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The kinematics, movement phasing and timing of a field hockey drive in response to varying conditions… Weicker, Dianne Louise 1983

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THE KINEMATICS, MOVEMENT PHASING AND TIMING OF A FIELD HOCKEY DRIVE IN RESPONSE TO VARYING CONDITIONS OF UNCERTAINTY by DIANNE LOUISE WEICKER B.Ed., The U n i v e r s i t y of V i c t o r i a 1976 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF PHYSICAL EDUCATION i n THE FACULTY OF GRADUATE STUDIES (S c h o o l of P h y s i c a l E d u c a t i o n and R e c r e a t i o n ) We ac c e p t t h i s t h e s i s as co n f o r m i n g to the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA May 1983 Dianne L o u i s e W e i c k e r , 1983 V I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t Of t h e r e q u i r e m e n t s f o r an advanced degree a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I agree t h a t t h e L i b r a r y 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 s t u d y . 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 e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by t h e head o f my department o r by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f ^ OKMOJOSJCA ^ eVw-CoJtoos^ The U n i v e r s i t y o f B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 DE-6 (3/81) ABSTRACT T h i s study was d e s i g n e d t o p r o v i d e a d e t a i l e d a n a l y s i s of the parameters which i n t e r a c t t o produce a f i e l d hockey d r i v e . The d r i v e was performed by an e l i t e p e r f o r m e r under two c o n d i t i o n s of uncertainty--BLOCKED and RANDOM o r d e r of b a l l speed p r e s e n t a t i o n . In the former c o n d i t i o n , b a l l speeds were d i r e c t e d toward the s u b j e c t u n t i l she performed ten s u c c e s s f u l d r i v e s a t a s i n g l e speed. T h i s c o n t i n u e d over t h r e e s u c c e s s i v e speed b l o c k s (20, 30 and 40 m.p.h.). Under the RANDOM c o n d i t i o n , the same t h r e e b a l l speeds were d e l i v e r e d t o the s u b j e c t i n a random and u n p r e d i c t a b l e o r d e r u n t i l t e n s u c c e s s f u l d r i v e s were r e c o r d e d a t each speed. Cine a n a l y s i s (50 f.p.s.) of the s u b j e c t ' s s u c c e s s f u l r e sponses under the two e x p e r i m e n t a l c o n d i t i o n s p e r m i t t e d c o n c l u s i o n s t o be drawn p e r t a i n i n g t o the k i n e m a t i c s , p h a s i n g , and t i m i n g of the s t r o k e . Measurements were r e c o r d e d f o r each s t r o k e segment. A l l movement phases of each s t r o k e remained c o n s i s t e n t over the r e c o r d e d t e m p o r a l v a r i a b l e s of movement d u r a t i o n and peak v e l o c i t y . The emphasis appeared t o be p l a c e d upon v a r y i n g the i n i t i a l phases of the s t r o k e ( i . e . , backswing, p r e p a r a t o r y phases) i n o r d e r t o produce a t e m p o r a l l y c o n s i s t e n t b a l l i s t i c downswing t o b a l l c o n t a c t . I t seemed l i k e l y t h a t the s u b j e c t a p p r a i s e d the b a l l ' s c h a n g i n g r e t i n a l image s i z e t o deter m i n e which b a l l speed was be i n g d e l i v e r e d and then i n c o r p o r a t e d a d d i t i o n a l s t i c k movement t o "mark t i m e " b e f o r e i n i t i a t i n g t e m p o r a l l y c o n s i s t e n t movement phases (C1, C 2). i As s p a t i a l u n c e r t a i n t y i n c r e a s e d , the s u b j e c t d e l a y e d her response i n i t i a t i o n , but then tended t o respond i n i n t e r v a l s of one r e a c t i o n time f o r each s t r o k e phase. C o n s i s t e n c y was e v i d e n t f o r d i s p l a c e m e n t and i n i t i a t i o n p o i n t v a l u e s , but t o a l e s s e r e x t e n t than e x i s t e d f o r the o t h e r v a r i a b l e s . However, as a r e s u l t of t h i s adjustment i n s p a t i a l l o c a t i o n and d i s p l a c e m e n t of the s t i c k e n d d u r i n g the p r e l i m i n a r y phases of the response, the s u b j e c t was a b l e t o produce a c o n s i s t e n t and a c c u r a t e b a l l i s t i c downswing. i i ACKNOWLEDGEMENTS The u n d e r t a k i n g of t h i s s t u d y was not p o s s i b l e w i t h o u t the support and c o o p e r a t i o n of many p e o p l e . I would l i k e t o thank my a d v i s o r , Dr. Ian F r a n k s , who p r o v i d e d d i r e c t i o n and support i n the p l a n n i n g , e x e c u t i o n , and p r e s e n t a t i o n of the r e s e a r c h . I g r e a t l y a p p r e c i a t e d h i s c o n t i n u e d i n t e r e s t and c o n f i d e n c e i n the p r o j e c t , and h i s a s s i s t a n c e w i t h the i n t e r p r e t a t i o n and a p p l i c a t i o n of the r e s u l t s . To the members of my committee, D r s . G. R o b e r t s o n , G. S i n c l a i r , and A. Treisman, thank you f o r p r o v i d i n g d i r e c t i o n and a s s i s t a n c e i n the d e s i g n and i m p l e m e n t a t i o n of the s t u d y . I w i s h t o e x p r e s s my ve r y s p e c i a l a p p r e c i a t i o n t o Jean Wessel f o r spending many hours a s s i s t i n g me w i t h the computer m a n i p u l a t i o n and documentation of my r e s u l t s . I would a l s o l i k e t o thank the f a c u l t y and s t a f f of the Department of P h y s i c a l Therapy a t the U n i v e r s i t y of A l b e r t a f o r p r o v i d i n g the f a c i l i t i e s and moral support n e c e s s a r y f o r the c o m p l e t i o n of t h i s work i n my absence from the U n i v e r s i t y of B r i t i s h Columbia. The s u b j e c t s who p a r t i c i p a t e d i n the many p i l o t s t u d i e s and i n the f i n a l p r o j e c t a l s o d e s e r v e thanks f o r the time and i n t e r e s t which they c o n t r i b u t e d . Table of Contents Chapter Page I. INTRODUCTION 1 II . EXPERIMENTAL DESIGN 9 I I I . METHOD 11 A. Subjects 11 B. Apparatus 11 C. Task 12 D. Procedure 14 Condition I:(BLOCKED) 14 Condition I I: (RANDOMIZED) 15 IV. DATA ANALYSIS 16 A. Description of the Swing Phases 17 B. Dependent Variables 22 Stick Displacement 22 Movement Velocity 23 Peak Velocity 23 Acceleration 24 Movement Duration 24 Ba l l Location 25 V. RESULTS AND DISCUSSION 26 A. Stick Displacement 26 B. Movement Velocity 34 C. Acceleration 43 D. Movement Duration 47 E. Ba l l Location 51 VI. CONCLUSION 58 i v REFERENCE NOTES 61 REFERENCES 62 Appendix A: S k i l l e d B e h a v i o r 68 Appendix B: Motor Program... 78 Appendix C: P r e l i m i n a r y S t u d i e s 108 Appendix D: Apparatus Design 129 Appendix E: D e s c r i p t i o n of the TaskrThe D r i v e 133 Appendix F: Raw Data 140 V LIST OF TABLES Ta b l e Page 1 K i n e m a t i c s of B l o c k e d T r i a l 11 (40 m.p.h.) I l l u s t r a t i n g the Method of D e t e r m i n a t i o n of the S u b j e c t ' s Four S t r o k e Phases 21 2 Mean P o s i t i o n of the S t i c k Segment R e l a t i v e t o the H o r i z o n t a l (Degrees) a t the I n i t i a l Frame of each Phase 29 3 Mean D u r a t i o n (msec) of the Four Movement Phases i n Response t o B l o c k e d and Random S t i m u l u s P r e s e n t a t i o n 32 4 Mean Peak V e l o c i t y of the S t i c k e n d ( r a d / s e c ) f o r Each S t r o k e P h a s e - B l o c k e d and Random T r i a l s 38 5 B a l l P o s i t i o n Along the Runway a t the I n i t i a t i o n of Each Swing Phase ( d i s t a n c e from b a l l machine i n meters ) 52 6 Mean D u r a t i o n (msec) of Each S t r o k e I n t e r v a l P r i o r t o B a l l C o n t a c t 54 A Mean A b s o l u t e E r r o r (AE), Constant E r r o r (CE) and Standard D e v i a t i o n as a F u n c t i o n of Randomized S t i m u l u s Speed and S k i l l L e v e l 116 B T r i a l Means CE-30 T r i a l s a t Randomized Speeds.... 117 C C e l l Means (AE AND CE) — 1 0 T r i a l s per S t i m u l u s Speed. . 120 D Tar g e t A c q u i s i t i o n - M e a n A b s o l u t e E r r o r (msec)....124 E T a r g e t A c q u i s i t i o n - M e a n Constant E r r o r (msec)....125 F Mean A b s o l u t e E r r o r and Constant E r r o r (msec) as a F u n c t i o n of S t i m u l u s Speed and T a r g e t A c q u i s i t i o n 126 G Randomized Speed P r e s e n t a t i o n as D e l i v e r e d by the B a l l Machine 141 H K i n e m a t i c s of the S t i c k Segment u s i n g F i n i t e D i f f e r e n c e a f t e r D i g i t a l F i l t e r i n g ( B l o c k e d ) 142 I K i n e m a t i c s of the S t i c k Segment u s i n g F i n i t e D i f f e r e n c e a f t e r D i g i t a l F i l t e r i n g (Random) 143 J A n a l y s i s of V a r i a n c e of the S t i c k L o c a t i o n (degrees) a t the I n i t i a l Frame of Each S t r o k e Phase 144 K Mean Disp l a c e m e n t of S t i c k Segment (degrees) D u r i n g Each S t r o k e Phase 145 L A n a l y s i s of V a r i a n c e of Mean S t i c k D i s p l a c e m e n t (degrees) D u r i n g Each S t r o k e Phase ..146 M A n a l y s i s of V a r i a n c e of the D u r a t i o n (msec) of the Four S t r o k e Phases 147 N A n a l y s i s of V a r i a n c e of the Peak V e l o c i t y ( r a d / s e c ) of the S t i c k e n d D u r i n g Each S t r o k e Phase 148 0 Summary of S t a t i s t i c a l l y S i g n i f i c a n t R e s u l t s 157 v i LIST OF FIGURES F i g u r e Page 1 Diagrammatic r e p r e s e n t a t i o n of the d i v i s i o n of HO's swing i n t o : a)phases I , I I , and I I I ; b)E1 , C1 , E2, C2 18 2 G r i d c o o r d i n a t e s of frame-by-frame s t i c k d i s p l a c e m e n t ( f i l t e r e d d a t a ) B l o c k e d r e s p o n s e s . . . . 27 3 G r i d c o o r d i n a t e s of frame-by-frame s t i c k d i s p l a c e m e n t ( f i l t e r e d d a t a ) Random c o n d i t i o n 30 4 Frame-by-frame v e l o c i t y of s t i c k segment d u r i n g r e p r e s e n t a t i v e B20, B30, B40 res p o n s e s 35 5 Frame-by-frame v e l o c i t y of s t i c k segment d u r i n g r e p r e s e n t a t i v e R20, R30, R40 responses 36 6 Frame-by-frame a c c e l e r a t i o n of the s t i c k segment f o r the r e p r e s e n t a t i v e R20, R30, R40 r e s p o n s e s . . . . 44 7 Frame-by-frame a c c e l e r a t i o n of the s t i c k segment f o r the r e p r e s e n t a t i v e R20, R30, R40 r e s p o n s e s . . . . 46 8 Mean d u r a t i o n (msec) of the f o u r movement phases i n response t o b l o c k e d and random s t i m u l u s p r e s e n t a t i o n 48 9 B a l l p o s i t i o n a l o n g the runway at the i n i t i a t i o n of each swing phase 53 A Component a n a l y s i s of the ta s k of c a t c h i n g or s t r i k i n g a b a l l i n f l i g h t 71 B Four h y p o t h e t i c a l s t a g e s of p r o c e s s i n g i n a memory s c a n n i n g experiment 74 C I n f o r m a t i o n p r o c e s s i n g model 77 D Flow diagram showing the two k i n d s of feedback l o o p s r e s p o n s i b l e f o r response e x e c u t i o n (gamma) and response s e l e c t i o n ( p f b , e f b , KR) 94 E A model of s k i l l l e a r n i n g and a mechanism f o r the d e t e c t i o n and c o r r e c t i o n of e r r o r s 96 F The motor response schema i n r e l a t i o n t o e v e n t s o c c u r r i n g w i t h i n a t r i a l 99 G The r e c a l l and r e c o g n i t i o n schema i n r e l a t i o n t o v a r i o u s s o u r c e s of i n f o r m a t i o n . . . 101 H B l o c k e d mean AE (msec) f o r 25 t r i a l s a t two speeds 112 I Equipment and a p p a r a t u s 132 J F i e l d hockey d r i v e t e c h n i q u e 135 K Mean g r i d l o c a t i o n of s t i c k e n d (degrees a t the frame of i n i t i a t i o n of E1 and C1 s t r o k e phases 149 L Mean g r i d l o c a t i o n of s t i c k e n d (degrees) a t the frame of i n i t i a t i o n of E2 and C2 s t r o k e phases 150 M Frame-by-frame d i s p l a c e m e n t of the s t i c k segment (degrees) of the r e p r e s e n t a t i v e B20, B30, B40 responses 151 N Frame-by-frame d i s p l a c e m e n t of the s t i c k segment (degrees) of the r e p r e s e n t a t i v e R20, R30, R40 responses 152 v i i 0 Mean d i s p l a c e m e n t of s t i c k segment (degrees) d u r i n g E1 and C1 phases 153 P Mean d i s p l a c e m e n t of s t i c k segment (degrees) d u r i n g E2 and C2 phases 154 Q Mean peak v e l o c i t y ( r a d / s e c ) of the s t i c k e n d d u r i n g phases I and I I of the s t r o k e 155 R Mean v e l o c i t y ( r a d / s e c ) of the s t i c k e n d a t b a l l c o n t a c t 156 v i i i I . INTRODUCTION A s k i l l e d b e h a v i o r may be d e f i n e d as one i n which s u c c e s s r e s u l t s from the c o n s c i o u s o r g a n i z a t i o n of movement p a t t e r n s which a r e d i r e c t e d towards the a t t a i n m e n t of a g o a l . T h i s g o a l i s d e f i n e d as t h a t i m m e d i a t e l y d e s i r e d response which i s n e c e s s a r y f o r the performance of a t e c h n i q u e p e c u l i a r t o the s p o r t i n v o l v e d . In most s p o r t s ' s k i l l s the g o a l i s i n v a r i a b l y d e t e r m i n e d by achievement of c o i n c i d e n t c o n t a c t w i t h an o b j e c t s p e c i f i c t o the game, be i t a b a l l , a t a r g e t or an opponent. In p u r s u i t of t h a t g o a l , however, the p h a s i n g of b o d i l y segments both s p a t i a l l y and t e m p o r a l l y i n t o "response u n i t s " ( G l e n c r o s s , 1975) i s e s s e n t i a l . Complex motor s k i l l s c o n s i s t of numerous response u n i t s which must be o r g a n i z e d r e l a t i v e t o each o t h e r and t o e x t e r n a l e v e nts or s i g n a l s f o r s u c c e s s f u l b e h a v i o r t o r e s u l t . Many a u t h o r s i n c l u d i n g F i t t s (1964), G l e n c r o s s (1978), and P r o v i n s (1956) have a l l u d e d t o the importance of s p a t i a l and t e m p o r a l p a t t e r n i n g i n s k i l l e d b e h a v i o r . ' D e t a i l e d a n a l y s i s of the parameters which i n t e r a c t t o produce a response u n i t w i l l p r o v i d e a more comprehensive u n d e r s t a n d i n g of the p e r f o r m e r ' s v o l u n t a r y c o n t r o l p r o c e s s . An example of t h i s a n a l y s i s c o u l d be the e x a m i n a t i o n of the t e m p o r a l r e c r u i t m e n t p a t t e r n of a g o n i s t i c and a n t a g o n i s t i c muscles as d e t e r m i n e d by e l e c t r o m y o g r a p h i c r e c o r d i n g s ( L u n d e r v o l d , 1951,1958; Wadman, D e n i e r van der Gon and ' A r e view of the o r g a n i z a t i o n of s k i l l f u l b e h a v i o r i s g i v e n i n Appendix A. 1 2 Derkson, 1980) or comparison of d i s p l a c e m e n t c u r v e s and t h e i r d e r i v a t i v e s r e s u l t i n g from d i g i t i z a t i o n of c i n e m a t o g r a p h i c data ( S p a e t h - A r n o l d , 1976; T y l d e s l e y , 1980; T y l d e s l e y and W h i t i n g , 1975). Such d a t a p r o v i d e c o n c r e t e measurements t o enable movement i n v e s t i g a t o r s t o d e v e l o p t h e o r i e s about movement c o n t r o l and e r r o r c o r r e c t i o n tendenc i e s . The a b i l i t y of s k i l l e d and u n s k i l l e d p e r f o r m e r s t o a d j u s t the s p a t i a l and te m p o r a l p h a s i n g of t h e i r movement i n response t o i n t r i n s i c and e x t r i n s i c feedback has been e x p l o r e d i n d i s c u s s i o n s r e g a r d i n g the e x i s t e n c e and o p e r a t i o n of a motor program. 2 The c o n c e p t u a l d e f i n i t i o n of motor programming has o n l y p a r t i a l l y been r e s o l v e d and c u r r e n t l i t e r a t u r e i s e v i d e n c e of the c o n t i n u i n g c o n t r o v e r s y ( N e w e l l , C a r l t o n and C a r l t o n , 1980; R a b b i t , 1978; Rosenbaum, 1980; Schmidt, 1980; Shea, 1980). The motor program produces an o b s e r v a b l e response which may o p e r a t i o n a l l y be d e s c r i b e d as c o n s i s t i n g of response u n i t s o r g a n i z e d t o g e t h e r t h r o u g h c e r t a i n i n v a r i a n t f e a t u r e s d e s p i t e performance w i t h i n a v a r i a b l e e n v i r o n m e n t a l d i s p l a y . V a r i a b l e parameters w i t h i n the b e h a v i o r p e r m i t a degree of i n t e r - r e s p o n s e v a r i a b i l i t y such t h a t a s u c c e s s f u l s k i l l i s s t i l l p o s s i b l e . A p e r f o r m e r who i s o p e r a t i n g i n c o n d i t i o n s of e n v i r o n m e n t a l u n c e r t a i n t y ( t e m p o r a l , s p a t i a l or event u n c e r t a i n t y ) w i l l a d j u s t a s p e c t s of t h e i r t e c h n i q u e s such 2A re v i e w of the te m p o r a l l i m i t a t i o n s i n the c o n t r o l of motor programming i s g i v e n i n Appendix B. 3 t h a t the g o a l may s t i l l be a c h i e v e d . On a p r a c t i c a l n o t e , s t u d i e s by a number of a u t h o r s have sought t o i d e n t i f y the v a r i a b i l i t y of the response of a s i n g l e p e r f o r m e r (Grose, 1967,1969; Hubbard and Seng, 1954; T y l d e s l e y , 1980; W h i t i n g , 1978). Each of the s e r e s e a r c h e r s has i d e n t i f i e d the between-response v a r i a t i o n as o c c u r r i n g d u r i n g the i n i t i a t i o n phase of the t o t a l response movement w h i l e m a i n t a i n i n g the c o n s i s t e n c y of the te m p o r a l and s p a t i a l parameters of the r e m a i n i n g p o r t i o n . T h i s f i n d i n g agrees w i t h Pew's (1974) s u g g e s t i o n t h a t a s k i l l e d p e r f o r m e r s t r i v e s f o r c o n s i s t e n c y p e r m i t t i n g v a r i a b i l i t y , however, such t h a t he may: f o r m u l a t e a motor a c t t o a c c o m p l i s h a g o a l c o n s i s t e n t w i t h the s t i m u l u s c o n d i t i o n s t h a t e x i s t a t the t i m e . As a f u n c t i o n of p r a c t i c e the s u b j e c t b u i l d s up more and more g e n e r a l schemata and h i g h e r - l e v e l g o a l s on which t o foc u s h i s a t t e n t i o n and from which t o e v a l u a t e s u c c e s s (p. 3 4 ) . G l e n c r o s s (1973) used f i l m and EMG a n a l y s i s of a number of s u b j e c t s as they performed a c o n t i n u o u s h a n d - c r a n k i n g t a s k . G l e n c r o s s i n t e n d e d t o study the p h a s i n g , or v a r i a b i l i t y of tempora l i n t e r v a l s between "response u n i t s " p l a c e d i n sequence and c o n c l u d e d t h a t the r e l a t i v e p h a s i n g of the p a r t s remained c o n s i s t e n t d e s p i t e v a r i a t i o n s i n c r a n k i n g speed and p e r f o r m e r s t y l e ( G l e n c r o s s , 1978, p. 6 2 ) . A s k i l l e d p e r f o r m e r must be c a p a b l e of o p e r a t i n g w i t h i n v a r i a t i o n s of p e r f o r m e r s t y l e ( i n t e r - r e s p o n s e v a r i a b i l i t y ) w h i l e u t i l i z i n g feedback c o n c e r n i n g b oth response s e l e c t i o n and e x e c u t i o n t o i d e n t i f y the s p e c i f i c causes of performance 4 e r r o r . Reason (Note 1) and Norman (1979) have i n v e s t i g a t e d c o g n i t i v e s l i p s as s o u r c e s of b e h a v i o r a l e r r o r s . In th e s e i n s t a n c e s the b e h a v i o r a l e r r o r s a r e not n e u r o p h y s i o l o g i c a l i n n a t u r e (e.g. t i m i n g or p h a s i n g which may a f f e c t t a r g e t a c q u i s i t i o n ) , but e r r o r s i n which an i n a p p r o p r i a t e response has been r e c a l l e d from memory. Such e r r o r s of response s e l e c t i o n c o n t r a s t t o e r r o r s of response e x e c u t i o n which are e v i d e n t i n the c o m b i n a t i o n of k i n e m a t i c f e a t u r e s n e c e s s a r y f o r s u c c e s s f u l t a r g e t a c q u i s i t i o n . I f a l l of the k i n e m a t i c f e a t u r e s of the t o t a l response were p r e d e t e r m i n e d by a motor program the p e r f o r m e r would be unable t o c o r r e c t h i s response i n accordance t o e n v i r o n m e n t a l or s t i m u l u s v a r i a b i l i t y . F o r t u n a t e l y , the motor program has been shown t o i n c l u d e both i n v a r i a n t f e a t u r e s as w e l l as v a r i a b l e parameters which may be a l t e r e d d u r i n g the r e s p o n s e , thus e n a b l i n g f i n a l c o r r e c t i o n s n e c e s s a r y f o r t a r g e t a c q u i s i t i o n . As Kimble and P e r l m u t e r (1970) r e f l e c t , a s k i l l e d a t h l e t e o p e r a t e s w i t h i n an open-loop s t r u c t u r e which e n a b l e s a t t e n t i o n t o be d i r e c t e d t o such f a c t o r s as response a c c u r a c y , e r r o r c o r r e c t i o n , or secondary t a s k s . C o r r e c t i v e movements are i d e n t i f i a b l e as a p e r f o r m e r a l t e r s the t r a j e c t o r y of h i s response t o a s p a t i a l p o s i t i o n which i s c l o s e r t o the i n t e n d e d g o a l than i f the o r i g i n a l t r a j e c t o r y were t o be m a i n t a i n e d . T h i s may be a c c o m p l i s h e d by m a n i p u l a t i n g the d i s p l a c e m e n t , v e l o c i t y or a c c e l e r a t i o n parameters of the response components. The i m p o r t a n t a r e a s of e x a m i n a t i o n then become the movement components of the 5 motor response r a t h e r than such response outcomes as a b s o l u t e e r r o r (AE), c o n s t a n t e r r o r (CE) or v a r i a b l e e r r o r (VE). W h i l e i n v e s t i g a t o r s have examined the e r r o r c o r r e c t i o n c a p a b i l i t i e s of p e r f o r m e r s d u r i n g v a r i a b l e response s e l e c t i o n t a s k s such as found i n CRT s t u d i e s ( H i g g i n s and A n g e l , 1970), i t i s d i f f i c u l t t o p r o j e c t t h e s e f i n d i n g s t o complex s p o r t s ' s k i l l s which p e r m i t a l a r g e amount of p e r f o r m e r v a r i a b i l i t y i n the accomplishment of the t a s k . However, T y l d e s l e y (1980) and T y l d e s l e y and W h i t i n g (1975) have s u c c e s s f u l l y examined the c h a r a c t e r i s t i c s of response e x e c u t i o n of d i f f e r e n t s k i l l l e v e l s of t a b l e t e n n i s c o m p e t i t o r s ( n o v i c e , i n t e r m e d i a t e , and e x p e r t ) . Computergraphic a n a l y s i s of the d i s p l a c e m e n t and v e l o c i t y c u r v e s of the w r i s t and elbow j o i n t c e n t r e s of the t h r e e l e v e l s of t a b l e t e n n i s p e r f o r m e r s p r o v i d e d an o b j e c t i v e d i f f e r e n t i a t i o n of the p h a s i n g of a f o r e h a n d d r i v e s h o t . In the T y l d e s l e y and W h i t i n g (1975) work, p l a y e r s were r e q u i r e d t o respond t o b a l l s d e l i v e r e d m e c h a n i c a l l y a l o n g a c o n s i s t e n t p a t h at a r a t e of 55 b a l l s per minute. Ss were t o p e r f o r m f o r both speed and a c c u r a c y and, once " o p e r a t i n g smoothly" (p. 174), Ss s h o t s were c i n e p h o t o g r a p h e d at 400 frames per second. R e s u l t s showed t h a t i n t e r m e d i a t e p l a y e r s o p e r a t e d w i t h a c o n s i s t e n t p a t t e r n of movement which was " i n i t i a t e d a t a d i f f e r e n t p o i n t i n space and time on each s h o t " (p. 176). The e x p e r t p e r f o r m e r was found t o be c o n s i s t e n t i n b oth the p a t t e r n and i n i t i a t i o n p o i n t (IP) of 6 a movement p r o v i d i n g a match of the da t a graphs a f t e r a u n i - d i m e n s i o n a l s h i f t a l o n g the time a x i s . The n o v i c e p e r f o r m e r , i n c o n t r a s t , l a c k e d c o n s i s t e n c y i n e i t h e r s p a t i a l or t e m p o r a l p a t t e r n i n g . None of the groups d i s p l a y e d c o n s i s t e n c y i n the a c c e l e r a t i o n p l o t s . S i n c e a c c e l e r a t i o n measures d e s c r i b e s y n e r g i s t i c muscle group a c t i v i t y ( W i n t e r , 1979), i t i s suggested t h a t t h i s d e r i v a t i v e i s d e s c r i p t i v e of the manner by which a performer m o d i f i e s a preprogrammed b a l l i s t i c a c t i v i t y t o c o r r e c t f o r e r r o r s i n response e x e c u t i o n . C i n e a n a l y s i s has a l s o been employed t o r e c o r d the s p a t i a l and temporal o r g a n i z a t i o n of the response i n a d a r t - t h r o w i n g t a s k ( S p a e t h - A r n o l d , 1976). The d a r t was d i r e c t e d towards a h o r i z o n t a l l y moving t a r g e t but u n l i k e the s u b j e c t s i n v o l v e d i n the t a b l e t e n n i s t a s k , these s u b j e c t s were unable t o f u r t h e r i n f l u e n c e the t r a j e c t o r y of the d a r t from the time i t l e f t t h e i r hands t o i t s a r r i v a l a t the t a r g e t . The t a b l e t e n n i s p e r f o r m e r s , on the o t h e r hand, were c a p a b l e of e x t e n d i n g c o n t r o l over t h e i r implement ( b a t ) r i g h t up u n t i l the moment of c o i n c i d e n c e w i t h the b a l l . S p a e t h - A r n o l d a l s o m a n i p u l a t e d the t a r g e t speed as i t moved h o r i z o n t a l l y a c r o s s the.Ss f i e l d of v i s i o n whereas s t i m u l u s u n c e r t a i n t y was e l i m a t e d i n T y l d e s l e y and W h i t i n g ' s work by d e l i v e r i n g the t a b l e t e n n i s b a l l s a t a s i n g l e , c o n s i s t e n t r a t e . In a d d i t i o n , S p a e t h - A r n o l d o b t a i n e d movement d i s p l a c e m e n t d a t a f o r the w r i s t and r e c o r d e d i t every t h i r d f i l m frame. Ss demonstrated a " t r a n s i t i o n a l change of 7 d i r e c t i o n from a backward movement of the w r i s t towards the body, t o f o r w a r d movement of the w r i s t towards the t a r g e t " . To summarize, the responses i n the d a r t - t h r o w i n g t a s k were found t o v a r y i n the " p r e p a r a t o r y phase of the movement w i t h r e s p e c t t o t a r g e t speed. In c o n t r a s t , i t seemed t h a t an attempt was made t o m a i n t a i n a c o n s t a n t d u r a t i o n of the a c t i o n phase of the movement" (p . 9 8 ) . The p r e s e n t study was d e s i g n e d t o add t o the i n v e s t i g a t i v e work of T y l d e s l e y (1980). S p e c i f i c a l l y , the s k i l l t h a t was a n a l y z e d was the f i e l d hockey d r i v e . W h i l e T y l d e s l e y imposed s p a t i a l v a r i a b i l i t y upon h i s s u b j e c t s , t h i s s tudy i n v e s t i g a t e d the e f f e c t s of t e m p o r a l u n c e r t a i n t y upon response o r g a n i z a t i o n . The d r i v e i s one of the most f r e q u e n t l y performed s k i l l s i n f i e l d hockey and i s used w i t h a p o w e r f u l b a l l i s t i c a c t i o n t o p r o p e l the b a l l over a l o n g d i s t a n c e . In or d e r t o c o n t a c t a b a l l i n motion the pe r f o r m e r must i n i t i a l l y make a number of judgments based upon the c h a r a c t e r i s t i c s of the s t i m u l u s ( b a l l ) w i t h i n the environment. These d e c i s i o n s w i l l then l e a d t o a s e l e c t i o n of movement parameters. When c o p i n g w i t h a t e m p o r a l l y and/or s p a t i a l l y v a r i a b l e s t i m u l u s , t h e r e i s an added problem f o r the p e r f o r m e r . As s t i m u l u s u n c e r t a i n t y i n c r e a s e s , a d d i t i o n a l c o n s t r a i n t s p l a c e d upon the p e r f o r m e r i n c r e a s e the l i k e l i h o o d t h a t he/she w i l l have t o c o r r e c t an i n a c c u r a t e l y e x e c u t e d response to a c h i e v e c o i n c i d e n c e w i t h the s t i m u l u s . I d e n t i f i c a t i o n of both the i n v a r i a n t f e a t u r e s and v a r i a b l e p arameters w i t h i n a response i s n e c e s s a r y t o u n d e r s t a n d how 8 such c o r r e c t i o n s o c c u r . The purpose of t h i s study was t o p e r f o r m a k i n e m a t i c a n a l y s i s of an e l i t e f i e l d hockey p l a y e r o p e r a t i n g under two c o n d i t i o n s of u n c e r t a i n t y — B L O C K E D and RANDOM o r d e r of s t i m u l u s speed p r e s e n t a t i o n . C i n e m a t o g r a p h i c a n a l y s i s of the s u c c e s s f u l s t r o k e s p e r m i t t e d q u a n t i f i c a t i o n of the o r g a n i z a t i o n , p h a s i n g , and t i m i n g of a s u c c e s s f u l s t r o k e . An a n a l y s i s of i n t e r t r i a l v a r i a n c e p e r m i t t e d i d e n t i f i c a t i o n of the s t r u c t u r e of the v a r i a n t and i n v a r i a n t p r o p e r t i e s w i t h i n the complex motor s k i l l . I I . EXPERIMENTAL DESIGN In both conditions of stimulus uncertainty, only those t r i a l s which resulted in successful target a c q u i s i t i o n were analyzed. The BLOCKED condition provided the S with 3 stimulus (ball) speeds, each of which had been well-rehearsed. Analysis by stimulus speed of the resulting stroke provided information regarding the response(s) produced and determined the degree of i n t e r - t r i a l v a r i a b i l i t y and tolerance for error at a p a r t i c u l a r stimulus speed. Trialwise stimulus variation was introduced in the second experimental condition (RANDOM) such that the 3 b a l l speeds were randomly delivered to the subject. In both conditions, only those t r i a l s resulting in successful target a c q u i s i t i o n were analyzed. Three kinematic factors (displacement, v e l o c i t y and acceleration) in two directions of motion (horizontal and v e r t i c a l ) were monitored for one anatomical landmark ( l e f t wrist) and the stickend. Cinematographical analysis was r e s t r i c t e d to discrete movement phases of the swing and was terminated at s t i c k / b a l l contact. Spe c i f i c research questions were: 1. Does a highly s k i l l e d performer produce a consistent stroke in response to a stimulus delivered at a par t i c u l a r speed? 2. Does th i s response vary when the temporal pattern of the environmental display i s altered (e.g., when the speed of the stimulus i s increased)? 9 10 3. How does the i m p o s i t i o n of a c o n d i t i o n of s t i m u l u s u n c e r t a i n t y ( t e m p o r a l u n c e r t a i n t y ) a f f e c t the response c h a r a c t e r i s t i c s ? Does the s t r o k e a t each response c o n d i t i o n remain the same as t h a t produced w i t h o u t u n c e r t a i n t y ? I s t h e r e a tendency t o v a r y a l l s t r o k e s towards a mean performance? 4. I f movement d u r a t i o n c o n s i s t e n c i e s can be i d e n t i f i e d ( T y l d e s l e y , 1980), where w i t h i n the s t r o k e i s a p e r f o r m e r c a p a b l e of m o d i f y i n g h i s / h e r response e x e c u t i o n i n or d e r t o c o r r e c t f o r an i n a c c u r a t e l y t i med response? 5. Can s t r o k e m o d i f i c a t i o n be i d e n t i f i e d t h r o u g h k i n e m a t i c a n a l y s e s ? 6. Can f e a t u r e s of the v i s u a l s t i m u l u s i n p u t ( i . e . , b a l l f l i g h t c h a r a c t e r i s t i c s ) be i d e n t i f i e d which c o i n c i d e w i t h the s u b j e c t ' s t i m i n g of v a r i o u s movement phases? To answer these q u e s t i o n s , t h r e e g e n e r a l c a t e g o r i e s were s e l e c t e d f o r d e s c r i p t i o n of a s k i l l e d p e r f o r m e r ' s response c o n s i s t e n c y . I n c l u d e d were the s p a t i a l c h a r a c t e r i s t i c s of the s t r o k e , the t i m i n g of the s t r o k e phases, and the k i n e m a t i c p r o p e r t i e s which d e s c r i b e a s u c c e s s f u l response. T h i s study i d e n t i f i e d the parameters and i n v a r i a n t f e a t u r e s as they combine i n a s k i l l f u l p e r f ormance. I I I . METHOD A. S u b j e c t s The s u b j e c t (HO) was a h i g h l y s k i l l e d female f i e l d hockey p l a y e r who had been i d e n t i f i e d a t the N a t i o n a l and P r o v i n c i a l l e v e l s f o r the p a s t t h r e e y e a r s . She was an 18 year o l d , r i g h t - h a n d e d p l a y e r . 3 B. A pparatus C i n e a n a l y s i s was made p o s s i b l e by use of a LOCAM 16 mm c i n e camera which was run a t a frame speed of 50 f p s w i t h a 2 - f a c t o r s h u t t e r ( f i l m exposure 1/100th of a se c o n d ) . F i l m type was Kodak Eastman Ektachrome 16mm (ASA 400; Tungsten, 3200K). Markers were p l a c e d on the s t i c k head, l e f t elbow, l e f t w r i s t , l e f t knee and l e f t t oe f o r d i g i t i z a t i o n p u r p o s e s . The s u b j e c t adopted a s t a t i o n a r y p o s i t i o n on an a s t r o t u r f mat such t h a t the t a r g e t (a 1.8 X 2.7m mat) was l o c a t e d 5.0 meters t o her l e f t . The b a l l d e l i v e r y a p p a r a t u s (MNW 1 1 5 - - M i t c h e l l and Ness Jugs F i e l d Hockey Machine) was p o s i t i o n e d 12.0 meters t o the s u b j e c t ' s f r o n t . T h i s 12.0 meter d i s t a n c e was f u r t h e r marked by a w h i t e tape mark l o c a t e d 10.0 meters from the b a l l r e l e a s e c h u t e . A v i d e o t a p e r e c o r d e r was s i t u a t e d even w i t h t h i s tape such t h a t a r e c o r d was made of the t a p e , an LED d i g i t a l c l o c k ( L a f a y e t t e ) and the b a l l each t r i a l as the b a l l c r o s s e d the 10.0 meter mark. 3 S u b j e c t HO's a n t h r o p o m e t r i c d a t a i s p r e s e n t e d i n Appendix D. 1 1 12 The d i g i t a l output p r o v i d e d v e r i f i c a t i o n of average b a l l v e l o c i t y . Masking of the motor of the a p p a r a t u s was n e c e s s a r y t o e l i m i n a t e c u i n g of the b a l l speed and was a c h i e v e d by p l a y i n g r e c o r d e d music throughout the t e s t i n g s e s s i o n . " C. Task The b a l l s were manually p l a c e d i n t o the machine f o r d e l i v e r y t o the s u b j e c t . A v a r i a b l e r a t e of s t i m u l u s p r e s e n t a t i o n was a c h i e v e d u s i n g a v a r i a b l e f o r e p e r i o d . T h i s was n e c e s s a r y t o p r e v e n t a n t i c i p a t i o n of the d e l i v e r y of the b a l l , thus e n s u r i n g t h a t HO's response was d e l a y e d u n t i l she r e c e i v e d v i s u a l i n p u t from the s t i m u l u s . The b a l l d e l i v e r y speeds were p r e s e n t e d as 20, 30, and 40 m.p.h. (8.9, 13.4, and 17.9 meters per s e c o n d ) . The t a s k r e q u i r e d t h a t the s u b j e c t d r i v e ' a f i e l d hockey b a l l towards the t a r g e t l o c a t e d 5 meters t o the Ss l e f t . 5 HO adopted a s t a t i o n a r y p o s i t i o n f o r each t r i a l which r e q u i r e d t h a t she s t a n d w i t h f e e t m o t i o n l e s s on a spot marked on the a s t r o t u r f . In response t o a s i g n a l from the e x p e r i m e n t e r , and i n p r e p a r a t i o n f o r d e l i v e r y of the s t i m u l u s b a l l , a Ready P o s i t i o n was assumed which had been d e t e r m i n e d as a r e s u l t of 5 t r a i n i n g s e s s i o n s . C r i t e r i o n markers had been p l a c e d on the a s t r o t u r f such t h a t c o n s i s t e n t performance was ensured. These r e q u i r e m e n t s d i c t a t e d t h a t : 4 D e t a i l s of the a p p a r a t u s appear i n Appendix D. 5A complete d e s c r i p t i o n of the f i e l d hockey d r i v e i s p r o v i d e d i n Appendix E. 13 1. HO s t a n d such t h a t the r i g h t and l e f t f o o t p o s i t i o n s commence on the a p p r o p r i a t e marks (R and L 1 ) ; 2. the s t i c k be r a i s e d t o the same s t a r t i n g p o s i t i o n p r i o r t o the e x p e r i m e n t e r p l a c i n g the b a l l i n t o b a l l machine; and 3. the l e f t f o o t s t e p t o the p r e d e t e r m i n e d s t e p p i n g p o i n t (L2) as the d r i v e was performed. The s u b j e c t was i n s t r u c t e d t o d r i v e the b a l l as hard as p o s s i b l e i n t o the t a r g e t mat. S u c c e s s f u l d r i v e s were judged a c c o r d i n g t o t a r g e t a c q u i s i t i o n and r e c o r d e d . A c r i t e r i o n of 80% s u c c e s s i n p r a c t i c e ( i . e . , warm-up t r i a l s p r i o r t o the f i l m i n g t r i a l s ) was r e q u i r e d b e f o r e the s t r o k e response was c o n s i d e r e d c o n s i s t e n t and f i l m i n g t r i a l s begun. A t r a i n i n g p e r i o d was p r o v i d e d t o e s t a b l i s h the l o c a t i o n of the f o o t and s t i c k c r i t e r i o n markers and t o pe r m i t f a m i l i a r i z a t i o n of the s u b j e c t w i t h the a p p a r a t u s and t a s k r e q u i r e m e n t s . T h i r t y minutes of d a i l y p r a c t i c e u t i l i z i n g the b a l l machine was p r o v i d e d f o r 5 c o n s e c u t i v e days. The s u b j e c t responded t o b a l l s d e l i v e r e d w i t h a randomized speed d i s t r i b u t i o n over a range from 20 m.p.h. (8.9 cm/sec) t o 40 m.p.h. (17.9 cm/sec) f o r 100 t r i a l s per s e s s i o n . At t h i s t i m e , the s u b j e c t d e t e r m i n e d c o m f o r t a b l e f o o t placement (R, L1 and L2) and the p o s i t i o n of the f i e l d hockey s t i c k i n the Ready P o s i t i o n . T h i s s t i c k c r i t e r i o n h e i g h t was marked by a s t a n d l o c a t e d 2.0m be h i n d the s u b j e c t . HO was p e r m i t t e d t o a d j u s t t h e s e markers throughout the t r a i n i n g s e s s i o n s , but changes were not p e r m i t t e d once 14 the f i l m i n g s e s s i o n s had begun. The s u b j e c t was i n s t r u c t e d i n the response r e q u i r e m e n t s of the s t r o k e i n o r d e r t o ensure performance of a c o r r e c t and c o n s i s t e n t response ( i . e . , low i n t e r - r e s p o n s e v a r i a b i l i t y was r e q u i r e d ) . D. Pr o c e d u r e Performance was a n a l y z e d i n each of two t r e a t m e n t c o n d i t i o n s as determined by the o r d e r of p r e s e n t a t i o n of the t h r e e b a l l speeds. Cond i t i on I:(BLOCKED) HO was p r e s e n t e d w i t h t h r e e b a l l speeds (20, 30, and 40 m.p.h.) which were d e l i v e r e d i n c o n s e c u t i v e b l o c k s of a s i n g l e speed. Each b l o c k commenced w i t h a minimum of 20 p r a c t i c e t r i a l s (or u n t i l 80% a c c u r a c y was a c h i e v e d ) . The p r a c t i c e t r i a l s were im m e d i a t e l y f o l l o w e d by f i l m i n g t r i a l s a t t h a t same s t i m u l u s speed. The s u b j e c t responded u n t i l 10 a c c u r a t e d r i v e s per speed were f i l m e d . The e x p e r i m e n t e r announced "Ready" and s i m u l t a n e o u s l y h e l d the b a l l i n the a i r f o r the s u b j e c t t o view. Once S assumed the Ready P o s i t i o n , the b a l l was p l a c e d i n the d e l i v e r y c h u t e of the b a l l machine. The b a l l was d i r e c t e d t o a c o n s i s t e n t p o s i t i o n o p p o s i t e the S's l e f t f o o t (L2) w h i l e the s u b j e c t i n i t i a t e d a d r i v e such t h a t i t coinci'ded w i t h the a r r i v a l of the b a l l , and was d i r e c t e d towards the t a r g e t . 15 C o n d i t i o n I I : (RANDOMIZED) The same 3 s t i m u l u s speeds and g e n e r a l p r o c e d u r e s were f o l l o w e d as i n C o n d i t i o n I . The s u b j e c t responded t o a randomized p r e s e n t a t i o n of 30 p r a c t i c e t r i a l s a r r a n g e d such t h a t each speed o c c u r r e d 10 t i m e s over the 30 t r i a l s . The f i l m i n g t r i a l s were a l s o p r e s e n t e d i n a randomized d i s t r i b u t i o n of speeds such t h a t each speed o c c u r r e d 10 tim e s per group of 30 t r i a l s . The o r d e r w i t h i n the 30 t r i a l s was r e p e a t e d u n t i l 10 s u c c e s s f u l t r i a l s were f i l m e d a t each speed. IV. DATA ANALYSIS A l l v a r i a b l e s were segmented t e m p o r a l l y r e l a t i v e t o the i n i t i a t i o n and c o m p l e t i o n of s p e c i f i c phases of the swing. A Numonics D i g i t i z e r was u t i l i z e d t o r e c o r d v a l u e s d i r e c t l y from the t e s t f i l m and determine g r i d c o o r d i n a t e s i n one p l a n e ( X , Y ) . S e q u e n t i a l a n a l y s i s by f i l m frame (0.05 cm e r r o r ) p e r m i t t e d k i n e m a t i c a n a l y s i s of the raw d a t a . T h i s was performed by a M i c r o n o v a microcomputer (MP200) and BIOMECH computer s o f t w a r e package. To e l i m i n a t e h i g h f r e q u e n c i e s i n d i c a t i v e of n o i s e w i t h i n the system, the d i s p l a c e m e n t d a t a was f i l t e r e d u s i n g a low-pass d i g i t a l f i l t e r w i t h a 5 Hz c u t - o f f ( P e z z a c k , Norman, and W i n t e r , 1977; W i n t e r , 1979). A subsequent f o u r i e r a n a l y s i s of a l l 60 t r i a l s c o n f i r m e d t h a t 99% of the s i g n a l was a c c o u n t e d f o r below t h i s c u t - o f f f r e q u e n c y . T r a n s l a t i o n a n a l y s e s were l i m i t e d t o the 'LEFT WRIST' and 'STICKEND' markers. The e l i m i n a t i o n of the o t h e r t h r e e markers ('LTOE', 'LKNEE', and 'LELBOW') from the a n a l y s i s was based upon i n f o r m a t i o n o b t a i n e d from the P r e l i m i n a r y S t u d i e s . I n i t i a l c o n s i d e r a t i o n of these markers r e i n f o r c e d T y l d e s l e y ' s concern over a g r e a t e r degree of freedom e v i d e n t i n the k i n e m a t i c s s u r r o u n d i n g movement of the more d i s t a l j o i n t s . These markers r e c o r d e d a l a r g e i n t e r - r e s p o n s e v a r i a b i l i t y which p r e v e n t e d the i d e n t i f i c a t i o n of k i n e m a t i c t r e n d s . T h e r e f o r e , the a n a l y s i s was l i m i t e d t o an i n v e s t i g a t i o n of the k i n e m a t i c s of the f i e l d hockey s t i c k end. S t i c k d i s p l a c e m e n t , v e l o c i t y ( f i r s t d e r i v a t i v e ) and 16 17 a c c e l e r a t i o n (second d e r i v a t i v e ) v a l u e s were computed and a n a l y z e d i n a 2 X 3 Repeated Measures d e s i g n . An a n a l y s i s of v a r i a n c e was performed t o t e s t Order ( B l o c k e d vs Random) and Speeds (20 m.p.h., 30 m.p.h., 40 m.p.h.) main e f f e c t s . S c h e f f e ' s method of comparison was used t o t e s t s i g n i f i c a n t Speed and Order main e f f e c t s w h i l e Tukey's m u l t i p l e - c o m p a r i s o n u s i n g the s t u d e n t i z e d range was used t o t e s t s i g n i f i c a n t Speed X Order i n t e r a c t i o n s . A p r o b a b i l i t y of 2<.05 was used i n a l l Tukey c o m p a r i s o n s . A. D e s c r i p t i o n of the Swing Phases The f i e l d hockey d r i v e i s performed i n a manner s i m i l a r t o a g o l f , t e n n i s or b a s e b a l l swing. The s t r o k e i s a b i p h a s i c movement c o n s i s t i n g of an i n i t i a l backswing f o l l o w e d by a b a l l i s t i c downswing. The S of t h i s s t u d y , however, demonstrated a t h i r d movement phase which she completed p r i o r t o i n i t i a t i o n of the backswing and i n d i c a t i v e of s t y l e v a r i a t i o n . The t h r e e phases of HO's s t r o k e a r e i l l u s t r a t e d i n F i g u r e 1a and may be d e s c r i b e d as c o n s i s t i n g o f : 1) Phase I : P r e p a r a t o r y Phase The b a l l was d e l i v e r e d once the s u b j e c t assumed the Ready P o s i t i o n ( s t i c k s t a t i o n a r y ) . The f i r s t s t i c k motion t o be r e c o r d e d on f i l m was d i r e c t e d towards the ground. T h i s movement appeared t o be a " r e f l e x i v e r e l a x a t i o n " and was most l i k e l y u s e f u l as a p a r t of HO's i n t e r n a l t i m i n g mechanism. As such, i t w i l l be a n a l y z e d as an i n t e g r a l p a r t 18 F i g u r e 1: Diagrammatic r e p r e s e n t a t i o n of the d i v i s i o n of HO's swing i n t o : a) phases I , I I and I I I ; and. b) E 1 , C l , E2, C2. 19 of the s t r o k e . 2) Phase I I : Backswing T h i s phase encompassed t h a t motion of the s t i c k i n the r e v e r s e d i r e c t i o n ( i . e . , away from the g r o u n d ) . 3 ) Phase I I I : Downswing T h i s b a l l i s t i c phase was d i s t i n g u i s h a b l e by a f u r t h e r change i n d i r e c t i o n ( e q u i v a l e n t t o Phase I ) and was c o n s i d e r e d t o be completed a t the moment of b a l l c o n t a c t . A l t h o u g h the f o l l o w - t h r o u g h i s imp o r t a n t from a t e c h n i c a l p o i n t of view, i t does not c o n t r i b u t e t o the b a l l ' s momentum and was not c o n s i d e r e d t o be r e l e v e n t t o t h i s i n v e s t i g a t i o n . A l t h o u g h these t h r e e segments a d e q u a t e l y d e s c r i b e the d i s p l a c e m e n t p a t t e r n of the s t i c k (see F i g u r e 1 ) , they were inadequate f o r c o n s i d e r a t i o n of the s y n e r g i s t i c muscle a c t i v i t y i n v o l v e d i n the e x e c u t i o n of the t a s k . A combined a n a l y s i s of the f i r s t and second d e r i v a t i v e s of the d i s p l a c e m e n t data produced f o u r d i s t i n c t a c t i v i t y phases. These p r e s e n t e d a more a c c u r a t e p i c t u r e of the t e m p o r a l r e l a t i o n s h i p between the movement and the a g o n i s t i c / a n t a g o n i s t i c muscle c o n t r a c t i o n s r e q u i r e d t o produce t h a t movement ( r e f e r t o F i g u r e 1.b). T a b l e 1 i l l u s t r a t e s the d e r i v a t i o n of the f o u r d i v i s i o n s from the raw k i n e m a t i c data which are d e s c r i b e d i n terms of e c c e n t r i c and c o n c e n t r i c muscle a c t i v i t y . The change of s i g n ( p o s i t i v e , n e g a t i v e ) between frames r e c o r d e d f o r the v e l o c i t y ( r a d / s e c ) and a c c e l e r a t i o n ( r a d / s e c 2 ) d a t a were 20 used t o i n f e r the moment when the muscle changed from an a g o n i s t i c t o an a n t a g o n i s t i c r o l e . A subsequent a n a l y s i s of f o r c e k i n e t i c s throughout the s t r o k e c o n f i r m e d t h i s method of d e s c r i p t i o n . 1) E c c e n t r i c 1 (E1) Phase: T h i s phase was used as the s t a r t i n g r e f e r e n c e f o r a l l k i n e m a t i c a n a l y s i s s i n c e i t c o u l d be d e t e r m i n e d u n e q u i v o c a l l y from the k i n e m a t i c d a t a . As the s u b j e c t approaches the c o m p l e t i o n of the P r e p a r a t o r y Phase I , Downswing, the a n t a g o n i s t i c muscles commence f i r i n g i n o r d e r t o d e c e l e r a t e the downward v e l o c i t y of the s t i c k head. T h i s e c c e n t r i c muscle a c t i v i t y c o n t i n u e s u n t i l the s t i c k v e l o c i t y r e aches z e r o (e.g. time 0.000 t o 0.060 sec i n c l u s i v e , T able 1) . 2) C o n c e n t r i c 1 (C1) Phase: Once z e r o s t i c k v e l o c i t y i s a t t a i n e d a r o l e r e v e r s a l o c c u r s such t h a t the a n t a g o n i s t s become a g o n i s t i c i n t h e i r i n f l u e n c e upon j o i n t motion and produce a c o n c e n t r i c f o r c e upon the s t i c k . Those muscles which r e a c t e d a g o n i s t i c a l l y d u r i n g the E1 phase r e l a x d u r i n g t h i s phase (time 0.080 t o 0.280 msec, Ta b l e 1). 3) E c c e n t r i c 2 (E2) Phase: As the s t i c k approaches the m i d p o i n t of i t s d i s p l a c e m e n t away from the ground ( i . e . , near the m i d d l e of Phase I I , Backswing) the a n t a g o n i s t s once a g a i n f i r e t o d e c e l e r a t e the 21 T a b l e 1 K i n e m a t i c s of B l o c k e d T r i a l 11 (40 m.p.h.) I l l u s t r a t i n g t he Method of D e t e r m i n a t i o n of t h e S u b j e c t ' s Four S t r o k e Phases Time Omega A l p h a Phase ( s e c ) ( r a d / s e c ) ( r a d / s e c 2 ) 0.000 0.716 3.345 0.020 0.688 -6.967 0.040 0.437 -16.165 0.060 0.041 -21. 132 0.080 -0.408 -23.843 0. 100 -0.912 -27.851 0. 120 -1.522 -33.465 0. 140 -2.251 -38.935 0. 160 -3.080 -43.705 0. 180 -3.999 -47.271 0.200 -4.971 -46.914 0.220 -5.876 -40.158 0.240 -6.577 -28.229 0.260 -7.005 -14.442 0.280 -7.155 -0.967 0.300 -7.044 10.978 0.320 -6.716 20.626 0.340 -6.219 28.697 0.360 -5.568 36.686 0.380 -4.751 45.628 0.400 -3.743 56.936 0.420 -2.474 73. 1 17 0.440 -0.818 96.364 0.460 1 .381 126.800 0.480 4.254 161.316 0.500 7.834 192.21 1 0.520 1 1 .943 207.108 0.540 16.118 198.010 0.560 19.863 182.027 0.580 23.399 186.821 0.600 27.336 162.597 0.620 29.903 18.908 0.640 28,092 -162.647 0.660 23.397 -205.705 ECCENTRIC PHASE ONE CONCENTRIC PHASE ONE ECCENTRIC PHASE TWO CONCENTRIC PHASE TWO ECCENTRIC ACTIVITY INCLUDED IN CONCENTRIC PHASE TWO 22 s t i c k ' s v e l o c i t y i n p r e p a r a t i o n f o r a f i n a l r e v e r s a l of d i r e c t i o n . The E2 phase c o n t i n u e s u n t i l t he s t i c k reaches z e r o v e l o c i t y (0.300 t o 0.440 s e c , Table 1). 4 ) C o n c e n t r i c 2 (C2) Phase: The muscles which were working e c c e n t r i c a l l y ( a n t a g o n i s t s ) d u r i n g the p r e v i o u s phase now a p p l y a p o w e r f u l c o n c e n t r i c f o r c e t o the s t i c k . T h i s b a l l i s t i c phase t e r m i n a t e s a t s t i c k / b a l l c o n t a c t (0.460 t o 0.660 s e c ) . T h i s phase has been expanded t o i n c l u d e any e c c e n t r i c a c t i v i t y of the elbow f l e x o r s r e c o r d e d d u r i n g those frames i m m e d i a t e l y p r e c e d i n g b a l l c o n t a c t . N e g a t i v e v a l u e s of the second d e r i v a t i v e p r o v i d e e v i d e n c e of a d e c e l e r a t i o n i n the s t i c k v e l o c i t y , but because they were r e c o r d e d so c l o s e t o b a l l c o n t a c t (0.020 t o 0.060 sec p r i o r t o c o n t a c t ) , i t was noted t h a t t h e i r e f f e c t s upon the s t i c k momentum a t the moment of b a l l c o n t a c t were m i n i m a l . B. Dependent V a r i a b l e s S t i c k D i s p l a c e m e n t Nine d i s p l a c e m e n t v a l u e s were o b t a i n e d from the s t i c k e n d raw s c o r e s (degrees) f o r each s t r o k e . The f i r s t f i v e v a l u e s c o n s i s t e d of the raw d a t a p o i n t s (degrees) d e r i v e d from the i n i t i a t i n g and t e r m i n a t i n g frames of each of the f o u r phases of muscle c o n t r a c t i o n (E1, C1, E2, C2). These v a l u e s p e r m i t t e d i n v e s t i g a t i o n of the Ss a b i l i t y t o i n i t i a t e the phases of her swing w i t h c o n s i s t e n t s p a t i a l 23 p o s i t i o n i n g of her s t i c k . Four subsequent v a l u e s were then c a l c u l a t e d from the m a t h e m a t i c a l d i f f e r e n c e s between i n i t i a l raw s c o r e s . T h i s p e r m i t t e d e x a m i n a t i o n of the d i s t a n c e (degrees) t r a v e r s e d by the s t i c k e n d d u r i n g the c o m p l e t i o n of each phase. Movement V e l o c i t y The frame-by-frame v e l o c i t y d ata ( r a d / s e c ) were c a l c u l a t e d f o r each t r i a l and p l o t t e d g r a p h i c a l l y a g a i n s t t i m e . A r e p r e s e n t a t i v e t r i a l from each speed and o r d e r of p r e s e n t a t i o n was s e l e c t e d f o r comparison and the v e l o c i t y v a l u e s were p l o t t e d back i n time commencing w i t h the frame of b a l l c o n t a c t . These s i x t r i a l s were s e l e c t e d because they produced v a l u e s c l o s e s t t o the mean v a l u e s c a l c u l a t e d f o r a l l v a r i a b l e s ( d i s p l a c e m e n t , v e l o c i t y , a c c e l e r a t i o n , and movement d u r a t i o n ) . These same t r i a l s were, t h e r e f o r e , used when p l o t t i n g a l l o t h e r v a r i a b l e s a g a i n s t t i m e . Peak V e l o c i t y Peak v e l o c i t y d a t a ( r a d / s e c ) were a n a l y z e d a c c o r d i n g t o the s t i c k segment v e l o c i t y r e c o r d e d d u r i n g Phases I , I I , and I I I . A two-way ANOVA was c a l c u l a t e d t o lo o k a t the d i f f e r e n c e s and a s s i s t i n the d e t e r m i n a t i o n of the s u b j e c t ' s a b i l i t y t o program a r a t e of movement i n t o each phase of the swing. From the a n a l y s i s of a P i l o t s t u d y , i t was found t h a t the peak v e l o c i t y d u r i n g Phase I o c c u r r e d c o i n c i d e n t l y w i t h the i n i t i a t i o n of E1 and was i n d i c a t i v e of the downward 24 v e l o c i t y of the s t i c k d u r i n g the Ss a c c e s s o r y movement p r i o r t o the backswing. Phase I I peak v e l o c i t y o c c u r r e d a p p r o x i m a t e l y midway th r o u g h the Ss backswing and c o r r e s p o n d e d t o the l a s t f r ame(s) of the C1 phase. The peak v e l o c i t y r e c o r d e d f o r Phase I I I o c c u r r e d v e r y c l o s e t o b a l l c o n t a c t . However, the v a l u e r e c o r d e d f o r d a t a a n a l y s e s was u n i f o r m l y taken as the s t i c k v e l o c i t y a t b a l l c o n t a c t . When b a l l c o n t a c t o c c u r r e d between two f i l m frames, an i n t e r p o l a t e d v a l u e was c a l c u l a t e d and r e c o r d e d . A c c e l e r a t i o n The a c c e l e r a t i o n d a t a ( r a d / s e c 2 ) were used i n c o n j u n c t i o n w i t h the v e l o c i t y d a t a t o d e f i n e the f o u r phases of each s t r o k e . T h i s s e c t i o n p r e s e n t s a d i s c u s s i o n of the frame-by-frame a c c e l e r a t i o n t r e n d s f o r each s t i m u l u s speed and o r d e r of speed p r e s e n t a t i o n . Curves f o r the s i x r e p r e s e n t a t i v e t r i a l s were p l o t t e d back i n time commencing from b a l l c o n t a c t . Movement D u r a t i o n The c o o r d i n a t i o n of a r a p i d b a l l i s t i c movement n e c e s s i t a t e s the a c t i v a t i o n (or i n h i b i t i o n ) of an a p p r o p r i a t e s e t of muscles such t h a t the a g o n i s t i c and a n t a g o n i s t i c c o - c o n t r a c t i o n o c c u r s i n an adequate tempo r a l r e l a t i o n s h i p (Shea, 1980). The time l a p s e from the onset of a g o n i s t i c a c t i v i t y u n t i l the onset of a n t a g o n i s t i c a c t i v i t y i s the i m p o r t a n t parameter i n the a c t i v a t i o n p a t t e r n of 25 muscles a c t i n g a c r o s s the same j o i n t (Wadman et a l , 1980). Movement d u r a t i o n i n the c u r r e n t study was d e f i n e d by t h i s time l a p s e . Movement times were a n a l y z e d a c c o r d i n g t o the fo u r s t r o k e phases (E1, C1, E2, C2). B a l l L o c a t i o n A comparison between the s p a t i a l l o c a t i o n s of the b a l l a l o n g i t s t r a j e c t o r y and the time of i n i t i a t i o n of each phase of the swing was conducted t o i n v e s t i g a t e the p o s s i b i l i t y t h a t the S timed her response on the b a s i s of b a l l f l i g h t i n f o r m a t i o n . V. RESULTS AND DISCUSSION The raw da t a f o r the 60 response t r i a l s have not been i n c l u d e d , but a r e p r e s e n t a t i v e t r i a l s e l e c t e d from each response c o n d i t i o n has been i n c l u d e d i n Appendix F (see T a b l e s H and I ; N=6 Speed X Order p e r m u t a t i o n s ; B l o c k e d 20 (B20), B l o c k e d 30 (B30), B l o c k e d 40 (B40), Random 20 (R20), Random 30 (R30), Random 40 ( R 4 0 ) ) . These d a t a i n c l u d e the frame-by-frame k i n e m a t i c s ( d i s p l a c e m e n t , v e l o c i t y , a c c e l e r a t i o n ) of the s t i c k segment. An a n a l y s i s of v a r i a n c e (ANOVA) was performed on a l l dependent v a r i a b l e s t o t e s t the e f f e c t s of s t i m u l u s speed (S) and o r d e r of p r e s e n t a t i o n (0) w h i l e S c h e f f e ' s and Tukey's post hoc t e s t s were conducted on s i g n i f i c a n t main e f f e c t s and i n t e r a c t i o n , r e s p e c t i v e l y . A. S t i c k D i s p l a c e m e n t A n a l y s i s of the f i e l d hockey d i s p l a c e m e n t d a t a f o r the r e p r e s e n t a t i v e B l o c k e d t r i a l s (see F i g u r e 2) shows t h a t , when the p e r f o r m e r was aware of the s t i m u l u s speed t h a t she was p r e s e n t e d w i t h , she i n i t i a t e d the swing ( E l and C1 phases) a t a d i f f e r e n t s p a t i a l l o c a t i o n a c c o r d i n g t o the s t i m u l u s speed. The t r i a l s p l o t t e d i n F i g u r e 2 r e p r e s e n t those t r i a l s s e l e c t e d as most t y p i c a l of the c a l c u l a t e d mean v a l u e s of a l l response v a r i a b l e s . T h e r e f o r e , c o n s i s t e n c i e s which a r e e v i d e n t i n the s e s i x s e l e c t e d r e s p o n s e s a re p r e s e n t i n a l l r e s p o n s e s t o s i m i l a r speed and c o n d i t i o n of s t i m u l u s p r e s e n t a t i o n . I t i s e v i d e n t i n t h i s f i g u r e t h a t an i d i o s y n c r a t i c s t i c k a c t i o n e x i s t e d i n response t o each speed 26 27 F i g u r e 2: G r i d c o o r d i n a t e s of frame-by-frame s t i c k d i s p l a c e m e n t ( f i l t e r e d d a t a ) B l o c k e d r e s p o n s e s . 28 such t h a t a more c u r v i l i n e a r p a t h of the s t i c k motion r e s u l t e d i n response t o the slowe r speed (B20). In c o n t r a s t , a s h o r t e r and more l i n e a r d i s p l a c e m e n t e x i s t e d d u r i n g the 40 m.p.h. response. T h i s d i f f e r e n c e i n d i s p l a c e m e n t p e r m i t t e d the s u b j e c t t o approach a c o n s i s t e n t s p a t i a l l o c a t i o n f o r the s t i c k e n d p r i o r t o the i n i t i a t i o n of the b a l l i s t i c C2 phase ( r e f e r t o T a b l e 2 f o r i n i t i a t i o n p o i n t means). A S c h e f f e ' s post hoc t e s t s u b s t a n t i a t e s t h i s d e c r ease i n d i s p l a c e m e n t accompanying an i n c r e a s e i n speed d u r i n g the i n i t i a l E1 phase (p_<.01), w h i l e a Tukey's comparison (p_<.05) shows t h a t the backswing d i s p l a c e m e n t (C1 and E2) a l s o d i f f e r s s i g n i f i c a n t l y between B20, B30, and B40. The t h r e e B l o c k e d d i s p l a c e m e n t means were s i m i l a r ( r e f e r t o Ta b l e K i n Appendix F; B20=197.09 d e g r e e s ; B30=197.37 de g r e e s ; B40=193.91 degrees) i n d i c a t i n g t h a t the s u b j e c t v a r i e d the d i s t a n c e s t h a t the s t i c k moved d u r i n g the p r e v i o u s response phases i n o r d e r t o make the b a l l i s t i c C2 phase c o n s i s t e n t . The e f f e c t of t e m p o r a l u n c e r t a i n t y upon performance i s i l l u s t r a t e d i n F i g u r e 3. T h i s u n c e r t a i n t y p r e v e n t e d the s u b j e c t ' s advance p r e p a r a t i o n of a c h a r a c t e r i s t i c i n i t i a t i o n p o i n t ( i . e . , E1 i n i t i a t i o n p o i n t ) i n response t o each s t i m u l u s speed. The t h r e e r e p r e s e n t a t i v e Random t r i a l s p l o t t e d i n F i g u r e 3 show t h a t the s u b j e c t p r e p a r e d f o r each Random t r i a l by i n i t i a t i n g her swing a t a r e l a t i v e l y c o n s i s t e n t p o i n t i n space f o r both E1 and C l phases (R20= 1 7 1 .29 degrees(E1 ) , 1 7 9 . 3 4 ( d ) ; R30=174.52, 178.15; 29 Ta b l e 2 Mean P o s i t i o n of the S t i c k Segment R e l a t i v e t o the H o r i z o n t a l (Degrees) a t the I n i t i a l Frame of each Phase 20 m.p.h. 30 m.p.h. 40 m.p.h. PHASE MEAN SD MEAN SD MEAN SD E1 B l o c k e d 193.57 ±5.74 177.36 ±5.40 171.52 ±4.52 Random 171.29 ±8.91 174.52 ±8.48 168.63 ±8.52 C1 B l o c k e d 203.22 ±5.78 182.27 ±4.96 173.54 ±4.39 Random 179.34 ±7.47 178.15 ±7.62 172.74 ±6.81 E2 B l o c k e d 141.68 ±4.18 137.25 ±3.60 133.04 ±6.98 Random 127.12 ±9.29 132.22 ±8.71 144.01 ±6.62 C2 B l o c k e d 79.57 ±2.88 83.98 ±5.82 86.74 ±9.00 Random 69.44 ±4.49 81.80 ±8.55 106.64 ±13.76 F i g u r e 3: G r i d c o o r d i n a t e s of frame-by-frame s t i c k displacement ( f i l t e r e d data) Random c o n d i t i o n . 31 R40=168.63, 172.74). A Tukey's p o s t hoc t e s t (p_<.05) of the s i g n i f i c a n t Speed X Order i n t e r a c t i o n c o n f i r m s t h i s c o n s i s t e n c y . In response t o an i n c r e a s e i n b a l l speed under t h i s Random c o n d i t i o n , the s u b j e c t ' s backswing (C1 and E2 phases) was s h o r t e n e d . As a r e s u l t , the i n i t i a t i o n p o i n t of the im p o r t a n t C2 phase d i f f e r e d f o r a l l t h r e e speeds. A Tukey's t e s t of the randomized C2 means shows t h a t the s t a r t i n g s t i c k p o s i t i o n f o r t h i s b a l l i s t i c phase d i f f e r e d g r e a t e s t i n the R40 response and was a l s o the most v a r i a b l e (R20=106.64 degrees r e l a t i v e t o the h o r i z o n t a l , 13.76 s t a n d a r d d e v i a t i o n ; R30=81.80, 8.55; R40=69.44, 4.49). K e e l e (Note 2) suggested t h a t r a p i d movements which a r e of too f a s t a n a t u r e t o be under v o l u n t a r y c o n t r o l a r e programmed t o seek l o c a t i o n s i n an attempt t o s i m p l i f y the c o m p l e x i t y of programming a number of response u n i t s i n t o a sequence. T h i s programming f o r l o c a t i o n appears t o be i n o p e r a t i o n d u r i n g the i n i t i a l phases of the Random s t i m u l u s c o n d i t i o n (see T a b l e 3 ) . The low s t a n d a r d d e v i a t i o n s ( r e f e r t o T a b l e 2) r e c o r d e d f o r the i n i t i a t i o n p o i n t s of both the B l o c k e d and Random t r i a l s a t each speed i l l u s t r a t e the a b i l i t y of a p e r f o r m e r t o r e p e a t e d l y i n i t i a t e t h e i r s t r o k e from a c o n s i s t e n t l o c a t i o n i n space. When observ e d i n an e x p e r i e n c e d p e r f o r m e r , an i n c r e a s e i n s p a t i a l c o n s i s t e n c y ( i . e . , a d e c r e a s e d s t a n d a r d d e v i a t i o n ) s u g g e s t s a b e t t e r c o o r d i n a t i v e e f f o r t and a g r e a t e r p o s s i b i l i t y t h a t the s y n e r g i s t i c muscle c o n t r a c t i o n 32 T a b l e 3 Mean D u r a t i o n (msec) of the Four Movement Phases i n Response t o B l o c k e d and Random S t i m u l u s P r e s e n t a t i o n 20 m.p.h. 30 m.p.h. 40 m.p.h. PHASE MEAN SD MEAN SD MEAN SD E1 B l o c k e d 242 ±3.5 ±88 ±1.0 62 ±1.0 Random 158 ±3.3 78 ±1.0 62 ±0.4 C1 B l o c k e d 254 ±0.4 192 ±0.3 192 ±1.0 Random 274 ±2.4 220 ±1.4 160 ±1.0 E2 B l o c k e d 158 ±0.5 162 ±0.5 150 ±0.6 Random 198 ±2.2 162 ±0.4 134 ±0.6 C2 B l o c k e d 210 ±0.3 212 ±0.3 222 ±0.2 Random 222 ±0.2 216 ±0.4 210 ±0.3 33 has been programmed. However, the p o s s i b i l i t y a l s o e x i s t s t h a t the s t a t i s t i c a l s i m i l a r i t y between the two sl o w e r speeds ( i . e . , mean, s t a n d a r d d e v i a t i o n ) may have been caused by the s e l e c t i o n of s t i m u l u s speeds which were t o o s i m i l a r i n t h e i r v i s u a l c h a r a c t e r i s t i c s t o e l i c i t d i s t i n c t i v e l y d i f f e r e n t r e s p o n s e s . A comparison of the Ss B l o c k e d responses t o those of the same s t i m u l u s speed i n the Random c o n d i t i o n produced the g r e a t e s t response v a r i a t i o n between the 20 and 40 m.p.h. s p e e d s - - t h a t i s , the two extreme c o n d i t i o n s . The B20 and R20 d i f f e r e n c e s i n s p a t i a l l o c a t i o n or i n i t i a t i o n p o i n t were e v i d e n t i n the f i r s t t h r e e phases of the swing (Tukey's t e s t , p_<.05), but not i n the C2 phase. The d i f f e r e n c e s i n mean and s t a n d a r d d e v i a t i o n which e x i s t e d between the 20 m.p.h. responses (B20, R20) and the 30 and 40 m.p.h. responses may have been due e i t h e r t o a change i n the s t r o k e e x e c u t i o n or as a r e s u l t of the t e s t i n g p r o c e d u r e s i n c e the B20 c o n d i t i o n was a d m i n i s t e r e d f i r s t i n the b a t t e r y of response c o n d i t i o n s . A B40 and R40 d i f f e r e n c e was p r e s e n t , however, i n the i n i t i a t i o n p o i n t of the C2 phase, and i n the d i s t a n c e c o v e r e d by the s t i c k over the two c o n c e n t r i c phases ( i . e . , C1 and C2). The s u b j e c t responded t o the v a r i a b i l i t y i n s t i m u l u s speed f o r the R20 response ( v e r s u s the B20 response) by r a i s i n g the h e i g h t of the s t i c k e n d a t the i n i t i a t i o n of each phase. And y e t , the d i s p l a c e m e n t data suggest t h a t the s t i c k c o v e r e d the same d i s t a n c e over each phase r e g a r d l e s s of whether i t was a B l o c k e d or Random 34 response ( r e f e r t o T a b l e K i n Appendix F ) . I t seems l i k e l y t h a t the s u b j e c t assumed a more r e l a x e d p o s t u r e and s t a n c e f o r the slow speed i n the p r e d i c t a b l e d i s p l a y (B20) such t h a t a lower s t i c k p o s i t i o n ( i . e . , Ready p o s i t i o n ) was p r e p a r e d p r i o r t o d e l i v e r y of the s t i m u l u s . Compare t h i s s t a n c e t o t h a t produced i n the u n p r e d i c t a b l e s t i m u l u s d i s p l a y (R20). In t h i s l a t t e r s i t u a t i o n , the s u b j e c t commenced her response w i t h a h i g h e r s t i c k p o s i t i o n which may be i n d i c a t i v e of an i n c r e a s e d muscle tonus r e s u l t i n g from the imposed i n c r e a s e d s t i m u l u s u n c e r t a i n t y . S i n c e the B40 and R40 d i s p l a c e m e n t and i n i t i a t i o n p o i n t d i f f e r e n c e s were l o c a t e d near the t e r m i n a t i o n phase (C2) of the s t r o k e , these d i f f e r e n c e s may have r e s u l t e d from the t e m p o r a l c o n s t r a i n t s p l a c e d upon the p e r f o r m e r i n response t o the f a s t speed. B. Movement V e l o c i t y The f i r s t d e r i v a t i v e of the d i s p l a c e m e n t d a t a has been p l o t t e d (see F i g u r e s 4 and 5) f o r B l o c k e d and Random t r i a l s r e s p e c t i v e l y . The graphs were a l i g n e d and p l o t t e d back i n time commencing w i t h the frame of b a l l c o n t a c t . I t i s e v i d e n t from th e s e graphs t h a t the s t i c k v e l o c i t y throughout the B l o c k e d responses f o l l o w e d a s i m i l a r t r e n d throughout the f o u r phases r e g a r d l e s s of s t i m u l u s speed. The B20 response was i n i t i a t e d e a r l i e r i n time when compared w i t h the B30 and B40 r e s p o n s e s . T h i s s u g gests t h a t the a d d i t i o n a l s t i c k movement o c c u r r i n g d u r i n g the e a r l y phases of the B20 35 Frames Preceding ball contact F i g u r e 4: Frame-by-frame r e p r e s e n t a t i v e v e l o c i t y of s t i c k segment d u r i n g B20, B30, B40 r e s p o n s e s . 36 Legend A R 2 0 X R 3 0 • R 4 0 30-, -to H 1 1 — ; 1 1 1 1 1 1 1 40 30 20 10 0 Frames Preceding Ball Contact F i g u r e 5: Frame-by-frame v e l o c i t y of s t i c k segment d u r i n g r e p r e s e n t a t i v e R20, R30, R40 r e s p o n s e s . 37 response was u t i l i z e d t o mark time u n t i l a time T1 (660 msec) p r i o r t o b a l l c o n t a c t . From T1 u n t i l b a l l c o n t a c t , the frame-by-frame average v e l o c i t i e s were s i m i l a r a c r o s s the t h r e e B l o c k e d speeds. An a n a l y s i s of the peak v e l o c i t i e s a t t a i n e d i n each phase (see T a b l e 4) showed t h a t t h e r e were no s i g n i f i c a n t d i f f e r e n c e s e x i s t i n g between the t h r e e B l o c k e d speeds d u r i n g e i t h e r the E1 phase or at b a l l c o n t a c t . However, the B20 peak v e l o c i t y d u r i n g the backswing (C1 and E2) p r o v e d t o be s i g n i f i c a n t l y g r e a t e r (Tukey's t e s t of means, p_<.05) than the B30 or B40 mean responses (B20=.959 r a d / s e c , .023 s t a n d a r d d e v i a t i o n ; B30=.960 r a d / s e c , .266 S.D.; B40=.572 r a d / s e c , .249 S.D.). T h i s d i f f e r e n c e s u g g e s t s a c o n t i n u a t i o n of the d i s p l a c e m e n t c o n s i s t e n c y problem (as e v i d e n c e d i n the h i g h s t a n d a r d d e v i a t i o n measures f o r s t i c k d i s p l a c e m e n t ; r e f e r t o T a b l e 2) which the s u b j e c t e x h i b i t e d d u r i n g t h i s phase of her B20 response. T h i s r e s u l t l e a d s one t o b e l i e v e t h a t t h r o u g h v a r i a b i l i t y i n d i s p l a c e m e n t and, t o a l e s s e r e x t e n t , i n peak v e l o c i t y d u r i n g the backswing, the s u b j e c t was a b l e t o b r i n g her s t i c k i n t o a s p a t i a l p o s i t i o n such t h a t her downswing c o u l d be i n i t i a t e d from a c o n s i s t e n t s p a t i a l l o c a t i o n . In c o n t r a s t , F i g u r e 5 i s an i l l u s t r a t i o n of the frame-by-frame v e l o c i t y f o r the r e p r e s e n t a t i v e Random t r i a l s . C o n s i d e r a b l y d i f f e r e n t v e l o c i t y c h a r a c t e r i s t i c s are e v i d e n t between the t h r e e s t i m u l u s speeds. T h i s i s p a r t i c u l a r l y t r u e d u r i n g the i n i t i a l frames of each swing. 38 T a b l e 4 Mean Peak V e l o c i t y of the S t i c k e n d ( r a d / s e c ) f o r Each S t r o k e Phase - B l o c k e d and Random T r i a l s PHASE 20 m.p.h. MEAN SD 30 m.p.h. MEAN SD 40 m.p.h. MEAN SD B l o c k e d Random I I B l o c k e d Random B a l l C o n t a c t B l o c k e d Random .959 .738 7.200 5.803 18.023 18.1 16 ±.023 ±.356 ±.356 ±.964 ±.879 ±.898 .960 .688 6. 132 5.784 18.139 18.206 ±.266 ±.257 ±.342 ±.670 ±.960 ±.993 .572 .829 5.410 4.728 18.379 17.842 ±.249 ±.386 ±.386 ±.680 ±.381 ±.428 39 The s u b j e c t i n c o r p o r a t e d a d d i t i o n a l movements i n t o her s t r o k e which a r e e v i d e n c e d i n the changes of s t i c k v e l o c i t y . The c u r v e p l o t t e d f o r the R20 response i l l u s t r a t e s how the s u b j e c t i n i t i a t e d her response e a r l i e r i n time than would be d e s i r a b l e t o produce smooth and c o n s i s t e n t ( a c r o s s Speeds and C o n d i t i o n s ) E1 and C2 phases. The s u b j e c t a d j u s t e d t h i s e a r l y i n i t i a t i o n by an almost immediate d e c e l e r a t i o n of her swing, f o l l o w e d by a second a c c e l e r a t i o n . C i n e a n a l y s i s showed t h a t t h i s v a r i a b i l i t y i n s t i c k v e l o c i t y was a c t u a l l y a c c o m p l i s h e d by a d o u b l e - s t e p w i t h the l e f t f o o t which e v i d e n c e d i t s e l f i n the k i n e m a t i c s of the s t i c k over frames 37 t o 42 (see F i g u r e 5 ) . In a l l of the R20 t r i a l s where adjustment t o i n c o r r e c t movement i n i t i a t i o n o c c u r r e d (6/10 t r i a l s ) , the s u b j e c t u t i l i z e d the i n i t i a l E1 or C1 phases f o r her c o r r e c t i v e a c t i o n . However, commencing w i t h the downswing phase (C2) and t e r m i n a t i n g a t b a l l c o n t a c t , the s u b j e c t produced a downswing which remained r e l a t i v e l y c o n s i s t e n t i n v e l o c i t y r e g a r d l e s s of b a l l speed d u r i n g the Random c o n d i t i o n , remained r e l a t i v e l y c o n s i s t e n t a c r o s s Random t r i a l s r e g a r d l e s s of b a l l speed. A l t h o u g h the frame-by-frame average v e l o c i t i e s of the t h r e e Random responses d i s p l a y e d an o v e r a l l d i s s i m i l a r i t y , the "peak" v e l o c i t i e s r e c o r d e d f o r the E1 and C2 phases p r o v e d , as w i t h the B l o c k e d r e s p o n s e s , t o be s t a t i s t i c a l l y s i m i l a r r e g a r d l e s s of s t i m u l u s speed (see Ta b l e 4 ) . The major d i f f e r e n c e i n peak v e l o c i t i e s f o r the backswing i n the Random t r i a l s , however, o c c u r r e d d u r i n g the Ss response t o 40 the R40 s t i m u l u s speed. T h i s v a l u e was s i g n i f i c a n t l y l e s s than t h a t r e c o r d e d f o r the R20 or R30 v a l u e s (Tukey's t e s t , p_<.05; R20 = 5.803 r a d / s e c ; R30 = 5.784 r a d / s e c ; R40=4.728 r a d / s e c ) . Once a g a i n , though, i t i s e v i d e n t t h a t the S u b j e c t a l s o produced a s i g n i f i c a n t l y d i f f e r e n t backswing v e l o c i t y i n t h i s performance c o n d i t i o n which s u g g e s t s t h a t both d i s p l a c e m e n t and v e l o c i t y a r e v a r i e d d u r i n g the backswing i n o r d e r t o p r e p a r e f o r an a c c u r a t e C2 downswing. As the s u b j e c t was f o r c e d t o o p e r a t e w i t h i n a s h o r t e r time d i m e n s i o n f o r the e n t i r e 40 m.p.h. response c o n d i t i o n , she seemed f o r c e d t o u t i l i z e a v a r i a b i l e backswing i n p r e p a r a t i o n f o r downswing c o n s i s t e n c y . As B l o c k e d and Random responses t o t h e same speed a r e compared, one i s aware t h a t t h e peak v e l o c i t i e s r e c o r d e d f o r the E1 phase the s t i c k v e l o c i t y a t b a l l c o n t a c t d i s p l a y e d no s i g n i f i c a n t d i f f e r e n c e s . In f a c t , the o n l y s i g n i f i c a n t l y d i f f e r e n t response throughout the e n t i r e swing e x i s t e d d u r i n g the backswing (peak v e l o c i t y ) of the B20 and R20 responses (B20=7.200 r a d / s e c , .356 S.D; R20=5.803, .964). T a b l e 4 shows t h a t the peak s t i c k v e l o c i t y reached i n Phase I I of the B20 response was g r e a t e r than any o t h e r speed i n e i t h e r c o n d i t i o n . When p r e s e n t e d w i t h s t i m u l u s v a r i a b i l i t y and u n p r e d i c t a b i l i t y , however, the Ss mean peak v e l o c i t y i n response t o a 20 m.p.h. s t i m u l u s speed approached t h a t of the m i d d l e speed (30 m.p.h.). T h i s r e s u l t may have been due t o an independent response component, ( e . g . , l a c k of time a v a i l a b l e d u r i n g which t o complete the response and 41 t h e r e f o r e a t t a i n the i n t e n d e d peak v e l o c i t y ) , or i t may i n d i c a t e t h a t the added u n c e r t a i n t y caused the s u b j e c t t o produce a response t h a t approached the mean speed. N e w e l l , C a r l t o n and C a r l t o n (1980) have s t u d i e d movement v e l o c i t y as a f u n c t i o n of movement t i m i n g a c c u r a c y . They suggest t h a t v o l u n t a r y movement g e n e r a t e s response i n f o r m a t i o n from a f f e r e n t mechanisms ( i . e . , muscle s p i n d l e s , tendon organs, j o i n t r e c e p t o r s , cutaneous r e c e p t o r s ) which i s f e d back to the c e n t r a l p r o c e s s i n g system. The i n f o r m a t i o n d e r i v e d from an i n c r e a s e d r a t e of movement i s ge n e r a t e d from an i n c r e a s e d r a t e of f i r i n g of j o i n t r e c e p t o r s and a lower d i s c h a r g e r a t e i n the muscle s p i n d l e s . These i n v e s t i g a t o r s c o n c l u d e d t h a t t i m i n g e r r o r c o n t i n u e d t o de c r e a s e as average v e l o c i t y i n c r e a s e d . As one i n c r e a s e s movement v e l o c i t y , one a l s o i n c r e a s e s the pe r c e n t a g e of a c t i v e motor u n i t s . In c o n t r a s t , s m a l l e r i m p u l s e s a t low v e l o c i t i e s would r e s u l t i n a d e c r e a s e i n the number of motor u n i t s r e q u i r e d t o produce slow v e l o c i t y movements. Basmajian (1977) has suggested t h a t the i n h i b i t i o n of motor u n i t s i s much more p r o b l e m a t i c than t h e i r e x c i t a t i o n . T h i s c o u l d w e l l be a f a c t o r i n the d e t e r m i n a t i o n of t i m i n g e r r o r . In o t h e r words, t h e r e i s , w i t h fewer motoneurons demanding i n h i b i t i o n d u r i n g movement c o m p l e t i o n a t a h i g h v e l o c i t y , l e s s l i k e l i h o o d of samp l i n g e r r o r than d u r i n g movement a t a low v e l o c i t y . T h i s i n c r e a s e i n the p r o b a b i l i t y of s u c c e s s i s b e n e f i c i a l when performance demands are i n c r e a s e d , as o c c u r s i n the Random ( e . g . , R40) c o n d i t i o n of t h i s i n v e s t i g a t i o n . 42 Bruner ( c f . T y l d e s l e y , Note 3) h y p o t h e s i z e d t h a t " v e l o c i t y c o n t r o l was more fundamental i n the l e a r n i n g p r o c e s s than d i s p l a c e m e n t c o n t r o l . C o n t r o l o r d e r changes from good v e l o c i t y c o n t r o l i n the n o v i c e t o good d i s p l a c e m e n t p l u s v e l o c i t y c o n t r o l i n the e x p e r t i n d i c a t e d a k i n e m a t i c e x t e n s i o n of the 'mastery of the degrees of freedom'. The r a t h e r unexpected s u p e r i o r i t y of f i r s t - o r d e r ( v e l o c i t y ) c o n t r o l over d i s p l a c e m e n t c o n t r o l i n the n o v i c e p r o v i d e d s u p p o r t i v e e v i d e n c e t h a t c o n t r o l of the k i n e m a t i c f e a t u r e s p r o g r e s s e s from f o r c e t h rough v e l o c i t y t o d i s p l a c e m e n t " . I t i s p o s s i b l e t h a t , as the u n c e r t a i n t y of the environment was i n c r e a s e d , and as the t o t a l d u r a t i o n p e r m i t t e d f o r the response was d e c r e a s e d due t o i n c r e a s e d s t i m u l u s v e l o c i t y and d e c i s i o n - m a k i n g demands, the s u b j e c t u t i l i z e d a slower output v e l o c i t y f o r the backswing--one which had been mastered. The s t i c k d i s p l a c e m e n t would thus d e c r e a s e commensurately. Megaw (1972) has shown t h a t the t i m i n g of a g o n i s t s and a n t a g o n i s t s i n a programmed movement of s h o r t d u r a t i o n e x h i b i t s a r e s i s t a n c e t o feedback, but t h a t t i m i n g m o d i f i c a t i o n s are p o s s i b l e by " i n t e n s i f i c a t i o n " of a c t i v i t y . T h i s r e s u l t s i n e a r l i e r muscle c o n t r a c t i o n s . The p r i n c i p l e used i n t e a c h i n g many s p o r t s k i l l s i s t h a t one s h o u l d commence the s t r o k e s l o w l y f o r i t i s e a s i e r t o speed up a movement than t o slow the same movement down. Such d e c e l e r a t i o n would i n v o l v e s t i m u l a t i n g the a n t a g o n i s t s sooner than i n t e n d e d ( W e l f o r d , 1974). However, a l t h o u g h 43 i n c r e a s e d movement v e l o c i t y f a c i l i t a t e s t i m i n g performance, i t d e t r a c t s from performance measured on a s p a t i a l c r i t e r i o n ( N e w e l l e t a l , 1980). S i n c e o n l y s u c c e s s f u l d r i v e s were e v a l u a t e d i n t h i s s t u d y , of i n t e r e s t here would have been a subsequent comparison of t h e s e v e l o c i t y v a l u e s d u r i n g u n s u c c e s s f u l r e s p o n s e s . S u c c e s s f u l performance w i t h i n an u n c e r t a i n environment (speed v a r i a t i o n s ) seemed t o d i c t a t e t h a t the p e r f o r m e r i n c o r p o r a t e a g r e a t e r number of output v a r i a t i o n s ( d i s p l a c e m e n t , peak v e l o c i t y ) w i t h i n t h a t p a r t of the motor program c o n t r o l l i n g the p r e p a r a t o r y backswing. C. A c c e l e r a t i o n A l t h o u g h the B20 response was i n i t i a t e d e a r l i e r i n time r e l a t i v e t o b a l l c o n t a c t , the t h r e e responses f o l l o w an i d e n t i c a l a c c e l e r a t i o n t r e n d from a p p r o x i m a t e l y 33 frames (660 msec) b e f o r e b a l l c o n t a c t (see F i g u r e 6 ) . T h i s r e s u l t s u g g e s t s t h a t the s u b j e c t i s c a p a b l e of p r o d u c i n g a w e l l - c o o r d i n a t e d and c o n s i s t e n t motor response when o p e r a t i n g w i t h i n a p r e d i c t a b l e environment ( r e g a r d l e s s of s t i m u l u s s p e e d ) . That i s , once she i n i t i a t e d a r e s p o n s e , her a g o n i s t i c and a n t a g o n i s t i c muscles responded s y n e r g i s t i c a l l y r e l a t i v e t o each o t h e r t o produce a s i m i l a r s t r o k e i n the l i g h t of advance i n f o r m a t i o n . A s l i g h t v a r i a t i o n i n a c c e l e r a t i o n v a l u e s between d i f f e r e n t B l o c k e d s t i m u l u s speeds was r e c o r d e d a p p r o x i m a t e l y 50 t o 60 msec f o l l o w i n g the i n i t i a t i o n of the C2 phase. S i n c e t h i s time o c c u r r e d s i m u l t a n e o u s l y w i t h peak 44 Legend A B20 x §30 • B40 2 5 0 - 1 - 3 0 0 - 1 1 1 1 1 1— 1— 1 1 1 1 50 40 30 20 10 0 Frames Preceding Ball Contact F i g u r e 6: Frame-by-frame a c c e l e r a t i o n of the s t i c k segment f o r the r e p r e s e n t a t i v e B20, B30, B40 r e s p o n s e s . 45 a c c e l e r a t i o n , t h i s i n t e r - r e s p o n s e v a r i a t i o n i s most l i k e l y a t t r i b u t a b l e t o the d i f f i c u l t y which e x i s t s i n t i m i n g the onset of the a n t a g o n i s t i c i m p u l s e s r e s p o n s i b l e f o r s l o w i n g down the a g o n i s t i c r e s ponse. I t i s i m p o r t a n t t o c o n s i d e r n e u r o - p h y s i o l o g i c a l and b i o m e c h a n i c a l maximum s t r e n g t h v a l u e s which the a g o n i s t s r e a c h p a r t of the way t h r o u g h t h e i r c o n t r a c t i o n . An assessment of the swing mechanics w i l l show t h a t as the muscles pass t h e i r o p t i m a l f i b r e l e n g t h they b e g i n t o d i s p l a y a decrement i n t h e i r c o n t r a c t i l e p r o p e r t i e s and c o r r e s p o n d i n g s t r e n g t h measures (Guyton, 1961). In g e n e r a l , i t appears from th e s e graphs t h a t the "smoother" d e c e l e r a t i o n c h a r a c t e r i s t i c s a re a s s o c i a t e d w i t h the f a s t e r s t i m u l u s speeds. The d i f f e r e n c e s o b s e r v e d between the t h r e e B l o c k e d responses may r e s u l t from the e r r o r messages r e t u r n i n g t o the s p i n a l c o r d from the a f f e r e n t s of the g o l g i tendon organs, muscle s p i n d l e s and the e x t r a f u s a l muscle f i b r e s . 6 A p r o p r i o c e p t i v e feedback l o o p c o u l d produce r a p i d a g o n i s t i c / a n t a g o n i s t i c c o n t r a c t i o n s which would be e v i d e n t i n the a c c e l e r a t i o n and d e c e l e r a t i o n v a l u e s . In c o n t r a s t t o the r e l a t i v e l y c o n s i s t e n t second d e r i v a t i v e of the B l o c k e d means, the g r a p h i c i l l u s t r a t i o n of the t h r e e Random responses (see F i g u r e 7) shows tremendous d i s s i m i l a r i t y a l o n g both the time and a l p h a ( r a d / s e c 2 ) axes. When p r e s e n t e d w i t h an u n p r e d i c t a b l e s t i m u l u s c o n d i t i o n , the s u b j e c t appears t o a l t e r the a c c e l e r a t i o n f e a t u r e s of what 6A b r i e f d i s c u s s i o n of the f o l l o w - u p s e r v o t h e o r y and alpha-gamma c o - a c t i v a t i o n t h e o r y i s i n c l u d e d i n Appendix B. 46 Legend A 820 x MO • R40 40 30 20 10 0 Frames Preceding Bail Contact F i g u r e 7: Frame-by-frame a c c e l e r a t i o n f o r the r e p r e s e n t a t i v e R20, of the s t i c k segment R30, R40 r e s p o n s e s . 47 has a l r e a d y been d e s c r i b e d as a r e l a t i v e l y c o n s i s t e n t average v e l o c i t y (frame-by-frame) t r e n d . T h i s v a r i a b i l i t y may r e s u l t from p h y s i o l o g i c a l c o n s t r a i n t s or i t may be the r e s u l t of the "exaggeration" of a number of smaller displacement or v e l o c i t y ( f i r s t d e r i v a t i v e ) e r r o r s as they were taken to the second d e r i v a t i v e . Although the alpha-gamma c o - a c t i v a t i o n theory suggests that the performer i s capable of programming a motor response by p r e - s e t t i n g muscle s p i n d l e l e n g t h , the a d d i t i o n a l stimulus u n c e r t a i n t y present i n the Random environment may have a f f e c t e d the s u b j e c t ' s a b i l i t y to p r e - s e t the s p i n d l e s and i n t e r p r e t i n t e r o c e p t i v e and p r o p r i o c e p t i v e feedback at the s p i n a l c o r d l e v e l . D. Movement D u r a t i o n F i g u r e 8 shows the mean movement d u r a t i o n s and standard d e v i a t i o n s f o r each of the three speeds and t h e i r two response c o n d i t i o n s . The data were analyzed a c c o r d i n g to the four s t r o k e phases (E1, C1, E2, C2). The standard d e v i a t i o n for each group of responses was low i n a l l four phases (0.2 to 3.5 msec) demonstrating response c o n s i s t e n c y . In response to both c o n d i t i o n s of stimulus u n c e r t a i n t y , the subject appeared to decrease her movement time f o r each of the f i r s t three phases (E1, C1, and E2) as stimulus speed i n c r e a s e d . Although a s i g n i f i c a n t Speeds e f f e c t (p_<.01) was present f o r these three phases, an Order e f f e c t d i d not e x i s t . That i s , movement times were c o n s i s t e n t f o r a l l responses at a s i n g l e 48 F i g u r e 8 : Mean d u r a t i o n (msec) of the f o u r movement phases i n r e s p onse t o b l o c k e d and random s t i m u l u s p r e s e n t a t i o n . 49 speed r e g a r d l e s s of whether the speed was d e l i v e r e d i n a B l o c k e d or Random p r e s e n t a t i o n o r d e r . A comparison between the d u r a t i o n of the a g o n i s t i c a c t i v i t y of the c o n c e n t r i c C1 phase and the d u r a t i o n of the E2 d e c e l e r a t i o n phase p r e s e n t s the p o s s i b i l i t y t h a t t h i s l a t t e r phase was dependent upon the movement time of the p r e c e d i n g phase. A l o n g e r C1 ( a g o n i s t i c ) movement time demanded l o n g e r E2 ( a n t a g o n i s t i c ) a c t i v i t y . The s u b j e c t m a i n t a i n e d , however, a c o n s i s t e n t movement time (mean time 210 t o 222 msec; s t a n d a r d d e v i a t i o n 0.2 t o 0.4 msec) over the most i m p o r t a n t C2 phase. T h i s o c c u r r e d r e g a r d l e s s of the Ss advance knowledge of b a l l v e l o c i t y . These r e s u l t s are i n agreement w i t h those of T y l d e s l e y (1980) who i n v e s t i g a t e d the response c h a r a c t e r i s t i c s of t a b l e t e n n i s p e r f o r m e r s of v a r y i n g s k i l l l e v e l s . He c o n c l u d e d t h a t t r a i n e d s u b j e c t s were c a p a b l e of p r o d u c i n g a b a l l i s t i c downswing ( a p p r o x i m a t i n g the C2 phase of t h i s s t udy) of a c o n s t a n t d u r a t i o n w i t h i n Ss. H i s s u b j e c t s o p e r a t e d w i t h i n a c o n d i t i o n of s p a t i a l u n c e r t a i n t y as opposed t o the t e m p o r a l u n c e r t a i n t y imposed i n t h i s i n v e s t i g a t i o n . Work performed by S p a e t h - A r n o l d (1976) and Hubbard and Seng (1954) a l s o p r o v i d e d i n v e s t i g a t i v e e v i d e n c e as t o the c o n s i s t e n c y which s u b j e c t s show i n t h i s movement parameter. S i n c e the B l o c k e d t a s k c o n d i t i o n s encourage t y p i c a l l y c l o s e d s k i l l p e rformance, the e x p e r t p e r f o r m e r of t h i s s tudy responded t o a l l t h r e e speeds s i m i l a r l y and appeared t o d i r e c t her a t t e n t i o n t o a d e c i s i o n r e g a r d i n g a time f o r the 50 i n i t i a t i o n of the b a l l i s t i c downswing ( i . e . , 200-220 msec p r i o r t o b a l l c o n t a c t ) . The s u b j e c t seemed t o , t h e r e f o r e , v a r y the d u r a t i o n of the p r e c e d i n g phases (E1, C l , E2) i n p r e p a r a t i o n f o r i n i t i a t i o n of her downswing 220 msec b e f o r e the b a l l a r r i v e d a t her f e e t . In s p i t e of the a d d i t i o n a l u n c e r t a i n t y p r e s e n t i n the Random c o n d i t i o n , the s u b j e c t d i d not p e r f o r m s i g n i f i c a n t l y d i f f e r e n t l y a l o n g the te m p o r a l parameter of any phase. A 20 m.p.h. response proved t o be t e m p o r a l l y e q u i v a l e n t over each phase r e g a r d l e s s of whether i t was performed i n response t o a B l o c k e d or Random d i s p l a y . L i k e w i s e , the B l o c k e d and Random 30 and 40 m.p.h. responses were a l s o s t a t i s t i c a l l y s i m i l a r (B20= 254 msec, R20=274 msec; B30=192 msec, R30=220 msec; B40=192 msec, R40=160 msec). Rather than reproduce a s t r o k e of te m p o r a l c o n s i s t e n c y a c r o s s a l l speeds ( i . e . , of a low s t a n d a r d d e v i a t i o n ) , the s u b j e c t v a r i e d the d u r a t i o n of the f i r s t t h r e e phases of her s t r o k e a c c o r d i n g t o the the time a v a i l a b l e f o r her performance. That i s , as the s t i m u l u s v e l o c i t y d e c r e a s e d and more time was a v a i l a b l e w i t h which to produce a response, the s u b j e c t was shown t o u t i l i z e t h i s extended time p e r i o d w i t h s t i c k m o t i o n . I t has been suggested t h a t t h i s movement i s r e g u l a r l y used by p e r f o r m e r s t o "mark t i m e " u n t i l a t e m p o r a l l y c o n s i s t e n t C2 phase can be i n i t i a t e d , and t o produce p r o p r i o c e p t i v e feedback as a means of e v a l u a t i n g the s t i m u l u s v e l o c i t y ( W e l f o r d , 1974). The low i n t e r - r e s p o n s e v a r i a b i l i t y ( r e f e r t o T a b l e 3) r e c o r d e d f o r the movement 51 d u r a t i o n of t h i s C2 phase i s i n d i c a t i v e of the a b i l i t y of t h i s p e r f o r m e r t o c o n s i s t e n t l y reproduce a l l phases of the s t r o k e ( s t a n d a r d d e v i a t i o n s : B20=.3 msec; B30=.3 msec; B40=.2 msec; R20=.2 msec; R30=.4 msec; R40=.3 msec). The f a c t t h a t t h e r e were no s t a t i s t i c a l d i f f e r e n c e s r e c o r d e d i n C2 movement d u r a t i o n o r , as mentioned p r e v i o u s l y , s t i c k v e l o c i t y at b a l l c o n t a c t a c r o s s Speeds or Order of p r e s e n t a t i o n agrees w i t h K e e l e ' s (Note 2) f i n d i n g t h a t p e r f o r m e r s m a i n t a i n t e m p o r a l c o n s i s t e n c y ( i . e . , movement d u r a t i o n and v e l o c i t y ) a t the expense of s p a t i a l c o n s i s t e n c y ( i . e . , d i s p l a c e m e n t and i n i t i a t i o n p o i n t ) . E. B a l l L o c a t i o n T a b l e 5 and F i g u r e 9 show the p o s i t i o n of the b a l l a l o n g the runway ( r e c o r d e d as meters from the b a l l d e l i v e r y a p p a r a t u s ) a t the i n i t i a t i o n of each phase. T a b l e 6 shows the time which the b a l l took t o t r a v e r s e each of these i n t e r v a l s . A " p r e - s t r o k e i n i t i a t i o n phase" (Pre~E1) has been i n c l u d e d i n Table 6 i n o r d e r t o r e p r e s e n t response p r e p a r a t i o n t i m e . As the speed i n c r e a s e d w i t h i n the B l o c k e d c o n d i t i o n , the s u b j e c t w a i t e d u n t i l the b a l l had t r a v e l l e d f u r t h e r a l o n g the runway b e f o r e i n i t i a t i n g her s t r o k e . The mean Pre-E1 phase d u r a t i o n was c a l c u l a t e d t o be 484, 239 and 44 msec f o r the 20, 30 and 40 m.p.h. responses r e s p e c t i v e l y . A s i m i l a r r e l a t i o n s h i p was e v i d e n t f o r the Random Pre-E1 phase (496, 220, and 108 msec). Both B l o c k e d and Random responses 52 T a b l e 5 B a l l P o s i t i o n Along the Runway at the I n i t i a t i o n of Each Swing Phase ( d i s t a n c e from b a l l machine i n meters) BLOCKED RANDOM Phase 20 30 40 20 30 40 E c c e n t r i c 1 4.31 3.21 0.79 4.41 2.94 1 .94 C o n c e n t r i c 1 6.46 4.39 1 .90 5.82 3.99 3.05 E c c e n t r i c 2 8.72 6.96 5.34 8.26 6.93 5.91 C o n c e n t r i c 2 10.13 9.80 8.03 10.02 9.11 8.31 53 F i g u r e 9: B a l l p o s i t i o n along the runway at the i n i t i a t i o n of each swing phase. 54 Ta b l e 6 Mean D u r a t i o n (msec) of Each S t r o k e I n t e r v a l P r i o r t o B a l l C o n t a c t PHASE 20 mph 30 mph 40 mph B R B R B R Pre-E1 484 496 239 220 44 108 E1 242 158 88 78 62 62 C1 254 274 192 220 192 160 E2 158 198 162 162 150 134 C2 2 1 0 222 2 1 2 216 220 210 TT 864 852 656 676 626 566 B a l l Time Down Runway 1348 896 670 55 t o v i s u a l i n f o r m a t i o n from the 20 and 30 m.p.h. s t i m u l i were d e l a y e d f o r an i n t e r v a l a p p r o a c h i n g one r e a c t i o n t i m e - - b u t the 40 m.p.h. responses were produced i n c o n s i d e r a b l y l e s s t i m e . In f a c t , the B40 and R40 responses of 44 and 108 msec r e s p e c t i v e l y i n d i c a t e a degree of s t i m u l u s a n t i c i p a t i o n . The i n i t i a t i o n s of the 20 and 30 m.p.h. responses ( B l o c k e d and Random) were d e l a y e d u n t i l s u f f i c i e n t b a l l d i s p l a c e m e n t had passed such t h a t the s u b j e c t c o u l d a s s e s s the c h a r a c t e r i s t i c s of the s t i m u l u s d i s p l a y . T h i s response d e l a y was e q u i v a l e n t t o a p p r o x i m a t e l y one r e a c t i o n t i m e . However, because of the d e c r e a s e d time a v a i l a b l e d u r i n g the 40 m.p.h. ( B l o c k e d and Random)ball speed, the E l phases of the response had t o be i n i t i a t e d sooner and, t h e r e f o r e , a f t e r the b a l l had o n l y t r a v e l l e d a minimal d i s t a n c e a l o n g the runway. A response d e l a y was e v i d e n t i n a l l responses t o the Random c o n d i t i o n when compared w i t h the B l o c k e d . T h i s e f f e c t i s i l l u s t r a t e d i n Table 5. As the u n c e r t a i n t y of the s i t u a t i o n f o r c e d the s u b j e c t t o d e l a y the i n i t i a t i o n of her response t o a l a t e r p o i n t i n t i m e , the b a l l had passed through a g r e a t e r d i s p l a c e m e n t . A l t h o u g h the s u b j e c t was c a p a b l e of s u c c e s s f u l l y i n i t i a t i n g and c o m p l e t i n g a r a p i d d r i v e i n as s h o r t a time i n t e r v a l as 566 msec (R40), her response t o the B20 s t i m u l u s took c o n s i d e r a b l e l o n g e r (864 msec). T h i s i n d i c a t e s t h a t she was not p e r f o r m i n g an i d e n t i c a l s t r o k e from s t a r t t o f i n i s h . I t may be suggested t h a t the "normal" response t i m i n g as i t r e l a t e s t o s t i m u l u s d i s p l a c e m e n t i s one which i s 56 e v i d e n t i n the B l o c k e d r e s p o n s e s . Without advance knowledge as t o s t i m u l u s speed ( i . e . , Random c o n d i t i o n ) , a d e l a y i n movement i n i t i a t i o n time and t o t a l response time was e v i d e n c e d i n the Pre-E1 phases. T h i s d e l a y was compensated f o r by a decrease i n E1 ti m e s f o r a l l Random speeds. The s u b j e c t appeared c a p a b l e of a d j u s t i n g each subsequent phase i n o r d e r t o pr e p a r e f o r i n i t i a t i o n of the C2 phase a t s i m i l a r b a l l l o c a t i o n s r e g a r d l e s s of Speed o r c o n d i t i o n of p r e s e n t a t i o n ( r e f e r t o T a b l e 5 ) . As an example, t e m p o r a l performance d u r i n g the R40 s t i m u l u s c o n d i t i o n was a f f e c t e d by the Ss c h o i c e r e a c t i o n time d e l a y . The u n c e r t a i n t y of the s i t u a t i o n was e v i d e n c e d i n the extended time r e c o r d e d f o r the Pre-E1 phase of the R40 response when compared t o the B40 response (108 msec and 44 msec r e s p e c t i v e l y ) . To accommodate t h i s added d e l a y , the s u b j e c t was then f o r c e d t o de c r e a s e both the C1 and E2 ( i . e . , backswing) phases i n comparison w i t h her B40 re s p o n s e . T h i s e n a b l e d her t o i n i t i a t e her downswing (C2 phase) a t a time when the b a l l was i n the same s p a t i a l l o c a t i o n as d u r i n g her B l o c k e d 40 response (B40 b a l l location=10.13m from the b a l l machine; R40=10.02m from b a l l machine). However, a t the f a s t e r speed, s u b j e c t s d i d not i n i t i a t e c o r r e c t i o n s t o the s t r o k e . The d i f f e r e n c e i n b a l l l o c a t i o n a t s t r o k e i n i t i a t i o n o b t a i n e d a c r o s s Speeds makes i t improbable t h a t the s u b j e c t i n i t i a t e d her response a c c o r d i n g t o a p r e d e t e r m i n e d b a l l image s i z e a t a s i n g l e t i m e , T1, f o r a l l 60 t r i a l s . However, she may have been r e s p o n d i n g t o p r e - d e t e r m i n e d t i m e s T1-4 57 f o r each phase (E1-C2) and f o r each speed by r e a c t i n g t o : 1) the r a t e of change of image s i z e - - f r o m the time of b a l l r e l e a s e t o t i m e s , T1-4; or 2) the d i f f e r e n c e i n r e t i n a l image s i z e a t a t ime T1 depending upon the b a l l speed ( i . e . , because the b a l l w i l l be c l o s e r t o the s u b j e c t , i t s image s i z e w i l l be l a r g e r f o r the f a s t e r b a l l v e l o c i t i e s ) . The s u b j e c t w i l l have dev e l o p e d an awareness of the d i f f e r e n c e s i n image s i z e a t these s p e c i f i c speeds as a r e s u l t of the p r e l i m i n a r y p r a c t i c e s e s s i o n s . The S may have sampled i n f o r m a t i o n v e r y e a r l y i n the d i s p l a y . I n f o r m a t i o n from the e a r l y t r a j e c t o r y of the b a l l would then a s s i s t the s u b j e c t i n her d e c i s i o n about the time at which t e m p o r a l l y c o n s i s t e n t c o n c e n t r i c (C1 and C2) movement phases must be i n i t i a t e d . The a c t u a l s t i c k movement i s then used t o mark time between these i n i t i a t i o n t i m e s . T h e r e f o r e , as T y l d e s l e y r e p o r t s , numerous response u n i t s (or movement phases) w i t h t h e i r a f f e r e n t i n f o r m a t i o n s u p p l y i n g c e n t r a l p r o c e s s e s r e p l a c e "an u n s a t i s f a c t o r y c o g n i t i v e 'time code' by a more c o n c r e t e s p a t i a l judgement" ( T y l d e s l e y , Note 3) . The r e s u l t s of t h i s study support T y l d e s l e y ' s c o n c l u s i o n t h a t i n response t o a c o i n c i d e n t - a n t i c i p a t o r y t a s k , " t r a i n e d p e r f o r m e r s seemed to d e c i d e , b e f o r e the b a l l was p r o j e c t e d , which p o i n t i n a b s o l u t e space the b a l l would have t o r e a c h t o t r i g g e r the b a l l i s t i c movement"(p. 506). V I . CONCLUSION 1. In response t o a l l s t i m u l u s speeds except the Random 40 m.p.h. (R40), the s u b j e c t ' s a g o n i s t i c / a n t a g o n i s t i c muscle a c t i v i t y tended t o oc c u r i n i n t e r v a l s of one r e a c t i o n t i m e . T h i s d u r a t i o n would p e r m i t b oth p r o p r i o c e p t i v e feedback and e x t e r o c e p t i v e feedback t o be p r o c e s s e d . The s u b j e c t c o u l d then a s s e s s the c h a r a c t e r i s t i c s of her response as w e l l as the c h a r a c t e r i s t i c s of the s t i m u l u s d i s p l a y such t h a t subsequent a d j u s t m e n t s c o u l d be made d u r i n g the re s p o n s e . 2. In a l l i n s t a n c e s , the p r e p a r a t o r y phases of the s t r o k e were i n i t i a t e d i n o r d e r t o o b t a i n a c o n s i s t e n t b a l l i s t i c phase ( C 2 ) - - p r i m a r i l y i n terms of movement d u r a t i o n and peak v e l o c i t y . To a l e s s e r e x t e n t , c o n s i s t e n c y was a l s o e v i d e n t f o r the d i s p l a c e m e n t and i n i t i a t i o n p o i n t . Low i n t e r - r e s p o n s e v a r i a b i l i t y was r e c o r d e d f o r a l l v a r i a b l e s a c r o s s a l l phases and e s p e c i a l l y d u r i n g the f i n a l b a l l i s t i c downswing l e a d i n g t o b a l l c o n t a c t . T h i s c o n s i s t e n c y e x i s t e d r e g a r d l e s s of s t i m u l u s speed or c o n d i t i o n of s t i m u l u s p r e s e n t a t i o n ( i . e . , p r e d i c t a b i l i t y ) . 3. P r i o r i t y d u r i n g the b a l l i s t i c downswing (C2 phase) seemed t o be p l a c e d on m a i n t a i n i n g t e m p o r a l c o n s i s t e n c y ( i . e . , as measured by movement d u r a t i o n and peak v e l o c i t y ) w h i l e a degree of s p a t i a l v a r i a t i o n ( i . e . , as measured by s t i c k d i s p l a c e m e n t and i n i a t i o n p o i n t ) was 58 59 u t i l i z e d f o r a c h i e v i n g response a c c u r a c y and c o i n c i d e n c e . There was no e v i d e n c e t o suggest t h a t the s u b j e c t used i n f o r m a t i o n based on an e s t a b l i s h e d b a l l l o c a t i o n a l o n g the runway as a means of e v a l u a t i n g b a l l v e l o c i t y w i t h i n the RANDOM c o n d i t i o n or as a means of d e t e r m i n i n g a time f o r s t r o k e i n i t i a t i o n . R a t h e r , i t seems l i k e l y t h a t the s u b j e c t a p p r a i s e d the b a l l ' s c h anging r e t i n a l image s i z e and used t h i s i n f o r m a t i o n t o determine which b a l l speed was b e i n g d e l i v e r e d . The s u b j e c t a l s o i n c o r p o r a t e d a d d i t i o n a l s t i c k movements (B20) t o "mark t i m e " b e f o r e i n i t i a t i n g t e m p o r a l l y c o n c e n t r i c movement phases (C1, C2). T h i s movement may r e p l a c e an a b s t r a c t 'time code' w i t h a more c o n c r e t e s e n s o r y i n p u t and awareness from j o i n t and muscle r e c e p t o r s . As s p a t i a l u n c e r t a i n t y i n c r e a s e d the s u b j e c t d e l a y e d her response i n i t i a t i o n . Due t o subsequent adjustment i n s p a t i a l l o c a t i o n and d i s p l a c e m e n t throughout the p r e l i m i n a r y phases of the response, the s u b j e c t was a b l e t o produce a c o n s i s t e n t and a c c u r a t e b a l l i s t i c downswing. The v a r i a b i l i t y which e x i s t e d i n the B20 response may have stemmed from e i t h e r a response d i f f e r e n c e due t o an i n c r e a s e d a v a i l a b i l i t y of time d u r i n g which a response may be produced or due t o the e x p e r i m e n t a l d e s i g n . In o t h e r words, t o a d m i n i s t e r the B20 c o n d i t i o n f i r s t may have b i a s e d the r e s u l t s , i n which case f u r t h e r s t u d i e s 60 s h o u l d i n v e s t i g a t e the e f f e c t s of the o r d e r i n which the BLOCKED speeds were p r e s e n t e d . The t h r e e b a l l speeds s e l e c t e d (20, 30, and 40 m.p.h.) s h o u l d a l s o be examined. The p o s s i b i l i t y e x i s t s t h a t the v i s u a l c h a r a c t e r i s t i c s of each d i s p l a y may be b e t t e r c o n t r a s t e d when u s i n g a d i f f e r e n t range of b a l l v e l o c i t i e s . 61 REFERENCE NOTES Reason, J . Lapses of a t t e n t i o n . M a n u s c r i p t s u b m i t t e d f o r p u b l i c a t i o n , 1980. K e e l e , S.W. B e h a v i o r a l a n a l y s i s of movement. To appear i n Motor C o n t r o l volume, Handbook of p h y s i o l o g y , e d i t e d by Vernon Brooks. T y l d e s l e y , D.A. P e r s o n a l Communication, 08/07/81. M a r t e n i u k , R.G. & MacKenzie, C L . I n f o r m a t i o n p r o c e s s i n g  i n movement o r g a n i z a t i o n and e x e c u t i o n . Paper p r e s e n t e d a t A t t e n t i o n and Performance V I I . P r i n c e t o n , New J e r s e y , Aug. 1978. 62 REFERENCES A l d e r s o n , G.J.K. P e r c e p t u a l s t u d i e s : v a r i a b l e s a f f e c t i n g the p e r c e p t i o n of v e l o c i t y i n s p o r t s s i t u a t i o n s . In H.T.A. W h i t i n g ( E d . ) , Readings i n s p o r t p s y c h o l o g y . London: Henry Kimpton Pub., 1972. B a s m a j i a n , J.V. Motor l e a r n i n g and c o n t r o l : a w o r k i n g h y p o t h e s i s . A r c h . Phys. Med. R e h a b i l . , 1977, 58, 3 8 - 4 1 . Bossom, J . Movement w i t h o u t p r o p r i o c e p t i o n . B r a i n R e s e a r c h , 1974, 7 J , 2 8 5 - 2 9 6 . Brooks, V.B. Some examples of programmed l i m b movements. B r a i n R e s e a r c h , 1974, 7J_, 299-308. D a v i s , R.C. The g e n e t i c development of p a t t e r n s of v o l u n t a r y a c t i v i t y . J o u r n a l of E x p e r i m e n t a l P s y c h o l o g y , 1943, 33, 4 7 1 - 4 8 6 . E v a r t s , E.V. R e l a t i o n of p y r a m i d a l t r a c t a c t i v i t y t o f o r c e e x e r t e d d u r i n g v o l u n t a r y movement. J o u r n a l of  N e u r o p h y s i o l o g y , 1968, 3J_, 14-27. F i t t s , P.M. P e r c e p t u a l - m o t o r s k i l l l e a r n i n g . In A. M e l t o n ( E d . ) , C a t e g o r i e s of human l e a r n i n g . New York: Academic P r e s s , 1964 F l e i s h m a n , E.A. & Hempel W.E., J r . The r e l a t i o n between a b i l i t i e s and improvement w i t h p r a c t i c e i n a v i s u a l d i s c r i m i n a t i o n r e a c t i o n t a s k . J o u r n a l of E x p e r i m e n t a l  P s y c h o l o g y , 1955, 49, 301-310. G l e n c r o s s , D.J. Temporal o r g a n i z a t i o n i n a r e p e t i t i v e speed s k i l l . Ergonomics, 1973, J_6, 7 6 5 - 7 7 6 . G l e n c r o s s , D.J. The e f f e c t s of changes i n t a s k c o n d i t i o n s on the t e m p o r a l o r g a n i z a t i o n of a r e p e t i t i v e speed s k i l l . E r gonomics, 1975, _1_8, 17-28. G l e n c r o s s , D.J. Output and response p r o c e s s e s i n s p o r t s s k i l l s . In D.J. G l e n c r o s s ( E d . ) , P s y c h o l o g y and s p o r t . Sydney, A u s t . : M c G r a w - H i l l Book Co., 1978. G r a y b i e l , A., J o k l , E., and Trapp, C. R u s s i a n s t u d i e s i n v i s i o n i n r e l a t i o n t o p h y s i c a l a c t i v i t y and s p o r t s . R e s e a r c h Q u a r t e r l y , 1955, 26, 4 8 0 - 4 8 5 . Grose, J.E. R e l a t i o n s h i p of the p a t t e r n of movements, i n c l u d i n g rhythm and t e r m i n a l s u c c e s s . R.Q., 1967, 38, 10-21. 63 Grose, J.E. R e l a t i o n s h i p of the p a t t e r n of movements, i n c l u d i n g rhythm and t e r m i n a l s u c c e s s . R.Q., 1967, 38, 10-21. Guyton, A.C. Textbook of m e d i c a l p h y s i o l o g y • P h i l a d e l p h i a : W.B. Saunders Co., 1961. H i g g i n s , J.R. & A n g e l , R.W. C o r r e c t i o n of t r a c k i n g e r r o r s w i t h o u t sensory feedback. J o u r n a l of E x p e r i m e n t a l  P s y c h o l o g y , 1970, 84, 412-416. H o i s t , E. von. R e l a t i o n s between the c e n t r a l nervous system and the p e r i p h e r a l organs. B r i t i s h J o u r n a l of Animal  B e h a v i o r , 1954, 2, 89-94. Hubbard, A.W. and Seng, C.N. V i s u a l movements of b a t t e r s . R.Q., 1954, 25, 42-57. H u t t , J.W.R. S t u d i e s i n g a m e s - p l a y i n g : s h o r t - t e r m s a m p l i n g i n b a l l - s k i l l a c q u i s i t i o n . In H.T.A. W h i t i n g ( E d . ) , Readings i n s p o r t p s y c h o l o g y . London: Henry Kimpton, Pub., 1972. James, W i l l i a m . The p r i n c i p l e s of p s y c h o l o g y ( V o l . 1 ) . New York: H o l t , 1890 ( r e p r i n t e d as Dover paperback, 1950). 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. P s y c h o l o g i c a l B u l l e t i n , 1968, 70, 387-403. K e e l e , S.W. Time and a t t e n t i o n i n r e t r i e v i n g i n f o r m a t i o n . P a c i f i c P a l i s a d e s , C a l i f o r n i a : Goodyear, 1973. K e e l e , S.W. & Summers, J . J . The s t r u c t u r e of motor programs. In G. Stelmach ( E d . ) , Motor c o n t r o l : i s s u e s and t r e n d s . New York: Academic P r e s s , 1976. K i m b l e , G.A. & P e r l m u t e r , L.C. The problem of v o l i t i o n . P s y c h o l o g i c a l Review, 1970, 77, 361-383. Kornhuber, H.H. Motor f u n c t i o n s of the c e r e b e l l u m and s a c a d i c ( b a l l i s t i c ) c l o c k , the c e r e b e l l o n u c l e a r h o l d r e g u l a t o r , and the b a s a l g a n g l i a ramp ( v o l u n t a r y speed, smooth movement) g e n e r a t o r . K y b e r n e t i k , 1971, 8, 157-162. L a s h l e y , K.S. The a c c u r a c y of movement i n the absence of e x c i t a t i o n from the moving organ. American J . of  P h y s i o l o g y , 1917, 42, 169-194. Lawther, J.D. The l e a r n i n g of p h y s i c a l s k i l l s . New J e r s e y : P r e n t i c e - H a l l , I n c . , 1968. L i u , I . E f f e c t s of r e p e t i t i o n of. v o l u n t a r y r e s p o n s e s : From v o l u n t a r y t o i n v o l u n t a r y . J.E.P., 1968, 76, 398-406. 64 L u n d e r v o l d , A. E l e c t r o m y o g r a p h i c i n v e s t i g a t i o n s of p o s i t i o n and manner of working i n t y p e w r i t i n g . A c t a P h y s i o l o q i c a , 1951, 24 Supp., 84, 1-171 . L u n d e r v o l d , A. E l e c t r o m y o g r a p h i c i n v e s t i g a t i o n s d u r i n g t y p e w r i t i n g . Ergonomics, 1958, J _ » 226-233. L u r i a , A.R. Human b r a i n and p s y c h o l o g i c a l p r o c e s s e s . New York: Harper and Row, Pub., 1966. Ma c N e i l a g e , P.F. Motor c o n t r o l of s e r i a l o r d e r i n g of speech. P s y c h . Review, 1970, 77, 182-196. Matthews, P.B.C. Muscle s p i n d l e s and t h e i r motor c o n t r o l . Phys. Review, 1964, 44, 219-288. McMahon, T.A. & Greene, P.R. F a s t r u n n i n g t r a c k s . S c i e n t i f i c  American, 1978, 239, 148-163. Megaw, R.D. D i r e c t i o n a l e r r o r s and t h e i r c o r r e c t i o n i n a d i s c r e t e t r a c k i n g t a s k . Ergonomics, 1972, J _ 5 , 633-643. Merton, P.A. How we c o n t r o l the c o n t r a c t i o n of our mu s c l e s . S c i e n t i f i c American, 1972, 226, 30-37. Merton, P.A. The p r o p e r t i e s of the human muscle s e r v o . B r a i n  R e s e a r c h , 1974, 71_, 475-478. M i l l e r , G.A., G a l a n t e r , I . , & P r i b r a m , K.H. P l a n s and the s t r u c t u r e of b e h a v i o r . New York: Henry H o l t , 1960. N e w e l l , K.M., C a r l t o n , L.G., & C a r l t o n , M.J. V e l o c i t y as a f a c t o r i n movement t i m i n g a c c u r a c y . J_;_ of_ Motor  B e h a v i o r , 1980, J _ 2 , 47-56. Norman, D.A. S I i p s of the mind and an o u t l i n e f o r a t h e o r y  of a c t i o n . San Diego: C e n t e r f o r Human I n f o r m a t i o n P r o c e s s i n g , 1979. O l s e n , E.A. R e l a t i o n s h i p between p s y c h o l o g i c a l c a p a c i t i e s and s u c c e s s i n c o l l e g e a t h l e t i c s . R.Q. , 1956, 2_7, 79-89. Pew, R.W. Human p e r c e p t u a l - m o t o r performance. In B.H. K a n t o w i t z ( E d . ) , Human i n f o r m a t i o n p r o c e s s i n g : T u t o r i a l s i n performance and c o g n i t i o n . H i l l s d a l e , N.J.:Erlbaum, 1974a. Pew, R.W. L e v e l s of a n a l y s i s i n motor c o n t r o l . B r a i n  R e s e a r c h , 1974b, 71, 393-400. Pe z z a c k , J.C., Norman, R.W., and W i n t e r , D.A. An assessment of d e r i v a t i v e d e t e r m i n i n g t e c h n i q u e s used f o r motion a n a l y s i s . B i o m e c h a n i c s , 1977, J _ 0 , 377-382. 65 P e z z a c k , J . C , Norman, R.W. , & W i n t e r , D.A. An assessment of d e r i v a t i v e d e t e r m i n i n g t e c h n i q u e s used f o r motion a n a l y s i s . B i o m e c h a n i c s , 1 9 7 7 , J_0, 3 7 7 - 3 8 2 . P i a g e t , J . and I n h e l d e r , B. The p s y c h o l o g y of the c h i l d . New York: B a s i c Books I n c . , 1 9 6 9 . P r o v i n s , K.A. Handedness and s k i l l . Q u a r t e r l y J . of Exp. P s y c . , 1 9 5 6 , 8 , 7 9 - 9 5 . R a b b i t t , P. D e t e c t i o n of e r r o r s by s k i l l e d t y p i s t s . Ergonomics, 1 9 7 8 , 2J_ , 9 4 5 - 9 5 8 . Rosenbaum, D.A. Human movement i n i t i a t i o n : S p e c i f i c a t i o n of arm, d i r e c t i o n and e x t e n t . J . E . P . : G e n e r a l , 1 9 8 0 , 1 0 9 , 4 4 4 - 4 7 4 . R o t h s t e i n , A.L. P r e d i c t i o n i n s p o r t : an i n f o r m a t i o n p r o c e s s i n g approach. In R.E. S t a d u l i s ( E d . ) , R esearch  and p r a c t i c e i n p h y s i c a l e d u c a t i o n . I l l i n o i s : Human K i n e t i c s Pub., 1 9 7 7 . Sanderson, G.J.K. P e r c e p t u a l s t u d i e s : v a r i a b l e s a f f e c t i n g the p e r c e p t i o n of v e l o c i t y i n s p o r t s s i t u a t i o n s . In H.T.A. W h i t i n g ( E d . ) , Readings i n s p o r t p s y c h o l o g y . London: Henry Kimpton Pub., 1 9 7 2 . Schmidt, R.A. A schema t h e o r y of d i s c r e t e motor s k i l l l e a r n i n g . P s y c h o l o g i c a l Review, 1 9 7 5 , 8 2 , 2 2 5 - 2 6 0 . Schmidt, R.A. C o n t r o l p r o c e s s e s i n motor s k i l l s . In J . Keogh & B.S. Hutton ( E d s . ) , E x e r c i s e and s p o r t s c i e n c e s  r e v i e w s ( V o l . 4 ) . Santa B a r b a r a : J o u r n a l P u b l i s h i n g A f f i l i a t e s , 1 9 7 6 . Schmidt, R.A. Pa s t and f u t u r e i s s u e s i n motor programming. Research Q u a r t e r l y f o r E x e r c i s e and S p o r t , 1 9 8 0 , 5_1_ , 1 2 2 - 1 4 0 . Schmidt, R.A., Z e l a z n i c k , H., Hawkins, B., Frank, J.S., & Quinn, J.T. Mot o r - o u t p u t v a r i a b i l i t y : a t h e o r y f o r the a c c u r a c y of r a p i d motor a c t s . P s y c h o l o g i c a l Review, 1 9 7 9 , 8 6 , 4 1 5 - 4 5 1 . Shea, C H . E f f e c t s of extended p r a c t i c e and movement time on motor c o n t r o l of a c o i n c i d e n t t i m i n g t a s k . R esearch  Q u a r t e r l y f o r E x e r c i s e and S p o r t , 1 9 8 0 , 5J_, 3 6 9 - 3 8 1 . S h i k , M.L. & O r l o v s k i , G.N. N e u r o p h y s i o l o g y of locomotor a u t o m a t i o n . Phys. Reviews, 1 9 7 6 , 5 6 , 4 6 5 - 5 0 1 . S k i n n e r , B.F. The b e h a v i o r of organisms ran exper i m e n t a l  a n a l y s i s . New York: A p p l e t o n - C e n t u r y . 1 9 3 8 . 66 S p a e t h - A r n o l d , R.K. S k i l l a c q u i s i t i o n under v a r i a b l e t e m p o r a l c o n s t r a i n t s : c i n e m a t o g r a p h i c a n a l y s i s of movement o r g a n i z a t i o n . of Human Movement S t u d i e s , 1976, 2, 98-113. S p a e t h - A r n o l d , R.K. P r e d i c t i o n i n s p o r t : an i n f o r m a t i o n i n f o r m a t i o n - p r o c e s s i n g t a s k . I n R.E. S t a d u l i s ( E d . ) , R e s e a r c h & and p r a c t i c e i n p h y s i c a l e d u c a t i o n . I l l i n o i s : • Human K i n e t i c s Pub., 1977. Sussman, H.M. What the tongue t e l l s the b r a i n . P s y c h .  B u l l e t i n , 1972, 77, 262-272. Taub, E., & Berman, A . J . Avoidance c o n d i t i o n i n g i n the absence of r e l e v a n t p r o p r i o c e p t i v e and e x t e r o c e p t i v e feedback. of_ Comparative and P h y s i o l o g i c a l  P s y c h o l o g y , 1963, 56, 1012-1016. Toburen, K.R. C o i n c i d e n c e - a n t i c i p a t i o n t a s k s u t i l i z i n g s e l e c t e d speeds, d i r e c t i o n s , and f i e l d i n g s i d e s i n f i e l d hockey. ( 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 of N. C a r o l i n a a t Greensboro, 1977). D i s s e r t a t i o n A b s t r a c t s  I n t e r n a t i o n a l , 1977. Turvey, M.T. P r e l i m i n a r i e s t o a t h e o r y of a c t i o n w i t h r e f e r e n c e t o v i s i o n . In R. Shaw & J . B r a n s f o r d ( E d s . ) , P e r c e i v i n g , a c t i n g and knowing: toward an e c o l o g i c a l  p s y c h o l o g y . H i l l s d a l e , N.J.: Erlbaum, 1977. T u s s i n g , L. The e f f e c t s of f o o t b a l l and b a s k e t b a l l on v i s i o n . R.Q. , 1940, ljL , 16-18. T y l d e s l e y , D.A. The r o l e of the movement s t r u c t u r e i n a n t i c i p a t o r y t i m i n g . In G.E. Stelmach and J . Requin ( E d s . ) , T u t o r i a l s i n Motor B e h a v i o r . N o r t h - H o l l a n d P u b l i s h i n g Co., 1980. T y l d e s l e y , D.A. & W h i t i n g , H.T.A. O p e r a t i o n a l T i m i n g . J ^ of  Human Movement S t u d i e s , 1975, J_ / 172-177. Wadman, W.J., D e n i e r van der Gon, J . J . , & Derkson, R.J.A. Muscle a c t i v a t i o n p a t t e r n s f o r f a s t g o a l - d i r e c t e d arm movements. J ^ o|_ Human Movement S t u d i e s , 1980, 6, 19-37. Wein, H. The s c i e n c e of hockey. London: Pelham Books L t d . , 1977. Weiner, E.L. Motor p r e d i c t i o n as a f u n c t i o n of t a r g e t speed and d u r a t i o n of p r e s e n t a t i o n . J ^ of_ A p p l i e d P s y c h o l o g y , 1962, 46, 420-424. W e l f o r d , A.T. I n t r o d u c t o r y l e c t u r e t o s e s s i o n IV on the sequencing of a c t i o n . B r a i n R e s e a r c h , 1974, 7_1, 381-392. 67 W e l f o r d , A.T. S k i l i e d performance. I l l i n o i s : S c o t t , Foreman & Co., 1976. W e s t e r l a n d , J.H. & T u t t l e , W.W. R e l a t i o n s h i p between r u n n i n g e v e n t s i n t r a c k and r e a c t i o n t i m e . R.Q., 1931, 2, 95-100. W h i t i n g , H.T.A. An o p e r a t i o n a l a n a l y s i s of a c o n t i n u o u s b a l l t h r o w i n g and c a t c h i n g t a s k . Ergonomics, 1970, 13, 445-454. W h i t i n g , H.T.A. Input and p e r c e p t u a l p r o c e s s e s i n s p o r t s s k i l l s . In D.J. G l e n c r o s s ( E d . ) , P s y c h o l o g y and s p o r t . Sydney, A u s t . : M c G r a w - H i l l Book Co., 1978. W i n t e r , D.A. Biomechanics of human movement. New York: John W i l e y and Sons, 1979. W o h w i l l , J . Development of p e r c e p 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 , 1960, 57, 249-288. 68 APPENDIX A 69 SKILLFUL BEHAVIOR In a m a j o r i t y of s p o r t i n g e v e n t s , an o b s e r v o r can i d e n t i f y a s k i l l e d p e r f o r m e r , e i t h e r by the e n d - r e s u l t of the t a s k , or by the p h a s i n g and t i m i n g c h a r a c t e r i s t i c s of the movement sequence i t s e l f . Thus the debate between w i n n i n g or l o s i n g the game and p l a y i n g w e l l r e g a r d l e s s of the r e s u l t c o n t i n u e s . A s k i l l e d response can be d e f i n e d as one " i n which r e c e p t o r - e f f e c t o r - f e e d b a c k p r o c e s s e s a re h i g h l y o r g a n i z e d , b oth s p a t i a l l y and t e m p o r a l l y . . . . S p a t i a l - t e m p o r a l p a t t e r n i n g , the i n t e r p l a y of r e c e p t o r - e f f e c t o r - f e e d b a c k p r o c e s s e s , and such c h a r a c t e r i s t i c s as t i m i n g , a n t i c i p a t i o n , and the graded response a re thus seen as i n d e n t i f y i n g c h a r a c t e r i s t i c s of s k i l l " ( F i t t s , 1964, p. 244). There a r e two i m p o r t a n t t e m p o r a l components t o a s k i l l e d r e s p onse. The f i r s t i s t h a t " t i m i n g must o f t e n , i n t u r n , p r o c e e d r e l a t i v e t o an e x t e r n a l event such t h a t the t o t a l a c t i s p r e c i s e l y , s e r i a l l y and t e m p o r a l l y o r g a n i z e d " ( G l e n c r o s s , 1978, p. 4 9 ) . T y l d e s l e y and W h i t i n g (1975) r e f e r t o t i m i n g as the a b i l i t y which c o n t r i b u t e s towards s k i l l e d b e h a v i o r , but i t i s not n e c e s s a r i l y r e l a t e d t o the a b i l i t y t o judge the passage of ti m e . J u s t as r e a c t i o n time v a r i e s between i n d i v i d u a l s , so does the a b i l i t y t o p r e d i c t or a n t i c i p a t e e v e n t s . S i n c e the environment remains c o n s t a n t w i t h i n a c l o s e d s k i l l , s p o r t s which u t i l i z e c l o s e d s k i l l s as t h e i r base a r e not u s u a l l y 70 c o n s i d e r e d i n d i s c u s s i o n s about t a s k s r e q u i r i n g an a n t i c i p a t o r y response. For example, gymnasts e s t i m a t e approach and t a k e - o f f p o s i t i o n s such t h a t movement time i n the a i r w i l l p o s i t i o n them s p a t i a l l y t o c o i n c i d e w i t h the v a u l t i n g h o r s e . In compa r i s o n , s u c c e s s i n an open s k i l l s p o r t , where the environment i s not s t a t i c , i s dependent upon the a b i l i t y of p e r f o r m e r s t o c o i n c i d e t h e i r a c t i o n s w i t h o t h e r p e r f o r m e r s ' and/or implements. A s i m p l i f i e d v e r s i o n of t h r e e s t a g e s e n c o u n t e r e d i n the s k i l l of c a t c h i n g or s t r i k i n g a b a l l i n f l i g h t d emonstrates both the c o g n i t i v e and motor p r o c e s s i n g i n v o l v e d ( r e f e r t o F i g u r e A ) . In t h i s model, r e a c t i o n time i s d e f i n e d as the time p e r i o d o c c u r r i n g between the c o m p l e t i o n of the f i r s t phase of a n a l y s i s and the i n i t i a t i o n of the o v e r t t h i r d phase. The perf o r m e r must come t o a d e c i s i o n r e g a r d i n g the f u t u r e l o c a t i o n of the b a l l i n t h a t time p e r i o d e q u a l t o the sum of h i s r e a c t i o n time p l u s h i s movement t i m e . He i s not o v e r l y concerned w i t h where the b a l l i s now. However, c e r t a i n p e r c e p t u a l p r o c e s s e s must be a t work i n o r d e r f o r the pe r f o r m e r t o make these p r e d i c t i o n s . Compare t h i s t o a young c h i l d who can n o t , p o s s i b l y due t o a l a c k of p e r c e p t u a l or p r e d i c t i v e m a t u r a t i o n , a n t i c i p a t e where the b a l l w i l l go. As a r e s u l t , he i s o n l y aware of and con c e r n e d w i t h where i t i s now. The development of such p e r c e p t u a l a b i l i t y has been viewed as o n t o g e n e t i c , "mediated by m a t u r a t i o n of the c e n t r a l nervous system, but r e s u l t i n g e s s e n t i a l l y from the i n t e r a c t i o n of c a p a c i t i e s f o r r e f l e x 71 2 3 P u r s u i t T r a c k i n g Task P r e d i c t i o n of where the b a l l w i l l be i n r e a c t i o n time p l u s movement time C a t c h i n g or s t r i k i n g movement P r e d o m i n a n t l y P r e d o m i n a n t l y P e r c e p t u a l C e n t r a l d e c i s i o n motor A n a l y s i s response C o v e r t P r o c e s s e s Overt response F i g u r e A: Component a n a l y s i s of the t a s k of c a t c h i n g or s t r i k i n g a b a l l i n f l i g h t . ( A l d e r s o n , 1977, p. 118) 72 b e h a v i o r p r e s e n t a t b i r t h and e n v i r o n m e n t a l s t i m u l a t i o n " ( A l d e r s o n , 1972, p. 138; P i a g e t and I n h e l d e r , 1969; W o h w i l l , 1960). Through a s s i m i l a t i o n and accomodation a c h i l d s h o u l d have d e v e l o p e d the concept of v e l o c i t y by the age of e i g h t or n i n e , which c u l m i n a t e s w i t h the a b i l i t y t o p r e d i c t v e l o c i t y by the age of e l e v e n ( A l d e r s o n , 1972). A number of s t u d i e s have c o n c l u d e d t h a t a n t i c i p a t o r y or p r e d i c t i v e judgment s k i l l s may be improved through p r a c t i c e or e x p e r i e n c e ( F l e i s h m a n and Hempel, 1955; G r a y b i e l et a l , 1955; W h i t i n g , 1970). A l d e r s o n (1972) r e p o r t s t h a t s p a t i a l cues a re e a s i e r t o use than v e l o c i t y , and v e l o c i t y e a s i e r than t e m p o r a l cues. I t i s Weiner's (1962) c o n c l u s i o n t h a t man e s t i m a t e s v e l o c i t y v e r y q u i c k l y and i s , t h e r e f o r e , a b l e t o l e a v e h i s e s t i m a t i o n u n t i l r e l a t i v e l y l a t e i n the f l i g h t p a t h . In c o n t r a s t t o t h i s i d e a , p e r h a p s , i s H u t t ' s (1972) p r o p o s a l t h a t , the l a t t e r p o r t i o n s of b a l l f l i g h t become redundant and the p e r f o r m e r ' s a t t e n t i o n can be s h i f t e d t o the t a r g e t . Both t h e o r i e s a g r e e , however, t h a t an e s t i m a t i o n of v e l o c i t y can be made i n the i n i t i a l s t a g e s . Combine t h i s e s t i m a t i o n w i t h a d e c r e a s e d amount of i n f o r m a t i o n b e i n g p r o c e s s e d due t o improved s e l e c t i v e a t t e n t i o n and more time becomes a v a i l a b l e f o r a s k i l l e d p e r f o r m e r t o o r g a n i z e a response or make c o r r e c t i o n s f o r e r r o r . The t r a n s l a t o r y p r o c e s s i s d e s c r i b e d by R o t h s t e i n (1977) as b e i n g an e s s e n t i a l requirement f o r e n a b l i n g p e r f o r m e r s t o group s i m i l a r s t i m u l i t o d i m i n i s h the amount of i n f o r m a t i o n t o be p r o c e s s e d and, hence, the time i n v o l v e d 73 i n such c o g n i t i v e a c t i v i t i e s . W e l f o r d (1976) r e f e r s t o t r a n s l a t i o n as the l i n k between p e r c e p t i o n and a c t i o n which i s d e v e l o p e d over t r i a l s as the p e r f o r m e r s t o r e s i n f o r m a t i o n about the environment and a b s t r a c t s knowledge s t o r e d i n memory t o produce a schema or schema r u l e ( S c h midt, 1975). The e s s e n t i a l i n f o r m a t i o n i n c l u d e s the i n i t i a l s t a t e of the p e r f o r m e r and c o n d i t i o n s of the environment; the response s p e c i f i c a t i o n s which w i l l p e r m i t accomplishment of the g o a l ; a copy of the a f f e r e n t i m p u l s e s a n t i c i p a t e d from the response outcome. Once the events of the environment have been p e r c e i v e d , they must s t i m u l a t e a r e s p o n s e . R e a c t i o n time i s a measure of the response p r o c e s s and i s most o f t e n t e s t e d t o demonstrate the e f f i c i e n c y of the c o v e r t p r o c e s s e s d e s c r i b e d i n F i g u r e B. K e e l e (1973) d e f i n e s RT as t h a t p e r i o d between the onset of the s t i m u l u s t o the onset of movement. C o n s i d e r the p r o c e s s i n g s t a g e s (see F i g u r e B) which demonstrate the s i n g l e - c h a n n e l c a p a c i t y of man's c o g n i t i v e o p e r a t i o n . In g e n e r a l , the time r e q u i r e d t o p r o c e s s the i n f o r m a t i o n from the t e s t s t i m u l u s t h r o u g h each of the f o u r s t a g e s d e t e r m i n e s the s u b j e c t ' s r e a c t i o n t i m e . P r o c e s s i n g d e l a y s may be a l l e v i a t e d by i m p r o v i n g S-R c o m p a t i b i l i t y , o r g a n i z a t i o n of a p r e p a r a t o r y s e t , a t t e n d i n g the s t i m u l u s as opposed t o the response or subsequent feedback, and a n t i c i p a t i o n of the t a s k components (Lawther, 1968; Schmidt, 1976). However, w h i l e i t has been demonstrated t h a t s i m p l e RT's f o r a group of s k i l l e d a t h l e t e s were b e t t e r than f o r a 74 T e s t S t i m u l u s S t i m u l u s E n c o d i n g S e r i a l -» — Compar i son Yes/No — D e c i s i o n Response 4 — O r g a n i z a t i o n O v e r t Response F i g u r e B: Four h y p o t h e t i c a l s t a g e s of p r o c e s s i n g i n a memory s c a n n i n g e x p e r i m e n t . (Legge and B a r b e r , 1976, p. 28) 75 group of n o n - a t h l e t e s , i t has a l s o been shown t h a t the person w i t h the f a s t e s t RT i s not always the b e s t p l a y e r ( O l s e n , 1956; H u t t , 1972; W e s t e r l a n d and T u t t l e , 1931). L i k e w i s e , a number of s t u d i e s of v i s u a l p arameters have r e s u l t e d i n the c o n c l u s i o n t h a t "the r o l e of v i s u a l a b i l i t y has been g r e a t l y over-emphasized as b e i n g an i m p o r t a n t f a c t o r i n a t t e m p t i n g t o e x p l a i n the f a c t o r s u n d e r l y i n g i n d i v i d u a l d i f f e r e n c e s i n motor l e a r n i n g and performance" (Saunderson, 1972 p. 157; T u s s i n g , 1940). However, t h e r e a r e s t u d i e s which show t h a t a t h l e t e s are s i g n i f i c a n t l y s u p e r i o r t o n o n - a t h l e t e s ( G r a y b i e l e t a l , 1955; O l s e n , 1956). In o r d e r t o d e c i d e upon the i n t e r p r e t a t i o n of t h e s e o p p o s i n g r e p o r t s , one may wish t o i n v e s t i g a t e the e x p e r i m e n t a l t e c h n i q u e . For example, one may q u e s t i o n the use of s t a t i c v i s u a l t e s t s as a means of p r e d i c t i n g s u c c e s s i n a dynamic s p o r t i n g s i t u a t i o n . In a d d i t i o n , one s h o u l d i n v e s t i g a t e the use of apparent motion t o study the p e r c e p t u a l and c o g n i t i v e p r o c e s s e s i n v o l v e d i n the a n a l y s i s of r e a l m o t i o n . What i s the c o r r e l a t i o n of a t e s t environment u s i n g the phi-phenomenon as a s u b s t i t u t e f o r a moving b a l l i n a r e a l i s t i c game environment where p l a y e r s may p r e d i c t on the b a s i s of a d d i t i o n a l cues b e s i d e s t h e i r a b i l i t y t o judge motion or v e l o c i t y of a b a l l ? A s k i l l e d p e r f o r m e r i s aware of l i m i t a t i o n s i n r e a c t i o n time and v i s u a l a c u i t y such t h a t compensation may be made f o r such d e f i c i e n c i e s . P e r t i n e n t cues such as an opponent's body p o s i t i o n , the sound of the b a l l l e a v i n g the bat or the 76 racquet, the spin of the b a l l and the arc of i t s f l i g h t trajectory may be attended to over irrelevent factors. Performance may also be enhanced by reducing the elements of uncertainty within the s i t u a t i o n . This i s accomplished in an experimental context by: 1. reducing the amount of information presented to the performer; 2. reducing temporal uncertainty by the i n i t i a l presentation of a constant foreperiod signalled by a warning l i g h t or buzzer; and 3. establishing a l i m i t to the number of possible responses. The environment i s , in r e a l i t y , a choice reaction time s i t u a t i o n . An experienced performer develops strategies to decrease his uncertainty such that a response can be prepared and executed to allow for reaction time and movement time delays which could af f e c t coincidence. In r e l a t i n g t h i s role of anticipatory timing in sport to the information processing model depicted in Figure C, the integration of the processing stages must be the predominant factor for determination of success. The performer is viewed as an "active, a n a l y t i c a l , problem-solving, hypothesis-testing, decision-making processor of information" (Spaeth-Arnold, 1977 p. 277) whose success depends upon an a b i l i t y to match the parameters of his movement response with c h a r a c t e r i s t i c s of the environment. 77. E K motor response schema DISPLAY SENSORY INPUT SHORT TERM STORAGE a : SELECTIVE FILTER or ient ing ENCODING interpretat ion and analysis select schema select schema instance coordination and phasing . M 1= short term response storage •-limited -* ^-capacity—> *-channel-* short term/ long term memory response execut ion Figure C: Information p. 208) processing model. (Rothstein, 1977 , 78 APPENDIX B 79 MOTOR PROGRAM Most research in cognitive psychology has investigated the functioning of the human mechanism as a processor of information directed towards e l i c i t a t i o n of a verbal response. This section w i l l present the cognitive and neurophysiological processes involved, or theorized to be involved, in the selection, i n i t i a t i o n and completion of a motor response. As an adaptable organism capable of voluntary behavior, man has been analyzed in regard to the e f f i c i e n c y of his movements towards attainment of a predetermined goal. The c r i t e r i o n for s k i l l e d behavior is usually based upon measurement of the accuracy and speed components of performance. Current research trends propose that motor performance i s structured and cont r o l l e d by hi e r a r c h i c a l levels of cognitive functioning which are d i f f e r e n t i a t e d according to the invariant features and variable parameters which they assign to movement. This Appendix w i l l include an h i s t o r i c a l overview of the development of the motor program paradigm; the neurophysiological basis of muscular a c t i v i t y from the inception of the plan to i t s r e a l i z a t i o n ; movement monitoring theories; and the investigation of errors which may occur at any le v e l of the human processing and performance systems. A. H i s t o r i c a l Overview 80 D i s c u s s i o n of v o l u n t a r y b e h a v i o r and c o g n i t i v e c o n t r o l of such b e h a v i o r n e c e s s i t a t e s p r i o r c o n s i d e r a t i o n of t h a t c o g n i t i v e a s p e c t of man which p e r m i t s such a c t i o n t o o c c u r . I t i s not f e a s i b l e t o c o n s i d e r motor c o n t r o l as a p r o c e s s d i s t i n c t from t h a t of c o g n i t i v e c o n t r o l . From Joseph Buchanan's ( c i t e d i n Kimble and P e r l m u t e r , 1970) i n i t i a l a t t e m p t s a t d e f i n i n g the concept of v o l i t i o n as the spark f o r a v o l u n t a r y a c t , a number of a b s t r a c t d e f i n i t i o n s have been proposed. Buchanan t h e o r i z e d t h a t v o l u n t a r y b e h a v i o r was the r e s u l t of l e a r n i n g , S k i n n e r (1938) t h a t i t was c o n d i t i o n e d and the r e s u l t of an a s s o c i a t i o n of a number of r e f l e x i v e s t i m u l u s e l ements. James (1890; U n a b r i d g e d , 1950) m a i n t a i n e d t h a t the s t i m u l u s f o r v o l u n t a r y b e h a v i o r i s the image of the r e s u l t s of the a c t and t h a t v o l u n t a r y b e h a v i o r i s a l e a r n e d phenomenon: v o l u n t a r y b e h a v i o r must be secondary, not p r i m a r y f u n c t i o n s of the o r g a n i s m . . . . R e f l e x , i n s t i n c t i v e and e m o t i o n a l movements are a l l p r i m a r y p e r f o r m a n c e s . . . when a p a r t i c u l a r movement, h a v i n g once o c c u r r e d i n a random, or i n v o l u n t a r y way, has l e f t an image of i t s e l f i n the memory, then the movement can be d e s i r e d a g a i n , proposed as an end, and d e l i b e r a t e l y w i l l e d . But i t i s i m p o s s i b l e t o see how i t c o u l d be w i l l e d b e f o r e , (p. 13) James' a n a l y s i s of l e a r n e d v o l u n t a r y b e h a v i o r can thus be d i f f e r e n t i a t e d from t h a t of u n l e a r n e d and i n v o l u n t a r y b e h a v i o r by the s t i m u l u s t h a t produces i t . In c o n t r a s t , von H o i s t (1954) proposed t h a t the most s a l i e n t c h a r a c t e r i s t i c of v o l u n t a r y b e h a v i o r i s i t s i n h i b i t a b i 1 i t y , f o r a " v o l u n t a r y a c t i s one t h a t we can v o l u n t a r i l y i n h i b i t " (p. 81 367). These " s t o p r u l e s " are b e l i e v e d t o be i n c o r p o r a t e d i n t o the mechanism such t h a t they a r e as much a p a r t of the program f o r a c t i o n as the p l a n and i n t e n t i o n f o r i n i t i a t i o n . L i u (1968) p r o v i d e d e x p e r i m e n t a l e v i d e n c e of programmed s t o p p i n g p o i n t s t h rough e x p e r i m e n t a l m a n i p u l a t i o n of the c o u n t e r w e i g h t r e s i s t a n c e of a response key. Each s u b j e c t p r e s s e d the key t o l i f t one weight ( e i t h e r 500 or 1,000 gm) f o r a c e r t a i n number of t r i a l s ( 1 , 5 or 10) f o l l o w e d by a t e s t t r i a l on which the weight was changed (from 500 t o 1,000 gm or from 1,000 t o 500 gm). For Ss i n the h e a v y - t o - l i g h t groups, i t was found on the t e s t t r i a l s t h a t the p r e s s d i s t a n c e and the speed of p r e s s i n g i n c r e a s e d . The o p p o s i t e t r e n d was o b t a i n e d f o r Ss i n the l i g h t - t o - h e a v y groups. L i u e x p l a i n s t h a t the f o r c e or energy n e c e s s a r y f o r the r esponses was p r e p a r e d b e f o r e h a n d . As a z o o l o g i s t , von H o i s t c o n s i d e r e d the concept of v o l i t i o n as would a n e u r o p h y s i o l o g i s t r a t h e r than a b e h a v i o r a l p s y c h o l o g i s t : T h i s p r o c e s s i n v o l v e s a number of s t e p s and has c e r t a i n i m p o r t a n t p r o p e r t i e s : (1) A motor i m p u l s e , a "command from a h i g h e r c e n t e r causes a s p e c i f i c a c t i v a t i o n i n lower c e n t e r which i s the c e n t r a l s t i m u l u s s i t u a t i o n g i v i n g r i s e to a s p e c i f i c e f f e r e n c e t o the e f f e c t o r , i . e . , a muscle, a j o i n t or the whole organism. T h i s c e n t r a l s t i m u l u s s i t u a t i o n i s the image of e f f e r e n c e r e f e r r e d t o above; i t may a l s o be c a l l e d an " e f f e r e n c e copy" (Kimble and P e r l m u t e r , 1970, p. 368). I t has been t h e o r i z e d t h a t a movement produces a "copy" of the e f f e r e n t a c t i v i t y of the m u s c u l a t u r e which i s r e t u r n e d t o the c e n t r a l nervous system f o r use i n 82 i d e n t i f i c a t i o n of e r r o r s w i t h i n the response s e l e c t i o n or e x e c u t i o n p r o c e s s e s (Schmidt, 1976). These a f f e r e n t s i g n a l s have been d e s c r i b e d as the h i g h e s t l e v e l of feedback and a r e i m p o r t a n t i n the p r o v i s i o n of a s i g n a l t o be compared w i t h lower l e v e l feedback f o r e v a l u a t i o n of the movement sequence. A d i s c r e p a n c y between i n t e n d e d neuromuscular a c t i v i t y and t h a t which was r e a l i z e d would i n d i c a t e t h a t an e r r o r had o c c u r r e d . R e s e a r c h e r s have, t h e r e f o r e , a t t e m p t e d t o measure Buchanan's a b s t r a c t i d e a of the re s p o n s e , James' and von H o i s t ' s image of the movement, M i l l e r , G a l a n t e r and P r i b r a m ' s (1960) p l a n , and L u r i a ' s (1966) motor p l a n as a n e u r o l o g i c a l e v ent. Kimble and P e r l m u t e r (1970) have proposed t h e f o l l o w i n g t h r e e c e n t r a l nervous system r e q u i r e m e n t s t o d e s c r i b e v o l u n t a r y b e h a v i o r : 1. i t b e g i n s w i t h an i d e a , e t c . as s t a t e d above, which i s dependent upon, or i n f l u e n c e d by k i n e s t h e t i c feedback; 2. i t i s a l e a r n e d response; and 3. a c o n t i n u o u s system must be p r e s e n t such t h a t response guidance i s a v a i l a b l e from i n i t i a t i o n t o c o m p l e t i o n . T h i s e a r l y t h e o r y , however, f a i l s t o c o n s i d e r the r o l e of a t t e n t i o n upon v o l u n t a r y motor responses f o r k i n e s t h e t i c feedback as a c o n t r o l l i n g i n f l u e n c e need not be a t t e n d e d t o by the p e r f o r m e r . T h i s source of p o t e n t i a l problems i n response s e l e c t i o n and e x e c u t i o n has been s t u d i e d i n some de p t h f o r i t s i n f l u e n c e i n p r o d u c i n g such e r r o r s as c o g n i t i v e s l i p s (Norman, 1979; Reason, Note 1). 83 Kimble and P e r l m u t e r (1970) have t r a c e d the development of a s k i l l e d motor response through t h r e e s t a g e s : the f i r s t s t a g e c o n s i s t s of t h a t b e h a v i o r which has been s t i m u l a t e d r e f l e x i v e l y and i n an unattended mode. T h i s b e h a v i o r g r a d u a l l y becomes more of a c o n s c i o u s and c o n s i s t e n t n a t u r e . I t i s i n i t i a l l y r e c o g n i z a b l e as a number of r e f l e x movements. E v e n t u a l l y , i t becomes e v i d e n t t h a t the performance i s a c o n s i s t e n t l y reproduced response which i s , as i t was i n the f i r s t s t a g e , v o i d of c o n s c i o u s a t t e n t i o n on the p a r t of the p e r f o r m e r . R.C. D a v i s (1943) s t u d i e d the a c t i o n p o t e n t i a l s g e n e r a t e d from a number of i p s i l a t e r a l and c o n t r a l a t e r a l r e f e r e n c e p o i n t s on c h i l d r e n and a d u l t s as they performed a w e i g h t - l i f t i n g e x e r c i s e . The i n c r e a s e d a c t i v i t y r e g i s t e r e d i n the n o n - u t i l i z e d e x t r e m i t i e s of the c h i l d r e n suggested t h a t an u n d i f f e r e n t i a t e d response o c c u r s d u r i n g the f i r s t s t a g e s of l e a r n i n g , f o l l o w e d by a f o c u s i n g i n on the d e s i r e d response. The e l i m i n a t i o n of e x t r a n e o u s i m p u l s e s may be a r e s u l t of p r a c t i c e , or a r e s u l t of the m a t u r a t i o n p r o c e s s . D a v i s does not d i f f e r e n t i a t e between the s e two p o s s i b l e f a c t o r s , though. In summary, a c i r c u l a r p r o c e s s o c c u r s which may be d e s c r i b e d as a "developmental sequence by which the i n d i v i d u a l f i r s t a c q u i r e s v o l u n t a r y c o n t r o l over i n i t i a l l y i n v o l u n t a r y responses t o r e t r e a t from c o n s c i o u s n e s s t o a t t e n t i o n , and i n t h a t sense, t o become i n v o l u n t a r y " (Kimble and P e r l m u t e r , 1970, p. 382). 84 M a r t e n i u k and MacKenzie (Note 4) i n r e v i e w i n g the l i t e r a t u r e have c o n c l u d e d t h a t the d e f i n i t i o n s of the term "motor program" are numerous and v a r i e d . An example of the more t y p i c a l d e f i n i t i o n s may be drawn from the i d e a t h a t the a b s t r a c t p l a n of a c t i o n i s the program ( M i l l e r , G a l a n t e r and P r i b r a m , 1960), or from the more c o n c r e t e concept t h a t the motor program c o n s i s t s of d e s c e n d i n g f o r c e s i g n a l s from the motor c o r t e x ( E v a r t s , 1968). M a r t e n i u k and MacKenzie d e f i n e the motor program as c o n s i s t i n g of a code which i s the i n t e r n a l r e p r e s e n t a t i o n of i n f o r m a t i o n d e r i v e d from p r o c e s s i n g o p e r a t i o n s w i t h i n the c e n t r a l nervous system (CNS). Schmidt, Z e l a z n i c k , Hawkins, Frank and Quinn (1979) c o n s i d e r the motor program an " a b s t r a c t memory s t r u c t u r e c o n t a i n i n g codes c a p a b l e of b e i n g t r a n s f o r m e d i n t o p a t t e r n s of movement. The p a t t e r n s produced from a g i v e n program have c e r t a i n i n v a r i a n t p r o p e r t i e s , even though two responses from the same program might have l a r g e d i f f e r e n c e s i n o t h e r r e s p e c t s . Under t h i s view, the program i s g e n e r a l i z e d , so t h a t parameters are r e q u i r e d t o s p e c i f y the p a r t i c u l a r way i n which the program i s t o be e x e c u t e d " (p. 417). In t h i s r e s p e c t , the per f o r m e r o p e r a t e s w i t h i n a h i e r a r c h y of motor c o n t r o l which p e r m i t s m o n i t o r i n g of performance t o occur a t d i f f e r e n t l e v e l s and the subsequent i d e n t i f i c a t i o n and c o r r e c t i o n of e r r o r s t o take p l a c e a t v a r i o u s t i m e s d u r i n g the performance. Such e r r o r s may be i d e n t i f i e d as e i t h e r e r r o r s i n response s e l e c t i o n or response e x e c u t i o n . 85 B. N e u r o p h y s i o l o g y of a Motor Response A s i g n i f i c a n t amount of t h e o r y has been d e v e l o p e d i n an attempt t o i d e n t i f y the components.of s k i l l e d b e h a v i o r as t h o s e f e a t u r e s which o c c u r i n the absence of feedback ( i . e . , o p e n - l o o p e d ) . T h i s absence of feedback has been e x p l a i n e d as b e i n g e i t h e r the r e s u l t of an absence of c o n s c i o u s a t t e n t i o n by the p e r f o r m e r t o the r e s p o n s e , or due t o the s h o r t d u r a t i o n of many movements which a r e l e s s than 250 msec or one r e a c t i o n time f o r c o m p l e t i o n . However, r e c e n t s t u d i e s have produced e v i d e n c e t h a t a n t a g o n i s t and a g o n i s t a c t i v i t y e x i s t s i n l a t e n c i e s as s h o r t as 50 msec and which has been i d e n t i f i e d as v o l u n t a r y c o n t r a c t i o n (Merton, 1974). A d d i t i o n a l work w i t h t w o - c h o i c e r e a c t i o n time t a s k s has r e v e a l e d t h a t Ss r e c o r d e d t i m e s of between 60 and 90 msec between the time the i n i t i a l f a l s e move was begun u n t i l movement was made i n the c o r r e c t d i r e c t i o n ( H i g g i n s and A n g e l , 1970). Such e v i d e n c e s u g g e s t s t h a t some degree of feedback i s p r e s e n t f o r response c o r r e c t i o n s d e s p i t e l i m i t a t i o n s of movement t i m e . The c e n t r a l v e r s u s p e r i p h e r a l argument of feedback i n f l u e n c e must be c o n s i d e r e d o b s o l e t e as a r e s u l t of such e v i d e n c e . In e x a m i n a t i o n of the h i e r a r c h i c a l n a t u r e of the motor program, the problem remains t o e x p l a i n the b a s i s of t r a n s l a t i n g the a b s t r a c t , non-motor p l a n of a c t i o n i n t o an o r g a n i z e d , c o o r d i n a t e d , and o b s e r v a b l e movement. Brooks (1974) has proposed t h a t : 86 i f anatomy be our g u i d e , we would lo o k t o the l i m b i c system f o r the d r i v e t o move and thence t o f r o n t a l and p a r i e t a l c o r t e x f o r f o r m a t i o n of the needed a s s o c i a t i o n s , t o be c h a n n e l e d by way of the c e r e b e l l u m and b a s a l g a n g l i a t h r o u g h the t h a l a m i c f u n n e l of the v e n t r o l a t e r a l n u c l e u s of the thalamus t o the motor c o r t e x . Thus s e v e r a l p a t h s t o the s p i n a l c o r d a r e p r o v i d e d as w e l l as c h a n n e l s f o r feedback between these v a r i o u s c e n t e r s , (p. 300) E v i d e n c e of the h i e r a r c h i c a l s t r u c t u r e of the n e u r o p h y s i o l o g i c a l system of c o g n i t i v e motor c o n t r o l has been p r o v i d e d by s t u d i e s of a n i m a l s and human p a t i e n t s s u f f e r i n g from l e s i o n d i s o r d e r s ; m i c r o e l e c t r o d e s t i m u l a t i o n ; b i o m e c h a n i c a l and e l e c t r o m y o g r a p h i c a l (EMG) d a t a ; c e r e b r a l c o r t i c a l p o t e n t i a l s ; and m a t h e m a t i c a l m o d e l l i n g . The f r o n t a l - 1 i m b i c system i s r e c o g n i z e d as the h i g h e s t l e v e l or d i r e c t i v e i n the f o r m u l a t i o n of an a c t i o n p l a n . T h i s p l a n may be used i n d i s c r i m i n a t e l y w i t h the term program, and has been d e f i n e d by M i l l e r et a l . (1960) as any h i e r a r c h i c a l p r o c e s s i n the organism t h a t can c o n t r o l the o r d e r i n which a sequence of o p e r a t i o n s i s t o be formed....We s h a l l say t h a t a c r e a t u r e i s e x e c u t i n g a p a r t i c u l a r p l a n when i n f a c t t h a t P l a n i s c o n t r o l l i n g the sequence of o p e r a t i o n s he i s c a r r y i n g out....The Image i s a l l the a c c u m u l a t e d , o r g a n i z e d knowledge t h a t the organism has about i t s e l f and i t s world....A P l a n can be l e a r n e d and so would be a p a r t of the Image" (pp. 16-18). The p r e f r o n t a l c o r t e x (which i s c o m p r ised of the o r b i t a l and d o r s o l a t e r a l r e g i o n s of the system) i s c o n n e c t e d r e c i p r o c a l l y w i t h the major a f f e r e n t systems so t h a t i t not o n l y s e r v e s as a r e c e p t o r of i n f o r m a t i o n , but i s c a p a b l e of e m i t t i n g i m p u l s e s back t o these systems as w e l l as t o the l i m b i c , d i e n c e p h a l i c , and m e s e n c e p h a l i c s t r u c t u r e s 87 (Marteniuk and MacKenzie, Note 4). Studies of dorsolateral lesions have revealed that these patients suffer in their a b i l i t i e s to formulate and evaluate plans for the i n i t i a t i o n and termination of their actions. Prefrontal patients are unable to recognize errors in execution or that their actions, in fact, deviate from the intended. Teuber (cf. Marteniuk and MacKenzie, Note 4) has postulated that i t is the prefrontal area of the cortex which i s responsible for the "corollary discharges" which, as a feedforward mechanism enables prediction of the anticipated consequences of an action. It has been postulated that representative codes are u t i l i z e d to define the position of the body and body parts r e l a t i v e to environmental referents (Bernstein, c f . Marteniuk and MacKenzie, Note 4). This s p a t i a l map is a topological motor image of space and i s ess e n t i a l i f the performer i s to translate a conceived plan of action into a goal-directed behavior. The motor cortex provides the f i n a l relay point of these codes in the CNS. E l e c t r i c a l stimulation studies have defined the mapping structure of the motor cortex and related this dimensional representation to the l e v e l of s k i l l e d usage of that p a r t i c u l a r body part. One of the major input pathways to the motor cortex i s through the ventrolateral nucleus (VL) of the thalamus. This relay center for the afferent impulses from the basal ganglia and cerebellum, along with the topographic relations of the VL thalamus and the diverging thalamo-cortical 88 p r o j e c t i o n s , s u g gests t h a t the e f f e r e n t motor i m p u l s e s which a r e r e l a y e d a t t h i s p o i n t a re d i r e c t e d t o the muscle groups r e s p o n s i b l e f o r the i n t e n d e d a c t i o n . W h i l e the motor c o r t e x i s d e f i n i n g output i n terms of f o r c e - t i m e c h a r a c t e r i s t i c s , i t i s d o i n g so i n a manner c o n s i s t e n t w i t h the l i m i t a t i o n s of s y n e r g i s t i c c o n t r o l ( M a r t e n i u k and MacKenzie, Note 4). Kornhuber (1971) has s t u d i e d v o l u n t a r y movement and the e f f e c t of l e s i o n d i s o r d e r s i n o r d e r t o p o s t u l a t e t h a t the c o n t r o l f o r the s p a t i o t e m p o r a l a s p e c t of motor p a t t e r n s a r i s e s from the f r o n t a l and p a r i e t a l a s s o c i a t i o n a r e a s of the c e r e b e l l u m . "Atrophy of the s e a r e a s ( a s s o c i a t i o n a r e a s - p a r i e t a l , t e m p o r a l , o c c i p i t a l , f r o n t a l ) but m a i n l y of the p a r i e t a l l o b e , r e s u l t s i n a p r a x i a , t h a t i s , i n a b i l i t y t o f o r m u l a t e s p a t i a l p l a n s f o r movement" (p. 158). The f u n c t i o n of the c e r e b e l l a r c o r t e x i s the c a l c u l a t i o n of the b u r s t d u r a t i o n f o r r a p i d preprogrammed movements w h i l e the b a s a l g a n g l i a f u n c t i o n t o ge n e r a t e slow smooth movements of v o l u n t a r y speed. A f f e r e n t i m p u l s e s a re s t i l l n e c e s s a r y d e s p i t e t h i s preprogramming a b i l i t y s i n c e the s t a r t i n g p o s i t i o n s of the movements v a r y i n f i n i t e l y , and hence the e n e r g i e s f o r movements w i l l a l s o v a r y . T h i s a r e a produces codes r e l e v a n t t o movement sequencing and p h a s i n g . G l e n c r o s s (1978) produced e v i d e n c e i n s t u d i e s i n v o l v i n g hand c r a n k i n g t o show t h a t , w h i l e the t o t a l movement time v a r i e d , the component p a r t s (phasing) remained p r o p o r t i o n a l l y c o n s i s t e n t . 89 The p a r s i n t e r m e d i a of the c e r e b e l l u m , i n r e c e i v i n g both c e r e b r a l and p e r i p h e r a l i n f o r m a t i o n , i s proposed as the comparator s t r u c t u r e f o r the " e f f e r e n c e copy" (von H o i s t , 1954) f o r i t appears t o p l a y a r o l e i n the r e g u l a t i o n of f u t u r e movement p a t t e r n s . The l a t e r a l hemispheres of the c e r e b e l l u m , however, have been proposed as the a r e a s concerned w i t h the a c t u a l s e t of o r g a n i z a t i o n and i n i t i a t i o n ' of the e l e m e n t a l movements t h e m s e l v e s . W h i l e the h i g h e r l e v e l c o n t r o l c e n t e r s appear r e s p o n s i b l e f o r a s s i m i l a t i n g the i n v a r i a n t f e a t u r e s of movement o r g a n i z a t i o n f o r g o a l achievement, the lower c e n t e r s ( s p i n a l c o r d and p e r i p h e r a l neuromuscular systems) d i c t a t e the more f l e x i b l e parameters of movement e x e c u t i o n . EMG p a t t e r n s o b t a i n e d by Sh i k and O r l o v s k i (1976) have been i n t e r p r e t e d t o suggest t h a t the nervous system e x e r t s c o n t r o l over a l i m b as a whole r a t h e r than i n the c o n t r o l of the i n d i v i d u a l muscles or j o i n t s about t h a t l i m b . S e c o n d l y , s p i n a l p a t t e r n g e n e r a t o r s which are p r e s e n t i n the s p i n a l c o r d e x e r t c o n t r o l over both a s i n g l e l i m b , and i n t e r l i m b c o o r d i n a t i o n . T h i s r e l a t i o n s h i p between commands from h i g h e r l e v e l s i n v o l v e d i n the p r e p a r a t i o n of the motoneurons r e s p o n s i b l e f o r subsequent v o l u n t a r y movements and those p e r m i t t i n g the s p e c i f i c a t i o n of parameters which are r e l e v a n t t o movement e x e c u t i o n , has been d e f i n e d as " t u n i n g " (Turvey, 1977). D e a f f e r e n t a t i o n s t u d i e s (Taub and Berman, 1963) p r o v i d e e v i d e n c e f o r b e l i e v i n g t h a t the h i g h e r c e n t e r s a r e 90 r e s p o n s i b l e f o r p r e p a r i n g f o r e f f e c t o r u n i t d i s c h a r g e by s t i p u l a t i n g the i n v a r i a n t f e a t u r e s upon which the movement w i l l be based. The e f f e c t o r u n i t s w i l l then execute the response i n an autonomous manner. D e a f f e r e n t a t i o n s t u d i e s ar e i m p o r t a n t c o n c e r n s when d i s c u s s i n g the r o l e of feedback i n response e x e c u t i o n , response p r o d u c t i o n . A l t h o u g h the f a c t t h a t Taub and Berman were a b l e t o e l i c i t an a c c u r a t e response a t a l l i n the absence of p e r i p h e r a l feedback i s n o t e w o r t h y , as Bossom (1974) n o t e s , t h e r e was an accompanying l o s s i n the e l e g a n c e of movement c o n t r o l . T h i s s u g g e s t s t h a t feedback i s r e q u i r e d f o r p r e c i s i o n and f i n a l movement c o r r e c t i o n s and t h a t a r e h e a r s e d motor program cannot proceed a c c u r a t e l y w i t h o u t such feedback systems. W h i l e i t i s markedly more d i f f i c u l t t o measure the e f f e c t s of k i n a e s t h e t i c o c c l u s i o n i n humans, K e e l e and Summers (1976) have c o n c l u d e d t h a t the o b s e r v a t i o n s thus f a r appear c o n s i s t e n t w i t h those based on a n i m a l s . An example of such e v i d e n c e i s L a s h l e y ' s (1917) infamous r e p o r t of the e f f e r e n t c o n t r o l e x h i b i t e d by a p a t i e n t h a v i n g i n c u r r e d a gunshot wound i n the back which r e s u l t e d i n a p a r t i a l a n a e s t h e s i a of both l e g s and motor p a r a l y s i s of the muscles below the knees. P r e l i m i n a r y t e s t i n g of the s u b j e c t r e v e a l e d a s e n s i t i v i t y t o movement of a l l j o i n t s e x cept the l e f t knee and a n k l e . T h i s e x c e p t i o n d i d not hamper the s t u d y . L a s h l e y c o n c l u d e d t h a t , d e s p i t e s u f f e r i n g a l a c k of sensory or a f f e c t i v e i n p u t about l e g movements, the p a t i e n t ' s m o b i l i t y d i s c r e d i t e d James' r e s p o n s e - c h a i n i n g h y p o t h e s i s f o r i t was 91 o b v i o u s t h a t such movement c o n t r o l d i d not depend upon response-produced feedback (Schmidt, 1976). Two p r e v a i l i n g t h e o r i e s pervade the l i t e r a t u r e which attempt t o e x p l a i n the t r a n s l a t i o n of a c e n t r a l r e p r e s e n t a t i o n of a movement i d e a i n t o the a p p r o p r i a t e n e u r a l i m p u l s e s f o r muscular a c t i v i t y . The f o l l o w - u p s e r v o t h e o r y (Matthews, 1964; Merton, 1972, 1974) d i c t a t e s t h a t the CNS programs the gamma neurons r a t h e r than the a l p h a motoneurons. A c t i v a t i o n of the gamma neurons c o n t r a c t s the muscle s p i n d l e s t o s t r e t c h the s p i n d l e r e c e p t o r s and, t h e r e f o r e , i n c r e a s e the n e u r a l d i s c h a r g e r e t u r n i n g t o the a l p h a motoneurons. These neurons then p r o v i d e the i n n e r v a t i o n t o the muscles r e s p o n s i b l e f o r l i m b movement such t h a t c o n t r a c t i o n r e l a x e s the s p i n d l e and r e s u l t s i n a decr e a s e i n r e c e p t o r o u t p u t . D u r i n g t h e i r r e s p e c t i v e i n v e s t i g a t i o n s of speech p r o d u c t i o n , MacNeilage (1970) and Sussman (1972) have proposed t h a t the muscle s p i n d l e s , r a t h e r t h a t the movement i t s e l f a r e programmed. Such a programming t h e o r y would resemble t h a t d e s c r i b e d by the f o l l o w - u p s e r v o t h e o r y . The movement i s , t h e r e f o r e , r e f l e x i v e l y d r i v e n by the s p i n d l e system such t h a t i t remains c o n t e x t - f r e e and may be e l i c i t e d i n o t h e r s i m i l a r , a l t h o u g h not i d e n t i c a l , i n s t a n c e s . A c o n t r a s t may be made between the b e h a v i o r i s t ' s S-R c h a i n i n g t h e o r y and t h i s f o l l o w - u p s e r v o t h e o r y . In the former, one movement i s s t i m u l a t e d by feedback from a p r e c e d i n g movement and the absence of feedback w i l l , 92 t h e r e f o r e , break the a s s o c i a t i o n and the c h a i n . In the l a t t e r t h e o r y , however, the movement i s c e n t r a l l y programmed and does not r e q u i r e feedback from a p r i o r movement. R a t h e r , the r e l e v e n t feedback a r i s e s from the a c t i v i t y of the muscle s p i n d l e s as they a r e s t i m u l a t e d d u r i n g t h a t p a r t i c u l a r c o n t r a c t i l e r esponse. The alpha-gamma c o a c t i v a t i o n t h e o r y p r e s e n t s a degree of s i m i l a r i t y t o the f o l l o w - u p s e r v o t h e o r y , but i n c o r p o r a t e s a p a r a l l e l programming of two e f f e r e n t systems. Programmed impulses a r e i s s u e d v i a the a l p h a r o u t e t o a c t i v a t e the major muscles of the d e s i r e d response and s i m u l t a n e o u s l y v i a the gamma system t o the muscle s p i n d l e s . The p a r a l l e l s t r u c t u r e p e r m i t s r a p i d e r r o r c o r r e c t i o n r e sponses w i t h o u t the expense of a d d i t i o n a l i n i t i a t i o n time f o r compensatory movements as would be the case i n the o t h e r t h e o r i e s (Matthews, 1964). Most e v i d e n c e s u p p o r t s the alpha-gamma c o - a c t i v a t i o n t h e o r y and a d e t a i l e d summary i s o f f e r e d by K e e l e and Summers (1976). R e s u l t s from more r e c e n t e x p e r i m e n t a t i o n , however, suggest t h a t a h y b r i d mechanism i s i n v o l v e d i n most movement i n i t i a t i o n and c o n t r o l . "Perhaps the a l p h a system conveys programs f o r the i n i t i a t i o n of movements and even t h e i r rough t e r m i n a t i o n . P a r a l l e l w i t h the i n i t i a t i o n of movements thr o u g h the a l p h a r o u t e , s p i n d l e s may be c o a c t i v a t e d " ( K e e l e and Summers, 1976, pp. 119-121). The r u l e s of each r o u t e may be dependent on whether or not the response r e q u i r e s f o c u s i n g i n t o a t a r g e t ( a c c u r a c y ) or c o r r e c t i o n of e r r o r s 93 in response execution. Figure D provides an anatomical overview of the feedback loops serving the muscular response. It is the interpretation of the control or acti v a t i o n of these impulses which i s open to discussion and investigation. Muscle fibres receive their stimulation via alpha motoneurons a r r i v i n g from the spinal cord. Information returns along afferent pathways via the nerve c e l l bodies located in the dorsal-root ganglion. These afferent pathways can be divided into two types: the Ia pathways innervate stretch receptors (muscle spindles) which are primarily sensitive to changes in muscle length. The stretch receptors act as muscles and, since they l i e in p a r a l l e l with the muscle f i b r e s , are stimulated by gamma motoneurons and are responsive to the rates of changes (velocity) in their stimuli as well as the length i t s e l f . In motor programming terms, i t has been proposed that a gamma command of a given magnitude w i l l always require the main body of the muscle to assume the same length in order to eliminate stretch on the sensory f i b r e s . Via this mechanism, the muscles may attain the same position regardless of length preceding the gamma command. The lb pathways innervate the receptors c a l l e d Golgi tendon organs (GTO) which are primarily sensitive to changes in muscle force. For years i t was believed that the tendon organs functioned to turn off the alpha-motoneuron a c t i v i t y in order to cause muscle relaxation and thereby preventing 94 D E C I S I O N " P R O C E S S E S " M O T O R ' P R O G R A M ' ex. E X T R A -F U S A L S L I M B i E N V I R O N . -J O U T C O M E -I N T R A -F U S A L S P F B E F B K R F i g u r e D: Flow diagram showing the two k i n d s of feedback l o o p s r e s p o n s i b l e f o r response e x e c u t i o n (gamma) and response s e l e c t i o n ( p f b , e f b , KR). (Note: pfb= p r o p r i o c e p t i v e , f e e d b a c k , e f b = e x t e r o c e p t i v e f e e d b a c k , KR=knowledge of r e s u l t s . ) ( S c h m i d t , 1976 p. 243) 95 muscle or l i g a m e n t o u s j o i n t i n j u r y . Recent work, however, su g g e s t s t h a t the GTO may a l s o modify the s t r e t c h r e f l e x so t h a t muscle s t i f f n e s s , as opposed t o muscle f o r c e or l e n g t h , i s the c o n t r o l l i n g f a c t o r (McMahon and Greene, 1978). The f o l l o w i n g model of s k i l l l e a r n i n g (see F i g u r e E) i s one example of numerous d e s c r i p t i o n s proposed about the r e l a t i o n of feedback w i t h i n the the motor program: I t has been c o n c e i v e d t h a t a motor program c e n t e r i s r e s p o n s i b l e f o r the g e n e r a t i o n of movement p a t t e r n s t h r ough e f f e r e n t o u t f l o w t o the m u s c l e s . T h i s movement, i n t u r n , g e n e r a t e s k i n e s t h e t i c feedback from the l i m b s and i s accompanied by such knowledge of performance (KP) f a c t o r s as a u d i t o r y , v i s u a l , and v e s t i b u l a r feedback. T h i s i n f o r m a t i o n i s then matched t o a t e m p l a t e p e r m i t t i n g any r e s u l t a n t e r r o r s t o l e a d t o a c o r r e c t i o n of the motor program. F u r t h e r p r a c t i c e of the program components r e s u l t s i n a s t a b l e program and c o n s i s t e n t performance (Ke e l e and Summers, 1976). E v e n t u a l l y , and i f the s k i l l i s performed i n a s t a b l e or p r e d i c t a b l e environment, the feedback l o o p can be c u t and the s k i l l m a i n t a i n e d by the program. The environment i n which many human s k i l l s a r e performed i s not always p r e d i c t a b l e , and the e x e c u t i o n pf the s k i l l not always e x e c u t e d w i t h the a p p r o p r i a t e p a r a m e t e r s . In t h e s e i n s t a n c e s , e r r o r i s i n e v i t a b l e . I t seems a p p r o p r i a t e , i n the l i g h t of the a f o r e m e n t i o n e d d e s c r i p t i o n of the u n d e r l y i n g n e u r o p h y s i o l o g i c a l p r o c e s s e s of movement o r g a n i z a t i o n , t o 96 Figure E: A model of s k i l l learning and a mechanism for the detection and correct i o n of errors. (Keele and Summers, 1976, p. 122) 97 r e t u r n t o a d i s c u s s i o n of the s t o r a g e of such p r o c e s s e s i n memory. Adams' ( c f . Schmidt, 1975) c l o s e d - l o o p t h e o r y has been proposed and examined e x t e n s i v e l y as a method of movement o r g a n i z a t i o n and c o n t r o l which i s dependent upon feedback f o r l e a r n i n g . Two memory s t a t e s were i d e n t i f i e d and def i n e d : 1) The memory t r a c e i s analogous t o r e c a l l memory i n the v e r b a l l e a r n i n g paradigm, and i s the a c t u a l motor program r e s p o n s i b l e f o r response i n i t i a t i o n . I t c o n t r o l s both the i n i t i a l d i r e c t i o n of the movement and " e a r l i e s t p o r t i o n s " . 2) The p e r c e p t u a l t r a c e , i n c o n t r a s t , may be compared t o r e c o g n i t i o n memory and i s r e s p o n s i b l e f o r the a c c u r a c y component of movement c o m p l e t i o n . I t i s dependent upon the p e r f o r m e r ' s p a s t feedback e x p e r i e n c e s and i s s t r e n g t h e n e d by i n c r e a s e d exposure t o feedback and KR. The s u b j e c t compares i n p u t p r o p r i o c e p t i o n , e t c . r e c e i v e d d u r i n g the movement t o the p e r c e p t u a l t r a c e i n o r d e r t o determine i f the l i m b p o s i t o n i s a c c u r a t e f o r t a r g e t a c q u i s i t i o n . However, Schmidt(1975) suggested a number of c r i t i c i s m s of t h i s c l o s e d - l o o p t h e o r y and l o o k e d t o open-loop c o n t r o l as an a l t e r n a t i v e . H i s Schema t h e o r y f i t s w e l l w i t h the h i s t o r i c a l v i e w p o i n t t h a t , i n the f i n a l s t a g e s of s k i l l a c q u i s i t i o n , the p e r f o r m e r r e t u r n s t o an un a t t e n d e d performance mode. For i n v e s t i g a t i o n of t h i s t h e o r y , however, r e s e a r c h must be d e s i g n e d such t h a t i t w i l l prove t h a t , e i t h e r feedback i s p r e s e n t but not used, or t h a t feedback i s 98 not p r e s e n t but movement can s t i l l o c c u r . B r i e f l y , when the s u b j e c t s t o r e s a motor program about a movement, he i s s t o r i n g a schema which has been d e f i n e d by Evans ( c f . Schmidt, 1975) a s : a c h a r a c t e r i s t i c of some p o p u l a t i o n of o b j e c t s , and c o n s i s t s of a set of r u l e s s e r v i n g as i n s t r u c t i o n s f o r p r o d u c i n g a p o p u l a t i o n p r o t o t y p e (the c o n c e p t ) (p. 233) More s p e c i f i c a l l y , the motor response schema w i l l o c c u r once the S produces a movement. From t h a t movement S s t o r e s f o u r t h i n g s : "(a) the i n i t i a l c o n d i t i o n s , (b) the response s p e c i f i c a t i o n s f o r the motor program, (c) the s e n s o r y consequences of the response produced, and (d) the outcome of t h a t movement" (p. 235). A f t e r a number of such movements S a b s t r a c t s the i n f o r m a t i o n i n each of these f o u r s o u r c e s i n terms of the r e l a t i o n s h i p s between them. T h i s i s t o be c o n t r a s t e d w i t h the s t o r a g e of the common f e a t u r e s between the elements of a number of movements which may be l i k e n e d t o a p r o t o t y p i c a l d i s p l a y . W i t h each s u c c e s s i v e movement of the same g e n e r a l t y p e , the s t r e n g t h of the r e l a t i o n s h i p i n c r e a s e s as does the schema memory. F i g u r e F demonstrates the r e l a t i o n s h i p of these s o u r c e s of i n f o r m a t i o n which form the schemata: KR and feedback are i m p o r t a n t i n motor r e c o g n i t i o n as f u n c t i o n s independent of motor r e c a l l memory ( i . e . , t h a t memory a s s o c i a t e d w i t h the r e s p o n s e - p r o d u c t i o n p o r t i o n of the schema) even though KR and feedback a r e s i m i l a r f o r both s t a t e s . "While the two schemata do share the i n i t i a l c o n d i t i o n s and a c t u a l outcomes as v a r i a b l e s , 99 INITIAL CONDITIONS S P E C I F I C A T I O N S MOTOR PROGRAM LIMBS ENVIRONMENT MEASURED OUTCOME DESIRED OUTCOME S U B J E C T I V E R E I N F O R C E M E N T ERROR LABELING MOTOR RESPONSE SCHEMA EXP PFB EXP EFB P R O P R I O C E P T I O N E X T E R O C E P T I O N K N O W L E D G E . OF R E S U L T S Figure F: The motor response schema in re l a t i o n to events occurring within a t r i a l ( r e c a l l and recognition schemata are combined for c l a r i t y ) . Abbreviations: KR=knowledge of res u l t s , EXP PFB=expected proprioceptive feedback, EXP EFB=expected exteroceptive feedback. (Schmidt, 1975, p. 238) 100 they a re s e p a r a t e because the r e c a l l schema i s the r e l a t i o n s h i p between these v a r i a b l e s and response s p e c i f i c a t i o n s , whereas the r e c o g n i t i o n schema i s the r e l a t i o n s h i p between th e s e two v a r i a b l e s and s e n s o r y consequences" (Schmidt, 1975, p. 237). F i g u r e G demonstrates the r e l a t i o n s h i p of the motor response schema, as a c o m b i n a t i o n of r e c a l l and r e c o g n i t i o n schemata, t o the events which o c c u r w i t h i n a s i n g l e performance e x p e r i e n c e . A r e s u l t i n g mismatch between i n f l o w and e x p e c t e d r e s u l t s w i l l produce an e r r o r . f e d back as such t o both the schema and the e r r o r l a b e l l i n g system. The e r r o r i s a l s o f e d t o the e r r o r system so t h a t the s u b j e c t can a s s i g n a l a b e l t o i t i n o r d e r t o make the a p p r o p r i a t e a d j u s t m e n t s t o i t t o reduce the e r r o r t o z e r o . To summarize, r e c a l l memory i s the s t a t e t h a t produces the movement and r e c o g n i t i o n memory i s the s t a t e t h a t d e t e r m i n e s t h a t the movement was c o r r e c t . C. I n v e s t i g a t i o n of Performance E r r o r s The e v i d e n c e a t t h i s time s u g g e s t s t h a t the sou r c e of performance e r r o r may be i d e n t i f i e d by the v a r i a t i o n i n l a t e n c y p e r i o d s r e c o r d e d d u r i n g movement a l t e r a t i o n or c o r r e c t i o n . For example,"the e v i d e n c e c o n c e r n i n g changes i n the s e l e c t e d s p a t i a l - t e m p o r a l p a t t e r n of movement ( i . e . , c o r r e c t i n g f o r e r r o r s i n s e l e c t i o n ) i n d i c a t e s t h a t s i g n a l s showing t h a t the e n v i r o n m e n t a l g o a l i s not goi n g t o be met r e q u i r e a r e a c t i o n time l a g (250 msec) b e f o r e changes can 101 PAST RESPONSE SPECIFICATIONS RESPONSE SPECIFICATIONS <i _ l o i UJ o cr C O INI HAL. CONDITIONS DESIRED OUrCOMF. PAST ACTUAL OUTCOMES o t <L COGt UJ I UJ to PAST SENSORY CONSEQUENCES EXPECTED SENSOffc CONSEQUENCES. F i g u r e G: The r e c a l l and r e c o g n i t i o n schema i n r e l a t i o n t o v a r i o u s s o u r c e s of i n f o r m a t i o n . (Schmidt, 1975, p. 236) 102 b e g i n t o be i n i t i a t e d . T h i s has l e d many t o c o n c l u d e t h a t the s u b j e c t d e t e r m i n e s the s p a t i a l - t e m p o r a l g o a l of the movement i n advance, and t h a t h i s p a t t e r n i s c a r r i e d out open l o o p " (Schmidt, 1976, p. 242; K e e l e , 1968; L a s h l e y , 1917; Schmidt et a l . , 1979). C o r r e c t i v e b e h a v i o r f o r e r r o r s i n response e x e c u t i o n i m p l y s t r o n g l y t h a t the program output d e t e r m i n e s both a l p h a and gamma e f f e r e n t a c t i v i t y , a p p r o p r i a t e l y c o o r d i n a t e d , so t h a t the muscle s p i n d l e system can e x e r t r a p i d c l o s e d - l o o p c o n t r o l over the response e x e c u t i o n . . . . T h i s feedback l o o p i s q u i t e r a p i d , w i t h a l o o p time of around 30-50 msec; i t i s r e s p o n s i b l e f o r the c o n t r o l over response e x e c u t i o n , but cannot c o r r e c t f o r e r r o r s i n response s e l e c t i o n . (Schmidt, 1976, p. 242) Merton (1974) examined the v o l u n t a r y f l e x i o n of the d i s t a l i n t e r p h a l a n g e a l j o i n t of the thumb a f t e r o c c l u s i o n . I n c r e a s e d EMG a c t i v i t y was r e c o r d e d f o l l o w i n g a l a t e n c y of a p p r o x i m a t e l y 50 msec and which was s u g g e s t i v e of c e r e b r a l c o r t e x i n f l u e n c e . H i g g i n s and Angel (1970) examined the c o r r e c t i v e l a t e n c i e s e x h i b i t e d i n a c h o i c e r e a c t i o n time t a s k and a l s o noted l a t e n c i e s of 110 msec. F i g u r e F demonstrated the p r e d i c t e d feedback l o o p s f o r response s e l e c t i o n and response e x e c u t i o n m o n i t o r i n g and c o r r e c t i o n . T h i s l a t e n c y d i f f e r e n t i a t i o n i s f u r t h e r e v i d e n c e f o r a h i e r a r c h i c a l c o n t r o l over the components of the motor program. The c u r r e n t problem, as i d e n t i f i e d by Schmidt (1976), i s one of i d e n t i f i c a t i o n of those " i n v a r i a n t f e a t u r e s " as c o n t r a s t e d t o "parameters" which a r e more m a n i p u l a b l e . I t i s su g g e s t e d t h a t the f o l l o w i n g f o u r program 103 f e a t r e s have been i d e n t i f i e d a t some p o i n t p r i o r t o the response i n i t i a t i o n : 1. which muscles a re t o c o n t r a c t ; 2. the o r d e r of c o n t r a c t i o n ; 3. the r e l a t i v e and a b s o l u t e f o r c e s w i t h which they a re t o c o n t r a c t ; and 4. the te m p o r a l r e l a t i o n s among the c o n t r a c t i o n s ( i . e . , p h a s i n g ) . (Schmidt et a l . , 1979, p. 417) In c o n t r a s t , i t has been suggested t h a t the parameters which are under c o n t r o l l a t e r i n the e x e c u t i o n of the performance may i n c l u d e : 1. the o v e r a l l speed of a re s p o n s e ; 2. the o v e r a l l g a i n of the f o r c e as i t a p p l i e s t o a l l of the muscles p a r t i c i p a t i n g i n the a c t ; and 3. perhaps c e r t a i n movement-size v a r i a b l e s . (Schmidt et a l . , 1979, p. 418) The n o t i o n of h i e r a r c h i c c o n t r o l p e r m i t s comprehension of the a b i l i t y t o t r a n s f e r a s k i l l from one s i t u a t i o n or c o n t e x t , t o a n o t h e r . A s i n g l e program, which has been d e f i n e d as an a b s t r a c t r e p r e s e n t a t i o n of a sequence of a c t i o n s , can be produced on d i f f e r e n t o c c a s i o n s by e n t i r e l y d i f f e r e n t muscle groups. Pew (1974b) observed human s k i l l e d b e h a v i o r as a c o o r d i n a t e d system of a number of i n t e r d e p e n d e n t l e v e l s of c o n t r o l which must f u n c t i o n a c c o r d i n g t o both Ss c u r r e n t s t a t e of l e a r n i n g , and the e n v i r o n m e n t a l c o n s t r a i n t s . P o s i t i v e t r a n s f e r of u n c o n s c i o u s 104 l e a r n i n g from one s k i l l over time was i n v e s t i g a t e d by o b s e r v i n g Ss as they moved a c o n t r o l s t i c k i n the performance of a p u r s u i t t r a c k i n g t a s k . The s i g n a l was p r e s e n t e d f o r 65 seconds, which i n c l u d e d a f i v e - s e c o n d a c q u i s i t i o n p e r i o d , and 3X20 second t r a c k i n g segments. The m i d d l e 20-second p e r i o d was r e p e a t e d e v e r y t r i a l . Pew found t h a t performance f o r the r e p e a t e d segment improved at a f a s t e r r a t e over t r i a l s than t h a t on the random segments. Ss were, t h e r e f o r e , a b l e t o take advantage of the p r e d i c t a b l e n a t u r e of the segment. In response t o q u e s t i o n s d e l i v e r e d d u r i n g a p o s t - t e s t i n t e r v i e w , Ss d e n i e d c o n s c i o u s l y i d e n t i f y i n g the r e p e t i t i v e n a t u r e of the t a s k . To t e s t the memory s t o r a g e of the i n f o r m a t i o n of the r e p e a t e d 20-second segment, Ss were a d m i n i s t e r e d e i g h t a d d i t i o n a l t r i a l s ( b e f o r e the i n t e r v i e w ) d u r i n g which t h i s m i d d l e segment was i d e n t i c a l but i n v e r t e d . Performance on t h i s segment remained r e l i a b l y b e t t e r than the unrepeated segments (t=2.53, p_<0.02) and r e l i a b l y worse (t = 3.05, p_<0.01) than the u n r e v e r s e d , but r e p e a t e d segment. Pew c o n c l u d e d t h a t "whatever i t i s t h a t was l e a r n e d appeared t o g e n e r a l i z e a t l e a s t t o some e x t e n t t o c o r r e s p o n d i n g p a t t e r n s s y m m e t r i c a l l y r e v e r s e d . That i s , symmetry need not be p r e s e r v e d t o p r e s e r v e the s i g n i f i c a n t f e a t u r e s of the p a t t e r n t h a t have been l e a r n e d " (p. 395). The f e a t u r e s of the motor response which may be u t i l i z e d i n the t r a n s f e r phenomenon may i n c l u d e a v a r i e t y of s p e c i f i c a t i o n s such as speed and l i m b of a c t i o n , 105 d i r e c t i o n a l i t y and s i z e . These f e a t u r e s can then be a p p l i e d t o the a l r e a d y d e f i n e d r e p r e s e n t a t i o n of a motor a c t i o n which i s more a b s t r a c t than i d e n t i f i c a t i o n of s p e c i f i c muscles ( K e e l e , Note 2 ) . T h i s phenomenon i s i m p o r t a n t when one c o n s i d e r s the i m p o s s i b l e n a t u r e of f i t t i n g one u n a l t e r a b l e program t o an i n f i n i t e number of c o n t e x t u a l s i t u a t i o n s o r , v i c e v e r s a , the tremendous s t o r a g e c a p a c i t y t h a t would be n e c e s s a r y t o p r o v i d e a unique program f o r each s i t u a t i o n . However, i f the p a t t e r n s o b s e r v e d from a g i v e n program p o s s e s s c e r t a i n i n v a r i a n t p r o p e r t i e s , i t i s p o s s i b l e t h a t two responses from the same program may have l a r g e d i f f e r e n c e s i n o t h e r r e s p e c t s . The program may be viewed as g e n e r a l i z e d , such t h a t parameters a r e r e q u i r e d t o s p e c i f y the p a r t i c u l a r way i n which the program i s t o be e x e c u t e d (Schmidt e t a l . , 1979). The p h a s i n g of a r e s p o n s e , d e f i n e d as the t e m p o r a l r e l a t i o n s h i p s between the c o n t r a c t i o n s which produce a movement p a t t e r n , and the r e l a t i v e f o r c e s w i t h i n t h e s e v a r i o u s c o n t r a c t i o n s have been proposed as the fundamental i n v a r i a n t p r o p e r t i e s of the motor program. V a r i o u s w r i t e r s have suggested t h a t some of the more l a b i l e p arameters w i t h i n the p h a s i n g of a response might be: 1. the o v e r a l l speed of a response ( G l e n c r o s s , 1978); 2. the o v e r a l l " g a i n " of the f o r c e as i t a p p l i e s t o a l l of the muscles p a r t i c i p a t i n g i n the a c t ; and 3. c e r t a i n movement-size v a r i a b l e s t h a t a r e r e s p o n s i b l e f o r d e t e r m i n a t i o n of the o v e r a l l s i z e of a r e s p o n s e . (Schmidt, e t a l . , 1979) 106 I t s h o u l d be made c l e a r t h a t the e v i d e n c e s u g g e s t s t h a t p a r t i c u l a r muscles a re not s p e c i f i e d i n the motor program (Merton, 1972). Such a c o n c l u s i o n comes a l s o from the o b s e r v a t i o n t h a t a s i g n a t u r e on a blank page or a s i g n a t u r e ten times l a r g e r on a b l a c k b o a r d w i l l p o s s e s s the same p a t t e r n , but has been produced w i t h d i f f e r e n t muscles and j o i n t a c t i o n . At t h i s h i g h e s t l e v e l of the program i t i s not o n l y the a b s t r a c t p l a n of a c t i o n which i s the con c e r n of the p e r f o r m e r , but a l s o the s p a t i a l map which i n c l u d e s r e p r e s e n t a t i o n s of the e f f e c t i n g l i m b s , the d i r e c t i o n of the movement, and the t e r m i n a l l o c a t i o n of the i n t e n d e d a c t i o n . These a b s t r a c t codes g r a d u a l l y become more c o n c r e t e w i t h the s e l e c t i o n of the a p p r o p r i a t e e f f e c t o r u n i t ( s y n e r g i s t i c groups of m u s c l e s ) , sequencing and p h a s i n g of these s t r u c t u r e s , and the s p e c i f i c a t i o n of f o r c e i n t e n s i t y and t i m i n g of f o r c e f o r each of the s e s t r u c t u r e s . In terms of f o r c e i n t e n s i t y and t i m i n g of f o r c e s , e v i d e n c e thus f a r d i s c u s s e d s u g g e s t s t h a t these parameters a r e o p e r a t i o n a l i z e d a t the l e v e l of the s p i n a l c o r d and m u s c u l a t u r e . T h i s o c c u r s as a r e s u l t of the e s t a b l i s h m e n t of " e q u i l i b r i u m p o s i t i o n s " which b i a s the e f f e c t o r u n i t s t o the i n t e n t i o n s of the h i g h e r c e n t e r s . When the movement b e g i n s they a c t t o auntonomously execute the i n t e n d e d movement. T h i s b i a s i n g a t the s p i n a l c o r d l e v e l a l s o c r e a t e s a f e e d f o r w a r d mechanism which i s c a p a b l e of r e c o g n i z i n g " f u n c t i o n a l u n i t y " of the CNS as i t p r e p a r e s f o r movement (M a r t e n i u k and MacKenzie, Note 4) . 107 One can thus see how h i e r a r c h i c a l control over response errors (in both selection and execution) can result in a di f f e r e n t operationalization of movement correction times and c a p a b i l i t i e s depending upon the feedback loop u t i l i z e d . The higher the l e v e l , the more invariant the defined dynamics, the more central the feedback processing, and the longer the latency period. D. Conclusion It i s extremely d i f f i c u l t to study behavioral performance to the degree necessary to investigate the issue of motor programming as response tasks become more complex and deviate from re f l e x i v e actions. The responses may, for example, be i d e n t i f i e d as discrete, b a l l i s t i c , continuous, single-aiming, or repetitive-tapping tasks. Each of these movements may present unique neuromuscular constraints which w i l l a f f e c t the movement permutations possible and, thus, r e f l e c t the a p p l i c a b i l i t y of such movement sequences to programmed control. Investigation of motor programming is well under way with current researchers u t i l i z i n g cinematographical methods, potentiometers, accelerometers, and EMG data to record the muscular display of the parameters of performance. Using consistencies reported by these measurement techniques, inferences may be made about the underlying cognitive control of voluntary behavior. 108 APPENDIX C 109 PRELIMINARY STUDIES Four p i l o t s t u d i e s were conducted i n o r d e r t o e v a l u a t e the a n t i c i p a t o r y a b i l i t y of f i e l d hockey p l a y e r s . The l a b o r a t o r y c o n d i t i o n s of the f i r s t t h r e e s t u d i e s were d e s i g n e d t o s i m u l a t e the a r r i v a l of a b a l l i n m o t i o n . The f o u r t h study examined an e c o l o g i c a l l y v a l i d s i t u a t i o n u t i l i z i n g a moving b a l l . Study I was conducted as an i n v e s t i g a t i o n of the number of t r i a l s r e q u i r e d b e f o r e s u b j e c t s became f a m i l i a r w i t h the B a s s i n A n t i c i p a t o r y Timer Timer C o n t r o l System ( L a f a y e t t e Instrument Co., Model 50-575). A b s o l u t e e r r o r (AE) was r e c o r d e d such t h a t 0.000 msec was a measure of p e r f e c t c o i n c i d e n t t i m i n g . S u b j e c t s were p r e s e n t e d w i t h two s t i m u l u s speeds randomly p r e s e n t e d over 50 t r i a l s and t r i a l s were b l o c k e d t o d e t e r m i n e when response s c o r e s had l e v e l l e d o f f and become c o n s i s t e n t . Study I I extended t h i s p r e l i m i n a r y study t o i n v e s t i g a t e the q u a n t i t a t i v e d i f f e r e n c e s i n a n t i c i p a t o r y a b i l i t y as a r e s u l t of f i e l d hockey s k i l l l e v e l (Toburen, 1977). Study I I I was d e s i g n e d a f t e r r e d e f i n i n g Ss response such t h a t the t a s k b e t t e r r e f l e c t e d the p e r f o r m e r ' s s k i l l l e v e l . T h i s was a c c o m p l i s h e d by a d d i n g a t a r g e t a c c u r a c y component t o the t a s k thus r e q u i r i n g s u f f i c i e n t f o r c e t o be i m p a r t e d t o the b a l l t o a c h i e v e t a r g e t a c q u i s i t i o n . Study IV was d e s i g n e d a c c o r d i n g t o the major i n v e s t i g a t i o n of t h i s t h e s i s . An e c o l o g i c a l l y v a l i d c o n s t r u c t was u t i l i z e d t o t e s t the response o r g a n i z a t i o n of 1 10 an e l i t e p e r f o r m e r w h i l e o p e r a t i n g w i t h i n v a r y i n g c o n d i t i o n s of t e m p o r a l u n c e r t a i n t y . Study I Method S u b j e c t s : The t e s t group was comprised of 19 female and 22 male u n i v e r s i t y s t u d e n t s who were randomly s e l e c t e d from the e n r o l l m e n t of P h y s i c a l E d u c a t i o n 468 (Term 1). A p p a r a t u s : The s u b j e c t s were s e a t e d a t a desk i n a darkened room. D i r e c t l y i n f r o n t , a t desk h e i g h t and e x t e n d i n g t en f e e t (3.05m) i n l e n g t h , was the BAT w i t h two e x t e n s i o n modules. A y e l l o w warning l i g h t (1.5sec) was l o c a t e d a t the extreme end of the t r a c k which c o n s i s t e d of r e d l i g h t s which f l a s h e d on and o f f i n s e r i e s towards the s u b j e c t . The q u a l i t a t i v e ( e a r l y or l a t e ) and q u a n t i t a t i v e (msec) r e s u l t s of each t r i a l were r e g i s t e r e d by a B a s s i n A n t i c i p a t i o n Timer C o n t r o l System ( L a f a y e t t e Instrument Co., Model 50-575). The system was a l s o used t o c o n t r o l the speed a t which the l i g h t s f l a s h e d i n s e r i e s . P r o c e d u r e : The s u b j e c t s were i n s t r u c t e d t o watch and a p p r a i s e the v e l o c i t y a t which the l i g h t s f l a s h e d down the t r a c k and e s t i m a t e the moment t h a t the l a s t l i g h t would become i l l u m i n a t e d . They were t o respond by d e p r e s s i n g a response key such t h a t i t c o i n c i d e d w i t h t h i s i l l u m i n a t i o n . Ss were then p r o v i d e d w i t h KR, i . e . , t o l d whether or not they were e a r l y or l a t e i n t h e i r judgment, and by how much (msec). Ss were g i v e n 50 t r i a l s and i n s t r u c t e d t h a t the 111 l i g h t s e r i e s would be p r e s e n t e d a t v a r y i n g v e l o c i t i e s . Ss were not i n f o r m e d , however, t h a t t h e r e were two d i f f e r e n t v e l o c i t i e s (20 m.p.h.(8.9 cm/sec); 30 m.p.h.(13.4 cm/sec)) randomly p r e s e n t e d f o r 25 t r i a l s each. Results and Conclusions The AE s c o r e s f o r each s u b j e c t were a n a l y z e d i n i t i a l l y i n a 2 X 50 (Sex by T r i a l s ) and a 2 X 2 X 25 (Sex by Speed by T r i a l s ) Mixed D e s i g n . The r e s u l t s i n d i c a t e t h a t 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 i n a n t i c i p a t o r y t i m i n g d u r i n g the 50 t r i a l s r e g a r d l e s s of the s t i m u l u s speed F ( 4 9 , 1 1 . 35) =0 . 000 ,p_<. 0 1. In a d d i t i o n , averaged between the two speeds, 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 the sexes over the 50 t r i a l s , F ( 4 9 , 0.69)=0.9509. A n a l y s i s of the 25 t r i a l s f o r each v e l o c i t y s u g g e s t s t h a t , averaged between the s e x e s , 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 i n the AE s c o r e s f o r the f a s t and slow speed p r e s e n t a t i o n s , F ( 1 , 8.09) = 0.000, p_<.01. A t r e n d a n a l y s i s performed on the r e s u l t s shows a second degree o r t h o g o n a l c o n t r a s t . In o r d e r t o d e t e r m i n e a l e a r n i n g e f f e c t , and t h a t the AE s c o r e s were no l o n g e r i m p r o v i n g , i . e . , d e c r e a s i n g , the r e s u l t s were b l o c k e d f o r f u r t h e r a n a l y s i s . F i g u r e H p r o v i d e s a g r a p h i c r e p r e s e n t a t i o n of the d a t a grouped i n t o 5 b l o c k s of 5 t r i a l s p er b l o c k . The p l o t t e d means show a s i g n i f i c a n t d e c r e a s e i n the mean AE between the f i r s t and second b l o c k s — w h i c h i n c l u d e s t r i a l s f i v e t o ten of each speed. T h e r e f o r e , one can c o n c l u d e t h a t the minimum number of t r i a l s n e c e s s a r y f o r l e a r n i n g t o produce a l e v e l l i n g o f f i n a n t i c i p a t o r y a b i l i t y .100 LEGEND --32.2 kph — 48.3 kph ,0801 a cu 10 c Females v Males N v .060 -a cu u o ^ -040 i CG Females Males .020 — i — 2.5 — i — 7.5 12.5 TRIALS 17.5 BLOCKS Figure H: Blocked mean AE (msec) for 25 t r i a l s at two speeds. 113 due t o a p p a r a t u s f a m i l i a r i z a t i o n would be t e n t r i a l s a t each speed. Study I I Method S u b j e c t s : Female s u b j e c t s were s e l e c t e d and grouped on the b a s i s of the h i g h e s t l e v e l of f i e l d hockey t h a t they had p a r t i c i p a t e d i n : Group 1 c o n s i s t e d of p l a y e r s who were c u r r e n t or r e c e n t members of the Canadian N a t i o n a l F i e l d Hockey Squad; Group 2 were c u r r e n t u n i v e r s i t y p l a y e r s ; Group 3 were h i g h s c h o o l p l a y e r s ; and Group 4 c o n s i s t e d of randomly s e l e c t e d c o n t r o l s u b j e c t s ( u n i v e r s i t y s t u d e n t s from the Department of P h y s i c a l E d u c a t i o n ) . Ten s u b j e c t s were a s s i g n e d t o each group w i t h the e x c e p t i o n of the h i g h s c h o o l group which c o n s i s t e d of seven s u b j e c t s . A p p a r a t u s : The same t e n f o o t (3.05m) t r a c k of l i g h t s was s e t up as was used i n Study I . Ss were i n s t r u c t e d t o s t a n d on a f o u r f o o t by f o u r f o o t (1.2m X 1.2m) plywood p l a t f o r m which was e l e v a t e d t o a l l o w the t r a c k of s t i m u l u s l i g h t s t o be l a i d on the f l o o r and s l i d u nderneath. T h i s e n a b l e d the t e r m i n a l cue l i g h t t o be l o c a t e d d i r e c t l y under a f i e l d hockey b a l l r e s t i n g i n a h o l e d r i l l e d i n t o the p l a t f o r m . P h o t o c e l l s were used t o t r i g g e r the t i m i n g d e v i c e such t h a t , as the s u b j e c t s drove the b a l l , the b a l l would be h i t out of the beam of the p h o t o c e l l s . As i n Study I , Ss were s u p p l i e d w i t h q u a l i t a t i v e and q u a n t i t a t i v e KR. P r o c e d u r e : Temporal u n c e r t a i n t y was reduced by p r e s e n t a t i o n 114 of a 1.5 second foreperiod. The l i g h t v e l o c i t i e s were 15 m.p.h. (6.7 cm/sec), 20 m.p.h. (8.9 cm/sec) and 30 m.p.h. (13.4 cm/sec) to simulate slow, medium and fast-paced b a l l s respectively, but Ss were not informed that there were three stimulus speeds. Ss were required to maintain a stationary position on the platform, facing the track such that the l i g h t s "moved" towards them. The platform was constructed such that the b a l l was positioned opposite the Ss l e f t foot. This provided some structure to the lesser s k i l l e d groups in order that a l l the performers struck the b a l l with as similar a technique as possible. Ss were instructed to observe the movement of the l i g h t s down the track and estimate when they f e l t that the la s t l i g h t (located under the b a l l ) would be illuminated. The response task was to "drive" the stationary b a l l off of the platform to coincide with the moment the la s t l i g h t flashed on. Ss were told that a number of speeds would be presented randomly and, that for the fast speeds, they would not have time to step into the b a l l . The stick was to be raised off of the platform prior to the f i n a l downswing and subsequent contact with the b a l l , but could be gripped with hands apart or together as the subject wished. Ss were told that t h i s apparatus was designed to simulate a f i r s t - t i m e drive to the l e f t of a b a l l in motion towards them. KR was provided after each t r i a l . Ss were informed that their f i r s t 21 t r i a l s would be learning t r i a l s (as determined by Study I) and that the subsequent 30 were to be 115 used f o r d a t a c o l l e c t i o n and a n a l y s i s . The l i g h t speeds were p r e s e n t e d i n a randomized o r d e r . R e s u l t s and C o n c l u s i o n s The AE and CE s c o r e s r e c o r d e d d u r i n g the da t a c o l l e c t i o n phase were a n a l y z e d i n a 4 X 30 (Groups by T r i a l s ) Randomized Groups d e s i g n . Table A shows t h a t the N a t i o n a l p l a y e r s demonstrated b e t t e r mean AE t i m e s , f o l l o w e d by the c o n t r o l group, u n i v e r s i t y p l a y e r s , and h i g h s c h o o l p l a y e r s . However, the mean CE, or response b i a s , shows the c o n t r o l group s u p e r i o r t o a l l o t h e r groups. A l t h o u g h the N a t i o n a l p l a y e r s demonstrated the lo w e s t s t a n d a r d d e v i a t i o n s , r e s u l t s f o r the o t h e r groups d i d not f o l l o w a r a n k i n g as would be a n t i c i p a t e d based upon s k i l l l e v e l . An a n a l y s i s of v a r i a n c e of the AE and CE r e s u l t s s u g g e s t s t h a t , averaged over the 30 t r i a l s and between s u b j e c t s , 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 i n c o i n c i d e n t t i m i n g a b i l i t y between the f o u r s k i l l l e v e l s , F ( 3 , 6.24)=0.002, £<.01; and f(3,3.20)=0.036, p<.05. Ta b l e B has been i n c l u d e d t o i l l u s t r a t e the CE t r i a l means f o r the f o u r groups over the 30 t r i a l s . I t s h o u l d be noted t h a t t h e r e were a number of n e g a t i v e , or e a r l y , e r r o r v a l u e s r e c o r d e d f o r the h i g h s c h o o l (low e x p e r i e n c e ) and c o n t r o l (no e x p e r i e n c e ) groups i n response t o the slow s t i m u l u s speed. Such r e s u l t s may be a r e f l e c t i o n of the i n a b i l i t y of such p e r f o r m e r s t o o p e r a t e o u t s i d e of a l e n g t h y 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 . Once they i n i t i a t e d t h e i r response they were unable t o c o r r e c t i t and an e a r l y 116 Ta b l e A Mean A b s o l u t e E r r o r (AE), Constant E r r o r (CE) and S t a n d a r d D e v i a t i o n as a F u n c t i o n of Randomized S t i m u l u s Speed and S k i l l L e v e l ABSOLUTE ERROR (msec) CONSTANT ERROR (msec) GROUP MEAN SD MEAN SD N a t i o n a l 0.088 ±0.041 0.066 ±0.062 U n i v e r s i t y 0.131 ±0.076 0.114 ±0.088 High S c h o o l 0. 150 ±0.055 0. 109 ±0. 102 C o n t r o l 0.096 ±0.068 0.047 ±0.079 1 17 Ta b l e B T r i a l Means CE - 30 T r i a l s a t Randomized Speeds TRIAL GROUP MEANS (msec) NATIONAL UNIVERSITY HIGH SCHOOL CONTROL MEAN SD MEAN SD MEAN SD MEAN SD 1 0. 145 ±0. 047 0. 182 ±0. 055 0. 219 ±0. 060 0. 124 ±0. 044 2 0. 140 ±0. 046 0. 125 ±0. 129 0. 216 ±0. 069 0. 104 ±0. 039 3 0. 020 ±0. 068 0. 079 ±0. 090 0. 093 ±0. 103 0. 021 ±0. 1 1 0 4 0. 051 ±0. 070 0. 135 ±0. 092 0. 064 ±0. 095 0. 024 ±0. 083 5 0. 033 ±0. 077 0. 068 ±0. 102 -0. 034 ±0. 131 -0. 062 ±0. 094 6 0. 063 ±0. 050 0. 152 ±0. 073 0. 081 ±0. 077 0. 075 ±0. 1 15 7 0. 032 ±0. 074 0. 1 15 ±0. 076 -0. 009 ±0. 097 0. 039 ±0. 072 8 0. 1 14 ±0. 039 0. 188 ±0. 056 0. 166 ±0. 050 0. 141 ±0. 072 9 0. 131 ±0. ,032 0. 186 ±0. ,060 0. , 189 ±0. , 100 0. 140 ±0. ,037 10 0. 001 ±0. ,115 0. 061 ±0. ,121 -0. ,010 ±0. , 189 -0. ,083 ±0. , 120 1 1 0. ,341 ±0. ,051 0. 068 ±0. , 102 0. ,040 ±0. , 123 0. ,040 ±0. ,067 1 2 0. ,060 ±0, .062 0. ,047 ±0, .069 0, .112 ±0, .101 0. ,043 ±0, .059 13 0. .027 ±0, .075 0. ,082 ±0, .110 0, .001 ±0, . 104 -0, .013 ±0, . 138 14 0, , 139 ±0, .036 0. , 167 ±0, .086 0. .231 ±0 .097 0, . 159 ±0, .094 15 0, .037 ±0 .064 0, .082 ±0 .097 0 . 146 ±0 .084 -o. .016 0 .081 16 0, .018 ±0 .088 0, .095 ±0 .073 -o .073 ±0 .090 -0 .035 ±0 . 125 17 0. .043 ±0 .075 0. . 124 ±0 .071 0 . 180 ±0 .191 0 .063 ±0 .080 18 0 .133 ±0 .059 0 . 156 ±0 .083 0 .304 ±0 .141 0 . 108 ±0 .041 19 0 .000 ±0 .082 0 .072 ±0 .090 0 .028 ±0 .132 0 .029 ±0 . 141 20 0 . 120 ±0 .036 0 . 153 ±0 .057 0 .245 ±0 .063 0 . 142 ±0 .052 21 0 .024 ±0 .053 0 .065 ±0 .081 0 . 142 ±0 . 128 0 .022 ±0 .070 22 0.01 1 ±0.081 0. 120 ±0.061 23 0.017 ±0.066 0.077 ±0.108 24 0.114 ±0.051 0.202 ±0.079 25 0.034 ±0.076 0.076 ±0.082 26 0.125 ±0.047 0.165 ±0.078 27 0.112 ±0.044 0.191 ±0.110 28 0.048 ±0.089 0.028 ±0.107 29 0.045 ±0.066 0.089 ±0.1 14 30 0.052 ±0.043 0.058 ±0.121 1 18 -0.047 ±0.074 0.052 ±0.184 0.214 ±0.048 0.100 ±0.070 0.246 ±0.060 0.206 ±0. 139 0.112 ±0.091 0.105 ±0.078 -0.036 ±0.088 -0.030 ±0.115 0.029 ±0.063 0. 137 ±0.062 -0.009 ±0.071 0.114 ±0.027 0. 122 ±0.034 -0.033 ±0.069 0.019 ±0.081 -0.011 ±0.110 Marg 0.066 0.114 0. 109 0.047 119 response resulted. The results were more interesting when the 30 t r i a l s were examined according to the responses obtained for each speed of stimulus presentation (see Table C). While the AE values for a l l four groups were similar for the two slower speeds, there was a large difference between the results at these slower speeds and the AE scores of the fastest speed. Averaged over the ten t r i a l s per speed, National players scored better for a l l speeds except the 30 m.p.h. speed, for which the control group surpassed them. For a l l other speeds, however, the ranking shows that the control group, the university group and then the high school group finished from second to fourth respectively behind the National players. Examination of the standard deviation values for each speed shows similar ranking for each speed--National players demonstrated the smallest standard deviation, followed by the control group, university and high school players. A l l groups demonstrated the greatest standard deviation at the slowest speed while performing more consistently at the fastest speed. S i m i l a r l y , the much larger AE and CE values for the fast stimulus speed may not r e f l e c t true anticipatory a b i l i t y , but rather RT plus MT since the stimulus speed may be such that Ss are forced to respond immediately upon presentation of the warning l i g h t . This temporal constraint may also have prevented the i n i t i a t i o n of an error correction response should S have been cognizant of such a T a b l e C C e l l Means (AE and CE)--10 T r i a l s per S t i m u l u s Speed GROUP N a t i o n a l U n i v e r s i t y H i g h S c h o o l C o n t r o l 2 4 . 1 k p h A E S D C E S D . 0 6 4 ±.046 . 0 2 3 ±.075 . 1 1 1 + . 0 6 1 . 0 8 2 ±.096 . 1 0 1 ±.066 - . 0 0 9 ±.121 . 0 8 5 ±.069 - . 0 1 0 ±.104 3 2 . 2 k p h A E SD C E S D . 0 6 5 ±.043 . 0 4 2 ±.067 . 1 0 6 ±.068 . 0 8 8 ±.088 . 1 2 3 ±.088 . 1 1 4 ±.102 . 0 7 3 ±.047 . 0 4 1 ±.082 4 8 . 3 k p h A E SD C E SD . 1 3 3 ±.044 . 1 3 3 ±.044 . 1 7 5 ±.074 . 1 7 1 ±.079 . 2 2 5 ±.074 . 2 2 3 ±.083 . 1 2 9 ±.050 . 1 2 9 ±.050 121 need. An a n a l y s i s of v a r i a n c e performed on the AE s c o r e s demonstrated t h a t , averaged between groups and over t r i a l s , 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 between the AE s c o r e s r e c o r d e d and s t i m u l u s speed, F ( 1 , 92.86)=0.000, £<.01. In f a c t , t h i s was a l i n e a r r e l a t i o n s h i p such t h a t , as the speed i n c r e a s e d , so d i d the degree by which Ss d i f f e r e d from the i d e a l response s c o r e of 0.000 msec. The ANOVA can be summarized as f o l l o w s : 1. 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 i n s c o r e s f o r t r i a l s a t each speed when averaged between groups. T h i s i s i m p o r t a n t s i n c e the e l i m i n a t i o n of s c o r e s d u r i n g the l e a r n i n g p e r i o d was d e s i g n e d t o e l i m i n a t e v a r i a t i o n s i n s c o r e s between t r i a l s ; 2. t h e r e was no s i g n i f i c a n t Speed by T r i a l s i n t e r a c t i o n when averaged over the f o u r s k i l l l e v e l s , nor was t h e r e a s i g n i f i c a n t three-way Speed by T r i a l s by Groups i n t e r a c t i o n ; 3. t h e r e was a s i g n i f i c a n t Groups e f f e c t , F ( 3 , 6.24)=0.002, p_<.05; and 4. f o r a l l s k i l l l e v e l s , 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 i n v a l u e s o b t a i n e d f o r each speed of s t i m u l u s p r e s e n t a t i o n , F ( 2 , 94 . 00 ) =0 . 000 , p_<.01. The a n a l y s i s of v a r i a n c e performed on the CE s c o r e s p r e s e n t e d a s i m i l a r p o r t r a i t of i n t e r a c t i o n s . In summary, the r e s u l t s show a d i f f e r e n c e i n the a n t i c i p a t o r y a b i l i t i e s of the f o u r groups t o p r e d i c t and 122 c o i n c i d e a response w i t h the a r r i v a l of a s t i m u l u s randomly p r e s e n t e d a t t h r e e d i f f e r e n t speeds. However, t h e r e a re a number of s u g g e s t i o n s t o e x p l a i n t h e s e d i f f e r e n c e s . For example, the c o n t r o l group c o n s i s t e d of many f i r s t - c l a s s a t h l e t e s from o t h e r s p o r t s and a n t i c i p a t o r y a b i l i t y may be a q u a l i t y a c q u i r e d over time or independent of a s p e c i f i c s p o r t . One must a l s o c o n s i d e r the t e c h n i c a l e x p e r t i s e demonstrated i n the s k i l l r e q u i r e d t o s t r i k e the b a l l . A l t h o u g h a l l of the s u b j e c t s were r e q u e s t e d t o " d r i v e " the b a l l o f f of the p l a t f o r m , the c o n t r o l group and many of the h i g h s c h o o l s u b j e c t s were unable t o d e l i v e r a swing which imp a r t e d much f o r c e t o the b a l l . The r e s u l t was t h a t , o f t e n , the b a l l b a r e l y t r i c k l e d o f f of the p l a t f o r m w h i l e the t i m e r r e g i s t e r e d a low VE or CE. In o t h e r words, a c r i t e r i o n of su c c e s s i n a game s i t u a t i o n would make a d i f f e r e n c e i n which of the t r i a l s would be a c c e p t a b l e as f u l f i l l i n g the s t r o k e r e q u i r e m e n t s . Study I I I was d e s i g n e d t o impose such r e s t r i c t i o n s . Study I I I In o r d e r t o e l i m i n a t e t h e s e problems of t e c h n i c a l adequacy i n response performance p r e s e n t i n Study I I , a t h i r d s t u d y was c o n d u c t e d . Method S u b j e c t s : The t e s t group c o n s i s t e d of 15 female and 21 male u n i v e r s i t y s t u d e n t s who were randomly s e l e c t e d from the e n r o l l m e n t of P h y s i c a l E d u c a t i o n 468 (Term 2 ) . 123 A p p a r a t u s and P r o c e d u r e : The a p p a r a t u s was the same as t h a t employed i n Study I I . The o n l y a d d i t i o n was t h a t Ss were i n s t r u c t e d t o respond such t h a t t h e b a l l was d r i v e n t o a t a r g e t mat (1.0 by 0.5 m) which was p l a c e d a g a i n s t a w a l l 5m to the s u b j e c t ' s l e f t . R e s u l t s and C o n c l u s i o n s The f i r s t q u e s t i o n which needed t o be answered was the e f f e c t of m o d i f y i n g the response upon c o i n c i d e n t t i m i n g . I n i t i a l a n a l y s i s by Sex shows a s u p e r i o r i t y by males over female s u b j e c t s f o r AE a t a l l s t i m u l u s speeds, and an o p p o s i t e e f f e c t upon the s t a n d a r d d e v i a t i o n s (see T a b l e D). The SD d e c r e a s e d as speed i n c r e a s e d f o r males, w h i l e SD i n c r e a s e d w i t h speed f o r f e m a l e s . Such i s not the r e s u l t when CE i s examined (see Ta b l e E ) . Females f a r e d b e t t e r a t the sl o w e r speed, and both groups showed an i n c r e a s e i n SD as the speed i n c r e a s e d . In o r d e r t o compare the e f f e c t s of imposing a t a r g e t a c q u i s i t i o n component t o the t a s k r e s p o n s e , the r e s u l t s of the c o n t r o l group (n=10) of Study I I were compared t o the females of Study I I I (n=15) f o r a Randomized Groups d e s i g n . The r e s u l t s showed t h a t the a d d i t i o n of the t a r g e t c o n s t r a i n t produced a f u r t h e r margin of e r r o r i n c o i n c i d e n c e (see Ta b l e F ) . Study IV Method S u b j e c t s : An e l i t e f i e l d hockey p l a y e r (DS)who was a l s o a 124 T a b l e D Ta r g e t A c q u i s i t i o n - Mean A b s o l u t e E r r o r (msec) SPEED kph 24. 1 32.2 48.3 MALES MEAN SD 0.076 ±0.056 0.070 ±0.053 0.138 ±0.045 FEMALES MEAN SD 0.082 ±0.055 0.122 ±0.067 0.232 ±0.073 125 Table E Target Acquisition - Mean Constant Error (msec) SPEED MALES FEMALES kph MEAN SD MEAN SD 24.1 0.032 ±0.029 0.029 ±0.091 32.2 0.053 ±0.108 0.108 ±0.091 48.3 0.138 ±0.208 0.208 ±0.130 126 Table F Mean Absolute Error and Constant Error (msec) as a Function of Stimulus Speed and Target Acquisition SPEED FEMALE TARGET GROUP CONTROL - NO TARGET kph AE SD CE SD AE SD CE SD 24.1 0.082 ±0.055 0.029 ±0.091 0.085 ±0.069 -0.010 ±0.104 32.2 0.122 ±0.067 0.108 ±0.091 0.073 ±0.047 0.021 ±0.082 48.3 0.232 ±0.073 0.208 ±0.130 0.129 ±0.050 0.129 ±0.050 127 member of the Canadian National F i e l d Hockey Squad was selected for p a r t i c i p a t i o n in a kinematic analysis of stroke performance within an e c o l o g i c a l l y v a l i d construct. Apparatus and Procedure: Study IV was designed as a preliminary study to develop an appropriate design and procedure for use in the main study. A detailed description of the apparatus and procedure is included in the body of the main study. A 16mm LOCAM cine camera (100 fps) was used to record each test t r i a l . Five data points were registered on the subject (Left toe, Left knee, Left elbow, Left wrist, and Stickend). The horizontal and v e r t i c a l coordinates of each data point were d i g i t i z e d in a frame-by-frame manner and a kinematic analysis was run on each location. R e s u l t s and C o n c l u s i o n s On the basis of the preliminary results i t was determined that s u f f i c i e n t information about the dependent kinematic variables could be obtained at a fi l m speed of 50 fps. Rather than analyzing these data points independently, a composite record of the Left wrist and Stickend ("Sticksegment") provided s u f f i c i e n t kinematic information about the l e v e l of inter-response consistency within the various movement parameters to warrant elimination of the other three anatomical data points. The information produced as a result of this preliminary kinematic analysis was u t i l i z e d to: 1. determine the appropriate and r e a l i s t i c b a l l stimulus speeds for an e l i t e performer's successful response; 128 2. determine fi l m speed adequate for accurate recording of recording kinematic information from the high speed b a l l i s t i c response; 3. determine the appropriate anatomical and sti c k reference points for kinematic analysis; and 4. determine the phases or "response units" of the f i e l d hockey drive. This subject responded with a biphasic movement which was then divided into three phases based upon the kinematic observation of concentric and eccentric mucle contractions. The procedure for this c l a s s i f i c a t i o n i s discussed in the text of the main study. 129 APPENDIX D 130 APPARATUS DESIGN A n t h r o p o m e t r i c Data Sheet S u b j e c t : H.O. Date: F e b r u a r y , 1982. Sex: Female. B i r t h d a t e : M a y 23, 1963. Age: 18 y e a r s . Weight ( c l o t h e d ) : 59.09 kg. H e i g h t ( i n s h o e s ) : 160 cm. 1) L e f t toe t o ground=3.5 cm. 2) L e f t knee t o ground=44.0 cm. 3) L e f t elbow t o l e f t w rist=23.0 cm. 4) L e f t w r i s t t o s t i c k marker= 60.0 cm. 5) S t i c k length= 92 cm. 6) S t i c k end ( p r o x i m a l ) t o s t i c k marker: 69.0 cm. 7) S t i c k weight= 2.48 g. 131 F i l m Data Sheet Camera: LOCAM Frame r a t e 50 frames/second C a l i b r a t e d S h u t t e r f a c t o r 2 Exposure time 1/100 second Lens: Type=Pancinor f - R a t i o = f / 4 F i l t e r s = S k y l i g h t F i l m : Type=VNX 449-7250, C o l o u r ASA=400 S c a l e : W a l l Grid=5 rows; 4 columns H o r i z o n t a l d i s t a n c e between p o i n t s = 50 cm. V e r t i c a l d i s t a n c e between p o i n t s = 50 cm. Board Grid=6 rows; 6 columns H o r i z o n t a l d i s t a n c e between points=25 cm. V e r t i c a l d i s t a n c e between points=25 cm. Di s t a n c e s : F i l m p l a n e t o w a l l g r i d = 966 cm F i l m p l a n e t o board g r i d = 735 cm. S c a l e t o f i r s t movement plane=231 cm. ( i . e . , W a l l g r i d ) Camera t o Subject=735 cm. (L1R1 marker) B a l l machine t o w h i t e tape= 1000 cm. L2 t o t a r g e t 500 cm L1R1 t o w a l l g r i d = 231 cm Ta r g e t dimensions= 180 cm. h e i g h t X 270 cm. w i d t h 13 7\ Ball Machine (see inset) Direction 16mm LOCAM VTR O Lights White tape Target Mat Wall Grid MNW 115-Mitchell and Ness Field Hockey Machine gure I.: Equipment and Apparatus. 133 APPENDIX E 134 DESCRIPTION OF THE TASK:THE DRIVE The d r i v e , as d e f i n e d by H o r s t Wein (1973), i n c l u d e s t h e f o l l o w i n g components ( r e f e r t o F i g u r e J ) : 1. The p l a y e r adopts a s i d e - o n p o s i t i o n t o the d i r e c t i o n i n which the b a l l i s t o be h i t , the l e f t s h o u l d e r p o i n t i n g i n t h a t d i r e c t i o n ; 2. Assuming a s i d e - o n p o s i t i o n , the t o e s do not p o i n t i n the d i r e c t i o n of the i n t e n d e d h i t . R a t h e r , the t o e s p o i n t f o rwards i n the same d i r e c t i o n as the body; 3. At the moment of impact, the b a l l s h o u l d be a t a c o m f o r t a b l e d i s t a n c e from the body, at a p o i n t between a l i n e drawn t h r o u g h the c e n t r e of the body and the l e f t f o o t ; 4. GRIP: t o impart power t o the h i t , both hands must be t o g e t h e r on the s t i c k , one below the o t h e r , such t h a t the i n d e x - f i n g e r of the upper or l e f t hand s h o u l d almost touch the l i t t l e f i n g e r of the r i g h t or lower hand. European p l a y e r s g e n e r a l l y h o l d b oth hands a t the upper end of the s t i c k , w h i l e A s i a n p l a y e r s l e a v e a p p r o x i m a t e l y 4 i n c h e s of the upper handle f r e e ; 5. BACKSWING: at the f i n a l p o i n t of the b a ckswing, the s t i c k i s h e l d as i f i t were an e x t e n s i o n from the r i g h t s h o u l d e r , so t h a t the t i p p o i n t s upwards; a t the f i n a l p o i n t of the backswing, the s t i c k h e a d s h o u l d be h i g h e r than the g r i p of t h e upper hand. Both w r i s t s are h e l d f i r m s i n c e the a c t i o n of the w r i s t s i s not as i m p o r t a n t 136 as the s t r e n g t h of the arms and upper p a r t of the body. D u r i n g the backswing, the r i g h t arm i s s l i g h t l y b e nt, i n c o n t r a s t t o the l e f t . The upper arm and lower arm form an a n g l e a p p r o a c h i n g 120 d e g r e e s . The backswing and e n s u i n g downswing must b o t h be made i n the v e r t i c a l p l a n e and, a t the f i n a l s t a g e of the b a c k s w i n g , the whole weight must be s h i f t e d onto the r i g h t , or r e a r , f o o t ; THE HIT: the h i t commences w i t h a s h i f t of weight from the r i g h t , or r e a r f o o t , on t o the l e f t , or f r o n t , f o o t . At the a c t u a l moment of c o n t a c t , both arms a r e o u t s t r e t c h e d , the r i g h t , however, more so than the l e f t . A moving b a l l , a t the moment of c o n t a c t , s h o u l d be i n the m i d d l e of the p l a y e r ' s f i e l d of v i s i o n . A c c u r a c y of d i r e c t i o n cannot be a c h i e v e d o n l y by a c l e a n , s t r a i g h t downswing, but the s t r o k e must c o n t i n u e a f t e r the moment of impact. To a v o i d g i v i n g s t i c k s t o the f r o n t , the l a s t s t a ge of the h i t i s the c h e c k i n g of t h i s f o l l o w t h r o u g h ; The FORCE of the H i t : a. the f o r c e w i t h which the b a l l i s s t r u c k i n c r e a s e s i n p r o p o r t i o n t o the speed a t which the p l a y e r h i m s e l f approaches the b a l l f o r the h i t ; b. the f u r t h e r back the swing i n i t i a t e s the g r e a t e r the a c c e l e r a t i o n which can be g i v e n t o the s t i c k . T h i s a c c e l e r a t i o n must be such t h a t the s t i c k reaches maximum speed a t the moment of impact w i t h the b a l l ; c. a t the moment of impact, a l l of the muscles i n v o l v e d 137 i n the movement of the downswing must be f u l l y t e n s e d f o r a h a r d h i t t o r e s u l t ; d. c o n s i d e r a b l e e x t r a f o r c e can be i m p a r t e d t o the b a l l by a f i r s t - t i m e shot a t g o a l and i f the b a l l i s coming from the r i g h t . The g r e a t e r the speed of the a p p r o a c h i n g b a l l , the g r e a t e r i s the f o r c e of the impact between s t i c k and b a l l and, c o n s e q u e n t l y , the harder the shot becomes, (pp. 57-70) There were no r e f e r e n c e s c i t e d by Wein t o su p p o r t of h i s c l a i m s f o r the s u p e r i o r i t y of t h i s t e c h n i q u e . H i s c r e d e n t i a l s as a w o r l d - a c c l a i m e d p l a y e r and coach have p r o v i d e d a b a s i s f o r the g e n e r a l a c c e p t a n c e of h i s i n t u i t i v e s t a t e m e n t s . In f a c t , t h i s s t u d y c o n s i d e r e d the v a l i d i t y of many of Wein's st a t e m e n t s i n terms of a b i o m e c h a n i c a l and motor s k i l l paradigm. An a n a l y s i s of a motor s k i l l i n terms of the muscle groups which a f f e c t the l i m b ( s ) i s e s s e n t i a l p r i o r t o embarking upon the e x a m i n a t i o n of the k i n e m a t i c f e a t u r e s of a complex movement. A c o n t r o l l e d and a c c u r a t e movement i s p o s s i b l e o n l y as a r e s u l t of the a p p r o p r i a t e l y timed and phased c o n t r a c t i o n and r e l a x a t i o n of s y n e r g i s t i c m u s c l e s . When the a g o n i s t i c muscles c o n t r a c t t o produce a c o n c e n t r i c movement, the a n t a g o n i s t s must be s u f f i c i e n t l y r e l a x e d t o p e r m i t j o i n t movement thro u g h o u t the i n t e n d e d range of motion . The a g o n i s t s commence f i r i n g as the extremes of t h i s range a r e neared thus e x e r t i n g an e c c e n t r i c f o r c e i n o r d e r 138 to retard/decelerate the angular v e l o c i t y produced on the joint by the agonists. A kinematic analysis of the timing of the contraction and relaxation phases i s possible once one understands the muscle a c t i v i t y e ssential for the performance of a p a r t i c u l a r complex motor s k i l l . The muscle forces necessary to produce a f i e l d hockey drive, as described by Horst Wein, may be compared to those involved in the throw of a discus. In both s k i l l s , the leg, hip, trunk and arm muscles f i r e sequentially to impart enough momentum to propel the implement. Evidence for the view that the learning of a motor s k i l l involves a reduction of the degrees of freedom permitted permitted in the wrist, elbow, shoulder, and f i n a l l y trunk movement has been presented by Tyldesley (Note 3). This view summarizes the be l i e f that as the s k i l l l e v e l of a performer increases, those muscles which contract e a r l i e s t in a movement sequence may contract again, and therefore exhibit a large i n t e r - t r i a l variance, but those which f i r e l a t e s t in the s k i l l produce consistent response measures. A subject operating at a high l e v e l of performance tends to display a high degree of i n t e r - t r i a l v a r i a b i l i t y in response measures recorded for the leg, hip and trunk mscles. One may infer that correction for performance error i s more l i k e l y to occr through these muscles. As a result Tyldsley's work, th i s study was limited to an analysis of the more invariant properties of wrist and s t i c k . Data records were limited to these two variables and their displacement values recorded 139 during the swing. The drive was i n i t i a l l y divided into two displacement phases. The f i r s t was defined as a Backswing, and was followed temporally by the second phase, the Downswing. This i n i t i a l movement consisted of abduction of the right arm and stick in a v e r t i c a l d i r e c t i o n . As the stick commenced i t s upward movement, the concentric a c t i v i t y of the right supraspinatus, right deltoid, right biceps, and l a t e r a l rotator muscles of the right shoulder (infraspinatus; teres minor) were responsible for thi s action. S i m i l a r l y , the l e f t arm muscle group worked in the reverse action such the l e f t adductors f i r e d simultaneously with the right abductors in the Backswing phase. As the stick neared the extreme range of i t s backswing at a position close to shoulder l e v e l , the eccentric contraction of the antagonistic muscles of the shoulder joint (triceps, subscapularis, p e c t o r a l i s major and minor, and latissimus d o r s i , teres major) and the medial rotators of the shoulder (rhomboids, levator scapula), functioned to decelerate the st i c k ' s movement. Once the stickend v e l o c i t y decreased to zero (radians/sec) the eccentric muscles exerted a concentric influence adduct the right arm (abduct the l e f t arm) during the Downswing to b a l l contact. 140 APPENDIX F 141 T a b l e G Randomized Speed P r e s e n t a t i o n as D e l i v e r e d by B a l l Machine TRIAL NUMBERS BALL NUMBE 1 31 61 86 40 2 32 62 30 3 33 63 20 4 34 64 40 5 35 65 40 6 36 66 20 7 37 67 30 8 38 68 20 9 39 69 40 10 40 70 40 1 1 41 71 20 12 42 72 30 13 43 73 40 14 44 74 40 15 45 75 30 16 46 7 6 20 17 47 77 20 18 48 78 40 19 49 79 20 20 50 80 30 21 51 81 20 22 52 82 20 23 53 83 30 24 54 84 40 25 55 85 40 26 56 30 27 57 30 28 58 20 29 59 30 30 60 30 Table H Kinematics of the Stick Segment using F i n i t e Difference after D i g i t a l F i l t e r i n g (Blocked) Time BLOCKED 20 m.p.h. BLOCKED (sec.) THETA OMEGA ALPHA THETA (deg.) ( " i e c ) ( " d s e c 2 ) (deg.) 0.00 195.06 1.283 0.551 180.06 0.02 196.54 1.284 -0.780 181.53 0.04 198.01 1.252 -2.434 182.95 0.06 199.41 1.186 -3.627 184.09 0.08 200.73 1.107 -3.933 184.71 0. 10 201.95 1.029 -4.059 184.55 0. 12 203.08 0.945 -4.613 183.35 0.14 204.11 0.845 -5.268 180.88 0.16 205.02 0. 734 -5.654 177.03 0. 18 205.80 0.619 -6.264 171.82 0. 20 206 .44 0.484 -7. 782 165.36 0.22 206.90 0. 307 -9.896 157.81 0. 24 207.14 0.088 -11.758 149.43 0. 26 207.11 -0.163 -13.731 140.52 0.28 206.77 -0.462 -17.460 131.36 0. 30 206.05 -0.861 -23.747 122.19 0. 32 204.79 -1.411 -31.516 113.24 0. 34 202.81 -2.122 -39.026 104.76 0. 36 199.93 -2.972 -45.2 39 97.02 0. 38 196.00 -3.932 -50.027 90. 30 0.40 190.92 -4.974 -53.103 84.79 0.42 184.60 -6.056 -52.781 80.68 0.44 177.04 -7.085 -4 7.455 78.27 0.46 168.36 -7.954 -37.774 78.11 0. 48 158.81 -8.596 -25.108 80.94 0.50 148.66 -8.958 -10.458 37.57 0.52 138.28 -9.014 3.079 98.54 0.54 128.01 -8.835 12.187 113.88 0.56 118.03 -8.527 18.924 132.90 0.58 108.46 -8.078 28.712 ' 154.96 0.60 99.52 -7.378 42.826 180.84 0.62 91.55 -6.365 57.719 212.57 0.64 84.9 3 -5.070 72.033 248.65 0.66 79.93 -3.484 90.172 281.10 0.68 76.95 -1.463 116.817 0. 70 76. 5£ 1.189 150.767 0. 72 79.6" 4 .568 184.34 7 0. 74 87. o: 8. 563 204.555 0. 76 99.2C 12.75C 200.227 0. 78 116.2 16.572 180.014 0.80 137.2 ? 19.951 174.626 0.82 162.0( ) 23.55 190.02 0.84 191.2 3 27.55 146.64< 0.86 225.1 . 29.42 -25.55 0.88 258.6 3 26.52 ) -212.39 3 0.90 285.9 4 20.92 J -257.27 3 (rad/ . sec) (rad/ 2, sec ) BLOCKED 40 m.p.h. THETA (deg.) OMEGA (rad/ . sec) ALPHA (rad/ 2. sec ) 1.235 1.261 1.120 0.769 0.200 .595 .602 755 .952 .094 115 -6.950 -7.543 -7:884 -8.000 -7.908 -7.605 -7.075 -6.309] 335 196 847 124 166 127 6791 11.481 14.990 17.926 20.920] 25.138 29.584 29.9001 25.086 3.526 -2.895 -12.288 -22.996 -34.118 -45.034 -53.998 -58.752 -53.462 -54.078 -46.411 -35.694 -23.335 -11.430 -0.602 9.866 20.816 32.412 43.490 52.813 62.222 76.805 100.322 131.277 162.820 183.849 182.775 161.109 148.245 180.304 216.611 119.059 -112.468 -254.670 174.36 175.24 175.94 176.24 176.04 175.30 173.94 171.81 168.79 164.76 159.62 153.36 146.15 138.29 130.10 121.89 113.96 106.50 99.70 93.74 88.82 85.17 83.15 83. 29 86. 31 93.04 104.26 120.41 141.20 165.93 194.83 228.58 263.36 292.97 0. 716 0.688 0.437 0.041 -0.408 -0.912 -1.522 -2.251 -3.080 -3.999 -4.971 -5.876 -6.577 -7.005 -7.155 -7.044 -6.716 -6. -5 . -4. -3. . 219 .568 .751 .743 -2.4.74 -0.818 1.381 4.254 7.834 11.943 16.118 19.863 23.399 27.336 29.903 28.092 23.397 3.345 -6.967 -16.165 -21.132 -23.843 -27.851 -33.465 -38.935 -4 3. 705 -47.271 -46.914 -40.158 -28.229 -14.442 -0.967 10.978 20.626 28.697 36.686 45.628 56.936 73.117 96.364 126.800 161.316 192.211 207.108 198.010 182.027 186.821 162.597 18.908 -162.647 -205.705 Table I Kinematics of the Stick Segment using F i n i t e Difference after. D i g i t a l F i l t e r i n g (Random) Time Random 20 m.p h. Random 30 m.p.h Random 40 m.p.h. (sec.) THETA OMEGA ALPHA THETA OMEGA ALPHA THETA OMEGA ALPHA (deg.) ( r a i e c ) (rad/ 2 sec ) (deg.) (rad/ , sec) (rad/ 2, sec ) (deg.) ( " s i ) (rad/ 2 sec ) 0.00 177.30 0.564 0.04 5 169.23 1.081 0.461 170.04 . 1. 205 2.426 0.02 177.95 0.534 -3.084 170.48 1.016 -7.412 171.46 1. 218 -4.08 3 0.04 178.53 0.441 -5.518 171.56 0. 784 -15.18.0 172.83 1. 042 -16.330 0.06 178.96 0. 313 -5.920 172.27 0.409 -20.554 173.85 0. 565 -32.203 0. 08 179.24 0. 204 -3.670 172.49 -0.038 -22.773 174.13 -0 . 247 -4 7.244 0.10 179.43 0.167 0.024 172.19 -0.502 -24.216 173.29 - 1 . 325 -57.085 0. 12 179.63 0.205 2.293 171.34 -1.006 -27.465 171.09 -2. 530 -59.165 0.14 179.90 0.258 1.105 169.88 -1.600 -31.444 167.49 -3. 691 -52.683 0.16 180.22 0.249 -2.533 167.68 -2.264 -32.895 162.63 -4. 6 37 -38. 879 0.18 180.47 0.157 -6.120 164.69 -2.916 -30.064 156.86 -5 247 -21.231 0. 20 180.58 0.005 -9.087 160.99 -3.467 -23.305 150.61 -5 486 -3.457 0. 22 180.48 -0.207 -13.382 156.75 -3.848 -14.610 144.29 -5 385 12,4 72 0. 24 180.10 -0.531 -20.978 152.17 -4.051 -7.100 138.27 -4 988 25.8 73 0. 26 179.27 -1.046 -31.449 147.46 -4.132 -3.249 132.86 -4 350 36. 27.7 0.28 177.71 -1.789 -41.572 142.70 -4.181 -3.798 128.30 -3 583 4-3-7 34 0. 30 175.17 -2.709 -47.718 137.88 -4.284 -7.792 124.75 -2 601 50.452 0. 32 171.50 -3.698 -49.370 132.88 -4.493 -12.535 122.34 -1 520 59.422 0. 34 166.69 -4.683 -49.047 127.58 -4. 786 -14.823 121.26 -0 224 71.956 86.967 0. 36 160.77 -5.659 -4 7.905 121.92 -5.086 -12.888 121.82 1 358 0. 38 153.72 -6.600 -43.460 115.93 -5.301 -7.018 124.37 3.255 103.368 0. 40 145.64 -7.398 -33.556 109.77 -5.366 1.181 129.28 5 493 120.601 0.42 0. 44 136.77 127.44 -7.942 -8.192 -19.851 -5.428 103.63 97.72 -3.254 -4.959 10.192 19.243 136.96 147.80 8 11 .079 .027 138.367 162.059 0.46 117.99 -8.159 7.950 92.26 -4.484 27.945 162.23 14 .561 203.836 0. 48 108.74 -7.874 19.194 87.45 -3.841 37.226 181.17 19 .181 245.141 0. 50 99.95 -7. 391 27.735 83.46 -2.995 50.563 206.19 24 .367 187.103 0.52 91.80 -6.765 34.594 80. 58 -1.818 71.404 237.02 26 .665 -13.864 0. 54 84.44 -6.007 42.007 79. 29 -0.139 99.692 267.31 23 .813 -188.831 0. 56 78.03 -5.084 51.861 80.26 2.169 133.136 291.59 19 .112 -190.954 0. 58 72.79 -3.933 64.972 84 .26 5.186 167.619 0.60 69.02 -2.485 82.202 92.15 8.954 203.871 0.62 67. 10 -0.645 105.375 104.79 13.341 220.579 0. 64 6 7.54 1. 730 136.133 122.73 17.777 200.860 0.66 71.06 4 .800 174.471 145.53 21.376 150.924 0. 68 78.54 8.709 214.512 171.71 23.814 102.201 0. 70 91.02 13. 381 234.127 200.11 25.464 55.553 0. 72 109.21 18.074 204.910 230.07 26.036 -20.099 0. 74 132.44 21.577 144.591 259.78 24.66C -110.207 0. 76 158.66 23.857 120.513 286.59 21.628 -160.067 0.78 187.12 26.398 123.752 0.80 219 .16 28.807 33.444 0.82 253.14 2 7.7 36 -14 7.204 0.84 282.73 22.919 -244.513 144 T a b l e J A n a l y s i s of V a r i a n c e of the S t i c k L o c a t i o n (degrees) a t the I n i t i a l Frame of Each S t r o k e Phase Phase Source df MS E1 Order (0) 1 1309.00 Speed (S) 2 764.00 0 x S 2 627.50 E r r o r w i t h i n 54 51 .09 C1 Order (0) 1 1383.00 Speed (S) 2 1672.00 0 x S 2 778.50 E r r o r w i t h i n 54 39.56 E2 Order (0) 1 125.00 Speed (S) 2 106.00 0 x S 2 832.00 E r r o r w i t h i n 54 47.54 C2 Order (0) 1 96.06 Speed (S) 2 2508.94 0 x S 2 1209.91 E r r o r w i t h i n 54 67.66 25.62** 14.95** 12.28** 34.96** 42.27** 19.68** 2.63 2.23 17.50** 1 .42 37.08** 17.88** *p<.05 **£<.01 145 Tab l e K Mean D i s p l a c e m e n t of S t i c k Segment (degrees) D u r i n g Each S t r o k e Phase E1 C1 E2 PHASE B l o c k e d Random B l o c k e d Random B l o c k e d Random C2 20 m.p.h. MEAN SD 9.66 8.05 61 .54 52.22 62. 1 1 57.67 B l o c k e d 197.09 Random 209.60 ±4.05 ±9.96 ±6.40 ±10.55 ±5.84 ±10.36 30 m.p.h. MEAN SD 4.91 3.63 45.02 45.93 53.29 50.43 ±3.23 ±2.94 ±5.75 ±6.62 ±4.65 ±6.99 ±12.26 197.37 ±6.30 ±6.05 190.45 ±16.17 40 m.p.h. MEAN SD 2.04 ±1.47 4.12 ±2.94 40.50 ±7.07 28.73 ±6.82 46.30 ±6.39 37.37 ±9.47 193.91 ±13.28 17-3.89 ±15.44 146 Table L A n a l y s i s of V a r i a n c e of Mean S t i c k D i s p l a c e m e n t (degrees) D u r i n g Each S t r o k e Phase tase Source df MS F E1 Order (0) 1 1 .08 .83 Speed (S) 2 189.96 .00** E r r o r between 56 24.13 0 x S 2 20.81 .43 E r r o r w i t h i n 54 24.26 C1 Order (0) 1 678.50 12.50** Speed (S) 2 2479.59 45.68** 0 x S 2 226.06 4.16* E r r o r w i t h i n 54 54.28 E2 Order (0) 1 438.65 7.72** Speed (S) 2 1636.15 28.80** E r r o r between 56 56.81 0 x S 2 49.47 .87 E r r o r w i t h i n 54 57.08 C2 Order (0) 1 349.00 2.32 Speed (S) 2 1892.50 12.58** 0 x S 2 1337.50 8 .89** E r r o r w i t h i n 54 150.46 *p_< .05 **p_<. 01 147 T a b l e M A n a l y s i s of V a r i a n c e of the D u r a t i o n (msec) of the Four S t r o k e Phases Phase Source df MS E1 Order (0) 1 .015 Speed (S) 2 .111 E r r o r between 56 .004 0 x S 2 .011 E r r o r w i t h i n 54 .004 C1 Order (0) 1 .0004 Speed (S) 2 .040 E r r o r between 56 . 002 0 x S 2 .005 E r r o r w i t h i n 54 .002 E2 Order (0) 1 .001 Speed (S) 2 .007 0 x S 2 .004 E r r o r w i t h i n 54 .001 C2 Order (0) 1 .00003 Speed (S) 2 .0007 0 x S 2 .00009 E r r o r w i t h i n 54 3.36 25.23** 2.53 .22 20.79** 2.95 .90 6.09** 3.89* .28 .28 7 .86** *g<. 05 **p<. 0 1 148 T a b l e N A n a l y s i s of V a r i a n c e of the Peak V e l o c i t y ( r a d / s e c ) of the S t i c k e n d D u r i n g each S t r o k e Phase Phase Source df MS F I Order (0) 1 .09 1 .05 Speed (S) 2 .13 1 .43 0 x S 2 .43 4 .82* E r r o r w i t h i n 54 .09 I I Order (0) 1 9.82 26 .31** Speed (S) 2 10.47 28 .06** 0 x S 2 1 .44 3 .85* E r r o r w i t h i n 54 .37 B a l l Order (0) 1 .24 .28 C o n t a c t Speed (S) 2 .05 .06 E r r o r between 56 .85 0 x S 2 .64 .75 E r r o r w i t h i n 54 .85 *p<.05 **£< • 0 1 149 Figure K: Mean grid location of stickend (degrees) at the frame of i n i t i a t i o n of E1 and C1 stroke phases. 150 Figure L: Mean grid location of stickend (degrees) at the frame of i n i t i a t i o n of E2 and C2 stroke phases. 151 Legend A B20 X B30 • B40 • -T r — 1 I 1 1 1 1 -10 15 20 23 30 35 40 *5 Frame Number F i g u r e M: Frame-by-frame d i s p l a c e m e n t of the s t i c k segment (de g r e e s ) of the. r e p r e s e n t a t i v e B20, B30, B40 r e s p o n s e s . 152 -\ 1 1 1 1 1 1 1 1 1 1 0 5 K> IS 20 29 30 35 40 45 50 Frame Number F i g u r e N: Frame-by-frame d i s p l a c e m e n t of the s t i c k segment (de g r e e s ) of the r e p r e s e n t a t i v e R20, R30, R40 r e s p o n s e s . 153 T" 1 1 1 r 30 40 20 30 40 Ba l l Speed (m.p.h.) Figure 0: Mean displacement of the sti c k segment (degrees'} during E1 and C1 phases. B a l l Speed ( m . p . h . ) Figure P: Mean displacement of the stick segment (degrees) during E2 and C2 phases. 155 Phase I I o OJ </> •o s-4-> • I — o o cu -a cu 1.000 .900 1 .800 .700 .600 .500 i Phase I i 1 « r -20 30 40 20 ( -x— 30 40 Ball Speed (m.p.h.) 7.5 h 7.0 6.5 - 6.0 - 5.5 ' 5.0 ' 4.5 Legend — BIocked — Random Figure Q: Mean peak v e l o c i t y (rad/sec) of. the stickend during phases I and II of the stroke. 156 Figure R: Mean v e l o c i t y (rad/sec) of the stickend at b a l l contact. 157 T a b l e 0 Summary of S t a t i s t i c a l l y S i g n i f i c a n t R e s u l t s PHASE DEPENDENT VARIABLES MOVEMENT TIME DISPLACEMENT VELOCITY (Peak) INITIATION POINT E1 S c h e f f e Tukey's Speeds** 20*30** 20*40** Speeds** 20*30** 20*40* S x O* No s i g d i f f Speeds** Order** S x O** . B 2 0 * a l l * C1 S c h e f f e Tukey's Speeds** 20*30** 30*40** Speeds** Order** • S x 0* B20*B30 R30 B40 R40 R40*A11 Speeds** Order** S x O* B20*A11 R40*B20 R20 B30 R30 Speeds** Order** S x O** B2 0*A11 E2 S c h e f f e Tukey's Speeds** S x 0* R20*R40 Speeds** Order** 20*30 20*40 30*40 S x O** B20*R20 R40*R20 R30 C2 S c h e f f e Tukey's S x 0** No s i g d i f f Speeds** S x O** R40*B20 R20 B30 • B40 No s i g d i f f Speeds** S x 0** R40*A11 R20*B30 B40 R40 *p<.05 **p<.01 

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