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The effect of proprioceptive feedback and delay interval on timing motor responses Morrison, Winson Gilbert 1972

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c l THE EFFECT OF PROPRIOCEPTIVE FEEDBACK AND DELAY INTERVAL ON TIMING MOTOR RESPONSES by WINSON GILBERT MORRISON B.A. (Psychology), B.P.E., McMaster U n i v e r s i t y , 1970 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF PHYSICAL EDUCATION i n the School of P h y s i c a l Education and Rec r e a t i o n We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA December, 1972 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced d e g r e e at the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t the 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 a g r e e 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 p u r p o s e s may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It 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 not 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 The U n i v e r s i t y o f B r i t i s h C o l u m b i a V a n c o u v e r 8, Canada Date D ^ ^ . ^ J p n ^ h i ABSTRACT The problem was to ascertain the effect of proprioceptive feedback developed from an I n i t i a l movement; and the effect of time delay between the termination of the I n i t i a l movement and the beginning of the following motor response on the temporal accuracy and consistency of that response. Thirty male Ss were randomly assigned, three to each of the ten experimental conditions composed of two levels of proprioceptive feedback (small and large) and five levels of time delay (0.3, 0.6, 1.0, 2.0 and 4.0 seconds). In the minimal proprioceptive feedback condition, the proprio-ceptive feedback was manipulated in the right index finger of the S by the press-release of a response-button whereas i n the proprioceptive feed-back condition, i t was manipulated in the right arm of the S by a passively induced and consistent movement of that limb. Both, of these sources of proprioceptive feedback ended immediately prior to the beginning of the time delay interva l . It was the task of the S to l i f t his le f t index finger from the responsebutton after the delay interval under which he was timing had elapsed. Each S was given 50 t r i a l s with knowledge of results Chis exact response time in milliseconds) on each t r i a l and with an i n t e r t r i a l interval of 30 seconds. The results of the analyses showed the following: one, that the Ss learned to time the motor response within the f i r s t ten t r i a l s under the influence of knowledge of results ; two, that proprioceptive feedback had no effect on the accuracy and consistency of the timing of the motor i v response; and last, that tlie time delay interval had a highly significant effect on the accuracy and consistency of tfie^ timing of the motor response where the accuracy and consistency of the timing of the motor response appear to be similar power functions of the time delay interval. TABLE OF CONTENTS Page LIST OF TABLES . . . . . v i i i LIST OF FIGURES ix. Chapter 1. STATEMENT OF THE PROBLEM 1 Introduction . . 1 Purpose ^ Sub-problems 3 D e f i n i t i o n s 4 Proprioceptive Feedback (PFB) PFB Trace Delay I n t e r v a l (DI) . . . . Delimitations 4 Limitations . . 4 2. REVIEW OF THE LITERATURE 5 Introduction 5 The Realm of Time Perception 5 Experimental Methods i n Time Perception . . . . . . . 7 F i l l e d Versus U n f i l l e d Intervals . . 8 Methods of Time Perception . . 8 A n t i c i p a t i o n and Timing 10 Proprioception and Timing 12 Proprioception . 12 v i Chapter P a g e Role i n Timing 12 Decay Hypothesis 14 Theory 14 Pre d i c t i o n s 17 Evidence . 18 Other Mechanisms of Timing 20 Cognitive View 20 Pre-programming View . 21 Assumptions • 22 Hypotheses 23 3. PROCEDURE 25 Research Design and Methodology 25 Subjects 25 Experimental Design 25 Random Assignment of Subjects 25 Methodology 25 Apparatus 27 Delay I n t e r v a l 30 Tasks and Procedures 30 Experimental Conditions 31 Independent Variables 32 Dependent Variables 32 Data Analysis 33 S l i d e Time Analysis 33 Learning and C r i t e r i o n T r i a l s 33 Analysis of Within-S V a r i a b i l i t y and Absolute Error. 34 v i i Chapter Page Hypothesis 0-1 34 Hypothesis Q-\ 36 Hypothesis C3) . . . . . . . 36 Hypothesis (4) 36 4. RESULTS AND DISCUSSION 37 Slide Time Analysis 37 ANOVA on Slide Time 37 Slide Time Versus Accuracy and Consistency . . . . . 37 Slide Time Fixed 39 Learning and Criterion Trials . . . . 39 Analysis of Absolute Error and Within-S Var i a b i l i t y . . 50 Hypothesis (1) 50 Hypothesis (2) 54 Hypothesis (3) . 56 Hypothesis (4) . 56 Comment on Hypotheses 57 Effect of DI on Timing 67 5. SUMMARY AND CONCLUSIONS 69 Summary 69 Conclusions 70 REFERENCES 72 LIST OF TABLES Table Page 3.1 Experimental Design: A 2 x 5 x 50 Factorial Design with. Repeated Measures on the Last Factor 26 3.2 Planned Orthogonal Comparisons for Within-S Va r i a b i l i t y and Absolute Error for th.e DI Means under the PFB Condition 35 3.3 Planned Orthogonal Comparisons.for Withing-S Va r i a b i l i t y and Absolute Error for the Interaction Effect between PFB and DI . . . . . . . . . 35 4.1 A 2 x 5 x 50 Factorial Anova with Repeated Measures on the Last Factor for Slide Times 38 4.2 Planned Comparisons: A 2 x 5 x 50 Factorial Anova with Repeated Measures on the Last Factor for Absolute Error 51 4.3 Planned Comparisons: A 2 x 5 Factorial ANOVA on Within-S Variability 52 4.4 Cell and Marginal Means for Absolute Error under PFB and DI Conditions in Seconds 53 4.5 Cell and Marginal Means for Within-S Variability under PFB and DI Conditions in Seconds 53 4.6 ANOVA Tables for Linear, Log-linear and Log-log Least Squares Fits for Within-S Variability VS Delay Intervals . . . 60 4.7 ANOVA Tables for Linear, Log-linear and Log-log Least Squares Fits for Absolute Error. VS Delay Intervals 61 4.8 A 2 x 5 x 40 Factorial ANOVA with Repeated Measures on the Last Factor for Algebraic Error °4 4.9 Cell and Marginal Means for Algebraic Error under PFB and DI Conditions in Seconds.. 6 5 LIST OF FIGURES Figure Page 2.1 Sequence of Eypothetlcal Events for Decay Mechanism 15 3.1 Apparatus . . . 28 4.1 Plots of the Absolute Error over Trials and Blocks of 5 T r i a l s for the PFB-0.3 Second Condition 40 4.2 Plots of the Absolute Error over Trials and Blocks of 5 Trials for the mPFB-0.3 Second Condition 41 4.3 Plots of the Absolute Error over Trials and Blocks of 5 Trials for the PFB-0.6 Second Condition 42 •4 .4 Plots of the Absolute Error over Trials and Blocks of 5 Trials for the mPFB-0.6 Second Condition 43 4.5 Plots of the Absolute Error over Trials and Blocks of 5 Trials for the PFB-1.0 Second Condition 44 4.6 Plots of the Absolute Error over Trials and Blocks of 5 Trials for the mPFB-1.0 Second Condition . . . . . 45 4.7 Plots of the Absolute Error over Trials and Blocks of 5 Trials for the PFB-2.0 Second Condition 46 4.8 Plots of the Absolute Error over Trials and Blocks of 5 Trials for the mPFB-2.0 Second Condition 47 4.9 Plots of the Absolute Error over Trials and Blocks of 5 Trials for the PFB-4.Q Second Condition . . 48 4.10 Plots of the Absolute Error over Trials and Blocks of 5 Trials for the mPFB-4.0 Second Condition 49 X Figure Page 4.11 Within-S V a r i a b i l i t y f o r each S Against Time (Length of DI) i n Seconds, with Log-log Curve F i t 58 4.12 Mean Absolute Error f o r each S Against Time (Length of DI) i n Seconds, with Log-log Curve F i t 59 ' i 4.13 Plot of Algebraic Error Versus Time (Length of DI) i n Seconds f o r the PFB and mPFB Conditions 63 x i ACKNOWLEDGMENTS To the members of my t h e s i s committee, Dr. K.D. Coutta, Dr. W.G. Davenport, Dr. R.G. Martenluk and Dr. R.W. Schutz, I wish, to express my a p p r e c i a t i o n f o r t h e i r a s s i s t a n c e throughout the p r e p a r a t i o n of t h i s t h e s i s . A very s p e c i a l thanks i s due my Chairman, Dr. R.W. Schutz, f o r the guidance and encouragement he has shown me In the course of my s t u d i e s here. A l s o I wish to thank Mr. Ernst Tarnie f o r h e l p i n g me w i t h the p l o t programme USER:SUPERPLOT and Mr. E r i c Roy f o r a s s i s t a n c e when my s t a t i s t i -c a l background was shaky. F i n a l l y , I f e e l o b l i g e d to acknowledge the f i n e Programme L i b r a r y of the Computer Center a t the U n i v e r s i t y of B r i t i s h Columbia without which the data a n a l y s i s would not have been humanly p o s s i b l e . Chapter 1 STATEMENT OF THE PROBLEM Introduction When an individual develops co-ordination i n a specific motor s k i l l , he must not only learn to develop a uniquely and intricately patterned sequence of muscle fir i n g s , but he must also learn to time each of the component firings of the sequence. Since the individual components of a s k i l l are essential to the development of s k i l l e d motor behaviour, i t was the intention of this study to investigate various pre-dictions derived from the proprioceptive feedback (PFB) decay hypothesis of timing proposed and i n i t i a l l y tested by Adams and Creamer (1962b). At this point, i t would seem opportune to br i e f l y mention what a timing task involves since the study was concerned with the accurate timing of motor responses. A timing task involves the estimation of a temporal interval bound by a set of internal or external stimuli, and a method of determining the accuracy of the time estimation, once made. With respect to the role of PFB in the timing of motor responses, the i n i t i a l stimulus for an S to begin timing the set temporal interval i s the end of the i n t i a l movement producing the PFB. On the other hand, a cue, the effect of the PFB, is used at a time prior to the end of the set temporal interval as the terminal stimulus by which an S can trigger his motor-timing response making i t coincident with the end of the temporal Interval. The measurement of the set temporal interval's estimated length is then taken to be the time from the i n i t i a t i o n of the interval to the 1 2 completion of the S's later motor-timing response. Briefly, the Adams-Creamer decay hypothesis states that PFB from an i n i t i a l movement i s placed into memory—possibly short-term memory (STM)—where i t begins to decay predictably as a function of time. The predictable nature of the trace decay i s said to provide cues which trigger the second response appearing at a later time. Three testable predictions have been derived from this hypothesis. The f i r s t i s that the larger the i n i t i a l movement (in force or amplitude) the greater the rate of PFB trace decay, and consequently, the greater the timing accuracy of the motor-timing response at a later time since the a v a i l a b i l i t y of cues i s greater under greater rates of trace decay. The second i s that the accurate timing of the motor-timing response at a later time i s a function of the consistency (of force, amplitude and direction) of the i n i t i a l movement with the greatest timing accuracy occuring when the i n i t i a l movement i s as consistent as possible from t r i a l to t r i a l . The third is that with a given i n i t i a l movement, short intervals should be timed more accurately than longer ones, based on the assumption that the trace decay function i s exponential causing the avai l a b i l i t y of cues to decline with the passage of time. A corollary of the third i s that although shorter intervals may be timed more accurately with the PFB from an i n i t i a l movement than with no PFB (no i n i t i a l move-ment) , very long intervals should be timed no more accurately within either condition. This follows since the condition with the PFB from the I n i t i a l movement has the advantage of the cues from the trace decay which the condition without the PFB from the i n i t i a l movement does not have at shorter intervals; however, at very long intervals the cues from the trace decay provide no advantage for either condition since the cues 3 from the trace decay function decline with time. Purpose Since the Adams-Creamer decay hypothesis had been strongly supported by only Quesada and Schmidt (1970) and since Schmidt (1971) assumes that the PFB trace decays as some exponential or decreasing, negatively accelerated function of time in his derivation of two of the predictions from the Adams-Creamer decay hypothesis, i t seemed necessary, then, to check the c r e d i b i l i t y of both, the decay hypothesis and the assumption concerning the nature of the trace decay in STM. Consequently, i t was the purpose of this research to test the v a l i d i t y of the Adams-Creamer decay hypothesis and to look at the nature of the PFB trace in STM. Sub-problems (1) The f i r s t was to ascertain the relationship between the i n i t i a l amount of PFB placed i n STM and the accuracy of timing a later response under a given delay interval (the duration of the set temporal interval from the end of the i n i t i a l movement to a point in time when that duration has elapsed) in which the decay mechanism is functioning, where the decay mechanism i s the hypothetical PFB process through which cues are made available to an S for timing a later response. (2) The second was to ascertain the relationship between the length of the delay interval (DI) and the accuracy of timing a later response under a given i n i t i a l amount of PFB placed in STM. (3) The third was to ascertain the joint effect of the i n i t i a l amount of PFB placed In STM and the length of the DI on the accuracy of timing a later response. 4 (4) The l a s t was to i n d i r e c t l y a s c e r t a i n the nature of the function generated by the PFB trace decay i n STM. D e f i n i t i o n s Proprioceptive Feedback. (PFB). PFB i s the afference that enters the c e r e b r al cortex a f t e r a r i s i n g from those receptors found i n the deep muscles, tendons and j o i n t capsules which determine movements and p o s i t i o n s of body segments (Schmidt, 1971). PFB Trace. PFB trace i s a s e r i e s of c o r t i c a l neurons reverber-ating a f t e r an i n i t i a l stimulation by s p e c i f i c PFB such that the neuronal reverberation subsides through time (P.uch, 1951). Delay I n t e r v a l (DI). The DI i s the duration of the set timing i n t e r v a l from the end of an i n i t i a l movement to a point i n time when that duration has elapsed. ( i . e . , I f an S were to coincide h i s motor-timing response with the end of the set temporal i n t e r v a l , h i s time estimate would consequently coincide with the set temporal i n t e r v a l and the DI). Delimitations (1) Any conclusions drawn pertained to the range of the DIs and the l e v e l s of PFB used i n the experiment. (2) Any conclusions drawn pertained to the population denoted by a volunteer sample drawn from the ranks of students attending the U n i v e r s i t y of B r i t i s h Columbia. Limitations (1) The study was l i m i t e d by the accuracy of the experimental equipment involved and the co-operation of the Ss Involved. Chapter 2 REVIEW OF THE LITERATURE Introduction The co-ordination so inherent in s k i l l e d athletic behaviour depends on the precise timing of the sequential components of the s k i l l . If the timing of the components were to vary beyond a set tolerance, the s k i l l would disintegrate, becoming unco-ordinated as a whole (Schmidt, 1968; 1971). In this respect, Glencross (1971) has shown that the speed of cranking depends on the consistency of s e r i a l timing (the v a r i a b i l i t y in the temporal application of the force i n cranking) and that s k i l l e d Ss maintain the temporal sequence between the prime force peaks in a repetitive task better than unskilled Ss. The Realm of Time Perception In the past, psychology did not concern i t s e l f with the role of timing in motor behaviour; but rather concentrated on the psychological nature of time, especially In the area of time perception. The percep-tion of time defines the capacity of an individual to judge or perceive the passage of i t . The nature of time is an i l l u s i v e quantity, be i t physical or psychological. Some theorists have conceptualized time as mono-phasic, existing solely within i t s psychological context; however, others have conceptualized i t as dichotomous in nature exhibiting both, a physical (objective) and a psychological (subjective) component. 5 • 6 According to Weber (1933), both. Bergson (1910, 1911a, 1911b) and Sturt (1923) supported the mono-phasic view. Bergson rejected the conventional concept of time as d e f i n i t e and unchanging i n i t s r a t e of flow for one i n which, the rate of flow f l u c t u a t e s from one I n d i v i d u a l to another or from one s i t u a t i o n to another. Sturt followed Bergson's formulation very c l o s e l y i n e l i m i n a t i n g the p h y s i c a l aspect from the nature of time, however, adding that the concept of time immerges from i n d i v i d u a l and s o c i a l experience. On the other hand, the s u b j e c t i v e - o b j e c t i v e dichotomy of the nature of time has been propounded by Montague (1904); and by R u s s e l l (1915) and Troland (1929) as reported i n Weber (1933). Montague argued that without the consciousness of an extended segment of time n e i t h e r the duration nor succession of events could be perceived. Metaphysical or conceptual time Is viewed as a point separating the past and the future; consequently, psychological time, extending w e l l i n t o the past, must be an i l l u s i o n . In t h i s concept, the psychological time (though perhaps an i l l u s i o n as aforementioned) i s held to l o o s e l y p a r a l l e l p h y s i c a l time (Troland). S i m i l a r l y , R u s s e l l believed that psychological time i s the r e l a t i o n s h i p between an i n d i v i d u a l and an object while p h y s i c a l time i s the r e l a t i o n s h i p between objects: the former being determined by sensation and memory; the l a t t e r , by simultaneity and succession. In conclusion, Weber in d i c a t e d the d i f f i c u l t y i n not viewing p h y s i c a l time as the sole r e a l i t y while disregarding psychological time a b s o l u t e l y — a n endeavour which, he f e l t would be rather f o o l i s h since p h y s i c a l time i s coloured so, by- the perceptual processes. The perception of time according to Montague (1904) a r i s e s from the amount of change during a temporal i n t e r v a l (an idea supported by 7 James (1950) and others) j u s t as the measure of space Is the s i z e of the body which f i l l s or might f i l l i t . Reviewing a number of papers on the perception of time, Woodrow (1951) mentioned the preceding concept i n d i c a t i n g I t implies that, I f there were a cessation of change, time would stop. The duration of a uniform sensory experience i s held to be perceived i n a d i r e c t and Immediate fashion i n psychology. This he concluded was incompatible with the stand of Montague (1904) and others since the duration of a uniform sensory experience might be conceived to occur during a period of uniform sensory stimulation i n which an absence of change would give r i s e to no perception of duration. This absence of change as proposed by Woodrow, however, during a uniform sensory experience i s questionable as receptor adaptation occurs; and as f l u c t u a t i o n s i n the stimulus i n t e n s i t y and i n the Ss at t e n t i o n focused on the stimulus, might occur. L a s t l y , he pointed out that t h i s concept of time perception i s one i n which time i s i n d i r e c t l y perceived through a process of cues. These cues a r i s e from any process changing p r o g r e s s i v e l y with. time. According to him, Lipps (1883) was the f i r s t to develop t h i s notion having conceptualized the fading of immediate memory images as cues while James (1908) continued t h i s concept of cueing only a l t e r i n g the s i t e of the process to the b r a i n where i t i s held that the cues are provided by the fading of b r a i n traces. Experimental Methods f or Time Perception The i n c l u s i o n of a review of the methods of time perception and of the s p e c i f i c topic of f i l l e d versus u n f i l l e d i n t e r v a l s was necessary since the study i n question involved the i n v e s t i g a t i o n of time percep-t i o n , i n a sense, i n an experimental s e t t i n g which contained f i l l e d temporal i n t e r v a l s . 8 F i l l e d Versus U n f i l l e d I n t e r v a l s . In a timing experiment the i n t e r v a l which i s presented to be timed can e i t h e r be f i l l e d with mental or p h y s i c a l content or not f i l l e d at a l l . Krech. and C r u t c h f i e l d 0.961) generalized by s t a t i n g that u n f i l l e d I n tervals are perceived as shorter than p h y s i c a l l y i d e n t i c a l f i l l e d I n t ervals which p a r a l l e l s the e a r l i e r ideas of William James. Both Weber (1933) and G i l l i l a n d , Hofeld and Echstrand (1946) came to the conclusion that, though an extensive amount of experimentation had been undertaken In the area, no conclusive evidence had been amassed to v e r i f y under which condition timing was most accurate. G i l l i l a n d , Hofeld and Echstrand explained that t h i s might be due to the d i f f i c u l t y i n determining whether an i n t e r v a l i s f i l l e d or u n f i l l e d . An i n t e r v a l f i l l e d with auditory or v i s u a l stimu-l a t i o n may carry l e s s a t t e n t i o n value f o r an S while the subjective content which he, himself, applies to the i n t e r v a l may have more atte n t i o n value. They elaborated f u r t h e r by s t a t i n g that the i n c o n s i s -tencies i n t h i s area were due to the f a c t that many more factors a f f e c t e d timing than the content of the i n t e r v a l — s u b j e c t i v e f i l l i n g of the i n t e r v a l and motivation to mention only a couple. F i n a l l y , using both f i l l e d (buzzer) and u n f i l l e d (lamps) i n t e r v a l s , Clausen (1950) found that the content of the i n t e r v a l d i d not a f f e c t the performance i n any of h i s three methods of timing (verbal, operative or reproduction). Methods of Time Perception. According to Clausen (1950), four methods are a v a i l a b l e f o r the i n v e s t i g a t i o n of short durations. F i r s t i s the method of reproduction i n which the experimenter (E) presents an S with an I n t e r v a l which he then reproduces. Second i s the method of verbal estimation In which the E sets an I n t e r v a l which i s v e r b a l l y 9 estimated by the S. Third i s the method of operative estimation i n which the E states an i n t e r v a l which, the S produces. Last i s the method of comparison i n which the E presents two i n t e r v a l s of which, the S has to i n d i c a t e which, i s longer. Several studies i n the past have investigated the merits of the d i f f e r e n t methods as p r e v i o u s l y o u t l i n e d . Spencer (1921) reported the e a r l i e r f i n d i n g s of Yerkes and Urban (1906) concerning the nature of the timing estimate when the method of statement (verbal estimation) i s used. Yerkes and Urban r e a l i z e d that the r e s u l t s of t h e i r study were biased toward a l a s t d i g i t ending i n e i t h e r a zero or a f i v e . Their r e s u l t s showed 66% of the male and 80% of the female judgements ended i n e i t h e r zero or f i v e . Spencer found that when the r e s u l t s of the previous authors had been corrected f o r t h i s bias they f e l l i n l i n e with h i s own r e s u l t s f o r average constant e r r o r based on the method of r e -production. He concluded, consequently, that the method of reproduction was superior to the method of statement because of the bias i n responding introduced by the l a t t e r . Clausen (1950) explained that the methods of reproduction, verbal estimation and operative estimation are composed of s i m i l a r components i n that they incorporate a stimulus i n t e r v a l and a response i n t e r v a l both of which are e i t h e r demonstrated or named by the E and the S r e s p e c t i v e l y . Investigating the methods of reproduction, verbal and operative estimation, he concluded that the method of operative estimation was to be preferred as a measure of time perception. The method of reproduction, he found, was independent of any r e l a t i o n s h i p between personal and objec t i v e time f o r which the other two methods were susceptible; however, he also found that i t provided a l e s s r e l i a b l e measure over conditions. The method of operative estimation, on the other 10 hand, gave more accurate r e s u l t s than the method of verbal estimation with l e s s s c a t t e r i n g of the scores than the method of reproduction and f i n a l l y eliminated any p o s s i b l e tendency toward round-off errors per-petuated by the method of verbal estimation. Richards (1964) described the respective merits of the methods of i n v e s t i g a t i n g time perception. He pointed out the Inadequacies of the method of comparison to form a r e l i a b l e measure of time d i s c r i m i n a t i o n since time d i s c r i m i n a t i o n appears to be a function of the space between i n t e r v a l s , the order of presenta-t i o n of the standard, the number of t r i a l s and the i n t e r v a l s comprising the s e r i e s . Contrary to Clausen (1950), Richards expounded the use of the method of reproduction since i t was influenced by very few f a c t o r s and was also independent of a personal time s c a l e . He f e l t , moreover, that the methods of verbal and operative estimation were not adequately c o n t r o l l e d , unstable and e a s i l y d i s t o r t e d . A n t i c i p a t i o n and Timing In tracking behaviour a timing phenomenon known as a n t i c i p a t i o n has been demonstrated to e x i s t . This phenomenon was f i r s t mentioned by Helson (1949) who found that tracking errors f o r a p r e d i c t a b l e course ware l e s s than that which would be accounted f o r by simple RT. This led to the formulation that an S was able to p r e d i c t the target motion and respond to i t so that h i s response would coincide with the target at a l a t e r time. Investigating a n t i c i p a t i o n i n tracking, Poulton (1952a and 1952b), i n two studies, uncovered some of the v a r i a b l e s involved i n a n t i c i p a t i o n . He found that the type of tracking d i s p l a y , the predict-^ a b i l i t y of the course (motion of the target) and the type of cues used by an S ( p o s i t i o n and speed) were a l l important to a n t i c i p a t i o n i n 11 tracking. Poulton (1957a) concluded, moreover, that the tracking of pr e d i c t a b l e courses was encoded i n a mixed v i s u a l - k i n a e s t h e t i c mode. Three forms of a n t i c i p a t i o n have been defined: e f f e c t o r a n t i c i p a t i o n i n which an S has to pr e d i c t the nature and s i z e of h i s muscle f i r i n g s i n order to h i t a s t a t i o n a r y target; receptor a n t i c i p a t i o n i n which an S not only has to d i s p l a y e f f e c t o r a n t i c i p a t i o n but also has to p r e d i c t the length of h i s motor response i n order to h i t a moving target when the target-motion i s previewed; and f i n a l l y , perceptual a n t i c i p a t i o n i n which an S not only has to display the previous two forms of a n t i c i p a t i o n but also has to be able to p r e d i c t the nature of the course through i t s s t a t i s t i c a l properties when the target-motion i s not previewed (Poulton, 1957b). A n t i c i p a t i o n was e a r l i e r r e f e r r e d to as a timing phenomenon as i t most c e r t a i n l y i s i n the form of perceptual a n t i c i p a t i o n . Perceptual a n t i c i p a t i o n as e a r l i e r mentioned not only involves the p r e d i c t i o n of the response motion and of the target motion which remains un-previewed though p r e d i c t a b l e , but al s o inherently involves the timing of these components of a n t i c i p a t i o n . To make an accurate timing response an S must be able to learn the duration of h i s response from i t s i n i t i a t i o n to i t s termination. He must also be able to learn the temporal r e l a t i o n -ship between the appearance of the target and the i n i t i a t i o n of h i s tracking response e s p e c i a l l y i n d i s c r e t e tracking such as coincident timing where the target appears a f t e r a constant duration without any preview. Not only was a n t i c i p a t i o n an important area of timing providing a l t e r n a t i v e l i n e s of evidence supporting the tenet that humans possess a timing a b i l i t y which has been expressed i n motor s k i l l s (see an exc e l l e n t review by Schmidt, 1968), but also i t was and s t i l l i s a v a l i d method f o r the i n v e s t i g a t i o n of the timing of motor responses. The 12 i n v e s t i g a t i o n of a n t i c i p a t o r y timing has led several experimenters i n t o the next area of d i s c u s s i o n — t h e area of proprioception and timing. Proprioception and Timing Proprioception. Sherrington Q.906) delineated three c l a s s i f i c a -tions of receptors: the exteroceptors on the external surface of the body (eyes, ears, e t c . ) ; the interoceptors on the inner surface of the body (chemoreceptors, e t c . ) ; and the proprioceptors l y i n g between the two surfaces. The proprioceptors l i e i n the deep muscles, tendons and j o i n t s where they are stimulated by muscular movement, tension and pressure, and o r i e n t a t i o n i n space without movement. Sherrington also included the l a b y r i n t h i n e mechanisms as part of the proprioceptive system as both sets of receptors appeared to o r i g i n a t e i n and maintain the t o n i c r e f l e x e s of s k e l e t a l muscle. Since the study was p r i m a r i l y involved with PFB mechanisms f o r the timing of motor responses the r o l e of both the proprioceptors and exteroceptors seemed important enough to warrant d e f i n i t i o n . This form of the d e f i n i t i o n has been previously used by both Adams (1968) and Schmidt (1971). Role i n Timing. Since Goldman, Boardman and Lhamon (1958) f i r s t noticed the s i g n i f i c a n c e of kinaesthesis i n timing behaviour the ro l e of proprioception i n timing studies has greatly accelerated. Adams and Xhignesse (1960) suggested a pos s i b l e mechanism to account f o r the d i f f e r e n t i a t i o n In response time and a n t i c i p a t o r y performance between two conditions having event-time c e r t a i n t y (knowing which, l i g h t was to come on and when) but d i f f e r i n g i n the time between responses. This PFB decay mechanism functions so that cues, derived from the pr o p r i o -ceptive a f t e r - e f f e c t s of the f i r s t response, were used to t r i g g e r the 13 accurate timing of the second response which would be coincident with the onset of the stimulus lamp. Later, Adams (1961) explained that bringing PFB into the sphere of anticipatory behaviour only required that motor movements become conditioned to the PFB traces from prior movements. The proper PFB configuration, consequently, would e l i c i t the next motor sequence through practice. This concept, Adams and Creamer (1962a) concluded, was tenable as i t provided one possible source of explanation for the transfer effects that they found in anticipation with verbal and motor responses. Weak support was then established for this hypothesis, that cues from PFB traces are used to aid in the timing of motor responses; in a visual step-tracking task conducted by Adams and Creamer (1962b); more recently however, Quesada and Schmidt (1970) have uncovered strong support for this PFB decay hypothesis. An offshoot of the Adams and Xhignesse (1960) concept expounds that the cues from the PFB input, i t s e l f , are used to trigger the accurate timing of a movement sequence. This particular proprioceptive mechanism of timing has been substantiated by several experimenters with varying degrees of val i d i t y . Grose (1967) found that whole body movements were more accurate than arm movements which in turn were more accurate than finger movements supporting the prediction from the hypothesis that the timing accuracy of a movement should increase with increased PFB input. This evidence, however, was tarnished by the confounding of the level of the PFB with the level of the task complexity in the procedure. Con-f l i c t i n g evidence was again provided for the input hypothesis by E l l i s , Schmidt and Wade (1968) who found that their weight-movement condition demonstrated increased timing accuracy over their control condition as predicted, but that with the removal of KR, the weight-movement condition 14 f a i l e d to r e t a i n i t s superior timing accuracy over the c o n t r o l condition as predicted from the proposed influence of the PFB on timing accuracy. In a two second operative timing task i n which the PFB was manipulated during the temporal i n t e r v a l , E l l i s (.1969) found that both the PFB from an appreciable arm movement and the PFB from the larnyx Cverbalization) were s u f f i c i e n t f o r r e l a t i v e l y accurate timing of motor responses; however, when both, forms of the PFB were removed the timing accuracy of the motor responses dropped considerably. Further supportive evidence has been shown f o r the proprioceptive input hypothesis of timing by several i n v e s t i g a t o r s who have found that increased PFB increases the timing accuracy of motor responses under varying experimental methods and procedures (Schmidt and C h r i s t i n a , 1969; C h r i s t i n a , 1970 and 1971). Having shown the relevance of proprioception to timing the scene has been set to explore the decay hypothesis i n d e t a i l . Decay Hypothesis Theory. The Adams-Creamer decay hypothesis has g r e a t l y evolved over the past decade since i t s inception (Adams and Xhignesse, 1960; Adams and Creamer, 1962a; 1962b; Schmidt and C h r i s t i n a , 1969; C h r i s t i n a , 1970; and Schmidt, 1971); consequently, i t was stated here i n i t s most recent mutation. The decay hypothesis states that the PFB from an i n i t i a l movement completed at time t enters a short-term storage system, p o s s i b l y STM, where i t i s proposed to decay p r e d i c t a b l y as a function of time. I f a l a t e r response i s to be made at time t + dt (dt a constant), the pre-d i c t a b l e — y e t unique—time-varying c h a r a c t e r i s t i c or time standard Ca given l e v e l of the trace decay) at time t + bt (bt a constant l e s s than dt) 15 INTERNAL HYPOTHETICAL EVENTS Initiation of movement producing PFB (1) End of 1; placement of PFB in STM Relevant cue and starting time reached For timing response; response initiated INTERNAL MOBILIZATION TIME(IMT) F0RTIMIN6 RESPONSE (IMT= dt-bt) Environmental appearance of timing response 1 HfcdE 0 t t+bt t+dt FIG. 2.1 SEQUENCE OF HYPOTHETICAL EVENTS FOR DECAY MECHANISM 16 i s used to cue that response appearing at time t + dt as shown i n Figure 2.1. This time standard CTS) at time t + bt can be viewed as the cue e l i c i t i n g the l a t e r response—the cue developed through stimulus-response (S-R) learning (Quesada and Schmidt, 1970). Over a number of t r i a l s i n a timing task, the S i s able, through. KR (Christina,. 1970) , to s e l e c t a given l e v e l of the PFB trace as a TS which develops the best p o s s i b l e timing of the second response at time t + dt. I f the timing mechanism i s a change detector r e q u i r i n g some minimum change to a c t i v a t e i t , as v i s u a l i z e d by Schmidt (1971), then what i s i t detecting a change i n and what i s the minimum required change? The mechanism may p o s s i b l y be detecting a change i n the l e v e l of the PFB trace (Quesada and Schmidt, 1970) with the minimum change required being that amount which would make two consecutive l e v e l s of the trace j u s t noticeably d i f f e r e n t and discriminable as learning cues (relevant cues). The greater the rate of change of the PFB trace decay, the shorter the time between these relevant cues, and the greater the number of them per unit time (cue density). I f the i n t e r n a l m o b i l i z a t i o n time (IMT) of a given response were constant (within the n a t u r a l l i m i t s of the v a r i a b i l i t y i n the human system), the accuracy of the response depends s o l e l y on the s t a r t i n g time (ST) of the response as found by Schmidt (1969) i n a coincident timing task. Given that an S learns to associate a relevant cue with the desired response providing the ST that develops the most accurate response; then, the greater the d i s c r i m i n a b i l i t y of the relevant cues the less i s the v a r i a b i l i t y i n choosing an ST as the relevant cues are more d i s t i n c t . Thus the "lag i n the decay mechanism" . (Schmidt, 1971) can be viewed as the time between two relevant cues; moreover, as the lag decreases the cue density increases with an increased d i s c r i m i n a b i l i t y 17 between the relevant cues. The shorter the l a g , the greater i s the accuracy of timing a second response. P r e d i c t i o n s . From the Adams-Creamer decay hypothesis as revised by Schmidt (1971), there follows three t e s t a b l e p r e d i c t i o n s . According to the decay mechanism, the greater the r a t e of trace decay the smaller the lag i n the mechanism and the more accurate the timing of the second response. I f the pattern of PFB trace decay were exponential Cor at l e a s t some decreasing negatively accelerated function of time), one method of increasing the rate of decay would be to increase the i n i t i a l amount of PFB placed i n STM, provided that the rate of trace decay were assumed to be proportional to the s i z e of the i n i t i a l amount of PFB placed i n STM ( i . e . , the decay time i s constant). This leads to the f i r s t p r e d i c t i o n that the l a r g e r the i n i t i a l movement ( i n force or amplitude) at time t , the greater the rate of PFB trace decay, and consequently, the greater the timing accuracy of the second response at time t + dt. Second, i f the i n i t i a l movement were inconsistent from t r i a l to t r i a l while the task were being learned, the S would have to cope with a d i f f e r e n t amount of PFB being entered into STM on each successive t r i a l . A s p e c i f i c l e v e l of PFB trace would be reached i n a d i f f e r e n t number of milliseconds on each t r i a l making the cueing l e v e l unpredictable at time t + b t . Thus the S would not be able to p a i r the second response with the l e v e l of PFB trace from the f i r s t response to provide an accurately timed response at time t + dt. The second p r e d i c t i o n , then, i s that the accurate timing of the second response at time t + dt i s a function of the consistency (of force, amplitude and d i r e c t i o n ) of the f i r s t response with the greatest timing accuracy occurring when the f i r s t response i s as 18 consistent as p o s s i b l e from t r i a l to t r i a l . T hird, i f the pattern of decay i s exponential Cor a decreasing, negatively accelerated function of time), the r a t e of decay i s decreasing from the time of the i n i t i a l movement; consequently, a response made at time t + dt where dt i s short should be more, accurately timed than where dt i s longer since the mechanism works most e f f e c t i v e l y at high rates of decay. This prompts the t h i r d p r e d i c t i o n that under a given l e v e l of i n i t i a l PFB, short i n t e r v a l s should be timed more accurately than longer ones. A c o r o l l a r y of the t h i r d p r e d i c t i o n i s that although shorter i n t e r v a l s may be timed more accurately under a PFB condition than under a no-PFB-control condition, very long i n t e r v a l s should be timed no more accurately under e i t h e r condition. This follows since the PFB condition has the advantage of the cues from the timing mechanism which the no-PFB-control condition does not have at shorter i n t e r v a l s ; however, at very long i n t e r v a l s the ones from the mechanism provide no advantage f o r the PFB over the no-PFB group. Evidence. In a v i s u a l step-tracking task, the decay hypothesis was formally tested by Adams and Creamer (1962b) who found support f o r two of the p r e d i c t i o n s derived from the hypothesis: one, that a shorter i n t e r v a l between the two responses would increase the accuracy of timing the second response; and two, that an increased i n i t i a l l e v e l of PFB would also increase the accuracy of timing the second response. Two p o s s i b l e sources of confounding e x i s t w i t h i n t h e i r experiment's methodo-l o g i c a l framework, however, which weakens any support they have l e n t to the decay hypothesis. F i r s t l y , as the amount of spring-tension i n the control-arm increases, not only does the amount of PFB increase but 19 the amount of mechanical advantage to respond also increases, since the increased spring-tension tends to center the tracking s t y l u s more f o r c e -f u l l y . Thus, i n t h i s experiment no r e a l determination can be made as to which f a c t o r a c t u a l l y increased.the timing accuracy of the motor response. Secondly, since the spring-tension may have generated PFB input during the timing i n t e r v a l , any i n t e r p r e t a t i o n i n favour of the decay view would be hopelessly confounded with the input view of timing and consequently would be meaningless i n substantiating the decay hypothesis. C h r i s t i n a (1970) used a coincident timing task i n which d i f f e r e n t extents and weighting of a slide-movement (co n t r o l l e d by the S's l e f t hand) were used to develop d i f f e r e n t l e v e l s of PFB j u s t p r i o r to the timing i n t e r v a l ; however, he found no support f o r the Adams-Creamer decay hypothesis. There are two po s s i b l e explanations f o r these contra-d i c t o r y f i n d i n g s . One, suppose an S uses the mechanism which produces the best p o s s i b l e timing i n a motor response. Then, i t i s po s s i b l e that the PFB trace cues from the l e f t hand-movement were not used since a more potent source of cues may have been a v a i l a b l e i n the form of PFB input from the larnyx ( E l l i s , 1969). These PFB input cues were developed, during the timing i n t e r v a l , by the steady v e r b a l i z a t i o n (A, B, C, repeated) which was used to c o n t r o l f o r the e f f e c t s of covert counting! I f these PFB input cues were used no d i f f e r e n t i a t i o n i n performance would be expected amongst the various conditions t e s t i n g the decay hypothesis. The l e v e l of PFB input would be i d e n t i c a l f o r each condition; consequently, according to the input hypothesis the timing should be the same. Two, perhaps an S i s confused by the presence of two d i f f e r e n t sources of s i m i l a r time-varying cues. I f t h i s i s the case the task of d i f f e r e n t i a t i o n i n performance may have been due to the S's i n a b i l i t y to use one or the 20 other of the two a v a i l a b l e sets of cues. On the other hand, Quesada and Schmidt (197Q) have s u p p l i e d the onl y strong support f o r the Adams-Creamer decay hypothesis. In a d i s c r e t e t i m i n g task, i n which there was a f i n g e r movement (developing a minimum p r o p r i o c e p t i v e d i s c h a r g e ) ; and. i n which, there was a p a s s i v e , c o n s i s t e n t , l e f t arm-movement (developing a grea t e r p r o p r i o c e p t i v e discharge) ending si m u l t a n e o u s l y w i t h the beginning of the temporal i n t e r v a l , i t was found that the I n t e r v a l was timed more a c c u r a t e l y under the PFB c o n d i t i o n than under the minimum p r o p r i o c e p t i v e feedback (mPFB) c o n t r o l c o n d i t i o n as p r e d i c t e d by the decay hypothesis. A l s o i t was found that i n the absence of KR the PFB group d r i f t e d l e s s from the time-standard than d i d the mPFB group. This supports the decay view by demonstrating that the PFB c o n d i t i o n was i n possession of a mechanism by which i t could continue i t s r e l a t i v e l y accurate t i m i n g behaviour i n comparison w i t h the mPFB group when no KR was a v a i l a b l e to e i t h e r group. This i s the t i m i n g mechanism proposed by the Adams-Creamer decay hypothesis. Other Mechanisms of Timing C o g n i t i v e View. According to Gooddy (1958) the p h y s i o l o g i c a l s t r u c t u r e of animals, and e s p e c i a l l y of the nervous system i t s e l f , contains an enormous number of c l o c k s . A c l o c k e x i s t s when any r e g u l a r l y repeated and continuous p h y s i c a l phenomenon i s used to provide an a r b i t r a r y u n i t of time which i s accumulated to time an event. The a r b i t r a r y u n i t a r i s e s as that i n t e r v a l between the beginning and end of the phenomenon, provided that the a c t i v i t y of the phenomenon i s p e r c e p t i b l e to an i n d i v i d u a l . The c a r d i o v a s c u l a r and r e s p i r a t o r y systems p r o v i d e r e g u l a r and continuous rhythms which might be used as a time base In time 21 perception; however, for the accurate timing of motor responses these systems and others (counting etc.) are too susceptible to variation to provide the empirical accuracy acquired in timing. Lastly, Gooddy dis-cussed the rhythms of the cerebral cortex and especially the alpha rhythm which, he considered the f i n a l abstraction from a l l other neuro-physiological rhythms—the f i n a l clock.. The concept of using alpha rhythm of the cerebral cortex as a time base for the timing of responses has been investigated by the Czech neurophysiologist Josef Holabar (1969) who found limited though positive evidence to support the theory. Pre-programming View. Out of the motor control system for human motor behaviour (Chase, 1965a) has grown the present adaptation of the pre-programming hypothesis for the execution- of motor responses. Similar though less detailed formulations have been made by Henry and Rogers (1960) and by Pew (1966). Briefly the hypothesis states that the motor programme (MP) for a given response, stored in a motor-programming unit (MPU), i s run off through the central nervous system (CNS) when the response i s required. The development of the MP for a response i s said to stem from the interaction of a standard (STD) or memory trace and the MPU where the STD i s that neural pattern closely paralleling the actual neural activity pattern for the correct execution of that response. The STD is acquired through practice under KR. Finally, a l l of the requirements for the timing of the sequential components of the response are built into the MP so that no periferal feedback is necessary for the execution of the response when i t i s run off through the CNS (Chase, 1965b; and Laszlo and Manning, 1970). Positive evidence of varying strength has been forthcoming to 22 s u b s t a n t i a t e the pre-programming hypothesis as shown i n numerous i n v e s t i -gations (Henry and Rogers, 1960; Taub and Berman, 1963; W h i t l e y , 1966; Pew, 1966; E e s t i n g e f et_ al_, 1967; L a s z l o , 1967a, 1967b; Higgins and Angel, 1970; and L a s z l o and Manning, 1970). These i n v e s t i g a t i o n s have shown the f o l l o w i n g : f i r s t t hat more complex responses w i t h more complex MPs have longer RTs s i n c e longer MPs take longer to be read out through the CNS; second that tapping to an a l t e r n a t i n g stimulus can be c a r r i e d on at a f a s t e r r a t e than the p r o c e s s i n g time f o r p e r i f e r a l feedback, suggesting that e r r o r c o r r e c t i o n i s independent of e x t e r n a l feedback; and l a s t , that p e r i f e r a l feedback i s not e s s e n t i a l to the performance of h i g h l y s k i l l e d motor behaviour. These s t u d i e s have not been, however, e n t i r e l y p o s i t i v e as i m p l i e d above. For i n s t a n c e , L a s z l o (1966) found th a t f a s t tapping performance was impeded by the e l i m i n a t i o n of k i n a e s t h e t i c feedback; moreover, L a s z l o and Manning (1970) found t h a t f a c i l i t a t i o n and i n h i b i t i o n of the STD had no e f f e c t on tapping when p e r i f e r a l feedback had been removed. Now that the mechanisms Of t i m i n g have been discussed and the decay mechanism has been f u l l y developed i t i s time to proceed to the assumptions made, and consequently to the hypotheses d e r i v e d to t e s t i t s v a l i d i t y . Assumptions Three assumptions were p o s t u l a t e d as f o l l o w s : (1) That the S cues the i n i t i a t i o n of h i s t i m i n g response on the l e v e l of the PFB t r a c e i n STM at time t + bt p r i o r to the appearance of i t at time t + d t . (2) That the amount of the PFB t r a c e i n STM i s p r o p o r t i o n a l to 23 the extent of the i n i t i a l movement at time t + bt. (3) That the timing error at time t + dt i s an indicator of the lag in the decay mechanism. Hypotheses The following four hypotheses have been developed from the Adams-Creamer decay hypothesis of timing. (1) In a given DI In which the decay mechanism is functioning, as the i n i t i a l movement-response increases (in force, amplitude or direction) at time t, the timing error (absolute error and within S variability) associated with the timing of a second response at time t + dt decreases. (2) Under a given i n i t i a l amount of PFB placed i n STM, a second response made at time t + dt after a short DI (dt short) has less timing error (absolute error and within S variability) associated with i t than a similar response made at time t + dt after a longer DI (dt longer). (3) A second response made at time t + dt after a short DI (dt short) has less timing error (absolute error and within S variability) associated with i t under a PFB condition than under an mPFB-control condition, but that a similar response made at time t + dt after a very long DI (dt very long) has no more timing error associated with i t under either the PFB condition or the mPFB-control condition. (4) The timing error (absolute error and within S variability) associated with a second response at time t + dt is an increasing, posi-tively accelerated function of time (length of the DI). In explication, hypothesis (4) was developed i n the following 24 manner. The decay mechanism, as proposed, operates as a change d e t e c t o r u s i n g j u s t n o t i c e a b l y d i f f e r e n t l e v e l s of the PFB t r a c e as r e l e v a n t cues, one of which at time t + bt cues the second response at time t + d t . I f the PFB t r a c e decay i s an e x p o n e n t i a l or decreasing n e g a t i v e l y a c c e l e r a t e d f u n c t i o n of time, the number of r e l e v a n t cues per u n i t time, (given a s p e c i f i c j u s t n o t i c e a b l e d i f f e r e n c e between d i s c r i m i n a b l e l e v e l s of the PFB t r a c e ) , i s a l s o an e x p o n e n t i a l or decreasing n e g a t i v e l y a c c e l e r a t e d f u n c t i o n of time. From t h i s i t can be seen t h a t the l a g i n the decay mechanism (the u n i t time over the number of r e l e v a n t cues i n that time u n i t ) i s an e x p o n e n t i a l , i n c r e a s i n g and p o s i t i v e l y a c c e l e r a t e d f u n c t i o n of time; t h e r e f o r e , the t i m i n g e r r o r a s s o c i a t e d w i t h the second response at time t + dt should be an i n c r e a s i n g p o s i t i v e l y a c c e l e r a t e d f u n c t i o n of time (the l e n g t h of the DI) provided that the t i m i n g e r r o r i s p r o p o r t i o n a l t o the l a g i n the decay mechanism and so long as the decay mechanism i s being used to time the second response at t h a t p a r t i c u -l a r l e n g t h of the DI. Chapter 3 PROCEDURES Research Design and Methodology Subjects. For this study 30 male Ss were enlisted (non-randomly) from the ranks of the Summer School Session in the School of Physical Education and Recreation and from the ranks of the graduate faculties of Computer Science, E l e c t r i c a l Engineering and Physics at the University of British Columbia. Experimental Design. The experiment was a three factor experiment with repeated measures in the last factor (Winer, 1971; 559). There were two levels of proprioceptive feedback (PFB and mPFB), five levels of delay interval (0.3, 0.6, 1.0, 2.0 and 4.0 seconds); and there were 50 learning t r i a l s presented to each S in each of the treatment conditions. For c l a r i f i c a t i o n of the design see Table 3.1. Random Assignment of Subjects. There were three Ss randomly assigned to each of the ten different treatment conditions. This was accomplished by having the order of presentation of the treatment con-ditions randomized with the limitation that any one treatment condition would only appear three times and by having the S take the treatment condition to be presented in that session. Methodology. The experimental design was chosen to allow the predictions from the Adams-Creamer decay hypothesis of timing (as stated 26 Table 3.1. Experimental Design: A 2 x 5 x 50 F a c t o r i a l Design With Repeated Measures on the Last F a c t o r . C o n d i t i o n C o n d i t i o n Subjects C o n d i t i o n I I I I I I P r o p r i o c e p t i v e Feedback. Delay I n t e r v a l T r i a l s Cseconds) 1 2 ... 50 0.3 •Si s 2  s 3  0.6 s , s 5 s 6 PFB 1.0 s 7 sa s 9 2.0 Sio Sj j s 1 2 4.0 s m S i s ' 0.3 Sie S17 0.6 S19 S20 S2 1 mPFB 1.0 S 2 2 S23 S2lf 2.0 S 2 5 • S 26 S2 7 4.0 27 in the hypotheses section of the thesis) to be tested experimentally. The range of the delay interval was selected to allow the investigation of the PFB trace decay function both at points where i t i s theorized to be decaying rapidly CO.3 and 0.6 seconds) and also at a point where i t is theorized to be decaying less rapidly (4.0 seconds). Since this timing mechanism proposes the use of S-R learning in the development of the relevant cues that trigger a later response at the required point in time, i t was necessary to administer a number of learning t r i a l s to each S so that the relevant cues might be developed. Apparatus Since a timing experiment with both a large source of consistent PFB and a source of mPFB in a non-responding appendage were required to test the Adams-Creamer decay hypothesis, Quesada and Schmidt (1970) developed a piece of apparatus to f u l f i l l these requirements. A modified version of this apparatus (Figure 3.1), built here and incorporating the same necessary features, was used to test the predictions developed from the Adams-Creamer decay hypothesis. With this apparatus, the large source of consistent PFB for the PFB conditions was generated passively in the right arm. The right hand was placed on the horizontal handle which was moved down the trackway on the vertical slide some 60 cm. to i t s resting position i n 3.22 + 0.05 seconds by a 0.4 H.P. variable speed drill-motor. The mPFB for the mPFB-control conditions was generated by the depression-release action of a push-button micro-switch (on the right arm-rest of the S's chair) with the index fingers of his right hand. The movement of the handle down the vertical slide was initiated either by the depression-release of the F I 6 . 3.1 APPARATUS 29 mi c r o - s w i t c h l e v e r on the handle or by the depr e s s i o n - r e l e a s e of the aforementioned push-button both, of which, c o n t r o l l e d the s t a r t i n g of the d r i l l - m o t o r and the s l i d e time timer Ca 0.001 second Hunter timer model 120A). The v e r t i c a l s l i d e was attached to two 0.32 cm. thick, n ylon cords: the f i r s t was attached to a 340 gm. counter-weight, the second to a 0.5 cm. s h a f t d r i v e n by the d r i l l - m o t o r . The f i r s t cord was fastened to the top of the s l i d e from which I t ran over two p u l l e y s : the f i r s t of which was s i t u a t e d d i r e c t l y above the s l i d e i n the center of the v e r t i c a l t r a c k s upon which the s l i d e t r a v e l l e d and the second of which was s i t u a t e d on the same l e v e l as the f i r s t , 23 cm. back of and i n l i n e w i t h the v e r t i c a l drop of the s l i d e . The nylon cord was a f f i x e d to the counter-weight which counter balanced the weight of the s l i d e and the hand placed on the handle of the s l i d e during the experiment. The second nylon cord was fastened to the bottom of the s l i d e from which i t ran down over a p u l l e y d i r e c t l y beneath the s l i d e i n the center of the v e r t i c a l t r a c k s to wind around the h o r i z o n t a l s h a f t which was p a r a l l e l to the a x i s of the bottom p u l l e y . The f u n c t i o n of t h i s cord was to p u l l the s l i d e down the trackway when the d r i l l - m o t o r was s t a r t e d by winding around the h o r i z o n t a l s h a f t h e l d i n the chuck of the d r i l l - m o t o r which was b o l t e d to the bottom p l a t f o r m of the equipment. The s l i d e and consequently the h o r i z o n t a l handle were moved down the trackway i n a very c o n s i s t e n t manner by the counter balanced p u l l e y system d r i v e n by the d r i l l - m o t o r . At the end of i t s t r a v e l down the trackway, the s l i d e opened two micro-switches: the f i r s t stopped the d r i l l motor and the s l i d e time c l o c k Cgiving the time f o r the s l i d e to move 60 cm); and the second s t a r t e d the time estimate timer CHunter 120A), 30 and turned on a red l i g h t (6 v o l t s ) mounted d i r e c t l y i n f r o n t of the S and a buzzer (6 v o l t s ) mounted d i r e c t l y behind the S. F i n a l l y the handle was h e l d i n the down-position by the t e n s i o n remaining i n the nylon cord a f t e r the d r i l l - m o t o r had been stopped. Delay I n t e r v a l The delay i n t e r v a l w i t h i n the procedure was o p e r a t i o n a l l y d e f i n e d as that number of seconds,determined by a p a r t i c u l a r treatment c o n d i t i o n , which the S was t r y i n g to estimate w i t h the r e l e a s e of the response-button. This delay i n t e r v a l s t a r t e d w i t h the onset of the l i g h t and buzzer and ended when the time designated under that p a r t i c u l a r c o n d i t i o n had elapsed. Tasks and Procedures Each S was seated i n an arm-chair and was t o l d what delay i n t e r v a l he would be expected to a c c u r a t e l y estimate. Each S was then i n s t r u c t e d to depress the response-button on the l e f t arm of the c h a i r w i t h h i s l e f t index f i n g e r . In the PFB c o n d i t i o n each S was t o l d to h o l d the handle of the s l i d e g e n t l y between the thumb and f i n g e r t i p s of h i s r i g h t hand without depressing the m i c r o - s w i t c h l e v e r on the handle which a c t i v a t e d the d r i l l - m o t o r . Each S i n the mPFB-control c o n d i t i o n , on the other hand was t o l d to p l a c e h i s r i g h t arm on the arm of the arm c h a i r w i t h h i s index f i n g e r r e s t i n g comfortably on the r i g h t push-button. A t r i a l was s t a r t e d when the E s a i d , "READY—GO". In the PFB c o n d i t i o n a t r i a l was i n i t i a t e d w i t h the d e p r e s s i o n - r e l e a s e of the l e v e r on the handle. In the mPFB-control c o n d i t i o n , however, the t r i a l was i n i t i a t e d w i t h the depression-release of the push-button on the r i g h t arm of the c h a i r . In both cases, the handle and s l i d e descended the trackway i n p l a i n view of 31 each S to t h e i r r e s t i n g p o s i t i o n where they s t a r t e d the set delay i n t e r v a l by t r i g g e r i n g the t i m e r , l i g h t and buzzer. At t h i s p o i n t the arms of the Ss i n each c o n d i t i o n were i n the same p o s i t i o n on the r i g h t arm of the c h a i r ; consequently, the only d i f f e r e n c e between the PFB and mPFB-c o n t r o l c o n d i t i o n s was the s i z e of the I n i t i a l movement i n the r i g h t arms of t h e i r Ss. F i n a l l y , the S i n each c o n d i t i o n estimated the set delay I n t e r v a l by r e l e a s i n g the response-button to stop the time estimate t i m e r , and buzzer; and to t u r n o f f the l i g h t : when he had pe r c e i v e d that h i s response was c o i n c i d e n t w i t h the t e r m i n a t i o n of the set delay i n t e r v a l ( i . e . , i f the delay i n t e r v a l had been 2.0 seconds, the S would have been attempting to respond at a time e x a c t l y 2.0 seconds a f t e r the onset of the l i g h t and b u z z e r ) . A l l Ss were i n s t r u c t e d n e i t h e r to count aloud nor to themselves and to t r y to remain p e r f e c t l y s t i l l producing no extraneous movements (tapping the f i n g e r s or f e e t , e t c . ) . V i o l a t i o n of these i n s t r u c t i o n s r e s u l t e d i n that t r i a l i n which the v i o l a t i o n occurred to be taken over again. P r i o r to the experiment f i v e p r a c t i c e t r i a l s were given to each S to acquaint him w i t h the procedures; however, no KR was given on these t r i a l s . Each S was then administered 50 t r i a l s under h i s c o n d i t i o n w i t h KR (the time to the nearest 0.001 second of h i s s u b j e c t i v e time estimate of the set delay i n t e r v a l ) w i t h an i n t e r t r i a l i n t e r v a l of 30 seconds to al l o w the reverberation of the neuronal t r a c e to subside. Experimental Conditions As s t a t e d above, t h e r e were t h r e e Ss i n each, of the ten treatment c o n d i t i o n s (comprised of the 2 x 5 ma t r i x generated by the l e v e l s of PFB and by the l e v e l s of delay i n t e r v a l ) . The task of t i m i n g a set of delay 32 i n t e r v a l s was performed by h a l f of the Ss under the PFB c o n d i t i o n ( w i t h t h e i r hand placed on the handle of the v e r t i c a l s l i d e ) and by the other h a l f , under the mPFB-control c o n d i t i o n ( w i t h t h e i r index f i n g e r placed on the push-button). W i t h i n each PFB c o n d i t i o n , the f i v e delay i n t e r v a l s were timed by 15 Ss of whom three were.placed i n . each of the f i v e delay i n t e r v a l c o n d i t i o n s . Independent V a r i a b l e s There were two l e v e l s of p r o p r i o c e p t i v e feedback (PFB and mPFB); and f i v e l e v e l s of delay i n t e r v a l (0.3, 0.6, 1.0, 2.0 and 4.0 seconds). Dependent V a r i a b l e s Two dependent v a r i a b l e s were used to t e s t the hypotheses proposed i n t h i s t h e s i s . They were absolute e r r o r and w i t h i n S v a r i a -b i l i t y (the SD of the S's responses about h i s own mean a l g e b r a i c e r r o r ) . The measure of absolute e r r o r was c a l c u l a t e d from the a l g e b r a i c e r r o r w i t h the s i g n removed. The s i g n of the a l g e b r a i c e r r o r was adopted so that undershoots ( t i m i n g responses s h o r t e r than the i n t e r v a l to be timed) were negative and overshoots were p o s i t i v e . I f the ST v a r i e s around the c o r r e c t s t a r t i n g time COST) f o r a second response w i t h i n a range of h a l f a l a g on e i t h e r s i d e of i t , then the greater the cue d e n s i t y the s m a l l e r the l a g and the sm a l l e r the v a r i a b i l i t y and e r r o r of the ST about the CST. Thus the co n s i s t e n c y and accuracy of t i m i n g a second response, as shown by w i t h i n - S v a r i a b i l i t y and absolute e r r o r r e s p e c t i v e l y should v a r y p r o p o r t i o n a t e l y as the v a r i a b i l i t y of the ST about the CST. I f the ST over a number of t r i a l s has an equal chance of f a l l i n g on e i t h e r s i d e of the CST a l g e b r a i c e r r o r 33 should be very s m a l l or zero w h i l e w i t h i n - S v a r i a b i l i t y and absolute e r r o r should vary p r o p o r t i o n a t e l y as the v a r i a b i l i t y of the ST around the CST. Data A n a l y s i s S l i d e Time A n a l y s i s . S l i d e time was taken on every t r i a l f o r each S and was analyzed w i t h a 2 x 5 x 50 f a c t o r i a l ANOVA w i t h repeated measures on the l a s t f a c t o r to determine i f any s i g n i f i c a n t v a r i a t i o n occurred i n i t . As a post hoc a n a l y s i s because of a source of s i g n i f i c a n t v a r i a t i o n i n the s l i d e time, the mean and the SD of the s l i d e time f o r each S i n the PFB c o n d i t i o n were c o r r e l a t e d f i r s t w i t h h i s mean absolute e r r o r to determine i f e i t h e r the amount or c o n s i s t e n c y of h i s i n i t i a l movement was r e l a t e d to h i s accuracy of t i m i n g and second w i t h h i s w i t h i n - S v a r i a b i l i t y to determine i f e i t h e r the amount or c o n s i s t e n c y of h i s i n i t i a l movement was r e l a t e d to h i s c o n s i s t e n c y of t i m i n g . Learning and C r i t e r i o n T r i a l s . The hypotheses t h a t were t e s t e d here are based on a decay mechanism i n which a r e l e v a n t cue i s p a i r e d w i t h a second response, through stimulus-response l e a r n i n g . This r e l e v a n t cue once lear n e d , i s used to t r i g g e r a second response a t time t + dt more a c c u r a t e l y than i f the cue were not a v a i l a b l e . Consequently to t e s t these hypotheses, i t was necessary to i n v e s t i g a t e the t i m i n g accuracy i n a second response under the two independent v a r i a b l e s a f t e r l e a r n i n g had occurred. To determine where l e a r n i n g had occurred, the mean absolute e r r o r f o r each consecutive t r i a l and each consecutive b l o c k of f i v e t r i a l s was p l o t t e d a gainst that t r i a l and that b l o c k of t r i a l s r e s p e c t i v e l y 34 fo r each of the ten treatment conditions. A f t e r the data had been p l o t t e d i t was c l o s e l y inspected to a s c e r t a i n approximately where no more lear n i n g had occurred over the t r i a l s or blocks of f i v e t r i a l s r e s p e c t i v e l y . When the t r i a l , at which no more learning was evident, was determined, i t was used to demarcate the c r i t e r i o n t r i a l s to be analyzed i n t e s t i n g the experimental hypotheses. A l l the t r i a l s which f e l l a f t e r t h i s t r i a l were used as c r i t e r i o n t r i a l s since the timing performance had improved over 50 t r i a l s but was no longer improving over the c r i t e r i o n t r i a l s . Analysis of Within-S v a r i a b i l i t y and Absolute E r r o r . Planned orthogonal comparisons were performed on the DI means under the PFB condition, Table 3.2; and on the i n t e r a c t i o n e f f e c t between PFB and DI, Table 3.3; moreover, the dif f e r e n c e s between the DI means under the mPFB condition were tested using the Scheffe test f o r dif f e r e n c e s between means. A 2 x 5 complete f a c t o r i a l anova was run on the within-S v a r i a b i l i t y to determine the PFB main e f f e c t ; furthermore, a 2 x 5 x 40 f a c t o r i a l anova with repeated measures on the l a s t f a c t o r was run on the absolute er r o r to determine the PFB main e f f e c t . The Ms err o r terms from these anovas were used to c a l c u l a t e t h e i r respective planned and post hoc comparisons between means. This set of analyses was used to v e r i f y the hypotheses as follows: Hypothesis (I) would have been supported i f the PFB main e f f e c t was s i g n i f i c a n t and i f the mean timing errors from the two dependent measures associated with, the PFB condition were les s than those associated with the mPFB-control co n d i t i o n . 35 Table 3.2. Planned Orthogonal Comparisons for Within-S Variability and Absolute Error for the Delay Interval Means under the PFB condition. Weights for DI Means in PFB Condition c w. w, . w, Wc ." 0 . . . . . . . . 2 3 t 5 M P 1 -1/4 -1/4 -1/4 -1/4 A R c 2 0 +1 -1/3 -1/3 -1/3 I S c 3 0 0 +1 -1/2 -1/2 0 N 0 0 0 +1 -1 Table 3.3. Planned Orthogonal Comparisons for Within-S v a r i a b i l i t y and Absolute Error for the Interaction Effect between PFB and DI. Weights for DI Means PFB Condition mPFB Condition c w2 W 3 W 6 w7 w9 0 M P A C 5 1 -1/4 -1/4 -1/4 -1/4 -1 1/4 1/4 1/4 1/4 R I C 6 0 1 -1/3 -1/3 -1/3 0 -1 1/3 1/3 1/3 S 0 C 7 0 0 1 -1/2 -1/2 0 0 -1 1/2 1/2 N C 8 0 0 0 1 -1 0 0 0 -1 1 36 Hypothesis (2) would have been supported i f the planned orthogonal comparisons f o r the DI means under the PFB c o n d i t i o n were s i g n i f i c a n t and i f the DI means increased as the DI in c r e a s e d . Hypothesis (3) would have been supported i f the planned com-p a r i s o n t e s t i n g the i n t e r a c t i o n between PFB and DI was s i g n i f i c a n t and i f the mean tim i n g e r r o r s from the two dependent measures were s i g n i f i -c a n t l y l e s s under the PFB c o n d i t i o n than the mPFB-control c o n d i t i o n a t short DIs but were not s i g n i f i c a n t l y l e s s under the PFB c o n d i t i o n than the mPFB-control c o n d i t i o n at very long i n t e r v a l s . (A very long DI has not been determined i n t h i s experimental context as yet but i t may be though of t h e o r e t i c a l l y as any time d u r a t i o n beyond which the decay mechanism does not f u n c t i o n . ) Hypothesis (A) would have been supported i f the planned comparisons f o r DI under the PFB c o n d i t i o n were s i g n i f i c a n t and i f the mean t i m i n g e r r o r s from the two dependent measures i n c r e a s e as the l e n g t h of the DI incre a s e s under the PFB c o n d i t i o n ; and more s p e c i f i c a l l y , i f t h i s i n c r e a s e i s an i n c r e a s i n g , p o s i t i v e l y a c c e l e r a t e d f u n c t i o n of time (the l e n g t h of the DI) under the c o n d i t i o n , of course, t h a t the PFB main e f f e c t i s s i g n i f i c a n t . Furthermore, by running an asymptotic r e g r e s s i o n a n a l y s i s on a l l of the i n d i v i d u a l raw scores w i t h i n the c r i t e r i o n t r i a l s over each of the DIs f o r the PFB c o n d i t i o n , i t was shown j u s t how w e l l an i n c r e a s i n g , p o s i t i v e l y a c c e l e r a t e d f u n c t i o n f i t the p a r t i c u l a r data from the experiment. Chapter 4 RESULTS AMD DISCUSSION Slide Time Analysis ANOVA on Slide Time. In a 2 x 5 x 50 fact o r i a l ANOVA with repeated measures (Table 4.1) only the S(DP) term was significant (F = 133, p < 0.01 for 20 and 980 d.f.). This slide time analysis demonstrated that even though there were no differences between the PFB and DI conditions on slide time there were differences within cells leading to the possib i l i t y that different levels and consistencies of PFB were being placed into STM for each S. These factors were hypothe-sized to influence timing accuracy by Schmidt (1971), who stated that timing accuracy varies in proportion to the level and consistency of PFB. If these two factors were not constant for Ss over conditions they might have influenced the timing accuracy over conditions irrespec-tive of the experimental conditions (in which these two factors were to have remained constant). Slide Time Versus Accuracy and Consistency. The correlations for the mean of the slide time for each S in the PFB condition against his own absolute error and within-S v a r i a b i l i t y were -0.28 and -0.24 respectively; moreover, the correlations for the SD of slide time for each S in the PFB condition against his own absolute error and within-S v a r i a b i l i t y were -0.03 and -0.05 respectively none of which were s i g n i f i -cant (as an r = 0.514, d.f. = 13 was needed for significance at the 0.05 37 38 Table 4.1. A 2 x 5 x 50 F a c t o r i a l ANOVA with. Repeated Measures on the Last F a c t o r f o r S l i d e Time. Source of V a r i a t i o n SS df MS F P Delay I n t e r v a l (D) 2.019 4 0.5050 1.51 -PFB (P) 0.414 1 0.4150 1.24 -T r i a l s (T) 0.136 49 0.0030 1.11 -DP 3.192 4 0.7980 2.38 -DT 0.558 196 0.0028 1.13 -PT 0.127 49 0.0026 1.03 -S(DP) 6.676 20 0.3338 133.11 <0.01 DPT 0.471 196 0.0024 - -ST(DP) 2.458 980 0.0025 _ 39 l e v e l ) . These c o r r e l a t i o n s determined that n e i t h e r the amount nor con-s i s t e n c y of an S's i n i t i a l movement was r e l a t e d to h i s accuracy of t i m i n g ; and second, determined that n e i t h e r the amount nor c o n s i s t e n c y of an S's i n i t i a l movement was r e l a t e d to h i s c o n s i s t e n c y of t i m i n g . I f the o r i g i n a l s u p p o s i t i o n of t h i s t h e s i s t s t e n a b l e , that v a r y i n g amounts and v a r y i n g c o n s i s t e n c i e s of PFB (as shown by the means and SDs of s l i d e time) i n f l u e n c e the accuracy and c o n s i s t e n c y of t i m i n g f o r an S w i t h i n the PFB c o n d i t i o n , the v a r i a t i o n i n the amount and c o n s i s t e n c y of PFB must have been n e g l i g i b l e f o r an S as none of the aforementioned r e l a t i o n s h i p s approached s i g n i f i c a n c e . S l i d e Time F i x e d . Since the above a n a l y s i s has demonstrated th a t the s l i d e time was f o r a l l i n t e n t s and purposes constant over a l l Ss and c o n d i t i o n s , the s l i d e time was f i x e d f o r the procedure s e c t i o n at the grand mean 3.22 seconds w i t h a v a r i a t i o n of + 0.05 seconds (as determined by the mean SD of the Ss' s l i d e t i m e ) . Learning and C r i t e r i o n T r i a l s A 2 x 5 x 50 f a c t o r i a l ANOVA w i t h repeated measures on the l a s t f a c t o r ( t r i a l s ) demonstrated a s i g n i f i c a n t t r i a l s e f f e c t (F = 14.99, p < 0.01 f o r 49 and 980 d.f.) on absolute e r r o r which i n d i c a t e d as shown i n Figure. 4.1 to F i g u r e 4.10 that l e a r n i n g d i d I n f a c t occur over t r i a l s as expected. A f u r t h e r i n s p e c t i o n of the mean abso l u t e e r r o r graphed f o r each consecutive t r i a l and each consecutive b l o c k of f i v e t r i a l s under each experimental c o n d i t i o n CFigure 4.1 to F i g u r e 4.10) showed that l e a r n i n g had ceased a f t e r the f i r s t ten t r i a l s and that no more l e a r n i n g had occurred over the l a s t 40 t r i a l s . On the other hand, the t r i a l s 40 to go o ft0 So go S 0 UJ 3 ° CC 0 0 -0 .10-3 .09-= .03 .07-3 .06 .05-; .04-1 . 0 3 4 .02-E .01-j .00 I I I I I I I I I I I I I I I I I I I I I I I I 10 20 i i i i I i i i i i i 30 TRIALS i i I i i i i i i i i i I 40 50 FIG. 4.1 PLOTS OF THE ABSOLUTE ERROR OVER TRIALS AND BLOCKS OF 5 TRIALS FOR THE PFB-0.3 SECOND CONDITION 41 m : g 0.10-co : zz. 0.08T cc 0.07-j o oE 0.06 UJ -£ 0.05-j §0.04-= to : £ 0.03^ 0.02-j 0.01-| -0.00 i i i i i i i i i j i i i i i i i i i | i i i i i i i i i | i i i i \ i i i i | i ' i i i i ' i ' | 10 20 30 40 50 TRIALS 0. co 9 0. o n UJ u. to cc 0. o £o U J £» 0. £o o. 0. -0. 11-1 0 1 09 4 08 -j 0 7 1 06-j 05-1 04-: 03-j 0 2 i 01-: 00 J - I 2 1 1 r 4 5 6 7 BLOCKS OF 5 TRIALS 1 10 FIG. 4.2 PLOTS OF THE ABSOLUTE ERROR OVER TRIALS AND BLOCKS OF 5 TRIALS FOR THE MPFB-0.3 SECOND CONDITION 42 gO.35-3 o U J i n 0 . 3 0 H g0.2SH Q : ^0.20-1 0 . 0 5 H -0.00 - | i i i i t t r i » i i i i i i i i i i i i » i i i i i » i ( i r r I » > t i i i i i11 i i i i i i l 10 20 30 40 50 TRIALS F I G . 4 . 3 P L O T S O F T H E A B S O L U T E E R R O R O V E R T R I A L S AND B L O C K S O F 5 T R I A L S F O R T H E PFB-0.6 S E C O N D C O N D I T I O N 43 0.43 -to -o gO.35 — o " 0 . 3 0 z gO.25 -as • S 0 . 2 0 UJ 3 0.15 c? Jo CQ • tt 0.10 0.05 -0 .00 — _ l T I l I I I i i [ i i i t i i i i i | i r i r r T i i i | t t i i i i i i i | i i i i i i t i i | 10 20 30 40 50 TRIALS 0.40 a o o UJ t o 0.35 0 . 3 0 H g 0 . 2 5 - 3 ae ^ 0 . 2 0 - 3 UJ § 0 . 1 5 - 3 ° = 0 . J 0 H 0.05 -j - 0 .00 T 2 3 1 1 1 r 5 6 7 8 BLOCKS OF 5 TRIALS 1 10 FIG. 4 . 4 PLOTS OF THE ABSOLUTE ERROR OVER TRIALS AND BLOCKS OF 5 TRIALS FOR THE MPFB-0.6 SECOND CONDITION 44 Io o 5 n 3 ° §o CX 0 0 -0 .50 .45-. .35-j .30 .25-f • 20- i • 15-j .10-j .05-j 00 » r i t T i i i i i r r r r r i i i i i i i i i i i i i i i i i i i i 10 20 30 TRIALS "I* 40 i i t i t I 50 0 . S 0 -to * § 0 . 4 5 Q U J 0 . 4 Q to • 5 0 . 3 5 o 0 . 3 0 ^ 0 . 2 5 — UJ • § 0 . 2 0 o S O . 1 5 cc • 0 . 1 0 0 . 0 5 - 0 . 0 0 : T 2 3 i 1 r 4 5 6 7 BLOCKS OF 5 TRIALS 8 T 9 ~1 1 0 F I G . 4.5 P L O T S O F T H E A B S O L U T E E R R O R O V E R T R I A L S AND B L O C K S O F 5 T R I A L S F O R T H E P F B - 1 . 0 S E C O N D C O N D I T I O N 45 0.65-q TRIALS 0.65-a | 0 . 6 0 - j § 0 . 5 5 - = & 0 . S H 50.45^ g 0 . 4 H S 0.35-i UJ • uj 0.30 § 0 . 2 5 - 1 § 0 . 2 0 - j " o . l S - j 0.10-: 0.05 -j -0 .00 J - T 2 T" 4 T 5 6 T -x-T 8 10 BLOCKS OF 5 TRIALS F I G . 4 . 6 P L O T S O F T H E A B S O L U T E E R R O R O V E R T R I A L S AND B L O C K S O F 5 T R I A L S F O R T H E MPFB-1.0 S E C O N D C O N D I T I O N 46 z ~ 0 OS So So BO CQ <= 0 0 0 - 0 ,20 -a .10 A .00 4 • s o i .eon .70 -j .60 -f .50-j .^0-j .30 -j • 2 0 i .10-1 .00 J i t i i i i t i i I c t r i i r r t > [ t i i i I i t i i | i i i r i i r i i | i i r i i i i I i { 10 2 0 3 0 4 0 5 0 TRIALS 1.20-a § 1 . 1 0 - 1 ^ 0 . 9 0 - j * O . E O - j I 0 . 7 0 - I ^ O . S H UJ 5 0 . 5 0 H c c o . 3 0 - : 0 . 2 0 - j o.io-i - 0 . 0 0 J 2 3 4 5 T 6 I 8 1 10 BLOCKS OF 5 TRJfiLS FIG. 4.7 PLOTS OF THE ABSOLUTE ERROR OVER TRIALS AND BLOCKS OF 5 TRIALS FOR THE PFB-2.0 SECOND CONDITION 47 1 - 2 0 -2 i.io-I TRIALS 1.20-8 1.OC 4 U J ^ 0 . 9 0 -i * 0.804 1 0.70-i ^0 .60- i 50 .50- i = 0.30-: 0.20-1 0.10 -j -o.oo J - T 2 T 3 4 5 T" 6 T 7 6 T 9 1 10 SLOCKS OF 5 TRIALS FIG. 4.8 PLOTS OF THE ABSOLUTE ERROR OVER TRIALS AND BLOCKS OF 5 TRIALS FOR THE MPFB-2.0 SECOND CONDITION 2.<0-a §2.20-! §2-001 « 1 - 6 0 1 I J . « H or : u 1.20-: H J .00-j go.HH 0.60-i 0.40-j 0.20-j -0.00 J - 2 nr 3 T~ 4 T 5 6 7 T" 8 T" 9 10 BLOCKS Of 5 TRIALS FIG. 4.9 PLOTS OF THE ABSOLUTE ERROR OVER TRIALS AND BLOCKS OF 5 TRIALS FOR THE PFB-4.0 SECOND CONDITION 49 2 . 4 3 - a i n : 0 2 . 2 0 -; 3 2 . 0 0 H UJ ^ l . B O - j ~ 1.604 1 1 . 4 H u 1.20-^ UJ 5 1.00-j § 0 . 8 0 - 1 = 0 . 6 0 -1 0.4) - j 0 . 2 0 -i - 0 . 0 0 J - 2 J 4 5 6 T " 7 8 9 "1 10 S L O C K S OF 5 T R I A L S TRIALS SECOND FIG. 4.10 PLOTS OF THE ABSOLUTE ERROR OVER AND BLOCKS OF 5 TRIALS FOR THE MPFB-4.0 CONDITION 50 e f f e c t from a 2 x 5 x 40 f a c t o r i a l ANOVA w i t h repeated measures on the l a s t f a c t o r (Table 4.2) f o r a b s o l u t e e r r o r was j u s t p o s s i b l y s i g n i f i c a n t (F = 1.42, p ~ 0.05 f o r 39 and 780 d . f . ) ; however, t h i s p o s s i b l e source of c o n t r a r y s i g n i f i c a n c e was not f e l t to be a t t r i b u t e d to l e a r n i n g i n the l a s t 40 t r i a l s but r a t h e r to the extreme f l u c t u a t i o n s i n the abso l u t e e r r o r t h e r e i n . When the abso l u t e e r r o r over 40 t r i a l s f o r each S was grouped i n t o b l o c k s of f i v e t r i a l s to reduce the extreme f l u c t u a t i o n s t h e r e i n , a 2 x 5 x 8 f a c t o r i a l ANOVA w i t h repeated measures on the l a s t f a c t o r (blocks of f i v e t r i a l s ) produced no s i g n i f i c a n t t r i a l s e f f e c t on absolute e r r o r , thus supporting the conte n t i o n that no l e a r n i n g had taken p l a c e over the l a s t 40 t r i a l s and that the p r i o r s t a t i s t i c a l s i g n i f i c a n c e f o r the a n a l y s i s over t r i a l s was due to extreme f l u c t u a t i o n s i n the i n d i v i d u a l t r i a l s . A l l subsequent analyses consequently were run on the c r i t e r i o n t r i a l s , t r i a l s 11-50 where l e a r n i n g was no longer o c c u r r i n g . Analyses of Absolute E r r o r and Within-S V a r i a b i l i t y Hypothesis (1). The main e f f e c t (PFB) was n e i t h e r s i g n i f i c a n t f o r the ANOVA on absolute e r r o r (Table 4.2) nor f o r the ANOVA on w i t h i n - S v a r i a b i l i t y (Table 4.3). The marginal means f o r both absolute e r r o r (Table 4.4) and w i t h i n - S v a r i a b i l i t y (Table 4.5); moreover, were h i g h e r f o r the PFB than f o r the mPFB c o n d i t i o n w i t h o n l y the 0.3 second c e l l mean f o r the PFB c o n d i t i o n being l e s s than t h a t f o r the mPFB c o n d i t i o n as p r e d i c t e d . This evidence was d e f i n i t e l y n egative and derogatory to the decay hypothesis: that g r e a t e r l e v e l s of PFB placed In memory i n c r e a s e the accuracy and co n s i s t e n c y of t i m i n g motor responses as shown by Quesada 51 Table 4.2. Planned Comparisons: A 2 x 5 x 40 F a c t o r i a l ANOVA w i t h Repeated Measures on the Last F a c t o r f o r Absolute E r r o r . Source of V a r i a t i o n SS df MS F P PFB (P) 0.0506 1 0.0506 Comparisons: 1 1.5190 1 1.5190 25.40 < 0.01 2 1.2781 1 1.2781 21.37 < 0.01 3 1.4770 1 1.4770 24.69 < 0.01 4 1.4484 1 1.4484 24.22 < 0.01 5 0.0194 1 0.0194 - -6 0.0009 1 0.0009 - -7. 0.0013 1 0.0013 - -8 0.0113 1 0.0113 - -T 0.7716 39 0.0198 1.42 0.05 DT 2.5274 156 0.0162 1.16 -PT 0.6363 39 0.0163 1.17 -S(DP) 1.1962 20 0.0598 4.30 < 0.01 DPT 3.2538 156 0.0209 1.49 < 0.05 ST(DP) 10.8575 780 0.0139 - -52 Table 4.3. Planned Comparisons: A 2 x 5 F a c t o r i a l ANOVA on Within-S V a r i a b i l i t y . Source of V a r i a t i o n SS df MS F P PFB (P) 0.00209 1 0.00209 1.19 Comparisons: 1 0.05152 1 0.05152 29.37 < 0.01 2 0.03792 1 0.03792 21.62 < 0.01 3 0.03733 1 0.03733 21.28 < 0.01 4 0.03281 1 0.03281 18.70 < 0.01 5 0.00096 1 0.00096 - -6 0.00000 1 0.00000 - -7 0.00011 1 0.00011 - -8 0.00084 1 0.00084 S(DP) 0.03508 20 0.001754 53 Table 4.4. Cell and Marginal Means for Absolute Error under PFB and DI Conditions in Seconds. ..•.•.•.Dt'.': PFB :—: • : MARGINAL 0.3 0.6 1.0 2.0 4.0 PFB 0.0391 0.0756 0.1040 0.1622 0.3176 0.1397 mPFB 0.0421 0.0620 0.0897 0.1325 0.3072 0.1267 MARGINAL 0.0406 0.0688 0.0969 0.1473 0.3124 0.1332 Table 4.5. Cell and Marginal Means for Within-S Variability under PFB and DI Conditions in Seconds. DI PFB MARGINAL 0.3 0.6 1.0 2.0 4.0 PFB 0.0443 0.0936 0.1321 0.1948 0.3427 0.1615 mPFB 0.0503 0.0718 0.1027 0.1589 0.3403 0.1448 MARGINAL 0.0473 0.0827 0.1174 0.1769 0.3415 0.1532 54 and Schmidt (1970) since the PFB condition displayed no s i g n i f i c a n t d i f f e r e n t i a l e f f e c t on e i t h e r the accuracy or consistency of timing. Both the accuracy and consistency of timing tended to decrease, although not s i g n i f i c a n t l y , with increased PFB i n contravention of the p r e d i c t i o n from the decay hypothesis. Consequently, hypothesis (1) stood unsub-st a n t i a t e d i n the l i g h t of the r e s u l t s . Hypothesis (2). A l l the planned comparisons 1-4 (Table 3.2) f o r the DI means were s i g n i f i c a n t at the 0.01 l e v e l of s i g n i f i c a n c e f o r both absolute e r r o r (Table 4.2) and within-S v a r i a b i l i t y (Table 4.3). As predicted, the means f o r absolute e r r o r (Table 4.4) and within-S v a r i a b i l i t y (Table 4.5) under the PFB condition increased as the DIs increased from 0.3 to 4.0 seconds. This evidence s u p e r f i c i a l l y supported hypothesis (2) that under heightened PFB, motor responses at shorter i n t e r v a l s are timed be t t e r than at longer i n t e r v a l s . This was demonstrated by the increased absolute e r r o r and within-S v a r i a b i l i t y with the increased length of the DIs i n d i c a t i n g that both the accuracy and consistency of timing motor responses decreased with the increased length of the DI. Inspired by an a p o s t e r i o r i inspection of the DI c e l l means under mPFB which i n d i c a t e d a s i m i l a r trend to that f or the means under PFB, a Scheffe test (Hays, 1963; Scheffe, 1959; and Winer, 1971) f o r an i d e n t i c a l set of comparisons on these means was performed to v e r i f y the s i m i l a r i t y . The a n a l y s i s showed that comparisons 3 and 4 (Table 3.2) and the comparison of the d i f f e r e n c e between the 0.3 and the 4.0 second means were s i g n i f i c a n t f o r absolute error with differences of 0.122, 0.147, and 0.147 being required f o r s i g n i f i c a n c e at the 0.05 l e v e l and 55 with differences of -0.130, -0.175 and -0.265 being obtained r e s p e c t i v e l y . I d e n t i c a l comparisons on within-S v a r i a b i l i t y showed that comparisons 2-4 (Table 3.2) and the comparison of the di f f e r e n c e between the 0.3 and the 4.0 second means were s i g n i f i c a n t with d i f f e r e n c e s of 0.129, 0.137, 0.158 and 0.158 seconds being required f o r s i g n i f i c a n c e at the 0.5 l e v e l and with d i f f e r e n c e s of -0.129, -0.147, -0.181 and -0.290 being obtained r e s p e c t i v e l y . This l a t e r evidence i n d i c a t e d that absolute e r r o r and within-S v a r i a b i l i t y Increased s i g n i f i c a n t l y as the DI i n -creased as shown by the Scheffe analysis on the DI means under mPFB— a r e s u l t almost i d e n t i c a l to that found for the DI means under PFB. This demonstrated that both the accuracy and consistency of timing motor responses decreased s i g n i f i c a n t l y over the range of DIs for the mPFB condition as i t did f o r the PFB condition. Coupled with the fac t that the e f f e c t of PFB on timing was i n s i g n i f i c a n t , t h i s l e d to the formulation that the e f f e c t of the DI appeared to be independent of the decay hypothesis and dependent s o l e l y on time. Even though the accuracy and consistency of timing decreased with increased DIs (as predicted f o r the PFB con d i t i o n ) , t h i s support for hypothesis (2) was deemed s u p e r f i c i a l i n l i e u of the post hoc analyses on the DI means under the mPFB condition as they also decreased with increased DIs under t h i s (mPFB) condition i n which no decay mechanism could be operating. This confirmed that PFB appeared not to be an instrumental f a c t o r i n the decreased accuracy arid consistency of timing as the DI increased but rather that time I t s e l f was the important f a c t o r i n the accuracy and consistency of timing motor responses. 56 Hypothesis ( 3 ) . The planned comparisons 5-8 (Table 3.3) designed to t e s t the i n t e r a c t i o n between the PFB and the DI c o n d i t i o n s were i n s i g n i f i c a n t f o r both absolute e r r o r (Table 4.2) and w i t h i n - S v a r i a b i l i t y (Table 4.3); moreover, as p r e v i o u s l y mentioned the PFB main e f f e c t was i n s i g n i f i c a n t f o r b o t h the abs o l u t e e r r o r and the wi t h i n - S v a r i a b i l i t y . Consequently, Hypothesis ( 3 ) ; that the t i m i n g of motor responses i s more accurate and c o n s i s t e n t at short DIs under PFB than under mPFB, but i s timed w i t h e q u i v a l e n t accuracy at longer i n t e r v a l s under e i t h e r c o n d i t i o n , was not v e r i f i e d by the present experimental r e s u l t s . F i r s t , there were no s i g n i f i c a n t d i f f e r e n c e s between the PFB and mPFB c o n d i t i o n s under the l e v e l s of DI and second, no i n t e r a c t i o n s occurred to v e r i f y the p r e d i c t e d outcomes. Hypothesis ( 4 ) . As mentioned e a r l i e r under Hypothesis ( 2 ) , the planned comparisons f o r the DIs under the PFB c o n d i t i o n were s i g n i f i c a n t f o r both absolute e r r o r and w l t h i n - S v a r i a b i l i t y , moreover, the means showed s i g n i f i c a n t i n c r e a s e s over the range of DIs as pr e -d i c t e d . On the other hand, the e f f e c t of PFB was not s i g n i f i c a n t and the trends d e s c r i b e d by the DI means f o r the PFB and mPFB c o n d i t i o n s were i d e n t i c a l . Even though the accuracy and con s i s t e n c y decreased w i t h i n c r e a s e d DIs as p r e d i c t e d , t h i s was not c o n c l u s i v e evidence i n support of Hypothesis (4) s i n c e the same trend was evident i n the same magnitude f o r the mPFB as I t was f o r the PFB c o n d i t i o n (Table 4.4 and Table 4.5). The r e s u l t s i n d i c a t e that the l e v e l of PFB played no r o l e i n the t i m i n g of motor responses and had no par t i n the trend developed f o r the t i m i n g of motor responses under i n c r e a s i n g DIs s i n c e the decay mechanism could not be ope r a t i n g under the mPFB c o n d i t i o n . 57 No apparent d i f f e r e n c e s e x i s t e d between the PFB and the mPFB c o n d i t i o n s under DIs. Consequently, the trends f o r bo t h a b s o l u t e e r r o r and w i t h i n - S v a r i a b i l i t y a g ainst time ( l e n g t h of the DI) were analyzed using the DI marginal means (with, the e f f e c t of PFB-mPFB pooled). L i n e a r r e g r e s s i o n analyses i n the l i n e a r mode w i t h untrans-formed data; and w i t h l o g - l i n e a r and l o g - l o g transformed data were used to determine the best f i t t i n g curves f o r the data s e t s . The best f i t t i n g curves f o r both w i t h i n - S v a r i a b i l i t y (Table 4.6) and absolute e r r o r (Table 4.7) were l o g - l o g f u n c t i o n s of time as shown by the curve f i t to the w i t h i n - S v a r i a b i l i t y data p o i n t s (Figure 4.11) and the curve f i t to the absolute e r r o r data p o i n t s (Figure 4.12). The equation f o r the absolute e r r o r took the form Y = 0.0968 X 0 ' 7 5 w h i l e the equation f o r w i t h i n - S v a r i a b i l i t y took the s i m i l a r form Y = 0.113 X 0' 7 1* where Y was e i t h e r absolute e r r o r or w i t h i n - S v a r i a b i l i t y and X was time (the le n g t h of DI) both i n seconds. Both of these equations, by the way, were i n c r e a s i n g , n e g a t i v e l y a c c e l e r a t e d e x p o n e n t i a l f u n c t i o n s of time. Hypothesis (4) s t a t e d that the accuracy and c o n s i s t e n c y of t i m i n g motor responses are i n c r e a s i n g , p o s i t i v e l y a c c e l e r a t e d f u n c t i o n s of time i n c o n t r a d i c t i o n to the r e s u l t a n t experimental trends. This added another l i n e of negative evidence to r e f u t e Hypothesis ( 4 ) . Consequently, Hypothesis (4) stood u n s u b s t a n t i a t e d . Comment on Hypotheses. None of the four hypotheses d e r i v e d from the Adams-Creamer decay hypothesis of t i m i n g f o r motor responses were c o n c l u s i v e l y s u b s t a n t i a t e d by the present experimental r e s u l t s , s i n c e a l l of them were based on the s i g n i f i c a n t e f f e c t of PFB which, 58 FIG. 4.11 WITHIN-S VARIABILITY FOR EACH S AGAINST TIME ILENGTH OF DI) IN SECONDS, WITH LOG-LOG CURVE FIT FIG. 4.12 MEAN ABSOLUTE ERROR FOR EACH S AGAINST TIME (LENGTH OF DI) IN SECONDS, WITH LOG-LOG CURVE FIT 60 Table 4.6. ANOVA Tables f o r L i n e a r , L o g - l i n e a r and Log-log Least Squares F i t s f o r Within-S V a r i a b i l i t y VS Delay I n t e r v a l s LINEAR FIT r = 0.94, r 2 = 0.89 Source of V a r i a t i o n df SS MS Due to Regression D e v i a t i o n about Regression T o t a l 28 0.3195 0.0405 29 0.3600 0.3195 0.0015 220.9 LOG-LINEAR FIT r = 0.91, r z = 0.82 Source of V a r i a t i o n df SS MS Due to Regression D e v i a t i o n about Regression T o t a l 28 2.327 0.511 29 2.838 2.327 0.018 127.3 LOG-LOG FIT r = 0.95, r 2 = 0.90 Source of V a r i a t i o n df SS MS Due to Regression D e v i a t i o n about Regression 28 2.559 0.280 2.559 0.Q10 255.9 T o t a l 29 2.838 61 Table 4.7. ANOVA Tables f o r L i n e a r , L o g - l i n e a r and Log-log Least Squares F i t s f o r Absolute E r r o r VS Delay I n t e r v a l s LINEAR FIT r = 0.94, r 2 = 0.89 Source of V a r i a t i o n df SS MS Due to Regression 0.276 0.276 227 D e v i a t i o n about Regression 28 0.034 0.001 T o t a l 29 0.310 LOG-LINEAR FIT r = 0.92, r 2 = 0.85 Source of V a r i a t i o n df SS MS F Due to Regression 1 2.51 2.51 162 D e v i a t i o n about 2 g Q > 4 3 Regression T o t a l 29 2.94 t LOG-LOG FIT r = 0.95, r 2 = 0.91 Source of V a r i a t i o n df SS MS F Due to Regression 1 2.68 2.68 285 D e v i a t i o n about „„ _ n „„„ „ , 28 0.26 0.009 Regression T o t a l 29 2.94 62 as shown e a r l i e r , d i d not m a t e r i a l i z e as p r e d i c t e d . The r e s u l t s of t h i s experiment then, with, respect to the e f f e c t of PFB and t i m i n g accuracy, are c o n t r a r y to those e f f e c t s found by Quesada and Schmidt (1970) who showed that i n c r e a s e d PFB improved the ti m i n g of motor responses f o r a 2.0 second DI. One f a c t o r may have become confounded w i t h the experimental manipulation of PFB. The sound from the motor acted c o n c u r r e n t l y w i t h the e f f e c t of PFB i n the PFB c o n d i t i o n and w i t h the e f f e c t of the minimal PFB i n the mPFB c o n d i t i o n . This sound might have provided a source of feedback which could have been placed i n t o memory to form a decaying t r a c e s i m i l a r to that proposed f o r the PFB c o n d i t i o n . Con-sequently, the PFB c o n d i t i o n would have been confronted w i t h two competing sources of t r a c e decay whereas the mPFB c o n d i t i o n would have only r e c e i v e d the t r a c e decay from the sound of the motor. With t h i s i n mind, the a l g e b r a i c e r r o r was analyzed to determine i f i t might shed some l i g h t on the p o s s i b l e i n f l u e n c e of t h i s sound on the t i m i n g of motor responses. In the subsequent a n a l y s i s of a l g e -b r a i c e r r o r , the e f f e c t of the PFB was s i g n i f i c a n t (F = 5.98, p < 0.025 f o r 1 and 20 df) and the i n t e r a c t i o n between PFB and DI was s i g n i f i c a n t (F = 3.82, p < 0.025 f o r 4 and 20 df.) as shown i n a 2 x 5 x AO f a c t o r i a l ANOVA w i t h repeated measures on the l a s t f a c t o r (Table 4.8). These two f a c t s along w i t h the a l g e b r a i c mean f o r the PFB and mPFB sub j e c t s (Table 4.9) and the p l o t of these means (Figure 4.13) I n d i c a t e d that there was a d i f f e r e n c e In the way In which the PFB and mPFB c o n d i t i o n s responded and that the manner of responding changed w i t h the inc r e a s e d l e n g t h of the DIs. What f a c t o r s might e x p l a i n these r e s u l t s ? This question brought back the t r a c e (from the sound of the motor) as a 63 FIG. 4.13 PLOT OF ALGEBRAIC'ERROR VERSUS TIME (LENCTH OF DIJ IN SECONDS FOR THE PFB AND MPFB CONDITIONS 64 Table 4.8. A 2 x 5 x 40 F a c t o r i a l ANOVA w i t h Repeated Measures on the Last F a c t o r f o r A l g e b r a i c E r r o r . Source of V a r i a t i o n SS df MS F P Delay I n t e r v a l (D) 0.3235 4 0.08205 - -PFB (P) 1.2833 1 1.28992 5.98 < 0.025 T r i a l s (T) 1.5267 39 0.03915 1.04 -DP 3.2717 4 0.82421 3.82 < 0.025 DT 5.6701 156 0.03635 - -PT 1.2046 39 0.03888 - -S(DP) 4.3153 20 0.21577 5.75 < 0.01 DPT 4.8747 156 0.03125 - -ST (DP) 29.2731 780 0.03752 _ — 65 Table 4.9. C e l l and M a r g i n a l Means f o r A l g e b r a i c E r r o r under PFB and DI Cond i t i o n s i n Seconds. DI PFB — : — MARGINAL 0.3 0.6 1.0 2.0 4.Q PFB -0.0172 -0.0290 0.0152 0.0288 0.1593 0.0314 mPFB -0.0160 -0.0117 -0.0191 -0.0127 -0.1100 -0.0340 MARGINAL -0.0166 -0.0203 -0.0019 0.0080 0.0245 -0.0013 66 p o s s i b l e answer. The unhindered t r a c e h y p o t h e t i c a l l y produced by the sound of the motor could have been used to develop the improved t i m i n g of the mPFB over the PFB c o n d i t i o n which had to dea l w i t h the two c o n f l i c t i n g t r a c e s at the same time. The c e l l means f o r abs o l u t e e r r o r (Table 4.4) and w i t h i n - S v a r i a b i l i t y (Table 4.5) tended to co n f i r m t h i s ; being lower f o r the mPFB than the PFB c o n d i t i o n under the l a s t f o u r DIs, even though the d i f f e r e n c e s were not s i g n i f i c a n t . Furthermore i n F i g u r e 4.13, the a l g e b r a i c e r r o r f o r the mPFB c o n d i t i o n remained f a i r l y con-sta n t over the f i r s t four DIs and then decreased c o n s i d e r a b l y f o r the 4.0 second DI. This e f f e c t would have been expected from the decay hypothesis which i m p l i e s that a l g e b r a i c e r r o r should remain constant over DIs w i t h i n the f u n c t i o n a l l i m i t s of the mechanism. The great i n c r e a s e at the 4.0 second DI could have been due to the n o n - f u n c t i o n a l i t y of the mechanism at that (extreme) l e n g t h of the DI. The undershooting trend a t a l l the DIs f o r the mPFB c o n d i t i o n might have been due t o the r e l u c t a n c e of i n d i v i d u a l s to respond l a t e . On the other hand, the PFB c o n d i t i o n had to cope w i t h two sources of c o n f l i c t i n g t r a c e decay: one from the sound of the motor, and one from the arm movement. I f the t r a c e s i n t e r f e r r e d w i t h each ot h e r , i t might be expected that the i n t e r f e r e n c e would i n c r e a s e as the t r a c e s became l e s s d i s t i n c t . ( I t would be more d i f f i c u l t to d i s t i n g u i s h between the cues from e i t h e r t r a c e when they had grown weak.) . Thus at short i n t e r v a l s as shown i n Fi g u r e 4.13, t i m i n g should be s i m i l a r to that f o r the mPFB c o n d i t i o n as both s e t s of cues would be d i s t i n c t i v e ; however, at longer i n t e r v a l s the cues would not be so d i s t i n c t i v e and ti m i n g would be a l t e r e d . Perhaps as the cues from the two tr a c e s became l e s s d i s t i n c t and the 67 i n t e r f e r e n c e i n c r e a s e d between them, the i n t e r n a l m o b i l i z a t i o n time f o r the t i m i n g response would Increase. Consequently, the i n c r e a s e d over-shooting f o r the PFB c o n d i t i o n as shown i n FLgure 4.13 would be accounted f o r by the combined e f f e c t of the proposed d u a l - t r a c e . Post hoc i n t e r p r e t a t i o n s of the above nature are always prone to the b i a s e s of the author and of the p a r t i c u l a r , s p e c i f i c set of experimental r e s u l t s ; moreover, they tend to be strewn w i t h convenient assumptions which may not be, i n f a c t , t r u e . For these reasons the foregoing e x p o s i t i o n was not meant to supply experimental support f o r the decay h y p o t h e s i s ; but r a t h e r , to i n d i c a t e that the PFB f a c t o r might not have been given much of a chance to manifest i t s e l f i n t h i s experiment because of the p o s s i b l e i n f l u e n c e of the sound of the .motor running c o n c u r r e n t l y w i t h the arm movement producing PFB. The i m p l i -c a t i o n here i s that i n other experiments of t h i s n a t u r e , the e f f e c t of other f a c t o r s , which may produce s i g n i f i c a n t source of t r a c e decay, must be e l i m i n a t e d . E f f e c t of DI on Timing. As shown i n both Hypothesis (2) and ( 4 ) , the only h i g h l y s i g n i f i c a n t e f f e c t was that found f o r the l e n g t h of the DI. In Hypothesis (4) i t was shown, moreover, t h a t both absolute e r r o r and w i t h i n - S v a r i a b i l i t y were l o g - l o g or power f u n c t i o n s of time (l e n g t h of D I ) ; consequently, the g r e a t e r the time to be estimated the l e s s the accuracy and c o n s i s t e n c y of the estimate. I f the decay mechanism i s not a v a i l a b l e to e x p l a i n t h i s outcome through the exponen-t i a l d e c l i n e i n r e l e v a n t cues as i n d i c a t e d by the o v e r a l l n e gative r e s u l t s f o r the hypotheses, then what source of e x p l a n a t i o n i s a v a i l a b l e ? Michon (1967) found t h i s p a r t i c u l a r r e l a t i o n s h i p between the w i t h i n - S 68 v a r i a b i l i t y and the time between taps i n a tapping sequence. He f e l t that the r e l a t i o n s h i p might be due e i t h e r to the i n e f f i c i e n c y of s t o r i n g a standard or to a c o n s i d e r a b l e decay f a c t o r a c t i n g upon the standard i n memory. The l a t t e r was not r e l e v a n t here as the e f f e c t i v e standard (KR on the l a s t estimate) had the same approximate time decay CDI p l u s the 30 second i n t e r t r i a l i n t e r v a l ) f o r each DI. Thus, i t d i d not present a v a r i a b l e e f f e c t to account f o r e i t h e r the accuracy or c o n s i s t e n c y of t i m i n g obtained. The i n e f f i c i e n t s t o r i n g of longer standards might have accounted f o r the decreased accuracy and c o n s i s t e n c y of the t i m i n g estimates w i t h the i n c r e a s e d l e n g t h of the standard but e x a c t l y how t h i s mechanism was hypothesized to f u n c t i o n was never e l u c i d a t e d f u r t h e r by Michon. Considering t h a t the accuracy and consistency of a second motor response are a power f u n c t i o n of the time between the responses, the s m a l l e r the time delay between the two responses the more accurate and c o n s i s t e n t they should be. Assuming t h a t the above r e l a t i o n s h i p holds f o r the s e q u e n t i a l components of a motor response or whole motor s k i l l , the f a s t e r the s e q u e n t i a l components are run o f f , the b e t t e r the accuracy and consistency of the t i m i n g between the components of the motor s k i l l , and consequently the more p r e c i s e the nature of the s k i l l . F a s t e r movements, then, should be more p r e c i s e than slower movements a f t e r l e a r n i n g has occurred. Chapter 5 SUMMARY AND CONCLUSIONS Summary The b a s i c problem was to a s c e r t a i n the e f f e c t of PFB (developed from an i n i t i a l movement) and the e f f e c t of time d e l a y (between the te r m i n a t i o n of the i n i t i a l movement and the beginning of the f o l l o w i n g motor response) on the temporal accuracy and c o n s i s t e n c y of th a t motor response. This comprized a t e s t of the Adams-Creamer decay hypothesis f o r the t i m i n g of motor responses i n which four p r e d i c t i o n s were conse-quently t e s t e d from i t . The f i r s t was th a t the l a r g e r the i n i t i a l movement i s , the g r e a t e r i s the temporal accuracy and c o n s i s t e n c y of the f o l l o w i n g motor response. The second was that under a given i n i t i a l movement a f o l l o w i n g motor response i s timed more a c c u r a t e l y and c o n s i s t e n t l y a f t e r s h o r t e r than a f t e r longer time delays. The t h i r d was that although a f o l l o w i n g motor response i s timed more a c c u r a t e l y and c o n s i s t e n t l y a f t e r short time delays f o r a l a r g e i n i t i a l movement than f o r a s m a l l e r one, a f o l l o w i n g motor response i s timed no more a c c u r a t e l y and c o n s i s t e n t l y under e i t h e r a l a r g e or s m a l l e r i n i t i a l movement f o r very long time delays. The fourth., and l a s t , was that the accuracy and c o n s i s t e n c y of a f o l l o w i n g motor response i s a i n c r e a s i n g , p o s i t i v e l y a c c e l e r a t e d f u n c t i o n of the time delay. T h i r t y Ss were randomly assigned t h r e e to each, of 10 experimental c o n d i t i o n s composed of two l e v e l s of I n i t i a l movement, l a r g e and s m a l l ; and f i v e l e v e l s of time delay. Each S took only one l e v e l of each f a c t o r . 69 70 In the s m a l l i n i t i a l movement c o n d i t i o n , an S only had to p r e s s -r e l e a s e a button to s t a r t the experiment w i t h h i s r i g h t index f i n g e r a f t e r which no more movement was r e q u i r e d u n t i l the f o l l o w i n g motor response was completed w i t h the removal of h i s l e f t index f i n g e r from a response-button. In the l a r g e i n i t i a l movement c o n d i t i o n , however, an S had to p l a c e h i s r i g h t hand on a s l i d e - h a n d l e which produced a c o n s i s t e n t movement i n the arm u n t i l the beginning of the time delay i n t e r v a l a f t e r which no more movement was r e q u i r e d u n t i l the f o l l o w i n g motor response was completed w i t h h i s l e f t Index f i n g e r as above. An S was r e q u i r e d to make the preceding motor response a f t e r one of f i v e delay i n t e r v a l s (0.3, 0.6, 1.0, 2.0, 4.0 seconds) which was the time between the end of the s l i d e handle movement when a red l i g h t and buzzer came on u n t i l that delay i n t e r v a l had j u s t elapsed. Thus an S i n the 0.3 second delay i n t e r v a l c o n d i t i o n would record a p e r f e c t l y accurate and c o n s i s t e n t motor response i f that response appeared at 0.3 seconds a f t e r the red l i g h t and buzzer came on. F i n a l l y , each S was given 50 t r i a l s i n which, under one of the i n i t i a l movement c o n d i t i o n s , he t r i e d to estimate one of the delay c o n d i t i o n s as a c c u r a t e l y as p o s s i b l e w i t h h i s l e f t i n d e x - f i n g e r response. A f t e r each t r i a l or es t i m a t e , he was t o l d how accurate h i s estimate was and was r e q u i r e d to wai t 30 seconds f o r the next t r i a l . Conclusions The conclusions were as f o l l o w s : (1) That s l i g h t v a r i a t i o n s i n the amount or co n s i s t e n c y of the i n i t i a l movement (because of equipment v a r i a b i l i t y ) d i d not i n f l u e n c e the accuracy and co n s i s t e n c y of the t i m i n g of a motor response. 71 (2) That the tim i n g of a motor response was acquired over 50 t r i a l s under the i n f l u e n c e of KR and that t h i s a c q u i s i t i o n e s s e n t i a l l y took p l a c e over the f i r s t 10 t r i a l s w i t h no more or very l i t t l e l e a r n i n g , t h e r e a f t e r . (3) That PFB had no e f f e c t on the accuracy and c o n s i s t e n c y of the t i m i n g of a motor response and that none of the p r e d i c t i o n s d e r i v e d from the Adams-Creamer decay hypothesis f o r the t i m i n g of motor responses were s a t i s f a c t o r i l y s u b s t a n t i a t e d . (4) That the accuracy and consistency of the t i m i n g of motor responses are power f u n c t i o n s of the DIs w i t h the former t a k i n g the form Y = 0.0968 X 0 ' 7 6 and the l a t t e r t a k i n g the form Y = 0.113 X 0 , 7" 1 where Y i s absolute e r r o r or w i t h i n - S v a r i a b i l i t y and X i s the l e n g t h of the DI (both i n seconds) r e s p e c t i v e l y . REFERENCES Adams, J.A. "Human t r a c k i n g behavior." P s y c h o l o g i c a l B u l l e t i n , 58: 55-79, 1961. Adams, J.A. "Response feedback and l e a r n i n g . " P s y c h o l o g i c a l B u l l e t i n , 70: 468-504, 1968. Adams, J.A. and Creamer, L.R. " A n t i c i p a t o r y t i m i n g of continuous and d i s c r e t e responses." J o u r n a l of Experimental Psychology, 63: 84-90, 1962a. Adams, J.A. and Creamer, L.R. " P r o p r i o c e p t i o n v a r i a b l e s as determiners of a n t i c i p a t o r y t i m i n g b e h avior." Human F a c t o r s , 4: 217-222, 1962b. Adams, J.A. and Xhignesse, L.V. "Some determinants of two-dimensional -v i s u a l t r a c k i n g b e h avior." J o u r n a l of Experimental Psychology, 60: 391-403, 1960. Bergson, H. Time and Free W i l l . New York: The Macmillan Co., 1910. Bergson, H. C r e a t i v e E v o l u t i o n . New York iHenry H o l t , 1911a. Bergson, H. Matter and Memory. New York: The Macmillan Co., 1911b. Chase, R.A. "An i n f o r m a t i o n flow model of the o r g a n i z a t i o n of motor a c t i v i t y I : Transduction, t r a n s m i s s i o n and c e n t r a l c o n t r o l of sensory i n f o r m a t i o n . " J o u r n a l of Nervous and Mental Disease, 140: 239-251, 1965a. Chase, R.A. "An i n f o r m a t i o n flow model of the o r g a n i z a t i o n of motor a c t i v i t y I I : Sampling, c e n t r a l p r o c e s s i n g , and u t i l i z a t i o n o f sensory i n f o r m a t i o n . " J o u r n a l of Nervous and Mental Disease, 140: 334-350, 1965b. C h r i s t i n a , R.W. " P r o p r i o c e p t i o n as a b a s i s f o r temporal a n t i c i p a t i o n of motor responses." J o u r n a l of Motor Behavior, 2: 125-133, 1970. C h r i s t i n a , R.W. " Movement-produced feedback as a mechanism f o r the temporal a n t i c i p a t i o n of motor responses." J o u r n a l of Motor  Behavior, 3: 97, 1971. Clausen, J . "An e v a l u a t i o n of experimental methods of time judgment." J o u r n a l of Experimental Psychology, 40: 756-761, 1950. E l l i s , M.J. "C o n t r o l dynamics and t i m i n g a d i s c r e t e motor response. J o u r n a l of Motor Behavior, 1: 110-134, 1969. 73 E l l i s , M.J.; Schmidt, R.A. and Wade, M.G. " P r o p r i o c e p t i o n v a r i a b l e s as determinants of lapsed time e s t i m a t i o n . " Ergonomics, 2: 577-586, 1968. F e s t i n g e r , L.; Ono, H.; C l a r k e , A.B. and Bamber, D. "Efference and the conscious experience of p e r c e p t i o n . " J o u r n a l of Experimental  Psychology monograph., Whole No. 637, 1967. G i l l i l a n d , A.R.; H o f e l d , J . and Eckstrand, G. "Studies i n time 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 , 43: 162-176, 1946. Gl e n c r o s s , D.J. " S e r i a l o r g a n i z a t i o n and t i m i n g i n a motor s k i l l . " J o u r n a l of Motor Behavior 2: 229-237, 1970. Goldstone, S.; Boardman, W.K. and Lhamon, W.T. " K i n e s t h e t i c cues i n the development of time concepts." J o u r n a l of Genetic Psychology, 93: 185-190, 1958. Gooddy, W. "Time and the nervous system: the b r a i n as a c l o c k . " Lancet, 1139-1144, 1958. Grose, J.E. "Timing c o n t r o l and f i n g e r , arm, and whole body movements." Research Q u a r t e r l y , 38: 10-21, 1967. Hays, W.L. S t a t i s t i c s f o r P s y c h o l o g i s t s . New York: H o l t , Rinehart and Winston, 1963. Helson, H. "Design of equipment and o p t i m a l human o p e r a t i o n . " American  J o u r n a l of Psychology, 62: 473-497, 1949. Henry, F.M. and Rogers, D.E. "Increased response l a t e n c y f o r complicated movements and a 'Memory Drum' theory of neuromotor r e a c t i o n . " Research Q u a r t e r l y , 31: 448-458, 1960. H i g g i n s , J.R. and Angel, R.W. " C o r r e c t i o n s of t r a c k i n g e r r o r s without sensory feedback." J o u r n a l of Experimental Psychology, 84: 412-416, 1970. Holubar, J . The Sense of Time: An E l e c t r o p h y s i o l o g i c a l Study of I t s  Mechanisms i n Man. T r a n s l a t e d from the Czech by John S. Barlow. Cambridge, Massachusetts: The M.I.T. P r e s s , 1969. James, W. P r i n c i p l e s of Psychology, (volume 1 ) , New York: H o l t , 1908. James, W. P r i n c i p l e s of Psychology, (volume 1 ) , New; York: Dover P u b l i -c a t i o n s , I n c . , 1950. Kretch., D. and C r u t c h f i e l d , R.S. Elements of Psychology. New York: A l f r e d A. Knopf, 1961. L a s z l o , J . I . " K i n a e s t h e t i c and e x t e r o c e p t i v e i n f o r m a t i o n i n performance of motor s k i l l s . " P h y s i o l o g i c a l Behaviour, 2: 359-365, 1967a. 74 L a s z l o , J . I . " T r a i n i n g of f a s t tapping w i t h r e d u c t i o n of k i n a e s t h e t i c , t a c t i l e , v i s u a l and a u d i t o r y s e n s a t i o n s . " Q u a r t e r l y J o u r n a l of  Experimental Psychology, 19: 344-349, 1967b. L i p p s , T. Grundtatsachen des Seelerilebens. Bonn: Max Cohen and Son, 1883. Michon, J.A. Timing I n Temporal Tracking. Soesterberg, The Netherlands: I n s t i t u t e f o r P e r c e p t i o n RVO-TNO, 1967. Montague, W.P. "A theory of ti m e - p e r c e p t i o n . " American J o u r n a l of  Psychology, 15: 1-13, 1904. Pew, R.W. " A c q u i s i t i o n of h i e r a r c h i c a l c o n t r o l over the temporal o r g a n i z a t i o n of a s k i l l . " J o u r n a l of Experimental Psychology, 71: 764-711, 1966. Po u l t o n , E.C. "Pe r c e p t u a l a n t i c i p a t i o n i n t r a c k i n g w i t h two-pointer and one-pointer d i s p l a y s . " B r i t i s h J o u r n a l of Psychology, 43: 222-229, 1952a. P o u l t o n , E.C. "The b a s i s of p e r c e p t u a l a n t i c i p a t i o n i n t r a c k i n g . " B r i t i s h J o u r n a l of Psychology, 43: 295-302, 1952b. Po u l t o n , E.C. "Learning the s t a t i s t i c a l p r o p e r t i e s of the Input i n p u r s u i t t r a c k i n g . " J o u r n a l of Experimental Psychology. 54: 28-32, 1957a. P o u l t o n , E.C. "On p r e d i c t i o n i n s k i l l e d movements." P s y c h o l o g i c a l  B u l l e t i n , 54: 467-478, 1957b. Quesada, D.C. and Schmidt, R.A. "A t e s t of the Adams-Creamer decay hypothesis f o r the t i m i n g of motor responses." J o u r n a l of Motor  Behavior, 2: 273-283, 1970. Ri c h a r d s , W. "Time e s t i m a t i o n measured by r e p r o d u c t i o n . " P e r c e p t u a l and  Motor S k i l l s , 18: 929-943, 1964. R u s s e l l , B. "On the experience of time." Monist, 25: 212-233, 1915. Ruch, T.C. Motor Systems. In S.S. Stevens (Ed.), Handbook of E x p e r i - mental Psychology. New York: Wiley, 164-208, 1951. Scheffe, H. The A n a l y s i s of Variance. New York: John Wiley and Sons, Inc., 1959. Schmidt, R.A. " A n t i c i p a t i o n and t i m i n g In human motor performance." P s y c h o l o g i c a l B u l l e t i n . 70: 631-646, 1968. Schmidt, R.A. "Movement time as a determiner of t i m i n g accuracy." J o u r n a l of Experimental Psychology, 79: 43-47, 1969. 75 Schmidt, R.A. " P r o p r i o c e p t i o n and the t i m i n g of motor responses." P s y c h o l o g i c a l B u l l e t i n , 76: 383-393, 1971. Schmidt, R.A. and C h r i s t i n a , R.W. " P r o p r i o c e p t i o n as a mediator i n the t i m i n g of motor responses." J o i i r n a l of Experimental Psychology, 81: 303-307, 1969. Sh e r r i n g t o n , C S . The I n t e g r a t i v e A c t i o n of the Nervous System. New York: S c r i b n e r , 1906. Spencer, L.T. "An experiment i n time e s t i m a t i o n using d i f f e r e n t i n t e r -p o l a t i o n s . " American J o u r n a l of Psychology, 32: 557-562, 1921. S t u r t , M. "Experiments on the e s t i m a t i o n of d u r a t i o n . " B r i t i s h J o u r n a l  of Psychology, 13: 382-388, 1923. Taub, E. and 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." J o u r n a l of  Comparative arid P h y s i o l o g i c a l Psychology, 56: 1012-1016, 1963. Troland, L.T. The P r i n c i p l e s of Psychophysiology. New York: Nostrand, 1929. Weber, A.O. " E s t i m a t i o n of time." P s y c h o l o g i c a l B u l l e t i n , 30: 233-252, 1933. W h i t l e y , J.D. "Faste r r e a c t i o n time through i n c r e a s i n g i n t e n t to respond." P e r c e p t u a l and Motor S k i l l s , 22: 663-666, 1966. Winer, B.J. S t a t i s t i c a l P r i n c i p l e s i n Experimental Design. (2nd ed.), New York: McGraw-Hill, 1971. Woodrow, H. Time P e r c e p t i o n . In S.S. Stevens (Ed.), Handbook of  Experimental Psychology, New York: Wiley: 1224-1236, 1951. Yerkes, R.M. and Urban, F.M. "Time-estimation i n i t s r e l a t i o n s h i p to sex, age, and p h y s i o l o g i c a l rhythms." Harvard P s y c h o l o g i c a l  S t u d i e s , 2: 405-430, 1906. 

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