C2  290  271  273  259  273  C3  274  267  258  250  262  x  261  253  246  239  250  TABLE OF MEANS FOR PHASE I I RT FOR I S I ISI 20  I S I 80  I S I 140  I S I 200  51  341  342  342  344  342  52  248  246  246  252  248  53  2 56  262  263  268  262  54 55  259  259  259  263  260  281  281  280  285  282  56  259  270  274  272  269  X  274  277  278  281  277  X  TABLE OF MEANS FOR PHASE I I RT FOR CONDITION BY I S I ISI 20  I S I 80  I S I 140  I S I 200  X  Cl  283  291  282  294  288  C2  270  275  277  277  275  C3  268  264  274  270  269  X  274  277  278  281  277  73.  TABLE OF MEANS FOR PHASE I I MT BY CONDITION C2  C3  X  Sl  200  222  211  S2  211  213  212  S3  133  207  170  S4  236  235  236  S5  195  212  203  S6  194  222  208  X  195  219  207  TABLE OF MEANS FOR PHASE I I MT BY I S I ISI  20  I S I 80  ISI 1 4 0  ISI 200  X  Sl  207  213  212  213  211  S2  209  213  213  215  212  S3  169  172  168  172  170  S4  231  238  237  237  236  S5  201 202  204 211  204 208  203  S6  205 211  X  203  208  208  208  207  208  TABLE OF MEANS FOR PHASE I I MT FOR CONDITION BY I S I ISI 20  I S I 80  ISI 1 4 0  I S I 200  X  C2  191  195  196  196  195  C3  215  222  219  220  219  X  203  208  208  208  207  74. TABLE OF MEANS FOR PHASE II PRT BY CONDITION Cl  C2  C3  X  186  220  228  211  S2  211  243  251  235  S3  208  201  260  223  S 4  203  254  257  238  S5  242  325  314  294  S6  212  216  231  220  X  210  243  257  237  )  SI  TABLE OF MEANS FOR PHASE II PRTBY ISI ISI 20  ISI 80  ISI 140  ISI 200  X  SI  236  205  205  211  S2  263  243  199 212  223  S3  213  213  231  S4  235 258  235 223  244  225  226  238  S5  310  291  276  296  294  S6  234  220  210  214  220  X  250  236  223  233  237  TABLE OF MEANS FOR PHASE II PRT FOR CONDITION BY ISI ISI 20  ISI 80  ISI 140  ISI 200  X  Cl  226  210  203  203  210  C2  265  237  227  242  243  C3  277  260  238  253  257  X  256  236  223  233  237  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0077323/manifest

Comment

Related Items