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Effect of past movement experiences on the reproduction of discrete movements Leveille, Serge Michel 1973

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THE EFFECT OF PAST MOVEMENT EXPERIENCES ON THE REPRODUCTION OF DISCRETE MOVEMENTS by SERGE MICHEL LEVEILLE B.Sc.  (KINAN), Universite d'Ottawa, 1971  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE DEGREE OF MASTER OF PHYSICAL EDUCATION  i n the School of Physical Education and Recreation  We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA June, 1973  In p r e s e n t i n g an  this  thesis in partial  advanced degree a t . t h e  the  Library  University  s h a l l make i t f r e e l y  f u l f i l m e n t of the  of B r i t i s h Columbia, I agree  a v a i l a b l e f o r r e f e r e n c e and  I f u r t h e r agree t h a t p e r m i s s i o n f o r extensive for  s c h o l a r l y p u r p o s e s may  by h i s r e p r e s e n t a t i v e s .  be  thesis for financial  written  permission.  Department of  June 15.  gain  1973  the  s h a l l not  P h y s i c a l E d u c a t i o n and  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, C a n a d a  Date  g r a n t e d by  Head o f my  Columbia  be  Recreation  that  thesis  Department  copying or  for  study.  copying of t h i s  I t i s understood that  of t h i s  requirements  or  publication  allowed without  my  i ABSTRACT  The possible proactive i n h i b i t i o n e f f e c t of long-term past  experiences  upon the reproduction of d i s c r e t e measurements was investigated. Ten subjects were assigned to each of the eight c e l l s of a 2x2x2 f a c t o r i a l design.  The  two retention i n t e r v a l s were, 0 sec. and 30 s e c ; the two l o c a t i o n s , 60° and 120°; the two movement lengths, 10° and 50°. Each subject received f i v e standard-reproduction t r i a l s with an i n t e r t r i a l i n t e r v a l of 30 sec. The biasing e f f e c t of long-term past experiences measured by constant error, was not s i g n i f i c a n t .  Different target locations did not influence  the i n t r a i n d i v i d u a l v a r i a b i l i t y of a given movement length.  Significant  differences were obtained between movement lengths f o r both constant error, i n that the shorter movement was overshot to a greater extent than the longer movement; and v a r i a b l e error, showing a greater v a r i a b i l i t y f o r the longer movement.  The s i g n i f i c a n t increase i n v a r i a b l e error over the  retention i n t e r v a l s indicates that the memory trace weakened as time elapsed between the presentation of the standard and i t s reproduction.  ii TABLE OF CONTENTS Page LIST OF TABLES CHAPTER I  STATEMENT OF THE PROBLEM Introduction Statement of the Problem Subproblems Hypotheses D e f i n i t i o n of Terms Delimitations Assumptions and Limitations Significance of the Study  II  CRITICAL REVIEW OF THE LITERATURE AND ITS RELATIONSHIP TO THE PRESENT PROBLEM Introduction Adaptation Level Theory Anchor Theory Proactive I n h i b i t i o n Learning E f f e c t s Cues Used i n Reproduction Assimilation Theory Summary  III  27 27 28 28 29 32  RESULTS AND DISCUSSION Results Analysis of Constant Error Analysis of Variable Error Test f o r Homogeneity Discussion  V  10 10 15 17 20 21 25 26  METHODS AND PROCEDURES Subjects Apparatus Organization Experimental Design Procedures Analysis of the Data  IV  1 3 3 4 5 7 7 8  34 34 35 35 37  SUMMARY AND CONCLUSIONS Summary Conclusions  44 45  BIBLIOGRAPHY APPENDICES A. B. C.  Apparatus S t a t i s t i c a l Analysis T a b l e s o f Means  iv  LIST OF TABLES  Table  Page  I  The Main E f f e c t s i n Constant Error  34  II  The Main E f f e c t s i n Variable Error  35  Homogeneity of Error Variance i n Data f o r CE and VE Measures  36  III  V  ACKNOWLEDGEMENTS  I wish to express my appreciation to the members of my committee, Dr. R. G. Marteniuk, Dr. R. W. Schutz, Dr. W. G. Davenport and Dr. K. D. Coutts, f o r their comments and collaboration throughout the preparation of this thesis making i t possible for me to complete the requirements i n due time.  To my chairman, Dr. Marteniuk, I wish to express  s p e c i a l appreciation f o r h i s patience and guidance during my academic years at The University of B r i t i s h Columbia.  CHAPTER I  STATEMENT OF THE PROBLEM  Introduction  In learning, short-term memory (STM) has always been associated with long-term memory (LTM).  Information coming from the senses i s placed  i n STM and i f this information i s rehearsed, i t i s then transferred into LTM.  Recently, Schutz (1972) proposed that STM could also be used during  r e t r i e v a l tasks to f a c i l i t a t e r e t r i e v a l of information.  That i s , information  most l i k e l y to be used i s brought back into STM where i t i s more r e a d i l y available.  Thus, information stored i n LTM could possibly i n t e r f e r e with  incoming information stored i n STM, by means of proactive interference.  Williams (1971) and Stelmach (1969) have reported that proactive interference can influence motor short-term memory (MSTM). To study the possible influence of LTM on MSTM, there must be a form of movement information that i s retained i n LTM.  Laabs (1973) has i d e n t i f i e d such a  form of information i n that he found l o c a t i o n information from a movement i s kept i n a c e n t r a l memory code. hypothesize  From h i s r e s u l t s i t i s possible to  that through this central memory code, LTM could a f f e c t the  retention of information i n MSTM.  Such an effect would be mediated through what Laabs (1973) describes as an adaptation l e v e l (AL).  I t accounts for overshooting and under-  shooting i n MSTM experiments where subjects are presented with a range of  2  movements.  When a subject reproduces a movement, he does so " i n reference to  an average movement," which i s a combination of movements i n the interpolated a c t i v i t y , i n addition to the memory trace of the given movement.  As the  memory trace of a given movement decays and causes forgetting, more emphasis i s given to the AL during reproduction.  This study i s an extension of Laabs' work.  Since interpolated a c t i v i t y  i n a given range i s said to produce an AL i n MSTM, i t i s also possible that such an AL could r e s u l t from a person's long-term and d a i l y past experiences (ALp ). E  Such-an ALp^ would be the mean of a l l movements (of a given limb)  i n the human range of movement.  This mean would take into account the  frequency as well as the location of the movements. Man usually works i n front of himself as evidenced by writing, eating, or any p r e c i s i o n work. The ALpg would probably be located i n front of the shoulder, perpendicular to the f r o n t a l plane.  To make this prediction, one must accept the assumption that  reproductions are more accurate when the target location coincides with the AL.  Since movements reproduced on one side of the AL are undershot,  while  overshot on the other, then i t i s l o g i c a l that movements reproduced at the same location as the AL would have zero constant error.  Then,the fact that  movement reproductions are more accurate i n a well-practiced range (Lloyd and Caldwell, 1965) and that reproductions are more accurate near v e r t i c a l In front of the shoulder (Brown et a l . , 1948; Stelmach, 1970) would support the prediction that such an A L  p E  would exist at such a l o c a t i o n .  Also, as  i n other experiments i n MSTM, this AL-,^ would become more important over retention i n t e r v a l s j u s t as the AL does.  3  The AL and ALpg would not have the same influence on reproductions i n time.  A strength and recency trade-off would be i n e f f e c t .  recent AL would have more influence than a more distant ALpg.  A more In other  words, an AL due to interpolated a c t i v i t y immediately preceding reproduction would cause most of the interference with the ALp none.  E  having l i t t l e or  However, i f the study i s done within the context of MSTM and each  subject reproduces only one length at one location, with an appropriate i n t e r t r i a l i n t e r v a l (ITI) to allow for s u f f i c i e n t trace decay, the occurrence of an AL, due to experimental conditions, would be minimized making i t possible to investigate the presence of an A L . p E  This i s the framework  for this study.  Statement of the Problem  The purpose of t h i s study i s to investigate the p o s s i b i l i t y that an adaptation l e v e l resulting from long-term d a i l y past experiences could influence the reproduction of a f i n e motor task when trace decay i s allowed to take place.  Subproblems  The subproblems are:  1.  To study the e f f e c t of d i f f e r e n t movement lengths on i n t r a -  i n d i v i d u a l v a r i a b i l i t y while maintaining the target location constant.  4  2.  To study the effect of d i f f e r e n t target locations on i n t r a -  i n d i v i d u a l v a r i a b i l i t y while maintaining the movement length constant.  Hypotheses The hypotheses are: 1.  An adaptation l e v e l due to past experiences causes a s h i f t i n  constant error (CE) towards the ALp^. This s h i f t i s evident only i n reproductions following a longer retention i n t e r v a l which w i l l cause a larger v a r i a b l e error (VE) when compared to the shorter retention i n t e r v a l .  The s h i f t i n CE w i l l not be evident i n the 0 sec. i n t e r v a l becuase only one movement length and l o c a t i o n w i l l be i n MSTM and the memory trace w i l l be strong enought to guide the reproduction.  As the memory trace decays  over time and becomes weaker, the AL^^, w i l l become more i n f l u e n t i a l and i t s influence w i l l be r e f l e c t e d i n a s h i f t i n CE.  The weaker memory trace used to guide reproductions a f t e r the 30 sec. retention i n t e r v a l w i l l be indexed by a larger VE score f o r that condition.  2.  The VE i s related to movement length i n that the longer movement has  a larger VE score when compared to the shorter movement.  The reasoning supporting this hypothesis i s that the longer movement has a greater potential for v a r i a b i l i t y .  This i s due to the fact that the  longer movement i s more complex and requires a longer time i n t e r v a l f o r i t s execution. Thus, the longer movement should be more v a r i a b l e .  5  3.  The change i n VE from the 0 sec. retention i n t e r v a l to the 30 sec.  retention i n t e r v a l w i l l be greater f o r the shorter movement than for the longer movement.  Laabs (1973) mentions that when d i s c r i m i n a b i l i t y of a given set of movements i s decreased, the VE can be expected to increase.  In this  experiment, only one movement i s given but the e f f e c t of d i s c r i m i n a b i l i t y could also apply to starting and target l o c a t i o n s .  This d i s c r i m i n a b i l i t y  being less for the shorter movement should r e s u l t i n a greater change i n VE when the memory trace i s allowed  to decay when compared to the change i n VE  of the longer movement under the same conditions.  4.  The VE for a given movement length i s not influenced by d i f f e r e n t  target l o c a t i o n s .  That i s , the VE for a given movement length w i l l not vary from one target l o c a t i o n to the other.  The e f f e c t of changing l o c a t i o n should be mediated  through an AL and r e f l e c t e d i n CE, not VE.  In this experiment, l o c a t i o n i s  not a factor which causes interference r e s u l t i n g i n a weakening of the memory trace (because each subject i s presented  only one target l o c a t i o n ) . Since VE  i s an index of the strength of the memory trace, i t w i l l not be affected by changing the target l o c a t i o n .  D e f i n i t i o n of terms Adaptation Level (AL).  The adaptation l e v e l i s the average movement made  6 up from the combination of movements to be reproduced i n the experimental s i t u a t i o n (Laabs, 1973). Adaptation Level Due to Past Experiences (ALp ). E  The adaptation l e v e l  due to past experience i s the average movement made up from the combination of frequency and location of a l l past movements i n d a i l y a c t i v i t i e s .  I n t e r t r i a l Interval (ITI).  The i n t e r t r i a l i n t e r v a l i s the time betwwen  the end of the reproduction of a standard and the s t a r t of the execution of the next standard.  Memory Trace.  The memory trace i s the memory state which represents  the correct response and develops as a function of practicing the correct response.  Movement Length.  The movement length i s the distance which the subject(s)  has to move i n order to reach the target l o c a t i o n .  In t h i s study, the lengths  are 10° and 50° counterclockwise.  Movement Location.  The movement location i s the target l o c a t i o n which  the subject has to reach i n order to achieve perfect reproductions.  In this  study, when 0° i s perpendicular to the s a g i t t a l plane, through the shoulder, the locations are 60° and 120° i n a counterclockwise d i r e c t i o n i n front of the subject.  When 90° i s v e r t i c a l to the f r o n t a l plane, i n front of the r i g h t  shoulder j o i n t , the locations w i l l be 30° away from the 90° and one on each side. Thesemovement locations and the associated movement lengths are presented i n diagram form i n Appendix A.  7  Retention I n t e r v a l .  The retention i n t e r v a l i s any b u i l t - i n time lapse  between the presentation of the standard and i t s reproduction.  In t h i s study,  the retention i n t e r v a l s w i l l be 0 sec. and 30 sec.  Trace Decay;  Trace decay i s the weakening of the memory trace due to  time.  Delimitations  The delimitations are: 1.  The study i s delimited to the r e c a l l of an arm movement In a counter-  clockwise d i r e c t i o n , i n the horizontal plane, executed with the r i g h t arm.  2.  The study i s delimited to two measurement lengths; 10° and 50°.  3.  The study i s delimited to two targets locations; 60° and 120°.  4.  The study i s delimited to two retention i n t e r v a l s ; 0 sec. and 30 sec.  Assumptions and Limitations  The following assumptions are made:  1.  Trace decay does not vary randomly but has a d i r e c t relationship  with movement lengths, and retention i n t e r v a l s .  That i s , for a given  length  and/or retention i n t e r v a l , the amount of trace decay w i l l always be the same.  8  2.  Counting backward w i l l have a uniform influence on a l l movement  reproductions, either length or locations, because i t i s acting through the central mechanism.  3.  I t i s assumed that the adaptation l e v e l f o r past experiences i s  located d i r e c t l y i n frong of the shoulder but an exact location i s not required f o r the v a l i d i t y of the study.  A reproduction further away from  the AL w i l l be influenced to a greater extent (Laabs, 1973).  For example,  i f the AL__ was located at the 120° location, reproductions a f t e r the r Ji  30 sec. retention i n t e r v a l at that location would show very l i t t l e or no biasing whereas reproductions at the 60° location a f t e r the 30 sec. delay would show a large biasing e f f e c t of the AL .. pE  The investigation i s limited by:  1.  The accuracy of the apparatus and of the experimenter.  2.  The degree of randomness of the sample.  3.  The i n t e g r i t y of the subjects.  Significance of the Study  The r e s u l t s of the study w i l l enable a more appropriate s e l e c t i o n of movements, with regard to length and location, f o r the f i r s t few practice  9  t r i a l s when a mature i n d i v i d u a l i s being trained at a new task. also indicate i f i n t r a i n d i v i d u a l v a r i a b i l i t y  It will  i s related to movement  length.  If such an A L  p E  e x i s t s , then the movements i n the f i r s t few practice  t r i a l s should be located further away from the AL-,,, than the desired locations of the movement.  final  I f c e r t a i n movements cause more VE than other  movements, then they should be given more practice t r i a l s .  (0  CHAPTER I I  CRITICAL REVIEW OF THE LITERATURE AND ITS RELATIONSHIP TO THE PRESENT PROBLEM  Introduction  When an i n d i v i d u a l makes a c e r t a i n movement, there are several factors acting upon the execution of that movement.  A movement i s never  made i n i s o l a t i o n but i s influenced by the experiences which the i n d i v i d u a l has had p r i o r to the movement.  These forces acting subconsciously upon an  i n d i v i d u a l at a given moment make up what Helson (1967) describes as an adaptation l e v e l .  By eliminating immediate past experiences, which are  usually present i n short-term memory studies because each subject i s given several d i f f e r e n t movements, an attempt can be made to evaluate the possible e f f e c t s of long-term past experiences on the execution of discrete movements.  For long-term past experiences to influence the execution of movements, the AL formed would act on these movements i n the form of proactive i n t e r ference.  Several other factors, such as distance, location, movement  anchoring, practice, and cues, can influence movement reproductions and their influences must be taken into consideration.  Adaptation Level Theory  The theory of adaptation l e v e l i s based upon the assumption that a certain order prevails over the judgements made by man (Helson, 1967).  11  Included In these judgements i s the psychophysical realm.  The AL works  i n such a way that stimuli located at the AL seem to be neutral whereas stimuli located above or below the AL value w i l l e l i c i t p o s i t i v e and negative responses from the subjects.  Helson maintains that this AL i s not s t a t i c  but changes i n accordance with the prevailing conditions of stimulation. The AL which becomes the frame of reference for psychophysical judgements i s a function of a l l the s t i m u l i acting upon or within an individual at the time of judgement as well as those s t i m u l i perceived i n the past.  Thus,  the p r e v a i l i n g AL would be comprised of a l l long-term and immediate past experiences as well as the given stimulus.  Helson (1967) i d e n t i f i e s three primary forces which make up the AL acting during a given experimental s i t u a t i o n .  The f i r s t one i s the  experimental stimuli which are the s t i m u l i being judged; second i s the contextual s t i m u l i which are forming the background or standard for judgement; and t h i r d i s a r e s i d u a l factor which represents the e f f e c t s of a l l related previous stimulations. In the present study, the experimental stimulus w i l l be the given distance at the given l o c a t i o n .  That part of the adapt-  ation l e v e l made up from the contextual s t i m u l i w i l l be the same as that made up from the experimental stimulus.  I t must be noted that there w i l l  be only one distance at one location presented to the subject.  Of special  importance for this study i s the residual factor which w i l l be comprised of  long-term past experiences only, because the subject i s presented with  only one distance at one location during the experiment.  Of the three  types of stimuli which combine to form the adaptation l e v e l , only the f i r s t  12  and t h i r d w i l l be present i n the study.  Another aspect of the adaptation l e v e l theory i s the importance given to the AL over time (Helson, 1967).  As the time lapse from the presentation  of a standard and the reproduction of that standard i s increased, more importance i s given to the AL when the reproduction of the standard i s made. That i s , the longer the i n t e r v a l between presentation and reproduction, the more the reproduction w i l l approach the value of the AL.  I t i s assumed that  when the memory trace decays and becomes weaker, i t i s less able to guide reproductions, making them more susceptible to other factors such as the AL.  Also implied i n this theory i s the importance given to each factor i n forming the p r e v a i l i n g AL.  A strong memory trace would have the most  influence i n the formation of the adaptaion l e v e l because of i t s strength and recency.  As the strength of the memory trace decreases as i t decays,  the contextual s t i m u l i gain i n importance and become more important i n forming the AL.  Although they are not as recent as the actual memory  trace, the pooling of several contextual s t i m u l i increase t h e i r strength i n r e l a t i o n to the decaying memory trace.  The l a s t i n importance are the  r e s i d u a l factors or the long-term past experiences.  I f both experimental and  contextual s t i m u l i are present, then l i t t l e importance would be given to the r e s i d u a l factors i n forming the p r e v a i l i n g adaptation l e v e l ; this i s not the case for the present study.  13  A s i m i l a r importance-recency trade-off has been reported by Levin, Craft and Norman (1971) when they tested an additive model f o r averaging motor movements.  When their subjects had to make a movement which was the  average of three or f i v e given movements, the averaging responses could be predicted by a weighted average of the given s t i m u l i .  The influence of the  l a s t given movement was greater than the influence of the e a r l i e r movements. Thus, i n AL terminology, the experimental s t i m u l i would have more importance i n forming the adaptation l e v e l than would have the contextual s t i m u l i which i n turn would have more importance than the residual f a c t o r s .  The problem to be examined by this study i s whether the r e s i d u a l factors can gain^enough importance i n the absence of contextual s t i m u l i to influence the reproduction of precise motor movements.  E l l i s (1973) attempted to evaluate the adaptation l e v e l theory  using  sounds as the experimental s t i m u l i and varying the i n t e n s i t y (loudness). In the f i r s t part of the experiment, the subjects received seventy-two t r i a l s centered at either 50, 65 or 80 decibels.  Three interstimulus  i n t e r v a l s of one, four and seven seconds were employed separating the presentation of the standard minus one d e c i b e l .  from the comparison which was equal, plus, or  In the second part, a l l subjects received 72 t r i a l s  centered on 65 decibels.  The adaptation l e v e l theory would predict that i n  the second part, as the interstimulus i n t e r v a l increases, the errors of the subjects who were given the 50 decibel sound i n the f i r s t part would become more negative whereas the error of the subjects who were given the 80 decibel  14  sound would become more p o s i t i v e while the error of the 65 decibel group should be maintained.  In accordance with the theory, a s i g n i f i c a n t effect  due to the p r i o r sound l e v e l was found but the d i f f e r e n t time i n t e r v a l s produced a similar negative s h i f t i n errors which i s contrary to the predictions.  However, i t i s f e l t that these r e s u l t s could s t i l l be explained  with reference to the adaptation l e v e l theory.  On the one hand, the 72 t r i a l s  of part one might not have been s u f f i c i e n t to create a contextual l e v e l strong enough to influence the judgement of the 72 t r i a l s of the second part, following the 5 minute rest between the parts.  Furthermore, the three  experimental l e v e l s of i n t e n s i t y might have been greater than the individual's AL f o r i n t e n s i t y before the experiment.  Thus, the negative s h i f t i n error  with increasing interstimulus i n t e r v a l s might r e f l e c t an adaptation towards the pre-experimental AL.  The effect of the f i r s t 72 t r i a l s would be to slow  down this adaptation to the pre-experimental  level.  More closely related to the present study i s the investigation by Laabs (1973) who  proposes a model of motor short-term memory based on the adaptation-  l e v e l theory and incorporating v a r i a b l e and constant error. uses movement reproduction as opposed to E l l i s '  The Laabs study  sound recognition, making i t  more similar to the present experiment.  There were 6 movement lengths ranging from 10° to 35° i n 5° steps and f i n a l locations which were also separated by 5° i n t e r v a l s .  The same  standard-reproduction sequence was used, with reproductions being made with a movement length d i f f e r e n t from the one used i n the standard to make the  12  15  distance cue u n r e l i a b l e .  In the group where the location cue was  to be  unreliable, the reproductions were made to d i f f e r e n t f i n a l locations. Two retention i n t e r v a l s were used, 0 sec. or 12 sec. with the l a t t e r being either a rest i n t e r v a l or f i l l e d with counting or a s p a t i a l reasoning t e s t .  The data reported i n the study support e n t i r e l y the adaptation l e v e l theory.  As the retention i n t e r v a l i s increased, more emphasis i s placed  on the experimental or contextual AL which r e s u l t s i n increased undershooting of the longer movements as opposed to increased overshooting of the short movements.  Of importance f o r the present study i s the fact that  this tendency toward the AL i s also postulated f o r location; that i s , movement reproductions w i l l be biased towards the AL a f t e r a retention interval.  I f , i n the absence of contextual s t i m u l i , the r e s i d u a l factors  or long term past experiences are a major influence i n the formation of the p r e v a i l i n g AL, then the biasing e f f e c t would be reflected i n a s h i f t of the constant error scores toward the adaptation l e v e l .  Anchor Theory  Another factor which can be of some help i n movement reproductions i s anchors.  Anchors serve as points of reference to which the movement to  be reproduced can be compared and/or located. MacKinnon (1972) has shown that the e f f e c t of anchors can combine with adaptation l e v e l s to influence the recognition of l i f t e d weights. two weights, 30 gm and 250 gm,  Three control groups were trained with  100 gm and 300 gm,  or 150 and 350 gm, which  16  were the p o s i t i v e s t i m u l i .  The three experimental groups were given  negative stimuli of 150 gm, 200 gm, or 250 gm i n addition to the p o s i t i v e stimuli.  Subjects learned not to respond to the negative s t i m u l i because  reinforcement followed only a correct response to the p o s i t i v e s t i m u l i and was withheld when the negative s t i m u l i were presented.  In the experi-  mental s i t u a t i o n , the subjects were presented with weights ranging from 50 gm to 500 gm at 50 gm i n t e r v a l s and were asked to recognize the learned weights.  The values of subjective equality seemed to be pushed away from  the negative s t i m u l i i n the experimental group when compared to the control groups.  Thus, the e f f e c t of known or learned anchors can influence the  judgement of weight when kinesthesis i s used as a means of evaluation. These anchors work i n a psychological manner similar to that of adaptation l e v e l s .  Caldwell and Herbert (1956) had previously shown that an anchoring e f f e c t was present i n a horizontal straight arm movement o r i g i n a t i n g from the shoulder j o i n t .  In their experiment,  0° was i n front of the shoulder  while 90° was perpendicular to the s a g i t t a l plane.  They report clear  evidence of perceptual anchoring at the ends of the range, 0° and 90° positions.  There was only a s l i g h t evidence of increased accuracy near  the midpoint of the range tested.  For the present investigation, considerations were given to the possible influence of anchors on the reproduction of movements when the s e l e c t i o n of movement lengths and locations was made.  The range of movement made  17  possible through the combination of elbow f l e x i o n and shoulder rotation used i n this study i s much greater than that of Caldwell and Herbert (1956), covering approximately one hundred and eighty degrees i n the horizontal plane.  The two movement locations are approximately s i x t y degrees  from the closer end of the range where the anchoring e f f e c t would be located and strongest. Unlike MacKinnon (1972), there are no negative s t i m u l i used within the range to create an anchoring e f f e c t .  Since a l l the movements  are to be executed i n a counterclockwise d i r e c t i o n , the movement lengths were selected so that they could be e a s i l y executed without undue stretching of muscle f i b e r s at both locations.  A movement longer than f i f t y degrees  could have been e a s i l y reproduced at the 120° location but would have caused greater stretching of the musculature to reach the s t a r t i n g location xtfhen the target l o c a t i o n was 60°, making the two conditions d i s s i m i l a r .  Proactive I n h i b i t i o n  Comparisons are always made between verbal short-term memory and motor short-term memory; this i s also the case for proactive i n h i b i t i o n (PI). In verbal STM, PI i s a strong factor.  On the other hand, several studies  i n MSTM have f a i l e d to find the e f f e c t of PI (Adams and D i j k s t r a , Posner and Konick, 1966).  1966;  However these two studies used r e l a t i v e l y long  IT1 which might prevent PI.  Schmidt and A s c o l i (1970) i n an attempt to  resolve the problem, gave their subjects either a 10 or 90 second ITI i n the reproduction of a l i n e a r movement.  Their r e s u l t s pointed to a n u l l  18  e f f e c t of ITI because no PI occurred i n the experiment which i s s i m i l a r to the r e s u l t s of Montague and H i l l i x (1968).  On the other hand, a s i m i l a r i t y between verbal and motor STM respect to proactive i n h i b i t i o n has also been reported.  with  Stelmach (1969a)  showed that absolute errors at r e c a l l were d i r e c t l y related to the number of p r i o r positions.  The number of p r i o r positions varied from 0 to 4.  The  same researcher (Stelmach, 1969b) related PI to the s i m i l a r i t y of responses. He found that absolute errors at r e c a l l were inversely related to the s i m i l a r i t y of the p r i o r responses about the target p o s i t i o n . was  r e p l i c a t e d l a t e r by Craft and Hinrichs  This r e s u l t  (1971).  A s c o l i and Schmidt (1969) used a simple l i n e a r positioning task to study the e f f e c t of PI i n MSTM.  The subject was  presented with either  0, 2, or 4 positions before being given the c r i t e r i o n which he was r e c a l l 10 or 120 seconds l a t e r . order.  to  A l l the movements were r e c a l l e d i n reverse  PI e f f e c t s were found only i n the group with 4 p r i o r positions  r e s u l t i n g i n greater absolute error and greater undershooting with algebraic error when compared to the other two groups.  In a similar study, Williams  •(1971) manipulated p r i o r positions, practice reinforcements of the c r i t e r i o n distance, and retention i n t e r v a l . Absolute error scores at r e c a l l indicated a PI e f f e c t but only for the condition of f i v e p r i o r learning, with c r i t e r i o n distance a f t e r 15 and 50 sec. retention i n t e r v a l s .  one  r  19  At best, proactive i n h i b i t i o n seems to be r e l a t i v e l y weak i n producing interference i n MSTM. H i l l i x (1968).  This i n d i c a t i o n i s similar to that of Montague and  They gave each subject seven t r i a l s with d i f f e r e n t lengths  with each t r i a l consisting of four standard-reproduction sequences. between t r i a l comparisons showed no e f f e c t of PI but such an e f f e c t  The was  evident when only the f i r s t standard-reproduction sequence of each t r i a l was compared.  Thus, the PI e f f e c t was not strong enough or important  enough i n the formation of the prevailing AL to o f f s e t the importance given to two or more repetitions of the experimental s t i m u l i i n making up t h i s AL.  The negative e f f e c t of PI with decreased ITI when each subject  i s given repeated presentations of the same p o s i t i o n could be due to the fact that with repeated presentations, the memory trace enters long term memory where i t could not i n t e r f e r e with information coming into shortterm memory.  This n u l l PI e f f e c t from long-term memory has been proposed  for verbal memory by Scott, Whimbley and Dunning  (1967).  Proactive i n h i b i t i o n seems to be the weaker factor when compared with retroactive i n h i b i t i o n .  This was shown by Craft and Henrichs (1971)  and Craft (1973) when they studied the effect of i n t e r f e r i n g movements either before the standard-reproduction sequence or interpolated between the standard and the reproduction.  Although weak, the proactive i n h i b i t i o n e f f e c t seems to be present. In the Levin, Craft and Norman (1971) additive model for motor movements,  20  the subject when asked to average a series of given movements, subconsciously placed more emphasis on the movement presented just before, indicating a PI e f f e c t .  When E l l i s  (1973), i n h i s evaluation of Helson's  adaptation  l e v e l theory, mentions that a s i g n i f i c a n t e f f e c t due to p r i o r l e v e l s was evident, he i s i n fact proposing a PI e f f e c t .  S i m i l a r l y , PI, as well as  retroactive i n h i b i t i o n , has to be a factor i n both Laabs' adaptation l e v e l theory f o r movements (1973) as well as Pepper and Herman's assimilation theory (1970).  I f i t wasn't f o r the interference factor, neither adaptation  nor assimilation could r e s u l t from a series of movements nor could they i n turn a f f e c t the next movement.  In the present study the only source of PI expected to influence reproduction i s that caused by long-term experiences p r i o r to the testing situation.  Some PI e f f e c t could be generated from t r i a l to t r i a l but the  experimental procedures used attempt to minimize this e f f e c t .  These w i l l  be discussed i n the next section of this chapter.  Learning Effects  The amount of learning that the subject does during the experiment i s very important.  I f a high l e v e l of learning i s achieved, then the  p r e v a i l i n g adaptation l e v e l would be formed primarily by the experimental s t i m u l i with l i t t l e importance given to long-term past experiences, defeating the purpose of this experiment.  In the Williams study (1971) the PI  21  e f f e c t appeared a f t e r a 15 sec. retention i n t e r v a l but disappeared when three practice reinforcements were given.  Montague and H i l l i x (1968)  report the disappearance of a PI e f f e c t after only two practice r e i n f o r c e ments.  On the other hand, Adams and D i j k s t r a (1966) report that s i x  reinforcements were needed to s i g n i f i c a n t l y influence absolute errors i n reproduction.  S i m i l a r l y , a study by L e v e i l l e (1973) showed that i n a l i n e a r  task, the majority of learning took place i n the f i r s t ten t r i a l s as r e f l e c t e d by a decrease i n variable error. of r e s u l t s and zero ITI.  I t was  This was without verbal knowledge  also shown that twenty-five p r a c t i c e  t r i a l s did not s i g n i f i c a n t l y a f f e c t constant error scores.  In the present study, the subject w i l l receive only f i v e presentations of the c r i t e r i o n distance i n a standard - reproduction sequence. be a t h i r t y second ITI.  The subject was  There w i l l  told not to rehearse the previous  movement during this i n t e r v a l i n order to minimize the PI e f f e c t from t r i a l to t r i a l thus reducing the learning e f f e c t as shown by Bjork, Laberge and Legrand, 1968.  The subjects i n the t h i r t y second retention i n t e r v a l group  w i l l have that extra time, i n addition to the ITI, to allow for trace decay; again reducing the learning e f f e c t .  Cues Used i n  Reproduction  Researchers have investigated three types of cues which could subserve the kinesthetic process; location, distance and force (or tension).  22  Recently, Marteniuk and Ryan (1972) suggested that a horizontal straight arm movement was subserved by a metathetic  (substitutive) process which would  indicate that f o r the given task, judgements were made through the use of l o c a t i o n cues rather than distance cues.  Marteniuk and Roy (1973) mention,  a f t e r reviewing the l i t e r a t u r e , that p h y s i o l o g i c a l evidence indicates the three types of kinesthetic receptors that subserve kinesthesis are found i n the j o i n t and project to the sensory cortex.  These receptors would code  p o s i t i o n , d i r e c t i o n , speed, and acceleration but not movement distance as such.  These facts and the experimental data support the researchers*  conclusion that distance cues, i n the given task, provided less precise information about arm displacement  than l o c a t i o n cues.  They further  conclude that there might not be any receptors for distance making this type of information uncodeable.  For distance information to be codeable,  the subserving  receptors  would have to be located i n the muscle and monitor the extent of contraction. Granit (1972) mentions the fact that the large primary afferents from the muscle spindles project to the sensorimotor  cortex.  Thus, t h i s would  indicate that distance information can be encoded ('assuming that e f f o r t can be equated with distance), which i s contrary to Marteniuk and Roy (1973).  On the other hand, these cues, as suggested by Marteniuk and Roy  (1973) would be of l e s s e r importance than l o c a t i o n cues.  According to  Granit (1973), the information from the muscle spindles i s integrated with the inflow of information from tendons and j o i n t s and i s included i n a  23  mechanism for v e r i f y i n g the execution of movements and i s not necessarily used i n the guidance of the movement.  Several researchers have isolated and studied l o c a t i o n and distance cues (Posner, 1967; Keele and E l l s , 1972; Marteniuk and Roy, 1973, Laabs, 1973).  The methodology i s quite simple; changing the starting l o c a t i o n  and asking the subject to reproduce the end l o c a t i o n makes the distance cue u n r e l i a b l e whereas changing the s t a r t i n g l o c a t i o n and t e l l i n g the subject to reproduce the movement extent renders the l o c a t i o n cues u n r e l i a b l e . Maintaining the same s t a r t i n g and target locations f o r reproductions allows for both cues to be a v a i l a b l e simultaneously.  The fact that movement  distance information decays over an empty retention i n t e r v a l whereas movement l o c a t i o n decays very l i t t l e combined with the fact that  inter-  polated a c t i v i t i e s requiring attention cause a r e l a t i v e l y small increase i n decay of distance information but a s i g n i f i c a n t decay of l o c a t i o n i n f o r mation led Laabs (1973) to suggest a two mode system of storage.  Location  information i s rehearsable and stored i n a c e n t r a l mode whereas distance information i s not rehearsable and stored i n a kinesthetic mode.  The e f f e c t s of retention intervals and interpolated mental a c t i v i t y have been studied i n r e l a t i o n to d i f f e r e n t movement lengths (Stelmach, 1970;  Stelmach and Wilson, 1970).  Longer movements decay over an empty  retention i n t e r v a l with interpolated mental a c t i v i t y adding very l i t t l e to the decay.  However, shorter movements suffer l i t t l e loss over an empty  24  retention i n t e r v a l but s i g n i f i c a n t loss when mental a c t i v i t y i s introduced. Since short  movements decay l i t t l e unless a secondary task i s introduced  would indicate that such movements depend on l o c a t i o n information which follow the same rule; s i m i l a r l y long movements would depend more on distance information.  This deduction i s contrary to Stelmach*s (1970) who maintains  that short movements depend on distance cues.  The e f f e c t s of force have been studied by Wllberg  (1969).  He showed  that constant pressure did not appear to have an e f f e c t upon the storage of information and i t s decay from STM.  In addition to proprioceptive feed-  back, Adams, Marshall and Goetz (1972) studied the e f f e c t of v i s u a l and auditory feedback.  The greatest loss i n retention occurred f o r the longer  i n t e r v a l of 90 sec. with the l e a s t amount of feedback a v a i l a b l e . That i s , making a l l sources of feedback (auditory, v i s u a l and proprioceptive) unreliable.  In a l l the experiments reported i n this section, the same subject had to reproduce several movements which vary i n length at several l o c a t i o n s . That i s , confounded i n the experimental r e s u l t s , are the possible influences of changing movement length and target l o c a t i o n as well as the influence of the experimental  treatment.  Such an influence has been proposed by  Brown (1948) Lloyd and Caldwell (1965) and Stelmach (1970) who have indicated that accuracy i n reproductions might vary with the amount of practice and the target l o c a t i o n .  These two factors of movement length and movement  25  l o c a t i o n are e s p e c i a l l y confounded i n experiments where distance or location cues are made u n r e l i a b l e .  A reproduction using either a d i f f e r e n t movement  length or a d i f f e r e n t target l o c a t i o n , depending on the s i t u a t i o n , i s compared to the standard, which means that the e f f e c t of the experimental manipulation i s not tested under the same conditions. Then the v a r i a t i o n s i n reproductions obtained could r e s u l t from the experimental treatment or the procedures used or both.  This experiment  i s designed to investigate  the possible e f f e c t s of changing the distance or location f o r the reproduction of a standard. Assimilation Theory For MSTM, Pepper and Herman (1970) have proposed an assimilation theory. In their model, a single memory trace either interacts with i n t e r f e r i n g movements and/or decays over time. movement  When the memory trace of a short  interacts with that of a long movement, the resulting memory trace  i s a combination of both traces along the extent dimension.  At r e c a l l the  short movement w i l l be overshot whereas the long one w i l l be undershot. When the memory trace i s allowed to decay, i t does so along the extent dimension r e s u l t i n g i n a shorter movement at r e c a l l .  Interpolated mental  a c t i v i t y i s said to cause a p o s i t i v e s h i f t i n CE at reproduction.  I t must be remembered that the AL theory of MSTM presented by Laabs (1973) makes the same predictions as the assimilation theory and i s more c l o s e l y related to the present investigation.  26  Summary  It has been shown that an adaptation l e v e l can be set up by the combination of several movements i n STM and that such an adaptation l e v e l could Influence movement reproduction through proactive i n h i b i t i o n .  The  experiment i s designed to investigate the p o s s i b i l i t y that a similar AL could be set up from long-term past experiences stored i n LTM and influence movement reproductions i n a s i m i l a r manner.  The experimental design w i l l permit an evaluation of the effect of changing movement length and target locations f o r the reproduction of c r i t e r i o n movements.  Comparison of the r e s u l t s of the present experiment  with those of experiments exposing the subject to a range of movement lengths and location w i l l also permit an evaluation of the e f f e c t of such a range on accuracy and v a r i a b i l i t y of movements.  Zl CHAPTER I I I  METHODS AND PROCEDURES  Subjects  Eighty right-handed male subjects participated i n the experiment. F i f t y - s i x of these subjects were from undergraduate and graduate studies at The University of B r i t i s h Columbia.  The remaining twenty-four were  either involved i n training or members of the Vancouver Y.M.C.A. The subjects were assigned to each of the eight groups i n a systematic, unbiased fashion making a t o t a l of ten subjects per group. subjects ranged from 18 to 47, giving a mean of 23.4 years.  The age of the The group  means ranged from 20 to 27 years.  Apparatus  The movement apparatus u t i l i z e d f o r the experiment i s the same as that used by Marteniuk and Roy (1973). apparatus i s shown i n Appendix A.  A p i c t o r i a l description of the  The apparatus consisted of a h a l f - c i r c l e  of masonite board which had a diameter of 5.0 feet. and half degree c a l i b r a t i o n s were drawn.  On the board an arc  A lever was attached to a near  f r i c t i o n l e s s pivot at the midpoint of the chord describing the arc.  On  the lever arm, one foot away from the centre of the pivot, there was a 5.5 inch handle which was used to move the lever.  A pointer extended from  the lever arm to the circumference where v e r t i c a l indicators  projected  28  downward making i t easier to read the performance score.  The subject moved  the lever i n the horizontal plane i n a counterclockwise d i r e c t i o n . Wooden blocks were used to indicate the starting and target locations.  The f r i c t i o n l e s s pivot was fastened to a table.  The base of the handle  on the lever arm was approximately 45 inches from the f l o o r , 7 inches higher than the table top.  Organization  The same experimenter  tested a l l the subjects at the rate of approx-  imately ten minutes per subject f o r a t o t a l of approximately hours.  twenty testing  The majority of the subjects were tested i n The University of  B r i t i s h Columbia Motor Learning Laboratory. at the Vancouver Y.M.C.A. locations and environmental  The same apparatus was used at both testing factors such as noise l e v e l , a i r temperature,  and size of testing room were almost  Experimental  The other subjects were tested  identical.  Design  The subjects were divided into eight groups. only one experimental treatment.  Each group was given  There was one group f o r each of the  movement lengths (10°, 50°), at each of the two locations (60°, 120°), and f o r each of the two retention i n t e r v a l s (0 s e c , 30 s e c ) .  Thus, a  subject received f i v e t r i a l s f o r a given length at a given l o c a t i o n f o r a  29  given retention i n t e r v a l .  These lengths and locations were selected to  minimize the possible effect of "anchors" as discussed i n Chapter I I . The design used was a 2x2x2x5 (retention i n t e r v a l x movement location x movement length x t r i a l s ) f a c t o r i a l design with repeated measures on the l a s t factor.  A diagram i l l u s t r a t i n g the d i f f e r e n t movement locations and movement lengths i s included i n Appendix A.  As can be seen, each location (60° and  120°) i s the movement l o c a t i o n f o r two movement lengths (10° and 50°).  In  addition, each movement length at each location w i l l have two groups; one for the 0 sec. retention i n t e r v a l and one f o r the 30 sec. retention i n t e r v a l .  Procedures  The subjects were not allowed to see the experimental apparatus to minimize the v i s u a l i z a t i o n of the task before the actual t e s t i n g . asked to s t r i p from the waist up to prevent extraneous  They were  cues from the stretching  of their clothing around the shoulder and elbow j o i n t s and along the arm. The subjects were blindfolded and given ear mufflers before entering the testing area.  The subject was guided to a standard position i n front of the apparatus by the experimenter.  The apparatus came approximately  between the standing subject's shoulder and hip.  to a height half-way  The subject stood as close  as possible to the table without touching i t with his f r o n t a l plane p a r a l l e l to the table.  The subject's right shoulder was d i r e c t l y i n l i n e and  perpendicular to the p i v o t .  The subject was instructed to remain i n this  30  p o s i t i o n for the duration of the experiment.  Once i n the standard p o s i t i o n , the subject's right hand was placed on the handle.  He was told to move the lever to get accustomed  to the  easiness of movements made possible by the near f r i c t i o n l e s s pivot. a few seconds, he was t o l d to bring both arms down to h i s side.  After  To move  the lever i n the horizontal plane, a combination of elbow f l e x i o n and shoulder rotation i s required.  The subject was instructed to maintain his movement as consistent as possible throughout the experiment.  I t was pointed out that time i n  movement was not a factor and that the movement should be of a comfortable and uniform v e l o c i t y .  On the command "ready" the subject was told to  move h i s hand from his side to the handle of the lever which was at the starting p o s i t i o n .  Verbal directions were given by the experimenter  to f a c i l i t a t e finding the handle.  The command "move" told the subject that  he was to move the lever at a constant speed i n a counterclockwise d i r e c t i o n u n t i l h i t t i n g a block.  The subject remained at the block for two seconds,  then released the handle and brought h i s hand back to h i s side.  This was  the beginning of the retention i n t e r v a l during which the experimenter returned the lever to the starting p o s i t i o n .  After the retention i n t e r v a l ,  the experimenter gave the command "ready" which signaled the subject to regrasp the lever.  On the command "reproduce", the subject t r i e d to  reproduce the standard, which he had been given before, as accurately as possible.  When the subject f e l t he was accurate, he released the handle  31  and brought his hand back to h i s side. t r i a l interval.  This was the s t a r t of the i n t e r -  The subject was given f i v e such pairs of movements to make  up the f i v e t r i a l s required f o r the experiment.  The retention i n t e r v a l s used i n the experiment were zero and t h i r t y seconds.  In the 0 sec. retention i n t e r v a l , the experimenter returned the  lever to the starting p o s i t i o n while the subject returned h i s hand to h i s side, as soon as this was executed, the experimenter gave the command "ready" followed by "reproduce".  The subjects i n the 30 sec. retention  i n t e r v a l groups were given a three d i g i t number as soon as they released the  lever a f t e r the standard movement.  They were instructed to count  backward from the given d i g i t by three's, out loud and as fast as possible. After 30 seconds of counting, the experimenter gave the command "ready" followed by "reproduce" when the subject had regrasped the handle.  The  t h i r t y second retention Interval was chosen because i t was f e l t that this time lapse would allow s u f f i c i e n t decay of the standard to allow the ALpg a s u f f i c i e n t gain i n importance so that i t s e f f e c t could be noticed i n the reproductions.  Some studies i n STM have used longer retention intervals  of 120 sec. (Ascoli and Schmidt, 1969); and 90 sec. (Marshall, 1972) but other researchers have had s i g n i f i c a n t r e s u l t s using retention intervals of 30 s e c , (Stelmach and Barker, 1970) 20 s e c  (Stelmach and Bassin, 1971,  Stelmach and Wilson, 1970), 15 sec. (Williams, 1971) and 12 sec. (Laabs, 1973).  32  The mental task was information.  introduced to prevent the rehearsal of l o c a t i o n  Laabs (1973) has shown that l o c a t i o n information decays very  l i t t l e over a rest period unless rehearsal i s prevented.  In this study,  the a v a i l a b i l i t y of both distance and l o c a t i o n cues at reproduction, made i t necessary  to introduce this mental a c t i v i t y to promote trace decay.  During the 30 sec. ITI, the subject was  asked not to rehearse  previous movement i n order to allow for i t to decay i n STM;  the  Bjork,  LaBerge and Legrand (1968) found that instructions to forget a p r i o r item reduced the proactive i n h i b i t i o n e f f e c t , hence the learning capacity. Here again, the t h i r t y second delay was judged s u f f i c i e n t for s u f f i c i e n t trace decay thus l i m i t i n g the amount of learning from t r i a l to t r i a l .  Analysis of the Data  The two dependent variables were constant error (CE) and variable error (VE).  CE i s defined as the mean algebraic error for each subject,  while VE i s the standard deviation of each subject's algebraic error scores about h i s CE.  These measures have been shown to be s t a t i s t i c a l l y independent  (Schutz and Roy,  1973).  Pepper and Herman (1970) suggested that CE measured the biasing e f f e c t of the experimental  treatment on the memory trace.  Laabs (1973) contends  that VE measures the strength of the memory trace; the smaller the VE,  the  33  greater the strength of the memory trace. postulated  In the present study, CE i s  to measure the biasing effect of the AL_„ whereas VE i s rfci  thought to measure the strength of the memory trace.  The CE was calculated as the mean of the S's f i v e t r i a l s .  These CE  means were analyzed i n a 2x2x2 (retention i n t e r v a l x movement length x movement location) analysis of variance.  The VE, or the standard deviation, f o r each S's f i v e t r i a l s , was determined.  These VE scores were analyzed i n a 2x2x2 (retention i n t e r v a l  x movement length x movement location) analysis of variance.  39 CHAPTER IV  RESULTS AND DISCUSSION  Results  Analysis of Constant Error  The analysis of variance of CE (Table 1, Appendix B) revealed a s i g n i f i c a n t main e f f e c t f o r distance F (1, 72) = 6.61, p<.05.  The other two  main e f f e c t s of retention i n t e r v a l F (1, 72) = 1.33, and l o c a t i o n F (1, 72) = 0.04 d i d not reach s i g n i f i c a n c e nor d i d any of the i n t e r a c t i o n s .  Thus the  only s i g n i f i c a n t d i f f e r e n c e i n CE was between the two movement lengths of 10° and 50°.  The CE values f o r these main e f f e c t s are represented i n  Table 1.  Table I The Main E f f e c t s i n Constant Error  Main E f f e c t Retention 0 sec.  30 sec.  1.5  2.5  * E f f e c t s i g n i f i c a n t , p<.05  (degrees)  Distance* 10° 3.1  50° 0.9  Location 60° 1.9  120° 2.1  35  Analysis of Variable Error  The analysis  of variance of VE (Table I I , Appendix B) revealed a  s i g n i f i c a n t main e f f e c t of retention distance F (1, 72) = 27.19, p<.01.  i n t e r v a l F (1,72) = 23.14, p<.01 and The other main e f f e c t of location  F (1, 72) = 2.93 d i d not reach s i g n i f i c a n c e nor d i d any of the i n t e r a c t i o n s . Thus, there was a s i g n i f i c a n t difference i n t e r v a l s of 0 sec. and 30 sec.  i n VE between the two retention  S i m i l a r l y , the VE f o r the short movement  of 10° was s i g n i f i c a n t l y d i f f e r e n t from the VE f o r the long movement of 50°.  The VE scores f o r these main e f f e c t s are represented i n Table I I  TABLE I I The Main E f f e c t s i n Variable Error  Main E f f e c t Degrees  Retention ** 0 sec.  30 sec.  2.6,  4.5  Distance ** 10° 2.5  50° 4.6  Location 60°  3.9  120° 3.2  ** E f f e c t s i g n i f i c a n t ; p<.01  Test f o r Homogeneity  A test f o r homogeneity of variance was applied  to the data.  Since  only the main e f f e c t s i n CE and VE were s i g n i f i c a n t (Table I and Table I I ) ,  36  i t was decided to apply Hartley's test (Winer, 1962: 92-96) only to those groups, giving two treatment groups with f o r t y subjects per group.  The  r e s u l t s of the test are summarized i n Table I I I .  As evident i n Table I I I there i s a borderline case of heterogeneity i n error variance of both dependent measures CE and and VE at the .01 l e v e l . Even though that i s the case, i t i s f e l t that the s i g n i f i c a n t e f f e c t s obtained are s t i l l v a l i d because the analysis of variance would be f a i r l y robust to deviations from homogeneity of error variance due to the equally large number of subjects (40) per group (Edwards, 1960: 132).  Table I I I Homogeneity of Error Variance i n Data for CE and VE Measures  Dependent Variable  Group  CE  —•  l  D  Variance 7.4  Fmax 2.4  ' D  2  18.0  2.4  2.6  Fmax (2, 39) = 1.96 p<.05 Fmax (2, 39) - 2.44 p<.01  37  Also to be taken into consideration i s the l e v e l of s i g n i f i c a n c e reached by the d i f f e r e n t main e f f e c t s .  The main e f f e c t of distance i n CE  reached a value of F (1, 72) = 6.61 which i s much closer to the F (1, 72) = 7.01 value which i s required f o r significance at the .01 l e v e l than the F (1, 72) = 3.98 value which i s required for significance at the .05 l e v e l . Here again, t h i s significance i s probably v a l i d because of the strength given to the analysis of variance by the large and equal number of subjects per group.  S i m i l a r l y , the F value obtained on VE scores f o r the main e f f e c t s of retention i n t e r v a l F (1, 72) = 23.14  and distance F (1, 72) = 27.19  are  highly s i g n i f i c a n t at the .01 l e v e l which requires an F value of only F (1, 72) = 7.01.  Thus, i t i s f e l t that these s i g n i f i c a n t differences  are v a l i d .  Discussion  Since no s i g n i f i c a n t differences were obtained i n the CE measure for retention i n t e r v a l s and locations, the f i r s t hypothesis must be rejected.  That  i s , long-term past experiences do not a f f e c t the reproduction of discrete movements.  To ensure that the possible e f f e c t of long-term past experiences  had not been influenced by a practice e f f e c t of the f i v e t r i a l s , for  the scores  CE of the f i r s t t r i a l of each subject were entered i n an analysis of  variance.  As shown i n Table I I I , Appendix B, none of the main e f f e c t s or  interactions reached significance.  This being a second proof that past  38  experiences i n LTM do not a f f e c t movement  reproductions.  The n u l l e f f e c t s show that either no ALp_; i s formed i n LTM or there i s no PI from LTM or both of these.  On the other hand, an AL for LTM  acting through PI might not be strong enough to influence  reproductions.  I t seems that the f i r s t two suggestions are l i k e l y to be occurring.  I f one accepts Hebb's physiological point of view (Hebb, 1961:41) that on unstable a c t i v i t y trace becomes a more stable s t r u c t u r a l trace with reinforcement,  without getting involved i n arguments concerning  mechanism memory theory theory  (Gruneberg, 1964,  1970)  a single  or a dual mechanism memory  (Scott, Whimbley and Dunning, 1967a, 1967b), then i t i s possible  that a f t e r s u f f i c i e n t reinforcements the r e s u l t i n g s t r u c t u r a l trace i s an e n t i t y i n LTM and as such i s treated i n d i v i d u a l l y during r e t r i e v a l .  Thus,  a l l traces i n LTM would be kept separate, although probably i n some h i e r a r c h i a l way,  and would not combine to form an AL for  LTM.  Scott, Whimbley and Dunning (1967a, 1967b) have shown that i n verbal memory, there i s no PI e f f e c t from previously learned items i n LTM upon newly learned items i n STM.  acting  This lack of PI could be explained for  motor memory using the model for MSTM developed by Craft (1973).  His  r e s u l t s indicate that the i n t e r f e r i n g e f f e c t of one movement on the r e c a l l of another occurs at the time of completion of the second movement rather than at r e c a l l .  Furthermore, the degree of interference i s related to the  amount of time elapsed between establishment  of the memory trace and the trace  39  which interferes with i t .  According to this model, the e f f e c t of PI i s  represented i n this form; I - A t - S - R where I i s the i n t e r f e r i n g trace, At i s the time elapsed between the i n t e r f e r i n g trace (I) and the stimulus (S).  R i s the reproduction of S.  In the present study, I i s located i n  LTM but i s not a c t i v e l y reproduced i n the experimental  situation.  The time  elapsed between I and S ( A t ) i s i n d e f i n i t e but greater than any time i n t e r v a l used i n studies of STM. p h y s i c a l l y present.  Thus, only the remaining  two factors S and R are  Because of the very weak or non-existent I and  the  r e l a t i v e l y long At, PI i n the present study could not influence the reproduction of the stimulus.  Of i n t e r e s t , concerning constant errors, i s the lack of s i g n i f i c a n t change over retention i n t e r v a l s for either of the distances at either location. This i s i n contrast to the study by Laabs (1973) and other s i m i l a r studies (Stelmach, 1970;  Stelmach and Wilson, 1970) which, a f t e r a retention  i n t e r v a l , report increasing undershooting overshooting  for short movements.  for long movements and increasing  Perhaps those biases toward an AL can only  be seen i n studies where the same subject i s given d i f f e r e n t movement lengths at d i f f e r e n t locations thus setting up what could be c a l l e d an experimental AL.  Therefore Laabs' (1973) p r e d i c t i o n that forgetting i n  the central mode of storage w i l l cause a biasing effect toward the l o c a t i o n AL, could only be applied to experiments where a subject i s presented  with  a range of distances and l o c a t i o n s . The same r e s t r i c t i o n could be applied to the prediction that forgetting i n the kinesthetic mode of a storage w i l l cause a biasing e f f e c t toward the movement length AL although  the  40  s i g n i f i c a n t e f f e c t of distance on CE found i n the present study might indicate the presence of an inherent adaptation l e v e l f o r movement length. Since the longer distance was only s l i g h t l y overshot, t h i s AL would be represented by a movement s l i g h t l y longer than 50°.  Hirschfield, Leveille  and Thomas (1973), also using independent groups, d i d not f i n d such a trend i n CE f o r l i n e a r movements of 6 cm., 12 cm., 18 cm., 24 cm. and 30 cm. Unlike the present study, the movements were reproduced  at d i f f e r e n t  locations to the l e f t of the r i g h t shoulder, which could be moving away from the location of greatest accuracy, front of the shoulder.  apparently located at 90° i n  More research i s needed i n t h i s area but Brown,  Knauft and Rosenbaum (1948) and Stelmach (1970) hint to i t s existence. In the present study, the two locations were symmetrical about the 90° which could explain why the CE were s i m i l a r l y inaccurate.  Another point of interest concerning constant error i s the p o s i t i v e s h i f t over retention i n t e r v a l .  These findings were not s i g n i f i c a n t but  are i n agreement with Pepper and Herman (1970) who postulate such a s h i f t when the retention i n t e r v a l i s f i l l e d with a mental a c t i v i t y such as counting. A quick look at the R x D interaction reveals that both distances have a s i m i l a r s h i f t i n CE.  The 10° distance went from 2.6 to 3.5; the 50°  distance, from 0.4 to 1.4.  Thus, i t seems that the assumption concerning  the e f f e c t of counting on d i f f e r e n t movement lengths was v a l i d although t h i s cannot be given unequivocal status because the experiment was not designed to look at t h i s problem.  I t i s possible that shorter movements decay less  41  and are influenced to a lesser degree by counting whereas longer movements could decay more but at the same time be more susceptible to counting; such a combination would y i e l d r e s u l t s similar to those obtained.  Such an  i n t e r a c t i o n could be possible since the VE scores d i d d i f f e r i n the predicted d i r e c t i o n for movement lengths with VE here being interpreted as an index of the strength of the memory trace.  The f i r s t hypothesis also suggested that i n t r a - i n d i v i d u a l v a r i a b i l i t y would increase following a retention i n t e r v a l . i n t e r v a l for VE was highly s i g n i f i c a n t .  The main e f f e c t of retention  This r e s u l t i s similar to Laabs  (1973) and i s seen to undermine the a s s i m i l a t i o n theory of Pepper and Herman (1970) which requires that the subject reproduce f a i t h f u l l y the extent represented by the decaying trace y i e l d i n g a negative s h i f t i n CE. However, i t has been shown that the v a r i a b i l i t y increases when the memory trace decays.  The second hypothesis which related VE d i r e c t l y to movement length was supported.  The main effect of distance was s i g n i f i c a n t f o r the VE  scores with the shorter movement being less v a r i a b l e than the longer one. This r e s u l t i s similar to those of H i r s c h f i e l d , L e v e i l l e and Thomas (1973) who found that VE scores increased as the movement length increased. This finding could be important, unless steps are taken to balance the e f f e c t , i n studies which have d i f f e r e n t movement lengths f o r the standards and reproductions.  When the reproduction length i s shorter, the subject  reproduces with a movement which i s less v a r i a b l e and could conceivably be less affected by manipulations.  However, a longer movement i n reproduction  42  i s more variable than that of the standard a greater degree by biasing f a c t o r s .  Unfortunately,  to look at the d i f f e r e n t cues subserving effect.  and could be influenced to studies attempting  kinesthesis have confounded this  To make the distance cue u n r e l i a b l e , d i f f e r e n t movement lengths  are used to reach the same l o c a t i o n ; the present study has shown that d i f f e r e n t movement lengths have d i f f e r e n t VE.  The t h i r d hypothesis predicted a s i g n i f i c a n t i n t e r a c t i o n between movement lengths and retention i n t e r v a l s . The greater increase i n VE for the shorter movement when compared to the VE increase of the longer movement did not m a t e r i a l i z e . a s i m i l a r manner.  In fact both movement lengths changed i n  Thus, when d i f f e r e n t movement lengths are subjected  to the same conditions, t h e i r changes are s i m i l a r .  I t seems that d i s c r i m i n -  a b i l i t y of s t a r t i n g and target locations i s not an important f a c t o r .  The predictions of the fourth hypothesis,  that changing the target  l o c a t i o n for a given movement length, would not influence the v a r i a b i l i t y of that movement, was correct.  The main e f f e c t of l o c a t i o n as well as  the interactions of l o c a t i o n and distance and l o c a t i o n and retention i n t e r v a l did not reach s i g n i f i c a n c e .  Thus, i n independent groups, changing  the target l o c a t i o n of a given movement does not a f f e c t that movement's variability.  In studies attempting to investigate the l o c a t i o n cues,  the same movement length i s used, hence having the same v a r i a b i l i t y , but the reproduction might be affected by PI since the same subject experiences  43  both locations.  Marteniuk and Roy (1973) have reported such bias.  CHAPTER V  SUMMARY AND CONCLUSIONS  Summary  The main purpose of this study was to investigate the p o s s i b i l i t y that an adaptation l e v e l made up of long-term past experiences could influence the reproduction of d i s c r e t e movements.  Interference from the  experimental s i t u a t i o n was kept to a minimum allowing such an AL to possibly influence movement reproduction.  Other problems investigated were (1)  the evaluation of VE for d i f f e r e n t movement lengths at the same location and (2) the differences of VE for a given movement length at d i f f e r e n t locations.  Eighty right-handed male subjects were tested.  Ten subjects were  assigned to each group.  The task involved the reproduction of a given standard a f t e r a given retention i n t e r v a l at a given l o c a t i o n . of the c e l l s of a 2x2x2 f a c t o r i a l design.  One group was assigned to each The two retention i n t e r v a l s  were 0 sec. and 30 s e c ; the two movement locations, 60° and 120°; and the two movement lengths, 10° and 50°.  Each subject was given f i v e standard-  reproduction sequences of the given standard f o r the given retention i n t e r v a l at the given location with an ITI of 30 s e c  45  The r e s u l t s indicated that long-term past experiences did not influence movement reproduction and that the target location d i d not a f f e c t the v a r i a b i l i t y of a given movement.  A s i g n i f i c a n t difference i n v a r i a b i l i t y  between the two movement lengths was evident, as well as between the two retention i n t e r v a l s .  Conclusions  The conclusions were:  1.  Long-term past experiences do not influence the reproduction of d i s c r e t e  motor movements.  2.  Changing the target location for a given movement length does not change  the v a r i a b i l i t y of that movement.  3.  The v a r i a b i l i t y of a movement i s related to the movement length.  In  this experiment, the longer movement was s i g n i f i c a n t l y more variable than the shorter movement.  4.  The v a r i a b i l i t y of a given movement increases as the retention i n t e r v a l  increases.  This v a r i a b i l i t y i s seen as an index inversely related to the  strength of the memory trace.  46  BIBLIOGRAPHY  ADAMS, J.A., A closed-loop theory of motor learning. Behavior, 3:111-149, 1971.  Journal of Motor  ADAMS, J.A. and DIJKSTRA, S., Short-term memory f o r motor responses. Journal of Experimental Psychology, 71:314-318, 1966. ADAMS, J.A., MARSHALL, P.H. and GOETZ, E.T., Response feedback and shortterm motor retention. Journal of Experimental Psychology, 92:92-95, 1972. ASCOLI, K.M. and SCHMIDT, R.A., Proactive interference i n short-term retention. Journal of Motor Behavior, 1:29-36, 1969. BJORK, R.A., LABERGE, D. and LEGRAND, R., The modifications of short-term memory through instructions to forget. Psychonomic Science, 10:5556, 1968. BROWN, S.S., KNAUFT, E.B. and ROSENBAUM, G., The accuracy of positioning reactions as a function of their d i r e c t i o n and extent. American Journal of Psychology, 61:167-182, 1948. CRAFT, J.L., A two process theory f o r the short-term retention of motor responses. Journal of Experimental Psychology, 98:196-202, 1973. CRAFT, J.L. and HINRICHS, J.V., Short-term retention of simple motor responses: s i m i l a r i t y of p r i o r and succeeding responses. Journal of Experimental Psychology, 87:297-302, 1971. f  EDWARDS, A.L., Experimental Design i n Psychological Research. Holt, Rinehart and Winston, 1960.  New York:  ELLIS, H.D., An examination of the adaptation-level theory account of time errors. Journal of Experimental Psychology, 98:160-163, 1973. GRANIT, R., Constant errors i n the execution and appreciation of movement. Brain: A Journal of Neurology, 95:649-660, 1972. GRUNEBERG, M.M., The limited capacity hypothesis and short-term memory. Acta Psychologica, 31:326-339, 1969. GRUNEBERG, M.M., A dlchotomus theory of memory - unproved and unprovable. Acta Psychologica, 34:489-496, 1970.  47  HEBB, D.O., D i s t i n c t i v e features of learning i n the higher animal. In J.F. DELAFRESNAYE (Ed.), Brain Mechanisms and Learning. Oxford: Blackwell, 37-46, 1971. HELSON, H. and BEVAN, W., Contemporary Approaches to Psychology. D. Van Nostrand Company, Inc., 273-310, 1967.  Toronto:  HIRSCHFIELD, T., LEVEILLE, S.M. and THOMAS, G., The e f f e c t of multiple movement lengths on constant and variable errors. Unpublished data, 1973. KEELE, S.W. and ELLS, J.G., Memory c h a r a c t e r i s t i c s of kinesthetic information. Journal of Motor Behavior, 4:127-135, 1972. LAABS, G.S., Retention c h a r a c t e r i s t i c s of d i f f e r e n t reproduction cues i n motor short-term memory. Journal of Experimental Psychology, 1973, i n press. LEVEILLE, S.M., The e f f e c t of practice on constant error and i n t r a i n d i v i d u a l v a r i a b i l i t y . Unpublished data, 1973. LEVIN, I.P., CRAFT, J.L. and NORMAN, K.L., Averaging of motor movements: tests of an additive model. Journal of Experimental Psychology, 91: 287-294, 1971. LLOYD, A.J. and CALDWELL, L.S., Accuracy of active and passive positioning of the leg on the basis of kinesthetic cues. Journal of Comparative and P h y s i o l o g i c a l Psychology, 60:102-196, 1965. MARTENIUK, R.G. and ROY, E.A., The c o d a b i l i t y of kinesthetic location and distance information. Acta Psychologica, 1973, i n press. MARTENIUK, R.G. and RYAN, M.L., Psychophysics of kinesthesis: angular movements. Journal of Motor Behavior, 4:135-142, 1972. MONTAGUE, W.E. and HILLIX, W.A., I n t e r t r i a l i n t e r v a l and proactive i n t e r ference i n short-term motor memory. Canadian Journal of Psychology, 22:73-78, 1968. PEPPER, R.L. and HERMAN, L.M., Decay and interference e f f e c t s i n the shortterm retention of a discrete motor act. Journal of Experimental Psychology, Supplement, 83:1-18, 1970. POSNER, M.I., C h a r a c t e r i s t i c s of v i s u a l and kinesthetic memory codes. Journal of Experimental Psychology, 73:103-107, 1967. POSNER, M.I. and KONICK, A.F., Short-term retention of v i s u a l and kinesthetic information. Organic Behavior and Human Performance, 1:71-86, 1966.  48  SCHMIDT, R.A. and ASCOLI, K.M., I n t e r t r i a l i n t e r v a l s and motor shortterm memory. Research Quarterly, 41:432-438, 1970. SCHUTZ, R.W., A theory of motor memory r e t r i e v a l . d i s s e r t a t i o n , University of Wisconsin, 1972.  Unpublished doctoral  SCOTT, K.G., WHIMBLEY, A.E. and DUNNING, G., Separate LTM and STM systems? Psychonomic Science, 7:55-56, 1967a. SCOTT, K.G., WHIMBLEY, A.E. and DUNNING, G., A functional d i f f e r e n t i a t i o n of STM and LTM. Psychonomic Science, 7:143-144, 1967b. STELMACH, G.E., P r i o r positioning responses as a factor i n short-term retention of a simple motor task. Journal of Experimental Psychology, 81:523-526, 1969a. STELMACH, G.E., Short-term motor retention as a function of responsesimilarity. Journal of Motor Behavior, 1:37-44, 1969b. STELMACH, G.E., Kinesthetic r e c a l l and information reduction a c t i v i t y . Journal of Motor Behavior, 2:183-194, 1970. STELMACH, G.E. and BASSIN, S.L., The r o l e of overt motor rehearsal i n kinesthetic r e c a l l . Acta Psychologica, 35:56-63, 1971. STELMACH, G.E. and WILSON, M., Kinesthetic retention, movement extent and information processing. Journal of Experimental Psychology, 85:425430, 1970. WILBERG, R.B., Response accuracy based upon r e c a l l from v i s u a l and kinesthetic short-term memory. Research Quarterly, 40:407-414, 1969. WILLIAMS, I.D., The e f f e c t of practice t r i a l s and p r i o r learning on motor memory. Journal of Motor Behavior, 3:205-211, 1971. 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. McGraw-Hill Book Co., 1962.  New York:  49  APPENDIX  Apparatus  A  MOVEMENT APPARATUS  ILLUSTRATION OF MOVEMENT LENGTHS AND LOCATIONS  52  APPENDIX B S t a t i s t i c a l Analysis  53  TABLE  I  Analysis of Variance of Constant Error  Source of Variance  df  M S  F  Retention  1  17.9  1.3  Location  1  0.5  0.0  Distance  1  88.8  6.6  RxL  1  0.5  0.1  RxD  1  0.6  0.  LxD  1  19.3  1.4  RxLxD  1  10.8  0.8  SwRxLxD  * <.05 P  72  13.4.  *  54  TABLE II Analysis of Variance of Variable Error  Source of Variance  df  M S  F  Retention  1  72.5  23.1  Location  1  9.2  2.9  Distance  1  85.2,  RxL  1  3.4  1.1  RxD  1  2.4  0.8  LxD  1  0.1  0.0  RxLxD  1  0.4  0.1  72  3.1  SwRxLxD  **  p<.01  27.2  55  TABLE I I I  A n a l y s i s o f Variance of Constant f o r the F i r s t  Source o f V a r i a n c e  df  Error  Trial  F  M S  Retention .  1  124.3  2.0  Location  1  1.4  0.0  Distance  1  102.4  1.6  RxL  1  7.9  0.1  RxD  1  0.6  0.0  LxD  1  94.8  1.5  RxLxD  1  9.6  0.2  72  62.7  Sw(RxLxD)  F ( 1 , 72) = 3.98 p .05  56  APPENDIX  C  Table of Means  57  TABLE  I  The E f f e c t of Retention Interval, Location, and Distance on Movement Reproduction  Retention  0 sec.  30 sec.  Location  i n Terms of CE  Distance  Error (deg)  58  TABLE  II  The E f f e c t of Retention Interval, Location, and Distance on Movement Reproduction  Retention  0 sec.  30 sec.  Location  i n Terms of VE  Distance  SD (deg)  

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