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The isolation of certain experimental issues in the continuity controversy Levey, Archibald Banks 1953

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THE -ISOLATION OF CERTAIN EXPERIMENTAL ISSUES IN THE CONTINUITY CONTROVERSY  by ARCHIBALD BANKS LEVEY  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS i n the Department of PHILOSOPHY AND PSYCHOLOGY  We accept t h i s t h e s i s as conforming t o t h e standard r e q u i r e d from candidates f o r the degree o f MASTER OF ARTS  Members of t h e Department o f Philosophy and Psychology.  THE UNIVERSITY OF BRITISH COLUMBIA October, 1953  THE ISOLATION OF CERTAIN EXPERIMENTAL ISSUES IN THE CONTINUITY CONTROVERSY  Abstract  The h i s t o r i c a l development o f t h e c o n t i n u i t y controversy i n d i s c r i m i n a t i o n l e a r n i n g i s reviewed i n i t s e s s e n t i a l aspects as a t h e o r e t i c a l and as an experimental problem. Some i m p l i c a t i o n s o f t h e controversy are d i s cussed and an a n a l y s i s i s made o f t h e trends o f experimenta l evidence t o date. I t i s found t h a t , i n experiments i n which a r e l a t i v e l y simple d i s c r i m i n a t i o n i s t e s t e d , t h e c o n t i n u i t y p o s i t i o n i s g e n e r a l l y upheld, while i n complex d i s c r i m i n a t i o n s t h e issues remain i n doubt. A f a i r l y det a i l e d statement o f each of the t h e o r e t i c a l p o s i t i o n s i s presented i n an e f f o r t t o c l a r i f y the experimental issues and t o a r r i v e a t c r i t e r i a which are o f f e r e d as being e s s e n t i a l f o r experiments d i r e c t e d a t the controversy. The design o f such an experiment i s presented. This experiment could not be completed and t h e p o s s i b l e causes of i t s f a i l u r e are analysed. I n the absence of f i n a l r e s u l t s t h e data f o r t h e i n i t i a l brightness d i s c r i m i n a t i o n are'analysed and found t o y i e l d s i g n i f i c a n t r e s u l t s i n favour o f the c o n t i n u i t y theory. I t i s suggested t h a t i f experiments which meet t h e c r i t e r i a a r i s i n g out o f the r e quirements o f both t h e theories are repeatedly found t o be inoperable or i n c o n c l u s i v e the controversy i n i t s present form cannot be held t o have o p e r a t i o n a l meaning. Areas o f t h e controversy i n which f u r t h e r c l a r i f i c a t i o n o f theory i s needed are i n d i c a t e d . References are included which o f f e r a balanced survey o f the l i t e r a t u r e .  ACKNOWLEDGMENT  The w r i t e r wishes t o express h i s g r a t i t u d e to the Department o f Philosophy and Psychology, U.B.C., f o r i t s generous p r o v i s i o n o f equipment and f a c i l i t i e s , and t o those f a c u l t y members who contributed c r i t i c i s m s and suggestions. Thanks are p a r t i c u l a r l y due t o Dr. D. T. Kenny whose s t i m u l a t i n g presentation o f i t s i s s u e s i n i t i a t e d t h i s study and who acted as i t s advisor; and to P r o f . E. S. W. Belyea, who k i n d l y f a c i l i t a t e d cons t r u c t i o n of the apparatus and provided the photographs. Thanks are a l s o due t o Dr. A. J . Wood, Department o f Animal Husbandry, U.B.C., who g r a c i o u s l y extended t h e loan o f cages and equipment and o f f e r e d advice on t h e caging and general economy o f the colony.  CONTENTS  Chapter  Page  I II —  III  IV  Introduction  1  H i s t o r i c a l background o f the controversy  5  T h e o r e t i c a l issues Experimental i s s u e s Recent trends Summary C l a r i f i c a t i o n o f the two p o s i t i o n s  36  The c o n t i n u i t y p o s i t i o n The non-continuity p o s i t i o n  36 41  The Experiment C r i t e r i a f o r an adequate experiment Rationale o f the present experiment Apparatus Controls Plan o f procedure Description o f procedure Analysis o f p o s s i b l e causes o f f a i l u r e  V  Results D e s c r i p t i v e a n a l y s i s o f data Analysis o f e r r o r scores The Spence assumptions  VI  5 15 26 34  Summary and conclusions References  48 48 52 56 58 60 65 69 72 72 76 94 99 103  T A B L E S  P o s s i b l e d i s p o s i t i o n s of e r r o r scores for given categories of p o s i t i o n r e sponses P r o b a b i l i t y of chance occurrence of the e r r o r scores presented i n Table I Performance o f each subject i n block of ten t r i a l s Frequency of occurrence of p o s s i b l e e r r o r scores permitted by the occurrence of 9, 8, or 7 p o s i t i o n responses i n ten t r i a l s T h e o r e t i c a l and observed d i s t r i b u t i o n of error scores during three phases o f the p r e - s o l u t i o n period D i s t r i b u t i o n of error scores i n the t h i r d and fourth quarters of the pres o l u t i o n p e r i o d f o r Category 7  P L A T E S  Plate I  II  III IV  Page Stimulus windows and double pronged jumping stand  57  Goal box and a l t e r n a t e non-reward compartments  59  Apparatus from i n f r o n t  61  F i n a l stimulus cards w i t h an animal approaching  64  CHAPTER I INTRODUCTION  The a c t i v i t y o f t h e r a t i n i n f i l t r a t i n g contemporary psychology, and i n winning o r usurping there a r a t h e r comfortable niche i n the h i e r a r c h y , i s a subject o f s u f f i c i e n t dispute t h a t the w r i t e r o f a r a t t h e s i s must f e e l impelled, before t u r n i n g t o h i s proper study, t o c l a r i f y h i s a l l e g i a n c e s i n the matter.  Perhaps not the l e a s t appropriate means  of doing t h i s i s t o present the aims o f such a study, together w i t h the biases o r f o c i o f i n t e r e s t which may have prompted them. A f i r s t aim o f the present study was t o attempt t o assess a t f i r s t hand some aspects o f t h e r o l e o f r a t studies i n psychology.  In  doing t h i s the i n t e r e s t was l i m i t e d t o the type o f study i n which r a t s are used as the instruments of systematic theory.  This i s t h e area i n  which objects o f the "many v a r i a b l e " type are naive, since such systems are not intended as l i v e d e s c r i p t i o n s o f r a t behaviour;  r a t h e r , the u n i t  i s an a b s t r a c t q u a n t i t a t i v e r a t analogous t o the w e l l known c o l o u r l e s s t a s t e l e s s odourless b i l l i a r d b a l l o f c l a s s i c a l physics.  Variables which  are not chosen as r e f e r e n t s i n the theory a r e o f no consequence other than f o r t h e i r masking e f f e c t , a p u r e l y o p e r a t i o n a l problem.  At present  such t h e o r i e s provide only a l i m i t e d model f o r a systematic psychology. Whether they may subsequently be extended as a b a s i s f o r psychology, o r whether they must e v e n t u a l l y be abandoned as inappropriate i s a question  2  f o r the f u t u r e and any s p e c u l a t i o n i n e i t h e r d i r e c t i o n i s merely an exp l o r a t i o n of b i a s e s .  The s i t u a t i o n may be analogous t o t h a t of a r i g o r -  ous p h y s i c a l science which i s l i m i t e d , however v a l i d , t o producing machines which must operate a t practical r a t h e r than t h e o r e t i c a l e f f i c i e n cy;  the question f o r psychology being whether the e f f i c i e n c y a t t a i n a b l e  f o r a complex f i e l d i s s u f f i c i e n t t o j u s t i f y the e l a b o r a t i o n o f theory r e q u i r e d by such a f i e l d .  On the other hand i t may prove t o be the  case t h a t the understanding o f i p s e i t y or uniqueness i s more fundamental t o the science than i n c l u s i v e systematization or i n other words t h a t a new d e f i n i t i o n of science may be r e q u i r e d .  The i n t e r e s t here however  i s i n attempting t o assess the p r a c t i c a b i l i t y o f such l i m i t e d - v a r i a b l e models by sustained observation o f t h e i r processes of data formation. A second aim i n undertaking the study l i e s w i t h i n the considera t i o n s o u t l i n e d above.  Granted the l i m i t a t i o n which was imposed, there  s t i l l remains the question o f a l t e r n a t i v e approaches t o system b u i l d i n g . I n t e r e s t i s centered here on the molecular versus "molar" pseudodichotomy which appears i n contemporary theory. be amiss.  One or two observations may  not  F i r s t i s the obvious, but sometimes neglected, e m p i r i c a l  f a c t t h a t a molecular theory must d e a l at some point w i t h molar u n i t s , together w i t h the l o g i c a l n e c e s s i t y t h a t a molar theory assume molecular processes, both emphasizing the r e l a t i v i t y of the terms.  Second i s the  l e s s obvious e m p i r i c a l f a c t t h a t a t some p o i n t i n the c o n s t r u c t i o n o f an axiomatic, deductive, or a l g e b r a i c system (which at present can be equated w i t h "molecular" theory i n psychology) there must enter a f a c t o r of a r b i t r a r y or value based judgments.  This i s the p o i n t a t which r e f e r e n t s  3  are chosen to produce an " i n t e r p r e t e d " system.  While t h i s type o f sys-  tem i s extremely impressive, i t s v e r y awesomeness tends to overshadow the a r b i t r a r y mechanisms involved i n choice o f r e f e r e n t s .  As an example  Woodger's use of the method, which i s perhaps more conservative than t h a t o f H u l l , involves as a q u a n t i f i e d v a r i a b l e i n i t s a p p l i c a t i o n t o embryology, the thickness of t h e microtome s l i c e , a convenient q u a n t i f i c a t i o n and one which i s j u s t i f i e d but one which i s t o t a l l y a r b i t r a r y i n terms o f the n a t u r a l phenomena i n v e s t i g a t e d .  I t i s axiomatic that the d e s c r i p t i o n  o f nature provided by any theory i s r i g i d l y confined t o the i n t e r p r e t i v e categories which i t contains.  This introduces the i n t e r e s t i n g problem  o f p o s s i b l e " c u l t u r e binding" i n the choice of r e f e r e n t s .  The choice  o f the c e n t r a l concept " d r i v e " ( i . e . , motivating force) i n a c u l t u r e dominated by the Faustian m o t i f o f s t r i v i n g , might f o r example i n a c u l t u r e emphasizing an Apollonian s t a b i l i t y never be u t i l i z e d .  (A con-  cept, i n c i d e n t a l l y , which seems t o move away from the c u l t u r e bound determinants of H u l l and others may be Schroedinge's "negative entrophy".) While these considerations may seem f a r a f i e l d they are by no means imp e r t i n e n t t o the broader aspects of the study.  A f u r t h e r aim then o f  t h a t study was t o attempt, b e a r i n g i n mind the suggestions above, an evaluation o f these two approaches.  The problem selected i s one o f the  few i n which these approaches come d i r e c t l y i n contact and are a t v a r i ance, and w h i l e the s p e c i f i c issues can determine nothing about the usefulness of the approaches, they can shed considerable l i g h t on the manner i n which they have been applied t o Learning Theory.  I t was f e l t t h a t a  f i r s t hand comparison of the two modes of d e s c r i p t i o n could not h e l p but  4  be f r u i t f u l , and i t i s o f i n t e r e s t t h a t the w r i t e r , who began with a strong molar b i a s , g r a d u a l l y found himself a c q u i r i n g an a p p r e c i a t i o n of the molecular approach, while at the same time deepening h i s understandi n g of the molar a t t i t u d e . A more immediate and p r a c t i c a l aim was that of a c q u i r i n g a basis on which t o evaluate the growing l i t e r a t u r e of r a t s t u d i e s , part i c u l a r l y i n view of the naive but a t t r a c t i v e temptation to generalize t o human behaviour, as w e l l as the more formal a p p l i c a t i o n o f t h i s process a t a s o p h i s t i c a t e d l e v e l .  I t was not hoped that a s i n g l e ex-  periment, however protracted, would accomplish t h i s e f f i c i e n t l y ;  rather  that i t would provide a matrix o f observations which could serve as a foundation f o r evaluation, i f o n l y as a s u b s t i t u t e f o r t h a t thorough s a t u r a t i o n of knowledge e s s e n t i a l to understanding. F i n a l l y , and most immediate, was the aim of studying the s p e c i f i c problems o f the c o n t i n u i t y controversy, together w i t h the o f a c q u i r i n g an experimental technique i n a c l e a r l y defined area.  adm This  aspect of the study was rewarding but f e l l f a r short o f y i e l d i n g conclusive results.  However, the w r i t e r wishes t o point out t h a t accom-  panying the sparse record of the experiment i t s e l f i s a y i e l d which owing t o i t s s u b j e c t i v e nature does not appear on the typewritten pages, but which represents rewarding experience accrued, and goes some cons i d e r a b l e distance toward f u l f i l l i n g the aims here o u t l i n e d .  CHAPTER I I HISTORICAL BACKGROUND OF THE CONTROVERSY  T h e o r e t i c a l Issues Before t u r n i n g t o the h i s t o r i c a l background o f the c o n t i n u i t y controversy i t would seem appropriate t o examine b r i e f l y the issues i n v o l v e d , and t o d e l i n e a t e the opposing points o f view. i t y " p o s i t i o n may be b r i e f l y s t a t e d thus :  The "continu-  the l e a r n i n g process i s a  gradual and continuous summation o f increments t o the e x c i t a t o r y or i n h i b i t o r y value o f cue s t i m u l i f o l l o w i n g upon reward or non-reward o f each response t o those s t i m u l i .  The opposing viewpoint, t h e "non-  c o n t i n u i t y " p o s i t i o n describes the l e a r n i n g process as being i n part a f u n c t i o n o f the organism's a c t i v e l y s t r u c t u r i n g the stimulus s i t u a t i o n , such t h a t i t s performance i s dependent not only upon past experience, ^ but a l s o upon i t s contemporary o r g a n i s a t i o n of the s i t u a t i o n , rewards being e f f e c t i v e i n determining the appropriateness o f a given stimulus organisation.  I t would probably be unwise t o conclude a t t h i s p o i n t  t h a t e i t h e r view i n v o l v e s a more extensive a r r a y o f assumptions than does the other; however, i t w i l l r e a d i l y be seen that the former p o s i t i o n i s more s u s c e p t i b l e of concise formulation than i s t h e l a t t e r . While these t e n t a t i v e summarisations a r e s t a t e d i n terms o f the broad i s s u e s o f l e a r n i n g theory, t h e c o n t i n u i t y controversy has i n f a c t been l i m i t e d f o r the most part t o the study o f d i s c r i m i n a t i o n  6  learning.  The problem i s h i s t o r i c a l i n t h e sense that i t has developed  w i t h a c e r t a i n consistency through experimental studies and t h e o r e t i c a l a r t i c l e s during t h e past twenty-three years.  The procedure here w i l l  be, f i r s t , t o trace t h i s development i n terms of the t h e o r e t i c a l issues which have contributed t o i t , and then t o examine the experimental l i t e r a t u r e i n s o f a r as i t i s p e r t i n e n t , before considering the as i t appears to-day.  controversy  I n view o f the frequent overlapping o f a r t i c l e s  i n the j o u r n a l s , the treatment w i l l be l o g i c a l , rather than c h r o n o l o g i c a l , i n the i n t e r e s t o f c l a r i t y . The " c o n t i n u i t y controversy" was conceived, so t o speak, by Lashley (26) i n 1930 ( i t was not d e l i v e r e d by Spence u n t i l 1936, and was christened by Krechevsky i n 193S) when he wrote i n p a r t , . . . i n the d i s c r i m i n a t i o n box, responses t o p o s i t i o n , t o a l t e r n a t i o n , or t o cues from the experimenters' movements u s u a l l y precede the reactions t o the l i g h t and represent attempted s o l u t i o n s which are w i t h i n t h e r a t ' s customary range o f a c t i v i t y . . . . ( E v i d e n c e ) strongl y suggests that t h e a c t u a l a s s o c i a t i o n i s formed v e r y q u i c k l y , and that both the p r a c t i c e preceding and t h e errors f o l l o w i n g i t are i r r e l e v a n t t o t h e a c t u a l forma t i o n o f the association.-^ Elsewhere i n t h e same source he r e f e r s t o the " a l l or nothing basis o f the d i s c r i m i n a t i o n h a b i t " •  The assumptions underlying these statements  form the core o f the non-continuity  hypothesis.  Krechevsky was d i r e c t l y stimulated by the foregoing statements to perform a s e r i e s o f experiments (15) (16) (17) designed t o t e s t these  I t a l i c s mine.  7  assumptions, h i s method being t o analyse the i n d i v i d u a l l e a r n i n g curves o f h i s subjects i n terms not o n l y o f the percentage o f " c o r r e c t " responses but a l s o t h e percentage o f l e f t going, r i g h t going, a l t e r n a t i n g responses, etc.  That i s , by assuming that no response was due t o chance, he was  able t o analyse i n d i v i d u a l performances as though the animals were attempti n g systematic s o l u t i o n s , and thus t o p l o t curves f o r t h e performance i n terms o f these s o l u t i o n s .  I t i s o f some h i s t o r i c a l i n t e r e s t t h a t  Krechevsky was t h e f i r s t t o use the i n d i v i d u a l curve as a t h e o r e t i c a l unit of learning.  While the t y p i c a l curve f o r d i s c r i m i n a t i o n l e a r n i n g  f o l l o w s t h e chance l i n e (50$) f o r approximately three quarters o f i t s l e n g t h , the curves p l o t t e d as described above revealed c l e a r cut descent from the chance l i n e d u r i n g the e a r l y t r i a l s f o r the"attempted s o l u t i o n s " , followed by a r e t u r n t o chance and the descent of the error curve t o zero. The c r i t e r i o n set f o r performance beyond chance was a r r i v e d a t by computi n g the standard d e v i a t i o n f o r the t o t a l number o f responses and exhausti n g the chance d i s t r i b u t i o n w i t h the formula  The chance  zone l i m i t thus e s t a b l i s h e d was assumed by Krechevsky t o l i m i t the range o f chance responses, and any curve f a l l i n g outside i t was taken t o i n d i c a t e t h e operation o f a systematic response.  The tautalogy inherent  i n t h i s method, which assumes no chance responses, was redeemed by comb i n i n g the scores f o r a l l types o f responses, which u s u a l l y f e l l c l o s e to 100$.  ( I t might, on the other hand, be held that t h i s procedure  merely demonstrates that t h e s e l e c t i o n of imputed "hypotheses" had exhausted t h e p o s s i b l e response combinations.) The experiments on which h i s conclusions were based were performed w i t h r a t s i n t h e m u l t i p l e choice problem box designed by Stone.  8  Brightness and hurdle d i s c r i m i n a t i o n s were employed, the l a t t e r t o meet the  Gestalt contention that there should be some necessary r e l a t i o n  between stimulus and response i n any problem designed as a paradigm o f the  l e a r n i n g process.  lem" was i n s o l u b l e .  The experiments included one i n which the "probKrechevsky concluded t h a t behaviour i n a novel  s i t u a t i o n i s "systematic", "purposive" ( i f . . . t h e n ) , i n v o l v e s " a b s t r a c t ion",  and i s "not e n t i r e l y dependent on the immediate environment".  Each o f these terms was o p e r a t i o n a l l y defined, the author wishing s p e c i f i c a l l y t o a v o i d a m e n t a l i s t i c i n t e r p r e t a t i o n (15 )•  The systematic  responses were l a b e l l e d "hypotheses", and t h i s concept was f u r t h e r developed by Krechevsky i n l a t e r a r t i c l e s (18) (19) (20) (21) i n which the  " d o c i l e " nature of the animal and the " l a b i l e " character o f the  response were emphasized. I t w i l l be seen that at t h i s p o i n t the " c o n t i n u i t y controversy", though not y e t so defined, centered on the i s s u e o f random versus systema t i c responses.  Krechevsky seems t o have made the error o f assuming  t h a t by demonstrating the f i r s t p r o p o s i t i o n of Lashley's a s s e r t i o n he had a l s o proven the second.  Spence (40) c l a r i f i e d the issue i n 1936 by  p o i n t i n g out that no s o p h i s t i c a t e d t r i a l and e r r o r theory would p o s t u l a t e p u r e l y random responses, and t h a t the "systematic" behaviour observed by Krechevsky was not incompatible w i t h t r i a l and e r r o r theory.  He p r o v i d -  ed an elegant demonstration of t h i s by presenting a t a b l e of h y p o t h e t i c a l responses based on the assumption that each reinforcement of an S-R conn e c t i o n produces an increment t o h a b i t strength as a f u n c t i o n of the o g i v a l curve postulated by H u l l , and that each non-reinforcement produces  9  a decrement which i s i n l i n e a r r e l a t i o n to i t s habit strength.  I t was  a l s o assumed t h a t the t o t a l e x c i t a t o r y p o t e n t i a l o f a stimulus configura t i o n i s the sum o f i t s component e x c i t a t o r y values, and that i n the case o f a n t a g o n i s t i c responses, the greatest h a b i t strength would p r e v a i l . These are e s s e n t i a l l y the b a s i c assumptions of t h e c o n t i n u i t y hypothesis. Through them i t i s easy t o demonstrate that i n the d i s c r i m i n a t i o n l e a r n i n g s i t u a t i o n (a) the correct and hence i n v a r i a b l y rewarded response w i l l e v e n t u a l l y dominate, and (b) that depending on the frequency w i t h which another component o f the stimulus c o n f i g u r a t i o n i s associated w i t h the c o r r e c t one, i t may acquire e x c i t a t o r y p o t e n t i a l s u f f i c i e n t so t h a t the animal w i l l appear f o r a time t o respond t o i t alone.  The animal's  behaviour, f a r from being "purposive" o r "systematic", i s determined by the combined e f f e c t s of the habit strength associated w i t h each stimulus component and the order o f presentation of the s t i m u l i themselves.  One  o f the deductions which Spence drew from h i s assumptions was t h a t i f the reward r e l a t i o n s of a given p a i r of s t i m u l i were reversed p r i o r t o the a c q u i s i t i o n o f the d i s c r i m i n a t i o n by the animal, i t s l e a r n i n g i n the subsequent t r i a l s would be retarded.  A r e s e r v a t i o n was imposed t h a t the  "connection between the r e l e v a n t stimulus and the required motor response" must be " s u f f i c i e n t l y obtrusive and c l e a r t o the animal".  The reversed  p r e - t r a i n i n g experiment thus suggested was performed by members o f each group w i t h c o n f l i c t i n g r e s u l t s . . I t i s t y p i c a l of the approach o f c o n t i n u i t y t h e o r i s t s that Spence's c r i t i c i s m s o f Krechevsky's "hypotheses" were framed i n the form of questions which the experimenter must ask.  Spence has e x p l i c i t l y  10  s t a t e d t h a t h i s concern i s not w i t h d e s c r i p t i o n o f behaviour but w i t h the axioms necessary t o p r e d i c t behaviour. first :  He consequently asks,  What, f o r the animal, c o n s t i t u t e s f a i l u r e o f a hypothesis l e a d -  i n g t o i t s abandonment?  second :  How i s the change made when an an-  i m a l adopts a new hypothesis i n preference t o the one i n use? What determines the order o f preference o f hypotheses?  third :  Unfortunately  these questions have never been d i r e c t l y answered i n the opposing camp p a r t l y because an answer, a t the present stage o f i n v e s t i g a t i o n cannot be given a u t h o r i t a t i v e l y . Krechevsky's p o i n t o f view was c l a r i f i e d by him i n an a r t i c l e (22) r e p l y i n g t o Spence.  The p o s i t i o n taken was t h a t the two approach-  es t o t h e problem o f systematic s o l u t i o n s were not contradictory, the l a t t e r w r i t e r simply p r o v i d i n g a theory of the mechanism u n d e r l y i n g t h e behaviour i s o l a t e d and described by t h e f o r m e r I t i s o f methodologi c a l i n t e r e s t here that Krechevsky regarded h i s approach as a molar d e s c r i p t i o n n e i t h e r more nor l e s s s c i e n t i f i c than the molecular viewpoint o f Spence.  This d i s t i n c t i o n i n approaches has p e r s i s t e d , and  c o n s t i t u t e s a pregnant source of misunderstanding i n comparing the two positions. The c r u c i a l i s s u e remaining was whether the animal, i n respondi n g , l e a r n s the correct s o l u t i o n gradually, throughout the p r e s o l u t i o n p e r i o d , o r r a p i d l y , w i t h t h e development o f the appropriate systematic  This was a g e n i a l o v e r s i m p l i f i c a t i o n on Krechevsky's p a r t . He continued t o defend the purposive nature o f hypotheses as he had p r e v i o u s l y defined i t .  11  response.  Krechevsky's p o s i t i o n was c o n c i s e l y formulated i n a subsequent  a r t i c l e (24) i n these terms, that with each correct or i n c o r r e c t response the animal learns something about the " s i g n i f i c a n c e " of the cue, but nothing about i t s Tightness o r wrongness, u n t i l i t has adopted the c o r r e c t hypothesis.  The same author's stand on the e f f e c t of reward r e v e r s a l  (22) was t h a t i f the animal were t o respond on the basis of an inapprop r i a t e hypothesis during the p r e s o l u t i o n period, r e v e r s a l would have no e f f e c t upon the r a t e o f l e a r n i n g .  However, i f the animal should respond  on the basis o f two or more c o n f l i c t i n g hypotheses, one o f them c o r r e c t , r e v e r s a l would i n t e r f e r e w i t h the l e a r n i n g .  The d i s t i n c t i o n , t h e o r e t i c a l -  l y , i s t h a t according t o Spence, r e v e r s a l must n e c e s s a r i l y i n t e r f e r e with l e a r n i n g , while to Krechevsky r e v e r s a l may or may not have t h i s e f f e c t . A f u r t h e r t h e o r e t i c a l i s s u e which appeared a t t h i s point concerned the d e f i n i t i o n o f the stimulus.  McCulloch (34) as w e l l as Spence  (41) made the point that the animal w i l l not acquire habit strength t o ward a stimulus of which i t i s not aware.  In the words o f the former  author, l e a r n i n g w i l l occur "only i f the relevant s t i m u l i so a f f e c t the sensorium that the a s s o c i a t i o n s formed are s i m i l a r t o those upon which the f i n a l h a b i t i s based".  I t w i l l be seen t h a t t h i s statment represents  a r e f i n i n g o f the c o n t i n u i t y p o s i t i o n and tends t o reduce the distance separating the t h e o r i e s .  A p a r a l l e l d i s t i n c t i o n concerns the d e f i n i t i o n  of awareness, which to the non-continuity p o s i t i o n i s a psychological o r i e n t a t i o n i n v o l v i n g a c t i v e s e l e c t i o n , and t o the opposing view i s a p h y s i c a l o r i e n t a t i o n which i s a f u n c t i o n o f the animal's response tendencies and r e s u l t s i n a l i m i t e d s e t o f s t i m u l i impinging on the sensorium.  12  This d i s t i n c t i o n was made by Haire (9) who a l s o put forward the i n t e r e s t i n g suggestion that the c r i t i c a l p o i n t at which the animal changes i t s hypothesis may be preceded by a period of r e o r g a n i s a t i o n and hence cannot be determined from the animal's behaviour.  That i s , t h a t the operat-  i o n a l d e f i n i t i o n o f hypotheses i n terms of the 3 sigma chance zone l i m i t a c t u a l l y r e f e r s t o the a p p l i c a t i o n of the hypothesis which may be preceded by the hypothesis i t s e l f , the l a b i l e p e r i o d being during the formation of the hypothesis and not determinable from an examination of response tendencies.  While the anthropocentrism of t h i s view i s probably not  acceptable t o e i t h e r group, i t i n d i c a t e s the d i f f i c u l t y o f p r e c i s e l y formulating the n o n - c o n t i n u i t y p o s i t i o n . This p o i n t also serves to introduce another t h e o r e t i c a l concept presented by Spence (43)> were l a t e r c a l l e d (45),  that of "preparatory responses", or as they  "receptor exposure adjustments".  These are the  s e r i e s o f responses which the animal makes on the b a s i s of the e x c i t a t o r y p o t e n t i a l of v a r i o u s elements i n the stimulus c o n f i g u r a t i o n , and which produce p r o p r i o c e p t i v e s t i m u l i which are cued i n t o the l e a r n i n g s i t u a t i o n . This concept w i l l be examined more f u l l y p r e s e n t l y . The t h e o r e t i c a l issues introduced thus f a r , v i z . , "random" v e r sus "systematic" responses, sudden discontinuous versus gradual continuous l e a r n i n g , "psychological" versus " p h y s i c a l " o r i e n t a t i o n , stimulus d i f f e r e n t i a t i o n a f u n c t i o n of s e l e c t i v e a t t e n t i o n as opposed t o response engendered exposure of the sensorium, and l a b i l e versus stimulus bound behaviour i n the p r e s o l u t i o n p e r i o d , represent what might be thought of  13  as the " c l a s s i c a l " period"'* i n the c o n t i n u i t y controversy.  I t i s con-  venient a t t h i s p o i n t t o summarise the major t h e o r e t i c a l assumptions which underly these issues before proceeding t o an examination of the experimental evidence f o r each p o s i t i o n .  They are as follows (the  l e t t e r s N and C are s e l f - e x p l a n a t o r y ) : (1)  C  -  the stimulus elements t o which the animal responds are those which have the highest e x c i t a t o r y potenti a l a t any point i n the l e a r n i n g process.  N  -  the stimulus elements t o which the animal responds are  those which are relevant t o i t s c o g n i t i v e  organisation o f the s i t u a t i o n a t any point i n the l e a r n i n g process. (2)  C  -  a l l stimulus elements impinging on the animals sensorium a t the time o f a response w i l l acquire an increment or a decrement i n e x c i t a t o r y p o t e n t i a l as the response i s r e i n f o r c e d or not r e i n f o r c e d .  N  -  only those stimulus elements which are relevant to the animal's hypotheses w i l l form the basis o f the  animal's l e a r n i n g .  These are the two b a s i c assumptions, though p o s s i b l y not the o n l y ones, employed by each p o s i t i o n .  From them c e r t a i n c o r o l l a r i e s  may be drawn : ^ This d i v i s i o n i s a r b i t r a r y but i s f e l t t o be convenient t o the presentation. The d i s t i n c t i o n i s between the period i n which b a s i c issues were introduced and t h a t i n which these issues were reapplied and refined.  14  (1)  C  -  the animal's performance i n a new s i t u a t i o n w i l l be a function o f t h e S-R connections i t has acquired i n the past.  N  - the animal's performance i n a new s i t u a t i o n w i l l be i n part a f u n c t i o n of i t s perceptual organisa t i o n o f t h e s i t u a t i o n as w e l l as o f i t s past experience.  (2)  C  -  performance a t any given time w i l l be t h e o r e t i c a l l y p r e d i c t a b l e on the basis of t h e animal's past experience.  N  -  performance a t any given time w i l l not be p r e d i c t able since the perceptual o r g a n i s a t i o n of the animal can o n l y be i n f e r r e d a f t e r the response.  In a d d i t i o n , the t h e o r e t i c a l issues mentioned i n t h e preceding d i s c u s s i o n may e i t h e r be derived from these assumptions, o r c o n s t i t u t e d e f i n i t i o n s necessary t o them.  C e r t a i n features o f the controversy  become c l e a r i n the l i g h t o f these assumptions.  I t w i l l be noticed that  the non-continuity p o s i t i o n cannot be s t a t e d as e x p l i c i t l y as the continui t y position.  I t w i l l a l s o be n o t i c e d that the d e f i n i t i o n o f terms i s  an important course o f t h e d i s t i n c t i o n between the two t h e o r i e s .  While  i t appears so s u p e r f i c i a l l y , i t would probably be unwise t o conclude that the number o f assumptions i n turn underlying these d e f i n i t i o n s (e.g., "reinforcement",  "cognition") i s any greater f o r t h e non-continuity than  15  f o r t h e c o n t i n u i t y theory. 1 Experimental Issues Having d i s c u r s i v e l y t r e a t e d t h e t h e o r e t i c a l background o f the c o n t i n u i t y controversy, i t i s appropriate t o t u r n t o t h e experimental evidence which has been adduced t o support each o f the views o u t l i n e d . While there has not been a l a r g e number o f experiments d i r e c t e d s p e c i f i c a l l y t o the controversy, t h e number has been s u f f i c i e n t l y great t o preclude a d e t a i l e d treatment here of each experiment.  Rather than  present a s u p e r f i c i a l treatment of every experiment, t h e r e f o r e , i t i s proposed t o t r e a t i n d e t a i l those representative experiments which have contributed t o t h e controversy, mentioning others i n passing only i f they seem t o add t o the development o f the d i s c u s s i o n . four h i s t o r i c a l approaches t o t h e controversy : s o l u t i o n behaviour  (a) observation o f p r e -  (15) (16) (17) (26) (27) (28);  t r a i n i n g experiments (5) (24) (33)  There have been  (b) the reversed pre-  (37) (41) (42) (44)J  w i t h a l t e r e d s e t during l e a r n i n g ( l ) (7) (30) (31);  (c) experiments  and (d) a p p l i c a t i o n  o f c o r r e l a t i o n techniques t o discover the r e l a t i o n s h i p between frequency o f reinforcement i n the p r e - r e v e r s a l period and number o f errors i n the p o s t - r e v e r s a l p e r i o d ( l ) (30) (41) (42). the experimental l i t e r a t u r e .  The references do not exhaust  The f i r s t type o f experiment, as has been  noted, d i d not prove f r u i t f u l and was abandoned e a r l y i n the controversy. The other three types w i l l be t r e a t e d i n t h e order l i s t e d .  P r o p e r l y , the terms " c o n t i n u i t y " and "non-continuity" r e f e r o n l y t o assumption number (2). x  16  The reversed p r e - t r a i n i n g experiment was f i r s t performed i n the i n t e r e s t o f the c o n t i n u i t y controversy by McCulloch and P r a t t (33). I t was undertaken t o t e s t t h e p r o p o s i t i o n that " r e p e t i t i v e t r a i n i n g produces a cumulative e f f e c t i r r e s p e c t i v e o f the 'hypothesis' being tested".  Two f u r t h e r questions were asked by t h e experimenters :  change i s cumulative, i s i t t h e same throughout? " f a m i l i a r i s a t i o n " period?  If  I s there an i r r e l e v a n t  The experiment employed a weight d i s c r i m i n -  a t i o n problem w i t h t h e f o l l o w i n g procedure.  Five groups o f r a t s  (N = 24 i 1) r e c e i v e d three successive days t r a i n i n g , 6, 8, and 10 t r i a l s per day, w i t h e q u a l l y weighted s t r i n g s (50 gms) t o secure food which was placed 110 cms. from the' t r a i n i n g cage.  Reward r e l a t i o n s were randomly  a l l o c a t e d and t h e animals were allowed t o eat f o r 5 seconds i f s u c c e s s f u l . T r i a l s were c a r r i e d out a t t h e same time each day.  This p r e l i m i n a r y t r a i n -  i n g was undertaken t o f a m i l i a r i s e the animals w i t h the apparatus and procedure.  The f i v e groups were then t r e a t e d as follows : Group  1 - 2 1  days minimum on the f i n a l problem (75 gms.  p o s i t i v e , 25 gms. negative) t o a c r i t e r i o n o f two successive days (24 t r i a l s ) without e r r o r . An e r r o r consisted i n drawing the i n c o r r e c t weight a distance o f 90 cms. Group  II -  28 t r i a l s i n the reverse of t h e f i n a l problem followed by the i d e n t i c a l procedure f o r Group I .  Group I I I -  Trained i n the reversed problem t i l l they "seemed to begin t o d i s c r i m i n a t e " , (2 days w i t h not more  17  than 6 e r r o r s ) .  Errors f o r t h i s c r i t e r i o n i n c l u d -  ed "negative e r r o r s " , i . e . , drawing the c o r r e c t weight not more than 15 cms., and "negative h a l f errors!', i . e . , drawing the correct t r a y not more than 90 cms.  T r a i n i n g i d e n t i c a l t o Group I f o l l o w -  ed. Group IV - Overtrained  on the reversed problem f o r 249 t r i a l s  beyond the mastery mean o f 99 t r i a l s , then t r e a t e d as Group I . Group  V - Trained on equal weights t o t h e median f o r Group I I I p r e - r e v e r s a l , then treated as Group I .  The r e s u l t s o f t h i s experiment were that each o f t h e experimenta l groups, w i t h t h e exception o f Group V, produced s i g n i f i c a n t l y higher e r r o r scores than d i d t h e Control Group, i n d i c a t i n g that i n each case r e v e r s a l o f reward r e l a t i o n s had had an adverse e f f e c t upon l e a r n i n g . In the case o f Group I I , r e s u l t s f o r which i n d i c a t e d t h a t e a r l y t r a i n i n g d i d not represent a f a m i l i a r i s a t i o n period, the authors suggest that the animals may already have been f a m i l i a r i s e d i n the preliminary t r a i n i n g . Results f o r Group V were i n c o n c l u s i v e .  The r a t i o o f p r e - s h i f t t o post-  s h i f t errors was a l s o analysed and increased s i g n i f i c a n t l y f o r p o s t - s h i f t errors.  A point o f i n t e r e s t i s the d i f f e r e n c e between Group IV pre-  s h i f t errors and t h e t o t a l errors f o r the Control Group, which showed a s i g n i f i c a n t l y b e t t e r performance i n mastery o f t h e reversed problem before the s h i f t .  This was a t t r i b u t e d t o the " p r i n c i p l e o f l e a s t e f f o r t " .  18  The authors concluded that l e a r n i n g i s cumulative from the beginn i n g o f t r a i n i n g , roughly p r o p o r t i o n a l t o e r r o r s , and i s i n progress before i t i s evidenced.  They a l s o concluded t h a t hypotheses were an i n s i g n i f -  i c a n t f a c t o r and t h a t t h e animals were not l a b i l e or d o c i l e a t the c r i t i c a l point as experimental 1y defined. This experiment  tiras  subjected t o a number o f c r i t i c i s m s which  throw some l i g h t both on the non-continuity theory and on the experimenta l issues.  Krechevsky (24) made the suggestion t h a t t h e p r e - s o l u t i o n  p e r i o d had been i n c o r r e c t l y defined and should have been shorter.  He  a l s o put forward the more cogent c r i t i c i s m t h a t the nature o f the problem had forced t h e animals t o attend to the relevant s t i m u l i from the beginning.  I t must be remembered that Krechevsky had never denied a possib-  i l i t y f o r the animal t o respond on the b a s i s o f c o n f l i c t i n g hypotheses and hence t o " p i l e up h i s score f o r e i t h e r k i n d " (16).  He also pointed  out t h a t "the t y p i c a l d i s c r i m i n a t i o n curve i s obtained only where the d i s c r i m i n a t i o n i s a more or l e s s d i f f i c u l t one".  I t was a l s o noted  t h a t the animals were s h i f t e d t o a harder problem, thus i n e f f e c t t h e animals s t a r t e d w i t h the " c o r r e c t " hypotheses from the beginning.  Haire  (8) suggested the p o s s i b i l i t y t h a t t h e weight d i s c r i m i n a t i o n problem favoured the formation o f m u l t i p l e hypotheses, which would b r i n g the e r r o r score near the chance l e v e l , and hence that the experimenters' conc l u s i o n t h a t e r r o r scores of t h e i r i n d i v i d u a l animals d i d not i n d i c a t e (with one exception) the simultaneous a c t i o n of two hypotheses was unfounded.  While there i s some s o p h i s t r y i n these c r i t i c i s m s , there i s  a l s o s u f f i c i e n t weight that the McCulloch and P r a t t experiment cannot be  19  regarded as s a t i s f a c t o r y evidence.  One o f the experimenters g a l l a n t l y  admitted, i n a lower case footnote t o a subsequent a r t i c l e , that the d i f f e r e n c e i n d i f f i c u l t y o f the two d i s c r i m i n a t i o n s tended t o weaken their results.  I t was a l s o agreed that the weight d i s c r i m i n a t i o n had  forced t h e animals to"make the proper muscular a d j u s t m e n t s f r o m the beginning and thus t o r e c e i v e d i f f e r e n t i a l s t i m u l a t i o n . An experiment which may be compared w i t h t h a t o f McCulloch and P r a t t , and was i n f a c t designed t o answer i t , i s that o f Krechevsky (24). The Lashley jumping apparatus was used t o set up a d i s c r i m i n a t i o n between two stimulus cards c o n s i s t i n g o f h o r i z o n t a l rows o f black dashes opposed to v e r t i c a l rows o f t h e same s i z e and number.  This f u l f i l l e d the r e -  quirement o f a d i f f i c u l t d i s c r i m i n a t i o n , which i s c r u c i a l t o the outcome Three groups of r a t s , ranging from N 14 t o N 17,  of the experiment.  were f a m i l i a r i s e d i n the apparatus by being jumped through black cards. The groups were then t r e a t e d as follows : Group  I  -  Trained on the v e r t i c a l rows, 10 t r i a l s per day to a c r i t e r i o n o f 18 o f 20 e r r o r l e s s t r i a l s on two successive days.  The p o s i t i o n s were random-  i s e d , and each p a i r remained standing t i l l t h e animal succeeded ( c o r r e c t i o n method). Group  II -  Trained f o r 20 t r i a l s (2 days) i n t h e reverse o f  This polemical tendency o f each o f the protagonists t o i n voke the jargon p e c u l i a r t o h i s bias i s an i n t e r e s t i n g comment on the o r i g i n s o f misunderstanding! x  20  the above d i s c r i m i n a t i o n , and then t r e a t e d as Group I . Group I I I -  Trained f o r 40 t r i a l s on the reversed problem, followed by treatment f o r Group I .  I n t r e a t i n g the r e s u l t s two methods were used.  The t o t a l  e r r o r s were scored f o r the Control Group from the beginning o f t r a i n i n g , 1  and each experimental group was scored on errors a f t e r the r e v e r s a l ;  then  the same procedure was used w i t h the corresponding number of p r e - s h i f t t r i a l s being deducted from the Control Group.  E r r o r scores were a l s o  d i v i d e d i n t o i n i t i a l and r e p e t i t i v e errors on the basis of the c o r r e c t i o n technique. Results f o r Group I I supported the non-continuity p r e d i c t i o n t h a t r e v e r s a l should s l i g h t l y f a c i l i t a t e l e a r n i n g since some of the errors of the non-reversed group are wasted.  Differences were s i g n i f i c a n t f o r  both t o t a l and i n i t i a l errors i n the e n t i r e t r a i n i n g s e r i e s , and f o r posts h i f t scores.  Group I I I , on the other hand, produced s i g n i f i c a n t l y high-  er e r r o r scores, thus f a i l i n g t o s u s t a i n the expectation of non-continuity theory.  This r e s u l t was explained by Krechevsky as an i n d i c a t i o n t h a t  f o r t y t r i a l s was too long f o r the p r e - s o l u t i o n p e r i o d .  This  reasoning  has been c r i t i c i s e d (37) but seems adequate on the b a s i s of Krechevsky's e a r l i e r statements.  From these r e s u l t s the experimenter concluded t h a t  l e a r n i n g i s not cumulative, that the p r e - s o l u t i o n p e r i o d i s i r r e l e v a n t to the a c t u a l l e a r n i n g of the problem, and that the r e s i d u a l e f f e c t of reward i s not the same i n the p r e - s o l u t i o n period as i n the p e r i o d a f t e r  I  21  adoption of the appropriate  hypothesis.  Several c r i t i c i s m s o f t h i s experiment a l s o have been put f o r ward.  One of these has been mentioned e a r l i e r , that the experimenter  must be c e r t a i n that the r e l e v a n t cues are a c t u a l l y impinging on the animal's sensorium (34)*  At the same time i t was pointed out t h a t the  decrease i n r e p e t i t i v e e r r o r s by the c o r r e c t i o n method favoured the experimental groups s i n c e such errors tend t o be eliminated i n the f i r s t two days.  Spence elaborated the f i r s t of these c r i t i c i s m s by p o i n t i n g  out that the r a t s tend t o jump t o the lower part of the card i n the Lashley apparatus, and a l s o t h a t they tend t o jump t o the b r i g h t e s t stimulus element, and consequently may not have been f i x a t i n g the approp r i a t e cues (43) i n the e a r l y phase of the experiments.  This argument  i n part r e s t s on e s t a b l i s h i n g the area of the r a t ' s binocular v i s u a l field.  Spence has i n mind, w i t h the term " f i x a t i o n " , the "area corres-  ponding t o the fovea c e n t r a l i s i n man"  with decreasing s e n s i t i v i t y from  t h i s p o i n t outward t o the periphery.  Lashley maintained that the expos-  ure of the stimulus cards was adequate since the r a t ' s binocular v i s i o n covers an angle of from 50 to 100 degrees.  Spence a l s o objected t o  Krechevsky's explanation of the r e s u l t s f o r Group I I I on the grounds that i t could not be proven t h a t the r a t s were responding on the b a s i s of the c o r r e c t hypotheses i n the l a t e r p r e - r e v e r s a l t r i a l s . Other experiments were run on the r e v e r s a l problem, one  by  Spence w i t h chimpanzees (42) which was unacceptable t o the non-continuity t h e o r i s t s because the animals were forced t o attend t o the c o r r e c t cues i n the p r e l i m i n a r y t r a i n i n g .  One f u r t h e r example of t h i s type of  22  experiment may be c i t e d , because i t attempted t o correct t h i s d e f i c i e n c y . Spence, i n 1945, performed an experiment w i t h r a t s (44) on a black and white a l l e y d i s c r i m i n a t i o n designed as f o l l o w s .  Two groups (N = 20)  were given t h i r t y rewarded runs t o t h e i r own p r e f e r r e d s i d e i n n e u t r a l grey a l l e y s .  The c o n t r o l group was then given twenty t r i a l s i n which  b l a c k and white were each 50$ rewarded, the p o s i t i o n response being r e t a i n e d by the animals under these c o n d i t i o n s .  The experimental group  was given the r e v e r s e of the f i n a l problem f o r twenty t r i a l s .  Both  groups were then given a s u f f i c i e n t number o f t r i a l s i n the grey a l l e y s to eliminate the p o s i t i o n preference. the  f i n a l problem.  They were then run t o mastery i n  There was a s i g n i f i c a n t d i f f e r e n c e i n the perform-  ance of the two groups i n the f i n a l problem (70-95 t r i a l s ) which favoured the  c o n t i n u i t y theory. The design of t h i s experiment was intended t o ensure that the  animals of the experimental group were responding on the basis of an i n appropriate "hypothesis" i n the p r e - r e v e r s a l period. open t o c r i t i c i s m ,  This procedure i s  however, on the grounds t h a t the experimental group  had been t r a i n e d t o two hypotheses each o f vihich was s u c c e s s f u l , w h i l e the  c o n t r o l group had been t r a i n e d t o one only.  Thus i n the f i n a l  problem the experimental group i s equipped w i t h two c o n f l i c t i n g hypotheses, which as noted p r e v i o u s l y would l e a d t o retarded l e a r n i n g under the assumptions o f the non-continuity t h e o r y . S p e n c e ' s assumption that because the p o s i t i o n response had been eliminated a f t e r the r e v e r s a l t r a i n i n g i t This c r i t i c i s m assumes added weight when Harlow's data. (10) are considered.  23  was no longer operant i s based on c o n t i n u i t y assumptions, and takes no account o f the l a b i l e aspect o f behaviour postulated by Krechevsky. A d i f f e r e n t type o f experimental t e s t was suggested and performed by Lashley (30) i n v o l v i n g a l t e r e d s e t during l e a r n i n g .  Four  r a t s were t r a i n e d t o d i s c r i m i n a t e between a l a r g e (8 cm.) and a s m a l l (5 cm.) white c i r c l e i n the jumping stand t o a c r i t e r i o n o f twenty errorless t r i a l s .  They were then presented w i t h two t r i a n g l e s o f these  dimensions i n which they demonstrated the s i z e preference e s t a b l i s h e d . They were t r a i n e d next t o the two t r i a n g l e s f o r 200 t r i a l s , r e i n f o r c i n g the  e s t a b l i s h e d preference.  A c i r c l e and t r i a n g l e o f equal intermediate  s i z e were then presented and the animals were f o r c e d t o jump, responses being a t a chance l e v e l .  T r a i n i n g t o the l a r g e t r i a n g l e and small c i r -  c l e was continued, a f t e r which the animals were presented with a l a r g e c i r c l e and s m a l l t r i a n g l e . the  The response was t o the l a r g e c i r c l e , on  b a s i s o f s i z e , and i n c o n t r a d i c t i o n o f o v e r t r a i n i n g t o form.  This  was one o f a s e r i e s of experiments the r e s u l t s of which were not s i g n i f i c a n t but which tended i n the same d i r e c t i o n . ^ The r a t i o n a l e o f t h i s experiment i s -that t h e animals are t r a i n ed t o two stimulus dimensions each o f which i s presumably being r e i n f o r c ed.  I f t h i s assumption i s granted the change from c i r c l e t o t r i a n g l e  should r e s u l t i n a chance l e v e l o f response on the b a s i s o f the continui t y hypothesis.  As noted, the animals responded throughout on t h e basis  of s i z e preference.  However, i t should be noted that o v e r t r a i n i n g t o a  The d i s c u s s i o n o f the v a l i d i t y o f t h i s type o f evidence i s not f e l t t o belong w i t h i n the scope o f t h i s s e c t i o n . x  24  given form would not n e c e s s a r i l y be t r a n s f e r r e d t o a s i m i l a r form o f d i f f e r i n g dimensions, under t h e assumptions o f c o n t i n u i t y theory, which emphasise the s p e c i f i c i t y o f each stimulus component. This experiment was re-run by Blum and Blum ( l ) w i t h m o d i f i c a t ions based on t h e i r c r i t i c i s m o f the o r i g i n a l .  B r i e f l y , these were  based on the summation o f i n h i b i t i o n a r i s i n g out o f the proximity o f t h e two sets of s t i m u l i on the g e n e r a l i s a t i o n continuum, which would slow the d i f f e r e n t i a l r e a c t i o n .  They s u b s t i t u t e d a small i n v e r t e d t r i a n g l e  f o r the small c i r c l e , and ran the experiment omitting the f i n a l t e s t . Five r a t s learned the p r e l i m i n a r y d i s c r i m i n a t i o n i n a comparable number of t r i a l s t o Lashley's r a t s .  When they were tested-on an i n v e r t e d and  an upright t r i a n g l e o f equal s i z e , t h e p r e d i c t i o n being that they would jump t o the rewarded f i g u r e , two of the r a t s f a i l e d t o make the d i s c r i m i n a t i o n , were r e t r a i n e d , and succeeded.  I t seems remarkable that  on t h i s evidence the authors concluded that t h e c o n t i n u i t y p o s i t i o n i s upheld, f o r while t h e r e s u l t s contradict those o f Iashley, the f a i l u r e o f the two animals t o make the d i s c r i m i n a t i o n i n t h e c r u c i a l t e s t can equally w e l l be explained on the basis o f t h e i r having d i f f e r i n g "hypotheses" . Space does not permit the f u l l e r discussion o f t h i s type o f experiment, o f which there have been s e v e r a l .  B r i e f mention might be  made o f an a l t e r n a t i v e design i n which the animals are divided i n t o two groups each o f which i s t r a i n e d t o a s i n g l e stimulus card.  Both groups  are then presented w i t h the two stimulus cards, the c o n t i n u i t y p r e d i c t i o n being t h a t the group which has been r e i n f o r c e d on the negative card  25  o f the f i n a l p a i r w i l l perform more p o o r l y than the group t r a i n e d t o the p o s i t i v e card.  Lashley and Wade performed t h i s experiment i n the jump-  i n g stand w i t h r e s u l t s contrary t o the c o n t i n u i t y expectations (31) • The experiment was repeated by Grice (7) using a d i s c r i m i n a t i o n box a l a r g e r number o f subjects w i t h the opposite r e s u l t .  However t h e r e  seems t o be some doubt as to the v a l i d i t y of t h i s experiment.  The tech-  nique i s t o present the s i n g l e stimulus opposed t o a b l a c k card. assumed t h a t  and  It is  the animal i s responding to the stimulus card only.  How-  ever, i t i s p o s s i b l e t h a t some o f the animals respond on the basis of a "figure/non-figure" or a brightness hypothesis.  Thus when the animal  comes t o the s i t u a t i o n i t has had experience w i t h two c o n f l i c t i n g hypotheses, and may be expected t o respond according t o the expectations o f e i t h e r theory on the basis of non-continuity assumptions.  While the  t r a n s p o s i t i o n experiments seem promising, the c o n t r a d i c t o r y r e s u l t s thus f a r obtained (7),  combined with the f a i l u r e of the experimenters t o meet  the assumptions of both t h e o r i e s , make them as yet an u n s a t i s f a c t o r y instrument.  The m a t e r i a l above serves a u s e f u l purpose, however, i n  i l l u s t r a t i n g the extreme d i f f i c u l t y of formulating the non-continuity theory w i t h any degree of p r e c i s i o n . One f u r t h e r general type of evidence remains t o be before t u r n i n g t o the recent work.  considered  Spence (42) suggested t h a t one con-  sequence of the c o n t i n u i t y assumption would be t o produce a c o r r e l a t i o n between the number o f errors made p r i o r t o the s h i f t of reward r e l a t i o n s , and the e r r o r scores a f t e r the s h i f t .  He a p p l i e d the method to h i s data  and obtained a h i g h rank order c o r r e l a t i o n .  Lashley (30) reviewing the  26  controversy i n 1942, pointed out t h a t a c o r r e l a t i o n could e x i s t even w i t h a high chance f a c t o r .  He suggested that a more c r u c i a l t e s t would be  t o remove systematic errors from the data, which, i f the c o n t i n u i t y assumptions were c o r r e c t , would r e s u l t i n a lowering of the c o r r e l a t i o n . i n g Spence's data, he found the opposite t o be t r u e .  Rework-  Blum and Blum ( l )  repeated h i s work, however, u s i n g a product-moment technique and obtained the opposite r e s u l t .  The conclusion of these authors i s t h a t the cor-  r e l a t i o n technique i s not s u f f i c i e n t l y s e n s i t i v e at present t o j u s t i f y i t s use i n t h i s  way.  Recent Trends I t w i l l be seen that during what we have chosen to regard as the " c l a s s i c a l " period of the controversy, two tendencies have been manifested.  On the one hand there was a progressive c l a r i f i c a t i o n and r e f i n e -  ment of the t h e o r e t i c a l p o s i t i o n of each group, w h i l e on the other there was a successive i n t r o d u c t i o n o f new experimental problems and techniques. Before reviewing the recent experiments, i t w i l l be o f i n t e r e s t t o summarise b r i e f l y some of the important experimental i s s u e s , s i n c e the value of an experiment d i r e c t e d toward the problem must be judged by the extent to which i t meets and overcomes the inadequacies of past attempts. ( l ) Probably the most important i s s u e l i e s i n the appropriate d e f i n i t i o n o f the p r e - s o l u t i o n p e r i o d .  For the non-continuity t h e o r i s t ,  the p r e - s o l u t i o n p e r i o d ends when the animal adopts the c o r r e c t hypothesis. I t has been seen that the c r i t e r i o n determining t h i s p o i n t , while i t must  27  be b e h a v i o u r a l l y defined i n a broad sense, cannot v a l i d l y be assumed t o be the point a t which t h e c o r r e c t response begins t o be evidenced. (2) The d i f f i c u l t y of the d i s c r i m i n a t i o n i s c r u c i a l f o r the experimental r e s u l t s .  _Only a problem of s u f f i c i e n t d i f f i c u l t y that the  animal i s forced t o t e s t s u c c e s s i v e l y a t l e a s t two "hypotheses" i s admissable as evidence f o r e i t h e r theory.  Of importance i n t h i s connection  i s the experimental p o s s i b i l i t y t h a t the animal i s responding simultaneously t o two hypotheses, w i t h apparent chance scores. (3) From the standpoint o f c o n t i n u i t y theory the question o f t h e a v a i l a b i l i t y o f the relevant cues i s perhaps a restatement o f the " d i f f i c u l t y " o f t h e problem.  However, here the terms o f reference are  the exposure o f the sensorium i n the apparatus, and p a r t i c u l a r l y the a c t u a l v i s u a l f i x a t i o n a t the moment o f response. (4) No l e s s important are the movements which the animal makes when f i r s t i n the apparatus, both those which may be considered receptor exposure adjustments, and those which are p u r e l y an outcome o f the p a r t i c u l a r apparatus or mode of entry. (5) F i n a l l y , the i s s u e o f c o r r e c t i o n versus non-correction methods o f t r a i n i n g has been demonstrated t o have some i n f l u e n c e on the r e s u l t s , s i n c e the c o r r e c t i o n method r e s u l t s i n the e a r l y e l i m i n a t i o n o f p o s i t i o n responses, and a l s o r e s u l t s , i n the terms o f the c o n t i n u i t y t h e o r i s t s , i n the summation of i n h i b i t i o n which may generalize t o each o f the s t i m u l i .  28  An experiment which was d i r e c t e d a t the f i r s t o f these i s s u e s , the  d e f i n i t i o n o f the p r e - s o l u t i o n p e r i o d , has been c a r r i e d out by  P r e n t i c e (36) w i t h human subjects. the  I t was based on t h e assumption t h a t  v e r b a l reports o f t h e subjects themselves w i l l provide the most ade-  quate d e f i n i t i o n o f the s t a t e o f s o l u t i o n .  The second experimental i s s u e  was a l s o attacked i n that t h e problem presented was extremely d i f f i c u l t . This experiment i s noteworthy i n that the stimulus r e l a t i o n s t o be l e a r n ed were such as would be expected t o c a l l f o r t h a considerable number of p o s s i b l e hypotheses.  Subjects were given two keys, one marked w i t h a  c i r c l e , t h e other w i t h a square.  They were i n s t r u c t e d t o press e i t h e r  key as each p a i r o f s t i m u l i were presented, a c o r r e c t response r e s u l t i n g i n a l i g h t , i n c o r r e c t i n a buzzer.  Stimulus cards consisted o f eight  p a i r s o f cards presented i n random order, such t h a t t h e choices t o be made were between c i r c l e o r square, l i g h t o r dark background, l a r g e o r small f i g u r e , r i g h t o r l e f t p o s i t i o n i n t h e i r various p o s s i b l e combinations »  The c o r r e c t response was t o press t h e key marked w i t h a c i r c l e  whenever a f i g u r e w i t h a dark background appeared on the r i g h t . j e c t s were asked t o v e r b a l i z e t h e i r responses.  Sub-  Two groups (N = 20)  were used, t h e c o n t r o l group being t r a i n e d t o a c r i t e r i o n o f twelve e r rorless t r i a l s . the  The experimental group was given twenty t r i a l s w i t h  reverse o f the problem, then t r a i n e d t o the same c r i t e r i o n as t h e  control.  They were not t o l d t h a t t h e problem had been changed.  Sub-  j e c t s who f a i l e d t o make t h e d i s c r i m i n a t i o n a f t e r 100 t r i a l s , and those who succeeded before twenty t r i a l s were t r e a t e d s e p a r a t e l y i n the r e s u l t s . Ignoring subjects who f a i l e d , t h e c o n t r o l group solved the  29  d i s c r i m i n a t i o n i n twenty t r i a l s l e s s than the r e v e r s a l group. the  Thus, i f  twenty p r e - s h i f t t r i a l s o f the c o n t r o l group are ignored ( c f . Krechevsky  (24) ), each group was approximately equal.  The authors argue t h a t s i n c e  f o r each group subjects were aware of only one problem, the t o t a l r e s u l t s should be compared.  This i l l u s t r a t e s the d i f f i c u l t i e s inherent i n the  non-continuity theory.  Provided i t s assumptions were c o r r e c t , the r e j e c t -  i o n o f a hypothesis would s t i l l have an e f f e c t on p o s t - r e v e r s a l l e a r n i n g , without granting any of the assumptions of the c o n t i n u i t y theory.  The  author i n t e r p r e t s the c o n t i n u i t y theory as p r e d i c t i n g a d i f f e r e n c e not of twenty t r i a l s but o f f o r t y , i . e . twenty t r i a l s t o unlearn the pres h i f t responses and twenty more t r i a l s t o l e a r n the p o s t - s h i f t problem. While o v e r s i m p l i f i e d , t h i s suggestion i s undoubtedly cogent.  Verbal  reports were not as h e l p f u l as might have been supposed i n determining the  s t a t e of s o l u t i o n .  A f u r t h e r r e s u l t was t h a t subjects who  failed  to make the d i s c r i m i n a t i o n showed 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 groups.  The author concludes t h a t there was some continuous r e i n f o r c e -  ment, but t h a t i t was not the major determinant, and suggests t h a t mechanical stimulus-response l e a r n i n g was probably most e f f e c t i v e i n the early t r i a l s .  The f a c t o r s i n t h i s experiment are obviously extremely  complex, and i t might be questioned whether the s i t u a t i o n i s even m i n i m a l l y comparable t o t h a t i n past experiments.  However, t h i s type  of study w i l l apparently introduce new issues and might prove of value. Cne conclusion that may be drawn from these r e s u l t s i s t h a t n e i t h e r the c o n t i n u i t y nor the non-continuity theory i s adequately s t a t e d . An experiment with r a t s which was aimed a t the c o n t r o l of  30  a t t e n t i o n presents more c l e a r - c u t r e s u l t s .  Ehrenfreund  (5), i n what i s  probably the best c o n t r o l l e d and c e r t a i n l y the most adequately reported experiment on the controversy t o date, d u p l i c a t e d Krechevsky's experiment (24), t a k i n g account of the c r i t i c i s m s which had been put forward by Spence (23).  I t w i l l be r e c a l l e d t h a t these centered on the question  o f the r a t s a c t u a l l y r e c e i v i n g the s t i m u l i on t h e i r sensoria during the pre-solution t r i a l s .  The experiment was conducted i n the Lashley jump-  ing stand modified so t h a t a two-pronged p l a t f o r m brought the animals d i r e c t l y i n f r o n t of the stimulus cards. used t o a l i m i t of four r e p e t i t i v e e r r o r s .  The c o r r e c t i o n technique  was  A f t e r being f a m i l i a r i z e d  w i t h the apparatus, both groups (N = 15) were given f i v e t r i a l s to the r i g h t i n response t o a white square on a black background, i n order t o establish a position habit.  The c o n t r o l group were then given equal  reward and f r u s t r a t i o n on each card, while the experimental group was t r a i n e d f o r f o r t y t r i a l s t o the card which appeared f i r s t on the r i g h t . The stimulus cards presented a choice between an upright and an i n v e r t e d t r i a n g l e , each placed at the top of the stimulus card.  Finally, five  t r i a l s p o s i t i o n r e v e r s a l were given each group, and each was t r a i n e d on the f i n a l d i s c r i m i n a t i o n t o a c r i t e r i o n of 9C$ e r r o r l e s s t r i a l s . The r e s u l t s of t h i s procedure were that the two groups d i f f e r ed only by chance expectations, as Krechevsky had found.  The experiment  was then repeated i n a l l d e t a i l s except that the stimulus f i g u r e s were placed a t the center of the card, and the platform was adjusted so that the r a t was obliged t o jump d i r e c t l y t o the f i g u r e .  Results gave high-  l y s i g n i f i c a n t d i f f e r e n c e s i n number of t r i a l s , number of i n i t i a l errors  31  and number o f r e p e t i t i v e errors i n favour of t h e non-reversed group. Further, t h i s group d i d s i g n i f i c a n t l y b e t t e r than d i d the c o n t r o l group i  i n t h e f i r s t experiment.  The author's conclusion i s that where an easy  d i s c r i m i n a t i o n i s made, t h e r e s u l t s are c l e a r - c u t f o r t h e c o n t i n u i t y t h e o r i s t s , who have never denied t h a t conditions could be arranged so t h a t no d i s c r i m i n a t i o n would be made, and consequently no h a b i t s t r e n t h accumulated.  This experiment w i l l be discussed f u r t h e r i n connection  w i t h the design o f the present i n v e s t i g a t i o n . Yet another group o f experiments i s o f i n t e r e s t , those o f Harlow (10), who demonstrated t h e capacity o f chimpanzees and c h i l d r e n to acquire l e a r n i n g s e t s .  His f i n d i n g s are pertinent i n i n d i c a t i n g  that something l i k e a "hypothesis" may be learned w i t h a high degree o f e f f i c i e n c y , such that the animals are capable o f changing t h e i r responses on t h e second reversed t r i a l . " " 1  I n a subsequent paper (11) the author  suggested t h a t the controversy i s a r t i f i c i a l i f past'experience i s taken i n t o account.  He a l s o states t h a t both t h e i n d i v i d u a l responses, and  the l e a r n i n g s e t s , are g r a d u a l l y acquired, apparently on t h e basis o f continuous reinforcement.  This statement must be evaluated, however,  w i t h reference t o t h e f a c t reported e a r l i e r , t h a t a l l the Discriminations used were those which "could r e a d i l y and probably immediately be perceived by the subjects" (10). These and s i m i l a r studies on primates introduce an aspect o f  This phenomenom i s c l o s e l y analogous t o the " c o n d i t i o n a l r e a c t i o n " described by Lashley i n 1938 (29), and i s i n f a c t an outgrowth of the e a r l i e r study.  32  the  controversy which has received l i t t l e a t t e n t i o n i n t h i s f i e l d o f  l e a r n i n g theory, v i z . , the p h y l e t i c i m p l i c a t i o n s o f behavioural d e s c r i p t ion.  While the issues remain i n doubt f o r experiments w i t h r a t s , the  recent work o f Harlow, Evart and Nissen, and others of the Orange Park groups suggests t h a t the controversy may be meaningless where primate behaviour i s concerned.  In p a r t i c u l a r the routine use o f t h e " s i n g l e  cue t e s t " o f ' a b s t r a c t i o n " , i n which the animals are t r a i n e d t o a d i s c r i m i n a t i o n o f m u l t i p l e stimulus dimensions and are then t e s t e d on each dimension separately, y i e l d s a "normal" performance i n which each dimension i s c o r r e c t l y responded t o ( c f . the " a l t e r e d s e t " experiments discussed e a r l i e r ) .  The f a c t t h a t t h i s behaviour i s r e l a t i v e l y sens-  i t i v e to c o r t i c a l a b l a t i o n implies that the phylum stage may be a major determinant, and suggests that the present controversy needs t o be placed i n an appropriate perspective.  (Indeed, the c o n f l i c t between  c o g n i t i v e and S-R theories o f l e a r n i n g , which the controversy represents, may hinge l a r g e l y on the developing d i s t i n c t i o n between "abstract" and "concrete" behaviour, and on the p r e d i c t i o n of the conditions under which each occurs i n various species.) One f u r t h e r type of experiment, although not d i r e c t e d primari l y at the controversy, merits a t t e n t i o n before t u r n i n g t o a review of the  very r e c e n t work.  These are the attempts t o apply f a c t o r a n a l y s i s  to the l e a r n i n g process.  Wherry (47) has a p p l i e d Thurstone's technique  to data from Yoshioko's experiments w i t h pattern d i s c r i m i n a t i o n , arranged so that i n t e r c o r r e l a t i o n s could be drawn f o r each r a t f o r each ten t r i a l s during the l e a r n i n g s e r i e s .  (This arrangement a r i s e s out of the con-  33  t r o v e r s y over the e f f i c a c y o f lumped data which does not p r i m a r i l y concern us here.)  One of h i s f i n d i n g s was a confirmation of Krechevsky's  "hypotheses" f o r i n s o l u b l e problems.  I t should be remembered however  t h a t the f a c t o r s producing hypothesis formation as a molar phenomenon! i n 3 X 1  i n s o l u b l e problem can be given adequate d e f i n i t i o n by the c o n t i n u i t y  t h e o r i s t s (40) •  A l a t e r study by Rethlingshafer (3&) u s i n g data from  Muenzinger, i s o l a t e d three f a c t o r s by a s i m i l a r technique. the  One o f these,  second i n order of percentage c o n t r i b u t i o n t o variance, was a " r i s i n g  and waning f a c t o r " which the author i d e n t i f i e s as " v a r i a b i l i t y i n the adoption of hypotheses".  While n e i t h e r space nor the w r i t e r ' s competence  permits a d e t a i l e d discussion o f t h i s type o f evidence i t i s apparent that the processes involved i n d i s c r i m i n a t i o n l e a r n i n g a t t a i n a l e v e l of complexity which i s not adequately met by e i t h e r the c o n t i n u i t y or the non-continuity d e s c r i p t i o n s o f l e a r n i n g . The most recent review o f studies i s that by Harlow i n the "Annual Review of Psychology, 1952".  These studies w i l l not be discussed  i n d e t a i l here, since t h e y contribute nothing e s s e n t i a l l y new i n approach or r e s u l t s .  The box score favours the c o n t i n u i t y p o s i t i o n , with the  reservations noted i n the next s e c t i o n . One o f these s t u d i e s , that by R i t c h i e (39) i s remarkable however c h i e f l y as an i l l u s t r a t i o n o f what i s not acceptable i n an experimenta l approach t o the controversy.  Rats were t r a i n e d i n the Lashley apparatus  u s i n g a p a t t e r n d i s c r i m i n a t i o n , and r e v e r s i n g the reward r e l a t i o n s i n the u s u a l manner.  The f i v e part design o f Spence was employed, which i s i n  i t s e l f objectionable, though perhaps not c r u c i a l l y so.  In d e s c r i b i n g  34  the experiment the authors mention t h a t t h e experimental animals were more "prone" t o p o s i t i o n hypotheses than were t h e c o n t r o l s , and that three o f the animals had t o be discarded because they had already l e a r n ed the d i s c r i m i n a t i o n during t h e " p r e - s o l u t i o n " p e r i o d !  Both o f these  f a c t o r s would l e a d t o a p r e d i c t i o n o f retarded l e a r n i n g on the b a s i s o f e i t h e r theory, i n s p i t e o f which the authors put forward t h e i r r e s u l t s as favouring t h e c o n t i n u i t y p o s i t i o n .  The tendency here t o place under  attack a l u d i c r o u s l y s i m p l i f i e d v e r s i o n o f t h e opposing theory has been noted p r e v i o u s l y .  Summary Summarising, very b r i e f l y , t h e h i s t o r i c a l development o f the controversy i t w i l l be seen t h a t w h i l e the t r e n d o f experimental studies has favoured the c o n t i n u i t y p o s i t i o n , there has been a s u f f i c i e n t weight o f evidence f o r the opposing view t h a t i t cannot be discounted.  Further,  there has been some d i f f e r e n c e i n the types of experiment which favour each viewpoint.  Thus Blum and Blum ( l ) p o i n t out that experiments i n -  v o l v i n g massed t r i a l s , punishment o f the i n c o r r e c t response, and the corr e c t i o n method tend t o favour the non-continuity p o s i t i o n , w h i l e those i n which these conditions do not obtain have tended i n t h e opposite d i r e c t ion.  Another d i s t i n c t i o n which i s evident i s t h a t experiments i n v o l v i n g  simple q u a n t i t a t i v e d i s c r i m i n a t i o n s , or v e r y simple form d i s c r i m i n a t i o n s have tended t o favour t h e c o n t i n u i t y p o s i t i o n , while those i n v o l v i n g more d i f f i c u l t d i s c r i m i n a t i o n s , or perceptual f a c t o r s , have not.  There  i s an i m p l i c a t i o n then t h a t each theory may be appropriate t o a p a r t i c u l a r  35  type o f l e a r n i n g ;  and there i s the a l t e r n a t i v e i m p l i c a t i o n that e x p e r i -  mental f a c t o r s demonstrating one or the other p r e d i c t i o n may have been inadequate.  These experimental f a c t o r s obviously need c l a r i f i c a t i o n .  C l a r i f i c a t i o n o f the t h e o r e t i c a l issues i s a l s o needed.  Blum  and Blum ( l ) suggest that f o r c o n t i n u i t y theory the f a c t o r s of e x t i n c t i o n , r e a c t i v e i n h i b i t i o n , and conditioned i n h i b i t i o n are not s u f f i c i e n t l y c l a r i f i e d t o permit o f adequate q u a n t i f i c a t i o n .  On the other hand the  d e f i n i t i o n o f "hypotheses" and p a r t i c u l a r l y the r e l a t i o n between s i m u l taneous and successive "hypotheses" needs c l a r i f i c a t i o n i n non-continui t y theory.  I f t h i s t h e o r y i s i n any way adequate i t should be p o s s i b l e  t o perform experiments i n which the number and nature o f "hypotheses" can be c o n t r o l l e d .  In both theories the d e f i n i t i o n s o f a t t e n t i o n and  awareness need f u r t h e r c l a r i f i c a t i o n .  I t i s unfortunate that the non-  c o n t i n u i t y t h e o r i s t s have a t no time attempted t r u l y rigorous d e f i n i t i o n of t h e i r concepts l i n k i n g them t o antecedent v a r i a b l e s .  Spence i n con-  s i d e r i n g t h i s aspect o f the controversy holds that the n o n - c o n t i n u i t y t h e o r i s t s have misunderstood the c o n t i n u i t y p o s i t i o n , which i s however not as yet adequately developed f o r problems o f perception. By way of summary a l s o , i t might be mentioned t h a t , while t h i s f a c t o r has been minimised i n the presentation, i n the i n t e r e s t of c l a r i t y , there has been a considerable tendency f o r the members o f each group t o misunderstand or misrepresent t h e i r opponents' case to gain a polemical advantage.  More s e r i o u s i s the extent t o which experiments have been  performed which v i o l a t e conditions of one or other o f the p o s i t i o n s , the r e s u l t s of which are then o f f e r e d i n support of the w r i t e r ' s b i a s .  36  Leeper (32) i n a b r i e f but v e r y cogent summary o f the issues notes t h a t the controversy has been hampered by loose use o f terms, i g n o r a l o f experiments, use o f t a c i t assumptions, and by the tendency t o c l a i m support f o r one p o s i t i o n by claiming t o have disproved the other.  He a l s o holds  t h a t the controversy i s p a r t l y a pseudo-issue and that both theories are p a r t i a l l y adequate.  CHAPTER I I I CLARIFICATION OF THE TWO  POSITIONS  The C o n t i n u i t y P o s i t i o n Having reviewed, i n i t s s a l i e n t features, the h i s t o r i c a l  develop-  ment o f the controversy, i t i s now p o s s i b l e t o undertake a more d e t a i l e d consideration o f the issues i n v o l v e d .  A convenient approach t o t h i s  task i s t o consider separately the two p o s i t i o n s , i n an attempt t o c l a r i f y t h e i r r e s p e c t i v e d e s c r i p t i o n s o f the l e a r n i n g process. I t has been seen t h a t a general statement of c o n t i n u i t y theory describes d i s c r i m i n a t i o n l e a r n i n g as a gradual and continuous summation of increments t o the response tendency o f the animal toward the a s s o c i a t ed s t i m u l i w i t h each rewarded occurrence of the response.  I t has a l s o  been seen t h a t t h i s general statement must be q u a l i f i e d by a considera t i o n of the f a c t o r o f a t t e n t i o n . e f f e c t o f stimulus g e n e r a l i z a t i o n .  A f u r t h e r q u a l i f y i n g f a c t o r i s the Blum and Blum ( l ) have presented  t h i s aspect o f c o n t i n u i t y theory i n explanation o f the experimental  trends  noted above, v i z . , e f f e c t o f massed t r i a l s , punishment, and t h e c o r r e c t i o n method.  Their explanation, based upon stimulus g e n e r a l i z a t i o n and  i n t e r a c t i o n , i s a model o f s o p h i s t i c a t i o n , and demonstrates n i c e l y the d i f f i c u l t y of t e s t i n g the two t h e o r i e s .  I t i s suggested that the a c t u a l  a f f e r e n t stimulus compound, t o which the appropriate response w i l l eventuall y be cued, i s composed o f three temporal u n i t s :  the p o s i t i v e stimulus  38  card, the s i t u a t i o n a l cues, i n c l u d i n g the presence of the other stimulus card and of movement cues, and the reward stimulus.  S i m i l a r l y the a f -  ferent stimulus compound which w i l l eventually e l i c i t an avoidant r e s ponse c o n s i s t s of the stimulus o f the negative card, the s i t u a t i o n a l cues, and the non-reward stimulus.  Obviously the stimulus component represent-  i n g s i t u a t i o n a l cues w i l l contribute the l a r g e s t element t o the a f f e r e n t compound i n the e a r l y phases of l e a r n i n g , and w i l l be i d e n t i c a l f o r the rewarded and the non-rewarded compounds.  Thus during a part of the  pre-  s o l u t i o n period the gradual accumulation of e x c i t a t o r y p o t e n t i a l to the p o s i t i v e card w i l l be masked by the presence of these elements.  I f the  s i t u a t i o n favours the summation of i n h i b i t i o n through massed t r i a l s ,  and  through punishment of the i n c o r r e c t response, p a r t i c u l a r l y the repeated punishment i n v o l v e d i n the c o r r e c t i o n method, the g e n e r a l i z a t i o n of i n h i b i t i o n and e x c i t a t i o n each way between the f i r s t two temporal elements of the stimulus compound w i l l make them v i r t u a l l y equivalent, and  the  p o t e n t i a l of each compound w i l l be determined almost s o l e l y by the t h i r d element, the reward stimulus.  But since i n h i b i t o r y p o t e n t i a l accumulates  more r a p i d l y than e x c i t a t o r y p o t e n t i a l , the r e v e r s a l of reward r e l a t i o n s may  a c t u a l l y have the e f f e c t of f a c i l i t a t i n g ,  rather than r e t a r d i n g the  l e a r n i n g , p a r t i c u l a r l y i f the two c r u c i a l s t i m u l i l i e close together on the h y p o t h e t i c a l g e n e r a l i z a t i o n continuum i n a d i f f i c u l t d i s c r i m i n a t i o n , ( i t w i l l be r e c a l l e d that i n Krechevsky's experiment the reversed group was  superior t o the control.)  This d e s c r i p t i o n r e s t s o f course on the  a d d i t i v e treatment accorded the a f f e r e n t compound i n c o n t i n u i t y theory, and would  be a p r i o r i meaningless i f each stimulus element were considered  39  separately.  The e f f e c t o f i n c i d e n t a l s t i m u l i i n masking the true stimulus  g e n e r a l i z a t i o n gradient has been elaborated and given systematic  elegance  by H u l l (14) f o l l o w i n g the suggestions of Blum and Blum. I t i s evident t h a t t h i s type of formulation can be extended w i t h almost i n f i n i t e complexity, and could be made to accommodate the e f f e c t s of d i s t r a c t i o n , momentary f l u c t u a t i o n s i n l e v e l of a c t i v i t y , the progress i v e diminishing of d r i v e during a s i n g l e experimental session w i t h each successive reward period and so on.-'-  Digressing f o r a moment i t i s  i n t e r e s t i n g t o speculate on p o s s i b l e a p p l i c a t i o n s of these minutiae t o other phases o f the process.  For example, a f t e r the f i r s t few t r i a l s  when the two stimulus compounds are s t i l l n e a r l y equal some secondary r e inforcement based on the a n t i c i p a t o r y goal r e a c t i o n would r e s u l t from the animal's merely l o o k i n g a t the c o r r e c t card, and the successive superposition of the two stimulus patterns on the r e t i n a (VTE) c o i n c i d ent w i t h t h i s s t a t e of reinforcement would r e s u l t i n a s l i g h t t r a n s f e r o f e x c i t a t o r y p o t e n t i a l t o the negative card, again r e s u l t i n g i n f a c i l i t a t e d l e a r n i n g of the reversed problem, under the appropriate circumstances.  While i t may be f e l t that t h i s d e s c r i p t i o n tends more t o  s o p h i s t r y than s o p h i s t i c a t i o n , i t i s not i n c o n s i s t e n t w i t h the p a t t e r n of c o n t i n u i t y theory, and serves to i l l u s t r a t e the p o t e n t i a l complexity of that position.  The obvious danger to molecular systematics i s i n producing an endless a r r a y o f minutely s o p h i s t i c a t e d explanations f o r any e x p e r i mental f a c t , w i t h a consequent s t i f l i n g o f research. I n t r i b u t e t o the energy of t h i s group of t h e o r i s t s i t should be noted t h a t the danger remains p o t e n t i a l r a t h e r than a c t u a l .  40  This pattern having been made c l e a r , i t becomes pertinent t o attempt a b r i e f d e s c r i p t i o n o f the animal's behaviour i n the d i s c r i m i n a t i o n l e a r n i n g s i t u a t i o n according to t h i s theory. p e r i o d two phases may be d i s t i n g u i s h e d ; not,  During the p r e - s o l u t i o n  the f i r s t i n which the animal i s  p r o p e r l y speaking, responding t o the relevant stimulus elements o f  the s i t u a t i o n , and the second i n which these are responded t o , but not i n such a way as t o be evidenced by systematic behaviour. Naive behaviour i n the apparatus i s not, of course, regarded as a t r i a l and e r r o r process, but r a t h e r as the r e s u l t o f response t e n dencies already present, e i t h e r n a t i v e or acquired, together w i t h a c c i d e n t a l factors.  Thus the animal when f i r s t placed i n the apparatus w i t h a  given momentary o r i e n t a t i o n o f the sensoria responds t o those stimulus elements which have e x c i t a t o r y value.  In the l i m i t e d s i t u a t i o n these  responses i n e v i t a b l y b r i n g him t o the goal box where he receives food, which c o n s t i t u t e s a r e d u c t i o n i n drive-'- and a consequent increment t o the e x c i t a t o r y p o t e n t i a l o f a l l stimulus elements impinging on the sensoria at the moment of the f i n a l response.  This a l s o occurs i n d i m i n i s h i n g  degree t o those elements present t o the sensoria p r i o r t o t h e response, depending on t h e i r temporal p r o x i m i t y .  Each subsequent t r i a l i n t h i s  phase o f t h e l e a r n i n g r e s u l t s i n successive increments t o t h e e x c i t a t o r y p o t e n t i a l o f those stimulus elements which were most c o n s i s t e n t l y present at the time o f the f i n a l response.  As a consequence there i s an i n -  creasing tendency on the part o f t h e organism t o attend, i n the sense o f p h y s i c a l o r i e n t a t i o n , t o these elements. The second phase, and t h i s i s not an abrupt d i s t i n c t i o n , i s ons a r y here.  The d e f i n i t i o n o f S-R terminology i s not f e l t t o be neces-  41  going when the animal i s responding t o the s i t u a t i o n p r i m a r i l y i n terms of the goal box, i . e . , when the instrumental response i s occurring consistently.  This does not n e c e s s a r i l y imply t h a t the animal i s respond-  i n g t o the stimulus r e l a t i o n s themselves, since the animal i n running o r jumping t o the goal box may not be f i x a t i n g the appropriate stimulus a t the moment o f response, h i s a t t e n t i o n t o these elements i n t u r n occurring g r a d u a l l y i n the manner described above.  I f inappropriate systematic  responses occur during t h i s p e r i o d t h e i r occurrence i s a s c r i b e d t o t h e accumulation o f e x c i t a t o r y p o t e n t i a l t o the inappropriate stimulus elements, due to the .fortuitous combination o f these w i t h the appropriate ones.  The r o l e s of stimulus g e n e r a l i z a t i o n and i n h i b i t i o n have been  described above.  During t h i s phase the gradual accumulation o f e x c i t -  a t o r y p o t e n t i a l t o the " c o r r e c t " stimulus i s masked by the e f f e c t s o f g e n e r a l i z a t i o n , and by the a d d i t i o n a l c o n t r i b u t i o n o f other stimulus elements which may a t any point outweigh the c o n t r i b u t i o n o f the approp r i a t e elements i n terms o f the r e a c t i o n t h r e s h o l d .  This phase ends  when a systematic tendency t o respond t o t h e appropriate cues i s evidenced by whatever s t a t i s t i c a l c r i t e r i o n i s s e l e c t e d .  The Mon-Continuity P o s i t i o n The non-continuity p o s i t i o n s u f f e r s by comparison w i t h t h e r e l a t i v e l y p r e c i s e formulation o f c o n t i n u i t y theory, i n t h a t i t does not admit o f so d e t a i l e d an e x p o s i t i o n .  I t i s concerned w i t h a broader  d e s c r i p t i o n o f the process, though w i t h the underlying i m p l i c a t i o n t h a t the minutiae o f determination a r e not i d e n t i c a l w i t h those o f the oppos-  42  i n g view.  I t has been seen that the fundamental i s s u e i s that o f d i s -  continuous a c q u i s i t i o n o f the response.  The o r i g i n a l formulation o f  Lashley regarding t h e " a l l or nothing" b a s i s of l e a r n i n g has received so l i t t l e support from, and has been contradicted so f r e q u e n t l y i n , e x p e r i mental s t u d i e s , that i t cannot be regarded as an adequate basis f o r t h i s position.  Consequently, n e a r l y the whole burden o f the non-continuity  p o s i t i o n devolves upon t h e p r o p o s i t i o n t h a t o n l y those aspects o f the stimulus complex which are relevant t o the animal's "attempted s o l u t i o n s " are e f f e c t i v e i n determining i t s behaviour.  The i m p l i c a t i o n i s t h a t the  animal s e l e c t s and organises various d i s c r e t e aspects o f the s i t u a t i o n and responds t o these.  The term "attempted s o l u t i o n " demands c l a r i f -  i c a t i o n which may be r e f e r r e d t o the notion o f s e l e c t i o n , which i m p l i e s organization, and t o t h e f u n c t i o n o f reward.  Learning i s regarded by  both p o s i t i o n s as p r i m a r i l y adaptive behaviour, i n which reward or s a t i s f a c t i o n i s the consequence o f the learned response, and sustains i t . The "attempted s o l u t i o n s " represent modes o f responding which are purposive i n the sense t h a t they f u n c t i o n as a means o f securing s a t i s f a c t i o n or reward.  I t seems t o be a necessary assumption o f t h i s type o f  theory that t h e organism i s equipped w i t h an a c t i v e tendency t o secure the maximum s a t i s f a c t i o n o f i t s needs, the mechanism o f such a tendency being found i n the modes o f response which a r e a v a i l a b l e t o i t .  (It  should be noted t h a t t h i s concept o f " a c t i v e tendency" does not go beyond t h a t o f H u l l ' s "drive".)  This i s purpose as Huxley defined i t f o r  biology, t h e n e c e s s i t y o f continuing the existence o f a given o r g a n i z a t i o n i n t o the succeeding i n s t a n t .  43  The r e a l d i s t i n c t i o n then, between the two t h e o r i e s reposes i n the f u n c t i o n o f reward, which f o r the non-continuity p o s i t i o n has the e f f e c t o f confirming those responses which a r e based on an appropriate o r g a n i z a t i o n of the s i t u a t i o n once that organization has been adopted. That rewards may have a cumulative e f f e c t i n the process i s not incons i s t e n t w i t h t h i s formulation.  (indeed t h e issues would be more c l e a r  i f the non-continuity a s s e r t i o n was simply that reinforcement  operates  i n terms o f response sets rather than i n terms of s i n g l e responses.) Supplementing t h i s d i s t i n c t i o n i s one which i s e q u a l l y r e a l but which cannot a t present be defined o p e r a t i o n a l l y .  I t serves, however, t o  i l l u s t r a t e a d i f f e r e n c e of c o n c e p t u a l i z a t i o n which i n part gives r i s e t o the controversy and which may have o p e r a t i o n a l consequences.  This i s  the d i s t i n c t i o n between the overview which regards behaviour as "stimulusbound", the s a t i s f a c t i o n of t i s s u e needs being accomplished i n the course o f stimulated a c t i v i t y , and that which regards behaviour as purposive i n the sense t h a t t h e organism's a c t i v i t y i s d i r e c t e d autonomously toward the s a t i s f a c t i o n o f i t s needs, by means which are appropriate t o i t s l e v e l of o r g a n i z a t i o n . Even t h i s sketchy presentation o f non-continuity t h i n k i n g goes somewhat beyond the formal p o s i t i o n adopted e a r l i e r i n the controversy. I t i s r e g r e t t a b l y the case t h a t there i s no recent statement o f t h e p o s i t i o n , and that there has never been a t r u l y adequate systematic statement o f i t .  However, i t i s p o s s i b l e t o attempt a c l a r i f i c a t i o n o f  i t s i s s u e s consistent w i t h the pattern o f the theory, w i t h a view t o presenting a meaningful background t o the experimental i s s u e s .  I n doing  44  t h i s i t seems f a i r l y evident t h a t the case f o r the cumulative e f f e c t o f reward i n a broad sense may be conceded.  The question then becomes what  i s rewarded or r e i n f o r c e d , and a consistent answer i s that i t i s the c o g n i t i v e s t r u c t u r e on which the response i s based.  I t has been seen  that experiments which present a simple q u a n t i t a t i v e d i s c r i m i n a t i o n , e.g., brightness, weight, or a very simple form d i s c r i m i n a t i o n tend t o support the c o n t i n u i t y p o s i t i o n .  These are also, however, experiments i n which  the stimulus elements are obtrusive, demand a simple l e v e l o f c o g n i t i v e organization and tend t o admit of o n l y two hypotheses, a p o s i t i o n hypot h e s i s and the " c o r r e c t " hypothesis.  I t would seem to be a meaningful  elaboration o f non-continuity theory t o suggest t h a t hypothesis  formation  occurs w i t h i n an h i e r a r c h y of l e v e l s of organization, beginning  with  o l f a c t o r y dominance, as manifested by the s n i f f i n g behaviour c h a r a c t e r i s t i c of r a t s i n a new s i t u a t i o n , and ascending through various l e v e l s of sensory dominance t o perceptual organization i n v o l v i n g the phenomena of pragnanz, and t o various systematic combinations of sense m o d a l i t i e s . This would postulate a "reluctance" to adopt a higher or more complex l e v e l of organization where a simpler one would achieve s a t i s f a c t i o n , such t h a t , i n general, the animal's c o g n i t i v e organization of a  new  s i t u a t i o n would be at a low l e v e l i n the postulated hierarchy, while the demands o f a complex s i t u a t i o n would subsequently force the adoption o f higher l e v e l s of organization.  The p o s s i b i l i t y i s open f o r i n d i v i d u a l  d i f f e r e n c e s t o determine the p r e c i s e order of s e l e c t i o n and t h e l e v e l of u s u a l f u n c t i o n as i s analogized i n s o r t i n g a c t i v i t i e s w i t h human subjects. This general view i s i m p l i c i t i n Krechevsky's studies on proximity as a  45  f a c t o r i n the v i s u a l closure of the r a t (23)  (25).  One of the outcomes  of such a view i s t h a t the response i t s e l f i s regarded as l a b i l e and t h a t a given "hypothesis" or c o g n i t i v e s t r u c t u r e may be r e a l i z e d v i c a r i o u s l y by a v a r i e t y of behaviours.  I t i s not suggested t h a t the f o r e -  going statement i s necessary or complete, nor t h a t an experimental v e r i f i c a t i o n of i t s c e n t r a l i s s u e s would v e r i f y the theory as a whole. This i s a l s o t r u e , however, of the r a m i f i c a t i o n s o f c o n t i n u i t y theory. A b r i e f attempt to describe the behaviour of the non-continuity r a t i n the d i s c r i m i n a t i o n apparatus w i l l serve to point out the d i f f e r ences between the two t h e o r i e s . i n the p r e - s o l u t i o n p e r i o d .  Again two phases may be d i s t i n g u i s h e d  The f i r s t may be regarded as t h a t i n which  the animal i s engaged i n "exploring" the new s i t u a t i o n , i . e . , h i s behavi o u r s are a c t i v e l y o r i e n t e d a t a low l e v e l of sensory dominance toward the s a t i s f a c t i o n of h i s needs.  x  Haire (9) has suggested t h a t -in t h i s  phase hypothesis formation i n c l u d e s attempts at escape and so on.  This  type of reasoning would seem t o c o n t r i b u t e l i t t l e t o the r e a l i s s u e s of the controversy.  Rather t h i s phase may be regarded as an a c t i v e attempt  to organize the s i t u a t i o n i n such a way t h a t the animal can f u n c t i o n w i t h i n i t t o achieve need s a t i s f a c t i o n .  During t h i s a c t i v i t y the goal  box acquires s i g n i f i c a n c e as a locus o f s a t i s f a c t i o n .  Again, t h i s phase  may be regarded as ended when the animal's a c t i v i t y i s oriented p r i m a r i l y  An a l t e r n a t i v e conceptualisation i s t h a t o f Weiss and o f Tinbergen by which t h i s r e l a t i v e l y unstructured " a p p e t i t i v e behaviour" i s regarded as the highest l e v e l i n the h i e r a r c h y of p h y s i o l o g i c a l mechanisms u n d e r l y i n g behaviour.  46  toward the goal  box.  In the second phase the animal responds i n accordance with h i s c o g n i t i v e organization o f the stimulus r e l a t i o n s .  I f the d i s c r i m i n a t -  i o n involves a simple l e v e l of organization the " c o r r e c t " hypothesis i s r e a d i l y acquired.  Under these circumstances, as i n those i n which the  animal i s forced t o attend t o the relevant discriminanda,  r e v e r s a l of  the reward r e l a t i o n s may v e r y e a s i l y r e t a r d l e a r n i n g of the f i n a l l y to be rewarded d i s c r i m i n a t i o n .  I t w i l l be seen that up t o t h i s point  there i s no e s s e n t i a l o p e r a t i o n a l d i s t i n c t i o n between the two  theories.  (To the w r i t e r ' s knowledge, no. c o n t i n u i t y t h e o r i s t has yet succeeded i n s a t i s f a c t o r i l y p r e d i c t i n g the r a t e of accumulation of e x c i t a t o r y p o t e n t i a l i n a given s i t u a t i o n , though t h i s could conceivably be done i f i t were a f u n c t i o n of the gradual accumulation o f increments r a t h e r than of the l a b i l e adoption of a response set.)  I f , however, the d i s c r i m i n a t i o n  involves a complex l e v e l of organization, as i n a d i f f i c u l t pattern d i s c r i m i n a t i o n , or one i n v o l v i n g two or more sensory m o d a l i t i e s , the animal w i l l be obliged t o adopt s u c c e s s i v e l y a number of hypotheses, and a l w i l l consequently have no e f f e c t on the f i n a l l e a r n i n g .  revers-  This phase  ends when the "correct" hypothesis i s more or l e s s c o n s i s t e n t l y adopted, depending upon the s t a t i s t i c a l c r i t e r i o n s e l e c t e d . These two presentations  of the c o n f l i c t i n g theories have  served to set a background f o r the experimental issues t o f o l l o w .  They  a l s o permit of comparision of wider t h e o r e t i c a l issues as, f o r example, the " p e r i p h e r a l i s t " versus the " c e n t r a l i s t " o r i e n t a t i o n s which they body, the d i s c u s s i o n of .which i s perhaps inappropriate here.  One  emissue,  47  however, which i s o f i n t e r e s t i n approaching the experimental problem i s again t h a t between the method o f axiomatic molecular theory c o n s t r u c t i o n and that o f molar d e s c r i p t i o n .  I t w i l l be seen t h a t each approach  r e s u l t s f i n a l l y i n the l i m i t e d f a c t u a l p r o p o s i t i o n :  r e v e r s a l o f reward  r e l a t i o n s does/does not i n t e r f e r e w i t h subsequent l e a r n i n g .  And w h i l e  i t becomes apparent t h a t the experimental answer t o t h i s question does not f i n a l l y v a l i d a t e e i t h e r theory, i t i s i n t e r e s t i n g that the proposi t i o n i t s e l f must be framed at the molar l e v e l , a f a c t which i n v a l i d a t e s a p r i o r i any ad hoc molecular explanation o f the experimental r e s u l t s .  CHAPTER IV THE EXPERIMENT  C r i t e r i a f o r an Adequate Experiment Holding i n view the m a t e r i a l thus f a r presented, a t t e n t i o n may now be d i r e c t e d toward a s c e r t a i n i n g what might be an adequate a l t e s t of the opposed t h e o r i e s ;  experiment-  that i s , how may the l i m i t e d p r o p o s i t i o n  be affirmed or negated without doing v i o l e n c e t o e i t h e r t h e o r e t i c a l position.  This question may be answered by considering the experimental  issues which have been r a i s e d .  Some o f these have been discussed ear-  l i e r i n t h e i r h i s t o r i c a l context and need only be reviewed here.  It  has already been noted t h a t i n order to s a t i s f y the requirement o f nonc o n t i n u i t y theory the d i s c r i m i n a t i o n must be s u f f i c i e n t l y d i f f i c u l t that the animal i s o b l i g e d t o adopt s u c c e s s i v e l y a t l e a s t two "hypotheses". Also noted was the problem o f d e f i n i n g the p r e - s o l u t i o n period.  I n the  absence o f adequate s t a t i s t i c a l c r i t e r i a the most s u i t a b l e means of doing t h i s would seem t o be by running a p i l o t study on the f i n a l d i s c r i m i n a t i o n under conditions c l o s e l y approximating those o f the experiment, and s e l e c t i n g the p o i n t of r e v e r s a l a t a convenient l o c a t i o n between the run i n which the slowest l e a r n e r began to g i v e the i n s t r u m e n t a l response c o n s i s t e n t l y , and the runs j u s t preceding those i n which the f a s t e s t l e a r n e r begins to manifest a b e t t e r than 50$ response t o the rewarded card.  49  Dealing f i r s t w i t h experimental issues which a r i s e out of the c o n t i n u i t y p o s i t i o n a t t e n t i o n i s d i r e c t e d to the problem of awareness of the s t i m u l i .  F i r s t there must be some means consistent w i t h c o n t i n u i t y  theory of ensuring that the animals are a c t u a l l y f i x a t i n g the area of the stimulus card at the moment of response. attempt to do t h i s (5) has been described.  appropriate  Ehrenfreund's  This condition must obtain  f o r a s i g n i f i c a n t number o f t r i a l s p r i o r t o the r e v e r s a l .  Second, and  complementary, there must be some means of ensuring t h a t the animals are not f i x a t i n g the ground r a t h e r than the f i g u r e . a r i s e out of Spence's c r i t i c i s m s (43) ment.  These two  conditions  of the o r i g i n a l Krechevsky e x p e r i -  A f u r t h e r c o n d i t i o n imposed by Spence i s t h a t the animals must  "receive d i s c r i m i n a b l y d i f f e r e n t s t i m u l a t i o n " from the beginning of the t r a i n i n g s e r i e s (42).  P r e c i s e l y what i s meant by t h i s i t i s d i f f i c u l t  t o i n f e r , and the matter has never been c l a r i f i e d .  Without a more  p r e c i s e statement of i t s meaning t h i s condition cannot be regarded as o f f e r i n g an operational i s s u e .  Again there must be an avoidance of  those factors which tend t o the summation and g e n e r a l i z a t i o n of i n h i b i t i o n , i n order t o meet the issues r a i s e d by Blum and Blum.  Thus punish-  ment of the " i n c o r r e c t " response i s unacceptable, and "non-reward" must be substituted.^  -  Massed t r i a l s should a l s o be avoided f o r the l e a r n i n g  s e r i e s , and the c o r r e c t i o n method which r e s u l t s i n repeated non-reward i s a l s o unacceptable.  The problem o f stimulus g e n e r a l i z a t i o n must of  course be met as f a r as p o s s i b l e w i t h i n the l i m i t s of the  difficult  1 I t may s t i l l , of course, be argued that t h i s i s a form of punishment, however i t i s the mildest form which i s o p e r a t i o n a l l y p o s s i b l e .  50  d i s c r i m i n a t i o n r e q u i r e d by the non-continuity p o s i t i o n .  The  double  pronged stand used by Ehrenfreund meets t h i s requirement t o some extent as f a r as s i t u a t i o n a l cues are concerned.  Faster l e a r n i n g w i t h t h i s  type of stand has been experimentally demonstrated by Haire (9) and others.  Another experimental i s s u e which f o l l o w s from c o n t i n u i t y theory  i s t h a t the presence of d i s t r a c t i n g elements during the r e v e r s a l p e r i o d w i l l tend t o produce a spurious r e s u l t i n favour of the non-continuity prediction. The i s s u e of c o r r e c t i o n versus non-correction, w h i l e included above, merits separate d i s c u s s i o n , since the objections t o t h i s method go beyond the problem of i t s i n h i b i t o r y e f f e c t .  Spence has pointed out  (43) t h a t the c o r r e c t i o n method favours the r a p i d e l i m i n a t i o n of p o s i t i o n responses during the f i r s t few t r i a l s , i . e . , those i n which the s t i m u l i are reversed, w i t h consequent d i s t o r t i o n o f the e r r o r scores before and after reversal.  There are other methodological disadvantages t o t h i s  technique which have been summarized by Leeper (32),  v i z . , that i t r e s u l t s  i n unequal weighting of the c o n t r i b u t i o n of each t r i a l i n the t o t a l scores;  t h a t the conditions of reinforcement or non-reinforcement  between i n i t i a l and r e p e t i t i v e t r i a l s ;  vary  t h a t the number o f t r i a l s i s not  c o n t r o l l e d , or comparable f o r each animal;  and t h a t the d e f i n i t i o n of  e r r o r i s not consistent from t r i a l to t r i a l .  On the whole i t would  seem i n a d v i s a b l e t o use t h i s technique i n c r i t i c a l experimental s t u d i e s , e n t i r e l y apart from i t s p a r t i c u l a r r o l e i n the controversy. By comparisicn w i t h the issues j u s t discussed, the r e l a t i v e p a u c i t y of experimental issues stemming from the non-continuity p o s i t i o n  51  i s probably a measure of the degree to which t h a t point of view has r e mained inadequately s t r u c t u r e d .  The issues can be reduced t o three :  the d i f f i c u l t y of the d i s c r i m i n a t i o n noted above, the i n v a l i d i t y of f o r c i n g a t t e n t i o n t o the r e l e v a n t discriminanda discussed e a r l i e r , and a t h i r d i s s u e which gains added importance i n that i t seems c o n s i s t e n t l y t o have been ignored or misunderstood by the opposing workers.  This i s the  i s s u e r a i s e d by the s o - c a l l e d " f i v e p o i n t " design of Spence.  The  essen-  t i a l feature o f t h i s design i s the i n d u c t i o n of a p o s i t i o n preference during t h e p r e l i m i n a r y t r a i n i n g , and i t s subsequent t r a i n i n g out, a f t e r the r e v e r s a l .  I t must be i n s i s t e d t h a t the i n d u c t i o n of a p o s i t i o n  preference by means of consistent rewards t o a given p o s i t i o n stimulus cannot be regarded, as a s u b s t i t u t e f o r l a b i l e hypothesis formation i n the sense defined e a r l i e r .  I t i s d o u b t f u l i f , i n view of the imposing  e d i f i c e of experimental evidence i n d i c a t i n g the contrary, any non-continui t y t h e o r i s t would wish t o deny e n t i r e l y the cumulative e f f e c t of reward. The i s s u e , as has been pointed out, does not r e s t here, but rather w i t h the problem of what i s rewarded.  This technique and i t s v a r i a n t s does  not then c o n s t i t u t e an adequate t e s t of the controversy from a non-continui t y p o i n t of view. I t f o l l o w s from the foregoing t h a t an adequate t e s t of the cont r o v e r s y would be an experiment designed t o meet a l l of the issues d i s cussed above.  C e r t a i n f a c t o r s should however be borne i n mind.  First  i s t h a t the s t a b i l i z a t i o n of issues presented here i s appropriate o n l y to the contemporary alignment of the controversy and should by no means be regarded as f i n a l .  However i f experiments which f u l f i l the s p e c i f -  52  i c a t i o n s given should repeatedly prove t o be i n c o n c l u s i v e or inoperable, those which do not are unacceptable as s u b s t i t u t e s , and i t must be concluded that t h e controversy i n i t s contemporary form does not present an operational issue.  Rationale of the Present Experiment The design o f t h e present experiment i s o f f e r e d as one which does f u l f i l t h e conditions of each p o s i t i o n .  Before d e s c r i b i n g i t how-  ever a v e r y b r i e f review o f t h e t h e o r e t i c a l p o s i t i o n on which i t i s grounded, together w i t h an a n a l y s i s o f the two relevant previous are i n order.  studies  The s p e c i f i c t h e o r e t i c a l i s s u e under consideration a r i s e s  out o f p o s s i b l e sources o f the controversy.  I t i s conceivable t h a t the  two theories a r e d e s c r i b i n g i d e n t i c a l processes a t d i f f e r e n t l e v e l s . t h i s case there i s no r e a l controversy.  In  I t i s also possible that the  c o n t i n u i t y p o s i t i o n i s e s s e n t i a l l y correct f o r simple s i t u a t i o n s w h i l e the non-continuity p o s i t i o n i s appropriate t o those which are more d i f f i c u l t . This d i s t i n c t i o n r e f e r s t o simple versus d i f f i c u l t d i s c r i m i n a t i o n s per se, t h a t i s , those i n v o l v i n g many t r i a l s and e r r o r s , as opposed t o those i n v o l v i n g r e l a t i v e l y few. against t h i s supposition.^  The weight o f evidence would seem t o be -  Another i n t r i g u i n g p o s s i b i l i t y i s that d i s -  criminations i n v o l v i n g stimulus i n t e n s i t y are adequately described by c o n t i n u i t y theory, while those i n v o l v i n g perceptual f a c t o r s are subject t o discontinuous l e a r n i n g , i n a sense s l i g h t l y d i f f e r e n t t o that  ^ invalid.  I t i s a l s o p o s s i b l e of course that one of t h e t h e o r i e s i s  53  o r i g i n a l l y proposed.  I t w i l l be r e c a l l e d that during the review of the  h i s t o r y of the controversy, experiments which tended t o favour the l a t t e r p o s i t i o n were those i n v o l v i n g perception, and were c a r r i e d out by workers i n t e r e s t e d i n t h i s aspect o f the f i e l d .  There i s some "face v a l i d i t y "  i n the notion that stimulus i n t e n s i t y i s "binding" on the organism w h i l e perceptual o r g a n i z a t i o n i s subject t o l e s s mechanical causation.  In  t h i s connection Lashley's term " a l l or nothing basis o f l e a r n i n g " while i t seems l e s s than adequate i n i t s o r i g i n a l context, seems p e c u l i a r l y appropriate t o the d e s c r i p t i o n o f perception i n the l i g h t o f studies on, e.g., c l o s u r e .  I t i s also i n t e r e s t i n g t h a t Hull's most adequate attempt  to q u a n t i f y the p o s t u l a t e o f a f f e r e n t n e u r a l i n t e r a c t i o n i s l i m i t e d t o s t i m u l i on the same p h y s i c a l continuum. (8). I t i s an experimental p o s s i b i l i t y then, that Krechevsky's o r i g i n a l r e s u l t s were due t o t h e f a c t t h a t h i s stimulus cards were o f a type which demand some degree o f perceptual o r g a n i z a t i o n i n order that they be d i f f e r e n t i a t e d .  Indeed these were the i d e n t i c a l cards used by  him and by Lashley i n studies on the f a c t o r o f proximity i n v i s u a l c l o s ure.  I t i s also p o s s i b l e , o f course, t h a t h i s r e s u l t s were due t o the  v i o l a t i o n o f one or more o f t h e f a c t o r s which have been discussed as e s s e n t i a l t o an adequate t e s t of the two t h e o r i e s .  An experiment which  included these factors,., together w i t h Krechevsky's stimulus cards, would, i f p o s i t i v e f o r the non-continuity p r e d i c t i o n , i s o l a t e t h e stimulus cards as the source o f these r e s u l t s , and l e n d some appearance o f v a l i d i t y t o the t h e o r e t i c a l considerations j u s t discussed, though not t o any conclus-  54  i v e degree.  Such a r e s u l t would, however, c o n c l u s i v e l y disprove the  c o n t i n u i t y p o s i t i o n as i t now stands, as f a r as the area o f perceptual o r g a n i z a t i o n i s concerned.  I t should be noted t h a t Spence has conceded  the p o s s i b i l i t y t h a t S-R theory as now organized i s inappropriate t o the problems of perception and has stressed t h e f a c t t h a t S-R t h e o r i s t s have not been p r i m a r i l y concerned w i t h t h i s area of behaviour (45).  I f how-  ever t h e r e s u l t s o f such an experiment were t o uphold the c o n t i n u i t y p r e d i c t i o n i t would c o n c l u s i v e l y demonstrate the i n v a l i d i t y of the nonc o n t i n u i t y p o s i t i o n i n what must be more o r l e s s i t s l a s t outpost, w h i l e l e n d i n g considerable weight t o the adequacy o f c o n t i n u i t y theory.^ I t i s now appropriate t o examine Krechevsky's experiment (24) i n order t o a s c e r t a i n the extent to which i t f a i l s t o meet t h e c r i t e r i a which have been put forward.  Spence's c r i t i c i s m that animals tend i n  the jumping stand t o f i x a t e the lower part o f the card has been noted. The c o r r e c t i o n method was used and the conventional technique of l o c k i n g the i n c o r r e c t door so that responses t o i t are punished was a l s o employed.  The data afforded three p o s s i b l e comparisons of which o n l y one i s  acceptable i n view of the use o f the c o r r e c t i o n method, v i z . , that comp a r i n g t r i a l s a f t e r r e v e r s a l f o r experimental and c o n t r o l groups.  The problem o f d i f f e r e n t i a t i n g the e f f e c t o f d i f f i c u l t y per se, as opposed t o d i f f i c u l t y a r i s i n g out o f perceptual f a c t o r s , would remain open t o experiment. Although the weight of evidence seems t o be against the former, i t i s not conclusive. o  I t i s acknowledged, o f course, t h a t a s i n g l e adequate negati o n o f an experimental p r o p o s i t i o n e s t a b l i s h e s the i n v a l i d i t y of the theory upon which i t r e s t s , while a s i n g l e a f f i r m a t i o n o f such a proposi t i o n merely lends an increment to i t s a c c e p t a b i l i t y .  55  L i t t l e more need be s a i d of t h i s experiment, c r i t i c i s m s of which have been summarized e a r l i e r .  C o n t i n u i t y t h e o r i s t s e x p l a i n the r e s u l t s as  the outcome of inadequate- f i x a t i o n (Spence) or the e f f e c t of i n h i b i t i o n (Blum and Blum);  Spence a l s o remarked that i f the f i g u r e and ground had  been reversed the r e s u l t s might have been e n t i r e l y d i f f e r e n t since the r a t tends t o respond t o the b r i g h t e s t p o r t i o n o f the card.  Munn's  c o l l a t i o n o f data from r a t studies does not bear t h i s out (36).  Itis  evident that t h i s experiment requires t o be re-run i n order to meet these c r i t i c i s m s . Ehrenfreund s experiment attempts to do t h i s f o r the problem 1  of f i x a t i o n .  This experiment, while i n many ways a model f o r technique  and r e p o r t i n g , i s nevertheless open t o serious c r i t i c i s m s .  His f i r s t  experiment was c a r e f u l l y designed t o provide a t e s t s i t u a t i o n the r e s u l t s o f which were already foregone on t h e basis o f p r e l i m i n a r y experiments. To argue, because he could demonstrate that the e f f e c t s of inadequate s t i m u l a t i o n produced r e s u l t s s i m i l a r t o those o f Krechevsky, that theref o r e Krechevsky's r e s u l t s were due t o t h i s f a c t o r i s merely invoking an analogy.  A f u r t h e r c r i t i c i s m i s t h a t while t h i s i s a d i s c r i m i n a t i o n  between f i g u r e s rather than stimulus i n t e n s i t i e s the f i g u r e s chosen are among the e a s i e s t f o r t h e r a t t o l e a r n (35)*  Again the use o f the  p o s i t i o n preference method has been shown t o be undesirable.  There i s  a l s o a suggestion, although the report i s ambiguous as t h i s p o i n t , t h a t the p r e - s o l u t i o n p e r i o d was defined under the conditions o f t h e d i f f i c u l t s i t u a t i o n of Experiment I .  I f t h i s were the case then t h i s s e r i e s would  p a r a l l e l that o f Krechevsky's Group I I I .  (Indeed i t i s i n t e r e s t i n g that  56  f o r t y t r i a l s reversed t r a i n i n g was the number used f o r each of these groups.)  The i n t e r e s t here however centers on the stimulus cards them-  s e l v e s , and i t i s evident from the considerations o u t l i n e d e a r l i e r that t h i s experiment requires t o be re-run u s i n g Krechevsky s stimulus cards 1  and r e t a i n i n g Ehrenfreund's precautions against inadequate f i x a t i o n . This i s the experiment which was undertaken by the w r i t e r and which w i l l now be described.  Apparatus The apparatus was i d e n t i c a l t o t h a t used by Ehrenfreund, s p e c i f i c a t i o n s f o r which w i l l be found i n h i s a r t i c l e (5)«  I t s essen-  t i a l features were the double pronged jumping stand (Plate I ) , so cont r i v e d t h a t i t could be r a i s e d or lowered i n r e l a t i o n t o the stimulus windows and moved back and f o r t h from a distance o f two inches t o a d i s tance of seven inches from them.  The windows themselves were s i x i n c h -  es on each s i d e and were separated by a distance o f two inches.  Illum-  i n a t i o n was provided by a goose neck lamp c e n t r a l l y placed so t h a t equal i n t e n s i t y was provided f o r each window, as measured by a standard photometer.  The goal box was painted white, the r e s t o f the apparatus black,  i n c l u d i n g the non-reward compartment, i n order t o avoid g e n e r a l i z a t i o n of the reward c o n d i t i o n s .  The stimulus cards were hinged at the base  so that they f e l l back e a s i l y when touched by the animal.  An e l e c t r i c  timer was provided t o regulate the reward period and was connected t o a lamp which was shielded from the animals i n order t o avoid c o n d i t i o n i n g to t h i s stimulus.  A stop watch w i t h a s i l e n t s l i d e was used t o time  PLATE I Stimulus windows and double pronged jumping stand. The card on the l e f t i s the f i r s t t r a i n i n g card o f the s e r i e s .  58  latencies.  Controls In a d d i t i o n t o those i m p l i e d above, a number o f s p e c i f i c cont r o l s were employed.  Munn (36) l i s t s f i v e requirements of d i s c r i m i n a t -  ion l e a r n i n g experiments,be randomised.  ( i ) The order o f stimulus presentation must  This was accomplished by s e l e c t i n g from Gellerman's  t a b l e (6) ten s e r i e s t o meet the f o l l o w i n g c r i t e r i a .  No s e r i e s contain-  ed more than two i d e n t i c a l p o s i t i o n s i n succession.  There were at l e a s t  two r i g h t s and two l e f t s i n both the f i r s t and l a s t h a l f of each s e r i e s of ten.  Each s e r i e s contained only f i v e r e v e r s a l s o f l e f t - r i g h t or  right-left.  Each s e r i e s o f f e r e d o n l y chance reward t o e i t h e r s i n g l e or  double a l t e r n a t i o n of p o s i t i o n responses. inncombining the s e r i e s .  These c r i t e r i a were a l s o met  ( i i ) I r r e l e v a n t cues must be removed.  nate p a i r s of stimulus cards were provided.  Alter-  The jumping stand was  scrubbed f r e q u e n t l y each day and the goal box and non-reward boxes were cleaned d a i l y , i n a d d i t i o n t o c o n t r o l s mentioned above.  ( i i i ) The pos-  s i b i l i t y o f the animals hearing the stimulus cards changed must be eliminated.  The reward and non-reward boxes were arranged such t h a t by  a p p r o p r i a t e l y s h i f t i n g them the s t i m u l i were changed (see P l a t e I I ) . These boxes were s h i f t e d a f t e r each t r i a l regardless of the stimulus r e lations, runs.  ( i v ) The experimenter must be behind the animals during t h e i r This was f u l f i l l e d .  the animals must be avoided.  (v) Giving of cues by manual guidance o f This was t e s t e d by having a strange  operator handle the animals from time t o time.  I n a d d i t i o n t o these  59  PLATE I I Goal box (center) and a l t e r n a t e non-reward compartments.  60  c o n t r o l s the apparatus was provided w i t h a d d i t i o n a l panels (see P l a t e I I I ) s h i e l d i n g t h e jumping stand.  I l l u m i n a t i o n i n the room was constant,  and d i f f e r e n t i a l brightness was c o n t r o l l e d by removing objects which would provide these cues and by the arrangements o f t h e room and the apparatus . Controls were a l s o i n v o l v e d i n the feeding and care of the animals.  The weight o f each animal was checked f r e q u e n t l y and feed was  apportioned such that weight l o s s was kept r e l a t i v e l y constant.  Two  animals were kept on ad l i b feeding throughout t h e experiment as a check on food i n t a k e and weight.  Since there was considerable v a r i a t i o n i n  the weight and s i z e of the animals d i f f e r e n t i a l feeding was regarded as the best means o f ensuring r e l a t i v e l y constant m o t i v a t i o n .  The temperat-  ure o f the room containing t h e cages was regulated by means of heaters and a d a i l y record o f maximum and minimum temperature was kept.  During  the a c t u a l running o f t h e experiment t h e animals were caged s i n g l y . The d i e t was a balanced r a t i o n provided by the Animal Husbandry Department .  P l a n o f Procedure F o r t y Albino r a t s , twenty male and twenty female, from four 100-day l i t t e r s of the Wistar s t r a i n were t r a i n e d as f o l l o w s , -  On the  f i r s t day'" the animals were placed on t h e stand and allowed t o "explore" The term "day" i s used throughout t h i s s e c t i o n t o denote a complete run o f a l l the animals. I n p r a c t i c e t h i s f r e q u e n t l y occupied two days owing t o t h e l a r g e number o f animals. I n general, males and females were r u n on a l t e r n a t e days. The order o f running was preserved from day t o day.  PLATE i n Apparatus from i n f r o n t . The window on the l e f t i s open t o the white goal box. The stand i s r a i s e d as i n Ehrenfreund's Experiment I I .  62  the apparatus.  The white goal box was a c c e s s i b l e through the open win-  dow on the r i g h t , while t h e non-reward window was closed w i t h a black card.  The jumping stand was placed so t h a t there was a two i n c h gap  l e v e l w i t h the lower edge o f t h e window.  Each animal was allowed t o  enter t h e g o a l box and eat f o r s i x t y seconds.  On the second day t h i s  procedure was repeated w i t h the goal box on the l e f t , thus a f f o r d i n g some i n d i c a t i o n of i n i t i a l preferences.  From t h i s point t h e procedure was  as f o l l o w s : (1) Three days t r a i n i n g (30 t r i a l s ) w i t h the apparatus arranged as above; box;  animals allowed t o eat f o r f i f t e e n seconds i n t h e open goal  t r i a l s spaced t h i r t y seconds apart.  I n t h i s phase t h e animals are  l e a r n i n g what i s e s s e n t i a l l y a brightness d i s c r i m i n a t i o n . (2) On the f o u r t h day the gap was widened t o three inches on the f i r s t t r i a l f o r every animal.  Subsequently, s i n c e the animals v a r i e d  i n s i z e and l e v e l o f a c t i v i t y , the gap was widened f o r each animal on successive t r i a l s as soon as each animal had s u c c e s s f u l l y crossed a given gap.  This t r a i n i n g was continued t o a l i m i t o f e i g h t y t r i a l s , a f t e r  which the few animals which had not yet mastered t h e f i n a l gap o f seven inches were given e x t r a t r i a l s .  I t w i l l be seen t h a t t h i s  results i n over-training of the faster learners.  procedure  I t was adopted i n  order t o avoid having a group o f animals out o f contact w i t h the apparatus for a f a i r l y l o n g p e r i o d of time.  I t was a l s o f e l t t h a t the v a r y i n g  degrees of t r a i n i n g , when equated i n c o n t r o l and experimental groups, would a f f o r d i n t e r e s t i n g cross  comparisons.  63  (3) A stimulus card, the upper three-quarters o f which was white and t h e lower area black, was now s u b s t i t u t e d f o r t h e open window and the stand was r a i s e d so t h a t i t was l e v e l w i t h the lower edge o f the white p o r t i o n (see Plate I, p. 57) • spaced.  From t h i s point on, t r i a l s were  This card was a l t e r n a t e d w i t h t h e open window (stand lowered)  for eight t r i a l s , balancing t h e random order o f stimulus presentation with this alternation. the card.  This was followed by four successive t r i a l s t o  Animals which were performing u n s a t i s f a c t o r i l y a t the end o f  the eight a l t e r n a t e t r i a l s were given a d d i t i o n a l balanced a l t e r n a t i o n o f card and open box before continuing. (4) The area o f the white part o f the card was now reduced a t a r a t e s u i t a b l e t o each animal u n t i l each would jump t o a rectangle, one and three-quarter inches by two and a quarter inches, placed d i r e c t l y i n f r o n t o f t h e r a i s e d stand.  This was done i n an e f f o r t t o t r a i n out t h e  avoidant tendency t o t h e black ground o f t h e card. (5) The next step was t o d i v i d e the animals i n t o  experimental  and c o n t r o l groups on a random basis using a standard t a b l e o f random numbers (4), and checking f o r t h e s i g n i f i c a n c e o f d i f f e r e n c e s between r a t e o f l e a r n i n g the brightness d i s c r i m i n a t i o n , r a t e o f l e a r n i n g t o jump the gap and t o knock over the card, percentage weight l o s s , and d i v i s i o n o f t h e sexes and l i t t e r s , i n order t o a s c e r t a i n that t h e a l l o c a t i o n o f these f a c t o r s could i n p r a c t i c e be a t t r i b u t e d t o chance. (6) F i n a l l y t h e experimental stimulus cards (see P l a t e IV)  :  PLATE IV F i n a l stimulus cards w i t h an animal approaching. The stance i s t y p i c a l o f the "scrambling" behaviour of an animal r e f u s i n g t o jump.  J  65  were t o be presented  i n accordance w i t h t h e reward r e v e r s a l design.  In  the absence o f a s a t i s f a c t o r y p i l o t study, the r e v e r s a l period was t o have been s e t a t t h i r t y t r i a l s .  This t r a i n i n g would have been continued  to an adequate c r i t e r i o n of mastery.  D e s c r i p t i o n o f Procedure While the preceding s e c t i o n o u t l i n e d t h e plan o f t h e experiment a statement o f t h e procedure would be incomplete without some d e s c r i p t i o n o f the animals' behaviour.  This w i l l f o l l o w the o u t l i n e o f the proced-  ure. On the f i r s t two days o f the experiment a l l the animals l o c a t e d the food i n t h e goal box a f t e r varying lengths o f time on the stand. (1) The behaviour o f t h e animals during the f i r s t t h i r t y t r i a l s was very uneven p a r t l y owing t o inadequate c o n t r o l of motivation.  In  s p i t e o f the c a r e f u l precautions i n feeding, the animals l o s t weight a t widely varying rates.  This i s a f u n c t i o n o f s k i n area (area of heat  l o s s ) and o f v a r y i n g degrees o f maturity w i t h i n t h e r e s t r i c t e d age range. Eleven o f t h e animals mastered the d i s c r i m i n a t i o n w i t h i n the t h i r t y trials.  ( F i r s t o f ten successive t r i a l s without e r r o r or two successive  days w i t h o n l y one e r r o r i n each day.) (2) During the t r a i n i n g t o t h e gap, motivation had become more  For a l l p r a c t i c a l purposes the experiment was discontinued at t h i s point f o r reasons presented i n t h e next s e c t i o n .  66  even. the  A problem was r a i s e d by the tendency of t h e animals t o f a l l i f  gap were too wide.  I t was found t h a t having once f a l l en v e r y few  animals would attempt the same gap again, and i t would have to be closed t o a point at which the animal would again respond.  This i s  probably accounted f o r i n part by the technique of t r a i n i n g by which, i n accordance w i t h the design, no pain o r a n x i e t y producing inducements t o jump were employed.  I n a " c o n t i n u i t y " frame o f reference t h i s r e s u l t  could be p r e d i c t e d from the steep l i n e a r curve f o r summation o f i n h i b i t ion  as opposed t o the o g i v a l curve f o r summation of e x c i t a t i o n r e s u l t i n g  i n r a p i d accumulation of i n h i b i t i o n w i t h the i n t r o d u c t i o n of a punishing factor.  An i n t e r e s t i n g feature of t h i s phase was t h a t f o r each animal  there was a point at-which i t could no longer step or walk Over the gap, but must adopt the r a d i c a l l y d i f f e r e n t muscular s e t involved i n jumping. Presumably the molecular d e s c r i p t i o n of t h i s behaviour would involve a decrease i n the e x c i t a t o r y p o t e n t i a l of the open window i n e l i c i t i n g the new response, while the view which emphasizes d o c i l i t y and e q u i f i n a l i t y would p o s t u l a t e a l a b i l e adaptation t o the new s i t u a t i o n . ive  impression was t h a t l i t t l e l o s s was occasioned.  The subject-  However, i t could  a l s o be argued t h a t the e f f e c t o f i n h i b i t i o n noted above would be sharpened by such a l o s s , i n conformity with the observed behaviour noted previously. the  That i s t o say, the decrease i n e x c i t a t o r y p o t e n t i a l o f  window a t t h i s point was added t o the summation o f i n h i b i t o r y  p o t e n t i a l generated by f a l l i n g as an a d d i t i o n a l f a c t o r preventing repeti t i o n of t h e response.  Obviously the measurement o f t h i s f a c t o r would  r e q u i r e a r i g o r o u s l y c o n t r o l l e d s i t u a t i o n , and measures more s e n s i t i v e  67  than those a v a i l a b l e here.  A f t e r e i g h t y t r i a l s fourteen o f the animals  had not yet l e a r n e d t o cross the seven i n c h gap and s i x o f the animals had not mastered the brightness d i s c r i m i n a t i o n .  These were given add-  i t i o n a l training. (3) The f i r s t p r e s e n t a t i o n of the white stimulus card presuma b l y takes advantage of the t r a n s f e r o f t r a i n i n g from t h e white square v i s i b l e through the open window to the white card.  I n p r a c t i c e there  was a tendency f o r the animals, a f t e r the f i r s t exposure o f the card, t o e i t h e r refuse the jump o r t o jump i n such a way t h a t they f e l l .  I t was  found that t h i s could be overcome by presenting the card and window a l t e r n a t e l y f o r a few t r i a l s .  I t w i l l be noted t h a t t h i s behaviour and  the stimulus conditions which overcome i t are both h i g h l y consistent w i t h molecular c o n t i n u i t y theory i n terms o f stimulus equivalence and the g e n e r a l i z a t i o n continuum.  I t i s not, however, i n c o n s i s t e n t w i t h the  opposing view. (4) The next step i n the procedure i s made necessary by the f a c t that the animals have been c o n s i s t e n t l y t r a i n e d t o avoid the black card.  The procedure of reducing the area o f white was a r r i v e d a t em-  p i r i c a l l y u s i n g a p a i r o f the animals as a p i l o t group. was s u c c e s s f u l w i t h i n l i m i t s .  The technique  However i t was during t h i s phase that  the animals began t o develop the behaviour which made i t necessary t o discontinue the experiment.  As t h e area o f white was decreased there  was an i n c r e a s i n g tendency f o r the animals t o jump " w i l d " , i . e . , t o miss the window and f a l l i n t o the net below.  Having once made such a jump  68 the tendency was t o repeat the f a u l t y jump and t o continue doing so u n t i l the animal had f a l l e n a s u f f i c i e n t number o f times t h a t i t would no l o n g er respond.  Numerous attempts a t "therapy  41  were undertaken, the most  s u c c e s s f u l being t o r e t u r n the animal t o an e a r l i e r phase i n the t r a i n i n g , and i n a few t r i a l s repeat the steps which had preceded the i n a d equate responses.  This procedure was e v e n t u a l l y adopted r o u t i n e l y as  soon as a f a u l t y jump occurred.  Before t h i s technique had been develop-  ed, however, eight o f t h e animals had developed h i g h l y stereotyped jumps and were discarded.  Four more animals developed these stereotyped i n -  adequate responses i n s p i t e of immediate r e t r a i n i n g .  x  (5) and (6) A t e n t a t i v e d i v i s i o n o f t h e remaining animals i n t o experimental and c o n t r o l groups y i e l d e d two groups which were f r e e o f significant variations.  However, when the remaining animals were present-  ed with the experimental d i s c r i m i n a t i o n the same type o f behaviour d e v e l oped.  I t would seem merely p r o d i g a l o f space and time t o record here  the various attempts which were made t o overcome t h i s tendency.  The  f i n a l technique, the r a t i o n a l e o f which i s evident, was t o s u b s t i t u t e a card which was intermediate between the two stimulus cards, i . e . , had an equal number o f squares e q u a l l y spaced and opposed t o the black card. This was f u r t h e r buttressed by adding t o the center o f t h e card a white patch the same s i z e as that t o which the animal would jump.  While t h i s  was t h e most successful technique, and one t o which twenty o f the animals responded, the tendency t o jump " w i l d " continued.  When the c r u c i a l p a i r  of cards was f i n a l l y presented, only four o f the animals continued t o 1 Eight animals died during t h e experiment, a m o r t a l i t y r a t e o f 17$.  69  respond a f t e r nine t r i a l s , w i t h i n t e r v e n i n g sessions f o r "therapy". While i t would have been p o s s i b l e t o continue, a l l o w i n g the animals t o f a l l t o t h e net and then be placed by hand i n t h e food box or non-reward box as appropriate, i t i s evident t h a t such a technique would have i n volved a d r a s t i c r e d u c t i o n i n c o n t r o l s , an increase i n i r r e l e v a n t s t i m u l i , and, not l e a s t , t h e i n v a l i d a t i o n o f the no punishment requirement essent i a l t o the experiment.  At t h i s p o i n t , therefore, the experiment was  discontinued.  A n a l y s i s of P o s s i b l e Causes o f F a i l u r e While i t would be u n p r o f i t a b l e t o devote much space t o t h i s t o p i c i t i s a t l e a s t not i r r e l e v a n t t o speculate on some o f t h e causes of the behaviour j u s t described.  F i r s t i s the obvious p o s s i b i l i t y that  t h e v i s u a l a c u i t y o f the animals was inadequate t o t h e task.  Not only  were the animals a l b i n o e s , a circumstance which could not be avoided, but t h e r e was no way o f adequately checking f o r t h e presence of cong e n i t a l v i s u a l defects other than microphthalmia which was absent."'"  It  might be noted too that s e l e c t i v e f a c t o r s i n the breeding o f these animals had been d i r e c t e d a t t h e i r s u i t a b i l i t y f o r n u t r i t i o n s t u d i e s , r a t h e r than f o r l e a r n i n g s t u d i e s .  These f a c t o r s might i n themselves  account f o r t h e wide range o f performance i n l e a r n i n g the i n i t i a l b r i g h t ness d i s c r i m i n a t i o n .  A l s o since t h e behaviour of some o f t h e animals i n  the apparatus i n t h e l a t e r t r i a l s resembled i n i t s stereotypy the behaviour Dr. A. J . Wood, Department o f Animal Husbandry, U.B.C  70  of r a t s i n an i n s o l u b l e d i s c r i m i n a t i o n , i t seems p o s s i b l e t h a t these animals were not r e c e i v i n g adequate s t i m u l a t i o n .  The degree o f s t e r e o -  typy was c u r i o u s l y exemplified by one animal which would jump and f a l l , and which learned unaided t o climb back t o the rjumping stand where i t would repeat t h e jump.  This cycle o f behaviour would continue u n t i l  the response had been exhausted, and would be continued a f t e r a p e r i o d of r e s t . Another p o s s i b i l i t y which should not be overlooked i s t h a t the o r i g i n a l avoidant t r a i n i n g t o t h e ground o f the f i n a l stimulus card presented a l e a r n i n g s i t u a t i o n which was too f i n e l y e q u i l i b r a t e d t o be s u s c e p t i b l e o f mastery by t h e animals.  I f t h i s i s the case i t i s d i f -  f i c u l t t o surmise what a l t e r n a t i v e method would ensure that the animals do not f i x a t e the ground d u r i n g r e v e r s a l .  A further p o s s i b i l i t y with  a s i m i l a r bearing i s t h a t a d i s c r i m i n a t i o n design o f t h i s complexity i s simply not s o l u b l e i n the absence o f some technique f o r f o r c i n g the jump and f o r some punishment of the inappropriate response.  I t should be  born i n mind t h a t t h e jumping stand w i t h these two features enabled Lashley t o o b t a i n d i s c r i m i n a t i o n s which had t h i t h e r t o been considered imp o s s i b l e , t h i s a t a time when the l e a r n i n g dynamics were not a major source o f i n t e r e s t .  I t may be merely naive then t o denude Lashley's  technique o f two o f i t s f e a t u r e s , and then t o expect l e a r n i n g of a d i f f i c u l t d i s c r i m i n a t i o n t o occur.  I n t h i s connection i t i s i n t e r e s t i n g  that an experiment, undertaken r e c e n t l y a t t h e U n i v e r s i t y o f C a l i f o r n i a , encountered a problem s i m i l a r t o t h e one encountered here i n that some  71  60$ of the animals jumped w i l d .  I t might be noted t h a t t h i s experiment  used hooded r a t s and d i d not attempt the figure-ground controls employed here.  I f i t i s the case that an experiment i n v o l v i n g a d i s c r i m i n a t i o n  s u f f i c i e n t l y d i f f i c u l t t o s a t i s f y the requirements of non-continuity theory cannot be performed without punishment f a c t o r s , i t follows from the previous d i s c u s s i o n that t h e r e i s not a t present a v a l i d operational d i s t i n c t i o n between the two t h e o r i e s .  x  O r a l communication from Mr. Wyers, A s s i s t a n t , Department of  Psychology, U. of C.  CHAPTER V RESULTS  D e s c r i p t i v e A n a l y s i s o f Data While the use o f the term " r e s u l t s " , i n the l i g h t o f t h e precedi n g d i s c l o s u r e s , i s p u r e l y gratuitous there are one or two areas o f i n t e r est i n the data c o l l e c t e d up t o the conclusion o f the experiment.  These  data i n c l u d e records o f t r i a l s and errors f o r t h e i n i t i a l brightness d i s c r i m i n a t i o n , mastery o f the seven i n c h gap, and performance d u r i n g the card presentations, a rather impure measure o f l a t e n c y f o r each t r i a l , records of "therapy" t r i a l s , a b r i e f d e s c r i p t i o n o f behaviour f o r each t r i a l (organized i n seven d i s c r e t e c a t e g o r i e s ) , and a record o f percentage weight l o s s f o r each animal a t s e l e c t e d periods during the s e r i e s . Not a l l o f these are o f i n t e r e s t .  However, i t i s i n t e r e s t i n g t o attempt  an a n a l y s i s o f the data, i n the absence of conclusive experimental r e s u l t s , bearing i n mind the two t h e o r i e s discussed.  While t h i s cannot be present-  ed as experimental evidence, i t c o n s t i t u t e s , perhaps, a u s e f u l m a t r i x o f observations. F i r s t a b r i e f s t a t i s t i c a l d e s c r i p t i o n o f the course o f the experiment may be o f i n t e r e s t . two days were as follows : animals;  The preference e x h i b i t e d on the f i r s t  r i g h t going, four animals;  dark-preference, nineteen animals;  seven animals;  not i n f e r r e d , two animals.  l e f t going, eight  brightness preference, Thus twelve o f t h e animals  73  had i n i t i a l p o s i t i o n preferences, w h i l e twenty-six animals had preferences.  phototaxic  This t a b u l a t i o n assumes of course that no responses were  due to random f a c t o r s , and i s probably h i g h l y contaminated. The brightness  d i s c r i m i n a t i o n was  37*75 t r i a l s , with a range from 2 t o 114  learned i n an average of  t r i a l s , and S.D.  o f 27«4»  Three of the animals learned t h i s d i s c r i m i n a t i o n i n l e s s than ten t r i a l s . The average number o f t r i a l s required t o master the s even i n c h gap, the t r i a l at which the gap was t o 86, S.D.  of 13*8  (N = 34)*  enlarged, was  from  44-08, w i t h a range from 8  There was more v a r i a t i o n i n the number  of t r i a l s required t o l e a r n the gap a f t e r mastery of the i n i t i a l b r i g h t ness d i s c r i m i n a t i o n , average being 34«73 w i t h range from 34 to 84, of 29*2.  This range includes negative values f o r four animals  S.D.  who  mastered the seven inch gap before the d i s c r i m i n a t i o n had been learned. I f e i t h e r of these functions were dependent upon the other or on a common f a c t o r some p o s i t i v e c o r r e l a t i o n would be expected between the number of t r i a l s t o l e a r n the brightness master the gap.  d i s c r i m i n a t i o n , and the number required to  ,An i n s i g n i f i c a n t product moment c o r r e l a t i o n of .33 i n -  dicates the u n l i k e l i h o o d of a common f a c t o r .  On the other hand, i f  l e a r n i n g of the two tasks i n t e r f e r e d with one another the rate o f mastery of the gap f o r those animals which learned the d i s c r i m i n a t i o n before the i n t r o d u c t i o n of the gap  (N = 13) would d i f f e r from that o f those animals  which learned a f t e r i t s i n t r o d u c t i o n .  While there i s a d i f f e r e n c e  t r i a l s favouring the former group, i t i s not s i g n i f i c a n t (t = .59). i s o f some i n t e r e s t to know i f a r e l a t i o n s h i p i s involved i n these measures since by the r a t i o n a l e of c o n t i n u i t y theory the e f f e c t of  of It  74  i n t r o d u c i n g the gap would be s l i g h t l y to r e t a r d l e a r n i n g of t h e d i s crimination by reducing the e x c i t a t o r y p o t e n t i a l o f the stimulus f o r the new response.  S i m i l a r l y the l e a r n i n g o f the gap would be retarded by  the reduced tendency t o make the response under these conditions.  It  i s o f course p o s s i b l e t h a t a r e l a t i o n s h i p o f t h i s k i n d i s masked by the extreme v a r i a b i l i t y , as suggested by the i n s i g n i f i c a n t d i f f e r e n c e i n this direction. An i n t e r e s t i n g comparison i s that between animals which refused to jump on the f i r s t presentation o f the reduced white area on a black ground and those which responded.  I t w i l l be r e c a l l e d that one of the  suggested causes of the breakdown of the jumping response was the presence of black to which an avoidant response had been learned. the  I f t h i s were  case, then o v e r t r a i n i n g to the brightness d i s c r i m i n a t i o n would presum-  a b l y bear a r e l a t i o n s h i p t o the f a i l u r e t o respond."*"  Since the continu-  ous v a r i a b l e representing the number of t r i a l s of o v e r t r a i n i n g i s haphazardly d i s t r i b u t e d , i n a roughly t r i m o d a l form, i t i s not f e a s i b l e t o attempt a c o r r e l a t i o n .  However, the f a i l u r e s are f a i r l y evenly d i s t r i b u t -  ed along the continuum, suggesting t h a t t h i s i s not a s i g n i f i c a n t f a c t o r . I n t e r e s t i n g l y enough when these groups a r e compared on the number o f t r i a l s o f o v e r t r a i n i n g i n jumping the seven i n c h gap i t i s found that of the 14 animals f a i l i n g , 10 had had 19 or more t r i a l s o v e r t r a i n i n g , w h i l e o n l y 4 had had 14 or l e s s .  The d i s t r i b u t i o n of these t r i a l s i s a l s o f a r  I n t h i s t r i a l a more d r a s t i c reduction of the white area was presented than was used i n subsequent t r i a l s , and i t seems u n l i k e l y t h a t the higher response tendency t o the white would o f f s e t the avoidant tendency to the black, although t h i s remains a p o s s i b i l i t y . x  75  from normal, but an approximate n o t i o n o f the r e l a t i o n s h i p may be o b t a i n ed by a r b i t r a r i l y d i v i d i n g the subjects i n t o two groups representing two populations and determining the s i g n i f i c a n c e o f the proportion o f f a i l u r e s i n each group.  I f the animals are d i v i d e d i n t o those f a l l i n g above, and  those f a l l i n g below, the median f o r o v e r t r a i n i n g t o t h e gap, i t i s found that 59$ o f the former group f a i l e d t o make the c r u c i a l response, w h i l e o n l y 26$ o f the l a t t e r group a l s o f a i l e d .  These proportions a r e s i g n i f -  i c a n t l y d i f f e r e n t a t the 5$ l e v e l o f confidence (two t a i l e d t e s t , corr e c t i n g f o r the c o n t i n u i t y o f the measure).  The mean number o f t r i a l s  o v e r t r a i n i n g f o r the two groups thus a r b i t r a r i l y formed are 26.23 and. 13.53  r e s p e c t i v e l y , t h i s d i f f e r e n c e being s i g n i f i c a n t a t t h e 1$ l e v e l o f  confidence.  A s i g n i f i c a n t d i f f e r e n c e (5% l e v e l o f confidence) a l s o  e x i s t s between the proportion: o f f a i l u r e s i n the group l y i n g above the midpoint o f the range, and i n t h a t l y i n g below the midpoint.  These  two a r b i t r a r y groups r e c e i v e d an average o f 38.40 and 1 6 . 5 0 . t r i a l s overtraining respectively.  While a v e r y crude comparison, these f i g u r e s  suggest that the greater t h e degree o f o v e r t r a i n i n g t o the jump, t h e l e s s t h e l i k e l i h o o d t h a t i t would be performed under a l t e r e d stimulus c o n d i t i o n s , regardless o f the amount o f o v e r t r a i n i n g t o t h e d i s c r i m i n a t ion.  I t i s not without i n t e r e s t t h a t these findings p a r a l l e l the  general Hull-Spence p o s i t i o n o f c o n t i n u i t y theory, and tend t o be i n o p p o s i t i o n t o a theory, such as t h a t o f Krechevsky or Tolman, which emphasizes l a b i l i t y o f the response i n terms o f means-end expectancies. (There i s no question here o f a response t o the i n c o r r e c t card.  The  u s u a l behaviour o f these f a i l u r e s was to run t o the correct prong o f t h e  76  stand where they would scramble and h e s i t a t e but refuse t o jump.)  It  i s stressed o f course t h a t the foregoing observations are i n no way r e garded as experimental evidence, and are made p r i m a r i l y f o r t h e i r i n t e r e s t value.  Analysis o f E r r o r Scores There i s a f u r t h e r area o f the data which seems t o present i n teresting p o s s i b i l i t i e s for analysis.  Before t u r n i n g t o t h i s a n a l y s i s  the r a t i o n a l e on which i t r e s t s w i l l be presented i n some d e t a i l i n order t o f a c i l i t a t e c r i t i c i s m o f i t s p o s t u l a t e s .  I t w i l l be remembered  t h a t Krechevsky's o r i g i n a l formulation o f t h e concept o f "hypotheses" r e s u l t e d from an a n a l y s i s which assumed t h a t no responses were the r e s u l t o f chance f a c t o r s , i n opposition t o t h e notion o f "random" t r i a l and e r r o r .  The r e s u l t o f t h i s a n a l y s i s was t o present an " e r r o r curve"  f o r various systematic p o s i t i o n responses which was compared t o the conv e n t i o n a l e r r o r curve representing s o l u t i o n o f the d i s c r i m i n a t i o n . "chance zone l i m i t " (50$ + ?>/t!Q) -^ N  A  was s e t and i t was shown t h a t f o r the  e a r l i e r t r i a l s t h e curve representing p o s i t i o n " e r r o r s " f e l l outside the chance zone, while t h e error curve f o r brightness hovered w i t h i n the chance zone l i m i t .  I n the l a t e r t r i a l s the p o s i t i o n curve rose t o  chance, while the error curve dropped.  On t h i s evidence i t was con-  cluded t h a t during the systematic p o s i t i o n responses the animals were not responding t o brightness.  There i s an erroneous i m p l i c a t i o n , a t  l e a s t i n a casual i n t e r p r e t a t i o n o f these r e s u l t s , that the curve f o r brightness, l i n g e r i n g a t the chance l e v e l , i s an independent f u n c t i o n  77  f r e e t o v a r y w i t h respect t o t h e p o s i t i o n curve and remaining i n t h e chance zone as a r e s u l t o f t h e chance l e v e l o f response t o brightness which the curve seems t o r e p r e s e n t .  x  I n point o f f a c t the two curves  are o f course r e c i p r o c a l , due t o the s t r u c t u r i n g o f t h e presentation o f the s t i m u l i , which presents an equal number o f randomly a l t e r n a t e d p o s i t i o n s o f the " c o r r e c t " card.  In other words, i n any given sequence  the number o f responses t o a given p o s i t i o n i s n e c e s s a r i l y r e l a t e d t o the number o f " c o r r e c t " responses. ten,  Thus, f o r example, i f i n a s e r i e s o f  there are nine r i g h t going responses (however determined) four o f  them must n e c e s s a r i l y be t o the " i n c o r r e c t " card, and t h e t e n t h or l e f t response may be e i t h e r c o r r e c t o r i n c o r r e c t , so t h a t the e r r o r score must be e i t h e r s i x or f o u r , depending on t h e d i s p o s i t i o n o f the remaini n g response.  I n any systematic s e r i e s o f p o s i t i o n responses then,  there i s a necessary l i m i t t o t h e p o s s i b l e error scores.  For convenience  of reference, these l i m i t s are presented i n Table I , which shows the poss i b l e d i s p o s i t i o n o f scores f o r any given number o f r i g h t going responses between f i v e and ten i n a s e r i e s of t e n responses.  (A r i g h t going  response l e v e l of four i s o f course equivalent t o a l e f t going l e v e l o f six.)  The scores are broken down i n t o r i g h t b r i g h t (RB), r i g h t dark  (RD), l e f t b r i g h t (LB),- and l e f t - d a r k (LD).  Dark going combinations  (RD, LD) represent conventional e r r o r s , and are summated i n column 5> g i v i n g the p o s s i b l e e r r o r scores f o r the s e r i e s ( E ) .  The number of  r i g h t going responses gives the name t o t h e category f o r each t a b l e . That misunderstandings o f t h i s process have occurred i s evidenced i n Haire's treatment o f t h e Spence theory ( 9 ) '  78 TABLE I POSSIBLE DISPOSITIONS OF ERROR SCORES FOR GIVEN CATEGORIES OF POSITION RESPONSES #  CATEGORY 10  CATEGORY 9  RB  RD  LB  LD  E  RB  RD  LB  LD  E  5  5  0  0  5  5  4  1  0  4  4  5  0  1  6  CATEGORY 7  CATEGORY 8 RB  RD  LB  LD  E  RB  RD  LB  LD  E  5  3  2  0  3  5  2  3  0  2  4  4  1  5  4  3  2  1  4  3  5  2  7  3  4  1  2  6  2  5  0  3  8  1 0  CATEGORY 6 RB  RD  5  1  4  2  3  3  2  4  1  5  LB  CATEGORY 5 LD  E  RB  RD  LB  LD  E  0  1  5  0  5  0  0  3  1  3  4  1  4  1  2  2  2  5  3  2  3  2  4  1  3  7  2  3  2  3  6  0  4  9  1  4  1  4  8  0  5  0  5  10  4  # The p o s s i b l e d i s p o s i t i o n o f p o s i t i o n responses f o r given e r r o r scores may a l s o be deduced from the Table by switching column headings.  79  I t w i l l r e a d i l y be seen t h a t the higher the number of responses t o a given p o s i t i o n the fewer the p o s s i b l e e r r o r scores.  This perhaps over  laborious presentation o f the obvious merely serves to i l l u s t r a t e the f a c t that the curve f o r p o s i t i o n responses and the curve f o r brightness responses are r e c i p r o c a l l y r e l a t e d without n e c e s s a r i l y representing a r e c i p r o c a l r e l a t i o n between the two functions measured.  I t w i l l also  be seen that where ten, nine, or eight r i g h t going responses occur, i n any s e r i e s of ten, the e r r o r score cannot f a l l higher than seven or lower than three, that i s , i t must remain w i t h i n the apparent "chance zone limit."  I t i s a l s o evident t h a t f o r these categories the chance zone  l i m i t i s spurious w i t h regard t o the brightness scores, since there i s permitted only a narrow l a t i t u d e of v a r i a t i o n .  The t r u e chance d i s t r i b u t -  ion w i t h i n t h i s l a t i t u d e i s a f u n c t i o n of the number o f p o s s i b l e combinations which w i l l produce the respective e r r o r scores.  For example,  where eight r i g h t going responses occur an error score of three i  can  o n l y be given by the occurrence of two LB responses, and s i m i l a r l y an e r r o r score of seven can only a r i s e out o f the occurrences of two responses. may  LD  Within the s e r i e s of ten, however, an e r r o r score of f i v e  r e f l e c t e i t h e r the s e q u e n t i a l combination LD-LB or LB-LD g i v i n g two  p o s s i b i l i t i e s of occurrence.  Thus the chance d i s t r i b u t i o n of responses  f o r the e r r o r scores 3> 5, and 7, would be 1:2:1.  S i m i l a r l y f o r other  categories, summarised i n Table I I , p. 80. Thus i t f o l l o w s , since the stimulus conditions are pre-arranged t o avoid any systematic r e l a t i o n s h i p between p o s i t i o n and  brightness,  t h a t i f the animals are a c t u a l l y responding a t a chance l e v e l to b r i g h t -  TABLE I I PROBABILITY OF CHANCE OCCURRENCE OF THE ERROR SCORES PRESENTED IN TABLE I  CATEGORY 10  CATEGORY 9  E r r o r Scores Chance D i s t r i b u t i o n  0  E r r o r Scores  4  Chance D i s t r i b u t i o n  1 :1  CATEGORY 8  6  CATEGORY 7  E r r o r Scores  3  Chance D i s t r i b u t i o n  1 : 2 : 1  5  7  E r r o r Scores Chance D i s t r i b u t i o n  2  4  6  8  1 : 3 : 3 : 1  81  ness during those s e r i e s of t r i a l s i n which responses t o a given p o s i t i o n are s i g n i f i c a n t l y high, the d i s t r i b u t i o n of t h e i r e r r o r scores should be i n accord w i t h the p r o b a b i l i t i e s o u t l i n e d . Armed w i t h these deductions i t i s appropriate to t u r n now t o an a n a l y s i s of the data accumulated f o r the i n i t i a l brightness d i s c r i m i n a t i o n . The data are presented i n Table I I I which f i r s t requires a word or two of explanation.  The f i r s t column represents the subjects by rank, the  second by code number, w h i l e the succeeding columns represent blocks of ten t r i a l s corresponding w i t h the "days" of t h i s phase of the experiment. The t o t a l number of responses" t o l e f t or r i g h t on each day, whichever i s higher, i s given on the l e f t of the column, the number of e r r o r s , i . e . , dark going responses i s given on the r i g h t .  The correspondence by days  i s not exact since a f t e r t r i a l 80 those animals which had learned the discrimination"and had mastered the seven i n c h gap were r e s t e d while the slow l e a r n e r s were continued.  Thus t r i a l s 81-100 f o r the former group  represent the f i r s t twenty successive jumps t o the card (Phase 3)« the slow l e a r n e r s t r i a l s 81-130 represent a d d i t i o n a l t r a i n i n g .  For Trials  101-130 include o n l y those animals which had not yet learned the d i s c r i m i n a t ion.  The post s o l u t i o n t r i a l s to a l i m i t of 100 are presented i n order  t o provide a summary of behaviour a f t e r the mastery of the d i s c r i m i n a t i o n . The c r i t e r i o n f o r l e a r n i n g i s ten successive t r i a l s without e r r o r , or two successive days w i t h only one error i n each day, unless i t i s obvious from the succeeding t r i a l s t h a t since (a) the c a l c u l a t i o n o f the S.D.  is  loaded w i t h the scores at the s i g n i f i c a n t extremes, and (b) i t i s customa r y i n non-continuity p r a c t i c e to l a b e l as "hypotheses", any s e r i e s of  &4 R 1 2 3 k 5 6 7 8 10 11 12 13 Hi 15 16 17 18 19 20 21 22 23 2k 25 26 27 28 29 30 31 32 33 3U 35 36 37 38 39  s  1 j  1-10  20M 6R 13 1 6R 13M I 6R 3 7R Hi 5 11 7L 2CP 7R 6L h 9M 10R 12M 6L' 19 5 2M 5 liM 6R 6 7R 10 5 IliM 5 5M 8R 8 6R 19M 7R 3M 7L 15M 5 16 7R 9R 17M 18M 9R 1 6L 5 5 8R 8M 11M 5 8R 7M 8L 15 17 7R 8R 16M 6R 7 8R 9 12 8R 1M 5L 2 6L 10M 7R 18 8R  82  trial*  1 5 1 5 1 •v 5 2 6R 2 5 2 6R 2 6L 1 5 5 f 7R 8L 7 6R U 0 "J 8R l / 5 2 6R 8R 2 2 7R 7 ; 8R 6R 3 2 5 6L li 6L I 6 7R 6R li 10R li 1 6R 2 5 7L 7 0 5 6R 7 10L 5 6 7L 6R 5 8L 7 3 9R 6R 3 2 10R 8R 5 6R li 3 9R  0 0 0  3D  0 1 1 2 2 3 3 5 2 1 3 2 3 3 6 3 1 2 3 5 3 2 U 0 3 5 6 3 3 U 1 5 3 5 li  31-I+0  21-30  li-20  '  5 5L 7R  0 0 2 0 0 0 0 0 1 1 0 li 2 2 5 3 2 3 1 0 2 1 3 1 3 3 3 3 3 2 2 2 5 3 1 5 U  5 5 5 5 6L 6R 5 7R 5 5 6L 8R 7L 6L 6R 7R 7L 6L 6R 6R 6R 6R 6R 8R 6L 5 7R 7R 6L 6L 6R 6L 7L 7R 2 5  5 5 6L 6L 6L  »  !  !  2  l l l l 5 0 5 0 5 0 1 5 0 5 0 6L 1 6L 1 6R 1 7L 2 6L 3 6L 3 5 2 2 5L 5 2 6R 3 7R 2 8L 5 6L 3 6R 3 8R 3 5 2 5 U 1 6R 2 5 3 6L 7 6R 2 5 6 7L li 5 6 9R 3 6R  '6R  ,  o  Ui-50 6R  5  6L  55  6L  _6a.  5 5 5  6L  5  6R  5 5 6R 6L 6L  5 5 5 5 5  6R 7L  5  8R 7R 6R 6R  5  10L  8R 8R 7R  5 5  8R 7R  1 ©J 1 0 0 1 6 0 0 3 0 1 0 0 1 1 1 0 0 0 0 0 1 li 2 3 2 1 3 0 5_ 3 5 2 2 0 5 li  51-60  61-70  71-80  5 5  5  5 5 5 5 5  6L  6R  5  6R  5 5 5  6R 6L '6"L 6R 7L  5 5 5  6L  6R 6R  5  6R  5  6R 6L 6R  6R 7R  7R 7R 8R 6R 7R  0 2 1 5 0 1 0 0 0 1 1_ "i l 2 0 0 0 1 1 1 0 3 2 1 1 1 3 2 2 li 3 1 6  JL  5  2 2  5  10  7R  6R  6L  0 1 1 9R li 5 10 6L 0 5 0 5 0 5 1 6R 1 6L 1 6L 1 6L 2 7L 0 5 1 6L r '6L 1 6R 5 00 5 0 5+ 6L 1 5 o 6L 1 6R 1 6R 1 5 0 7R 2 10L 5 7R 2 6R 3 7L li 6L 3 7R li 5 0 6B 5 5 2 7L li 6R 6L  5  5  Q2  Table I I I : showing the performance o f each subject i n b l o c k o f t e n t r i a l s  V »  \  0 0 0 li  0 6L l 5 0 1 6L 1 6L 2 7R 5 30 8L 1 6L 2 7L 0 5 0 5 0 5 1 6L 0 5 1 6R 1 6L 5 2  5 _o 6L  5 5  6w 5R 6L 6R 5 6R 6R 5 7L 6L 6L 8R  1  o o  1 0 1 1 6 1 1 li 2 5 l 7  81-90  91-100  7L  5  5 5  5 5  +  6L  5  7L  5• 6L  5  7L  5  6L  2 0 0 0 0 1 0 1 0 1 0 1 0 1  . +  6L  1  5 5  o o  5 5 5  o o  2  5^  o  6R  +  I  7L. 2 6R 1 _5 D_ 0 5 6L 3 2 5 7R 2 9R l i 5 2 + 6L. 3  6R  5 5 5 5  6R 6L  5 5 5  o o o  5 5 5 5 5  7L  5 5 5 5 5  0 0 2 0 0  6L  1 2 2. 1 1 0 1 1  7R 6E  5  6R 6R  5  7R  ii  Pi  9/3 0/3 0/3 e/3 o/3 0/2  oA  0/3  oh  1 0 0 0 0 0 2  5 5  121-130  111-120  0 1 0 0 0 0 1 3  6R  101-110  0/2  o/5  2/5 0/3  0/3 1/3  °£ oA °oA £  2/3  oAo oA 2/8 0/3 0/3  5  %  5  0 2 .li  5  6L  n  7R  2  6R  1  7L  • j |  8R  0/3 1/2 2Al  83  responses which are f a i r l y consistent ( i . e . , an "hypothesis" i s of course not thought o f as coming i n t o existence j u s t at t h e point a t which t h e curve crosses the 3 sigma l i n e ) . The o p e r a t i o n a l i s s u e , then, l i e s i n the d i r e c t i o n and degree of departure, i f any, o f the e r r o r scores from the chance d i s t r i b u t i o n which i s t o be expected i f , during the appearance of p o s i t i o n "hypotheses", the animals are a c t u a l l y " i g n o r i n g " brightness cues, as the non-continuity p o s i t i o n a s s e r t s .  The d e s c r i p t i o n given by c o n t i n u i t y  theory leads t o the p r e d i c t i o n t h a t t h e error scores w i l l d i f f e r from chance i n the d i r e c t i o n favouring a response tendency t o brightness, since t h e animal's response tendencies from t r i a l t o t r i a l are regarded as a f u n c t i o n of the combined e x c i t a t o r y p o t e n t i a l of a l l the stimulus elements present.  The technique of the a n a l y s i s i s to s e l e c t a l l the  instances during the p r e - s o l u t i o n period i n which the operation of a p o s i t i o n response during a run of ten t r i a l s may be i n f e r r e d from the l e v e l o f response t o r i g h t or l e f t .  The technique could be extended  to " a l t e r n a t i n g " , "double a l t e r n a t i n g " , "perserverative hypotheses", and so on, but f o r the present purpose of demonstration the choice has been l i m i t e d t o l e f t and r i g h t going "hypotheses".  The t e n - t r i a l  u n i t s have been l i m i t e d t o the s e r i e s representing "days" on the assumpti o n s that t h i s sample represents the data, t h a t i t avoids the i n c l u s i o n of day t o day v a r i a t i o n s i n running conditions, and i n order t o avoid d u p l i c a t i o n s or overlapping.  Results are presented i n Table'IV f o r 9,  8, and 7 p o s i t i o n responses r e s p e c t i v e l y , the l a t t e r category being i n cluded because, w h i l e not s i g n i f i c a n t as a departure from the chance zone  84  TABLE IV FREQUENCY OF OCCURRENCE OF POSSIBLE ERROR SCORES PERMITTED BY THE OCCURRENCE OF 9, 8, OR 7 POSITION RESPONSES IN TEN TRIALS CATEGORY 9 (6 cases) (1)  E r r o r scores  4  (2)  T h e o r e t i c a l frequency  1  1  (3)  Observed frequency  5  1  (4)  ft %  50  50  (5)  fo % (rounded)  83  17  or  6  CATEGORY 8 (24 cases) (1)  E r r o r scores  3  5  7  (2)  ft  1  2  1  (3)  fo  Ik  6  4  (4)  ft %  25  50  25  (5)  fo %  58  25  17  CATEGORY 7 (43 cases) (1)  E r r o r scores  2  4  6  8  (2)  ft  1  3  3  1  (3)  fo  25  12  6  0  (4)  ft %  12.5  37-5  37-5  12.5  (5)  fo %  52  25  13  0  85  l i m i t i t i s consistent with, the  general notion of "hypothese" and contains  e r r o r scores which do remain w i t h i n the chance zone. i s asked of these r e s u l t s i s :  The question which  When there i s a momentary departure from  the "hypothesis", what i s i t s d i r e c t i o n and what i s i t s degree?  The  answer t o t h i s question may throw some l i g h t on the issues which have been discussed. An examination of Table IV reveals consistent departures from chance i n the d i r e c t i o n of the lowest e r r o r score f o r each category. D i s t r i b u t i o n s i n each category y i e l d h i g h l y s i g n i f i c a n t values of c h i squared at the 1% l e v e l of confidence, t h a t f o r Category 9 being of course questionable owing t o the s m a l l number of cases.  While t h i s t e s t of  s i g n i f i c a n c e does not take account o f d i r e c t i o n , i t i s obvious by i n spection Tvhere the major c o n t r i b u t i o n l i e s .  These r e s u l t s would seem,  granting the assumptions of the a n a l y s i s t o o f f e r r a t h e r s t r i k i n g conf i r m a t i o n of the c o n t i n u i t y p r e d i c t i o n i n a simple brightness d i s c r i m i n a t ion.  The p o s s i b i l i t y that the m a j o r i t y of animals were responding  on  the b a s i s of two c o n f l i c t i n g hypotheses w i l l be d e a l t w i t h i n consideri n g i n d i v i d u a l scores.''* A f u r t h e r p r e d i c t i o n of the c o n t i n u i t y p o s i t i o n , i s that t r i a l s during the e a r l i e r phases of l e a r n i n g the d i s c r i m i n a t i o n would produce l e s s tendency t o low e r r o r scores, than those during the l a t t e r I t should be noted t h a t t h i s a n a l y s i s does not represent an "ad hoc" reduction of the data, since the p r e d i c t i o n i s c l e a r before the technique of a n a l y s i s i s a p p l i e d , and the a n a l y s i s i s a p p l i e d t o a l l cases. This i s not hoxvever t r u e of the next s e c t i o n as noted i n the text.  86  phase.  Table 7 presents the data arranged f o r the f i r s t quarter of  the p r e - s o l u t i o n p e r i o d , the second quarter and the l a s t h a l f .  The  t h i r d and f o u r t h quarters are not shown s e p a r a t e l y owing t o the drop i n number of " p o s i t i o n hypotheses" during t h i s l a t t e r phase.  The  first  and second quarters are therefore combined i n Column 3 as a comparison. I t w i l l be seen that the trend i s i n the d i r e c t i o n p r e d i c t e d by c o n t i n u i t y theory.  This i s p a r t i c u l a r l y exemplified i n passing  from the f i r s t quarter t o the second quarter (Columns 1 and 2) and from the f i r s t h a l f to the second h a l f (Columns 3 and k)>  None o f these  d i s t r i b u t i o n s y i e l d s i g n i f i c a n t values of chi-squared when t e s t e d f o r independence, so t h a t t h i s breakdown of the data can only be regarded as being suggestive of conformity to the p r e d i c t i o n .  Nevertheless, i t i s  i n t e r e s t i n g t o speculate on the drop i n proportion o f b r i g h t going responses i n the l a s t h a l f ( c f . Columns 2 and /».)•  I t has so f a r been  assumed t h a t the p o s i t i o n l e v e l was the main determinant of the l i m i t a t i o n i n e r r o r scores f o r each category.  This assumption was merely  f o r convenience i n c l a r i f y i n g the presentation.  More r i g o r o u s l y the  expression of p o s i t i o n tendencies i s regarded i n c o n t i n u i t y theory as a combined f u n c t i o n of the strength of the response t o the given p o s i t i o n stimulus, and the g r a d u a l l y i n c r e a s i n g response tendency to the c o n s i s t e n t l y rewarded brightness stimulus.  Thus the appearance o f a given  l e v e l of p o s i t i o n responses i n any ten t r i a l s e r i e s may e i t h e r be a f u n c t i o n of high e x c i t a t o r y p o t e n t i a l i n the p o s i t i o n stimulus, or r e l a t i v e l y low values i n the brightness stimulus, the a c t u a l responses from t r i a l t o t r i a l being a f u n c t i o n of both these f a c t o r s .  It is  TABLE V THEORETICAL AND OBSERVED DISTRIBUTION OF ERROR SCORES DURING THREE PHASES OF THE PRE-SOLUTION PERIOD  CATEGORY 9 ( l ) E r r o r Scores (2) f t (3) f o (4) f t % (5) f o % (rounded)  6  4 1 4 50 100  CATEGORY 8 ( l ) E r r o r Scores (2) f t (3) f o (4) f t % (5) f o %  3 1 5 25 50  CATEGORY 7 ( l ) E r r o r Scores (2) f t (3) f o (4) f t % (5) f o %  2 4 1 3 3 5 12.5 i 37-5 27 45  01 & 02  02  01 4 1 0 50 0  1 0 50 0  5 2 2 50 20  6 3 3 37-5  27  7 1 3 25 30  3  5 2 3 50 33  1 6  25 66 8 1 0 12.5 0  6 1 1 50 100  2  4  6 1 3 3 9 1 1 12.5 37-5 37-5  82  9  9  6 1 1 50 20  4 1 4 50  80 7 1 0 25 0  8 1 0 12.5 0  3 1 11 25 55  2 1 25 12.5 58  4 3 12 37-5  28  03 & Q4  5 2 5 50 25 6 3 6 37-5 14  6 1 0 50 0  4 1 1 50 100  7 1 3 25 15  3 1 3 25 60 8 1 0 12.5 0  2 1 13 12.5 ; 62  5 2 1 50 20  4 3 6 37.5;  28  6 3 2 37.5 10  7 1 1 25 20  8 1 0 12, 0  0> —•3  88  therefore p o s s i b l e t h a t animals which develop high p o s i t i o n values during the second h a l f o f t h e p r e - s o l u t i o n period are those whose rate o f a c q u i s i t i o n o f the brightness response has been slow, w i t h consequent p i l i n g up o f p o s i t i o n tendencies, as opposed t o animals whose p o s i t i o n tendencies i n the f i r s t h a l f are the main determinant o f the l e v e l o f p o s i t i o n response w i t h consequent masking of the brightness response. Note that t h i s i s not a d i s t i n c t i o n between f a s t and slow learners per se,  but between two populations o f l e a r n e r s , those whose p o s i t i o n respons-  es are c h i e f l y a r e f l e c t i o n o f high p o s i t i o n tendency, and those whose p o s i t i o n responses are expressed p r i m a r i l y as a r e s u l t o f the r e l a t i v e l y slow r a t e o f a c q u i s i t i o n o f the brightness response consistent w i t h v a r y i n g slopes f o r the o g i v a l curve r e p r e s e n t i n g t h i s f u n c t i o n i n cont i n u i t y theory.  Two trends i n the data would bear t h i s out.  (l) I f  the animals c o n t r i b u t i n g high p o s i t i o n l e v e l s i n the s econd h a l f were a d i f f e r e n t population from those c o n t r i b u t i n g high p o s i t i o n l e v e l s i n the f i r s t half.  Table I I I i n d i c a t e s t h a t t h i s i s a c t u a l l y the case, w i t h  the exception o f t h r e e animals out o f the four slowest l e a r n e r s .  (2)  I f the c o n t r i b u t i o n o f error scores f o r the t h i r d quarter were higher than those f o r the f o u r t h quarter.  This breakdown i s shown i n Table VI  f o r category 7, the o n l y one having a s u f f i c i e n t number o f cases t o j u s t i f y the demonstration. The d i r e c t i o n o f the trend i s appropriate i n each column, and bears out the t e n t a t i v e hypothesis that these scores may represent animals whose p o s i t i o n responses are the r e s u l t o f a depressed gradient i n the curve f o r the a c q u i s i t i o n of brightness tendencies, w i t h consequent  89  TABLE V I DISTRIBUTION OF ERROR SCORES IN THE THIRD AND FOURTH QUARTERS OF THE PRE-SOLUTION PERIOD FOR CATEGORY 7  03 (1) E r r o r Scores  2  (2) f t  1  (3) f o  7  4 3 5  04 6  8  2  3  1  1  2  0  6  (4) f t %  12.5 37-5 37-5  (5) f o %  51  36  14  12.5 0  4 3 1  6  8  3  1  0  0  12.5 37-5 37.5 12.5 85  15  0  0  90  f o r t u i t o u s p i l i n g up of p o s i t i o n tendencies.  I t i s again emphasized  that none o f the r e s u l t s presented i n Tables V and VI represent a l l y significant differences.  statistic-  The d i s c u s s i o n has been presented merely  to show that the d i s t o r t i o n of the trend toward lowering of the e r r o r scores during l e a r n i n g i s not n e c e s s a r i l y i n c o n s i s t e n t with c o n t i n u i t y theory.  These r e s u l t s a l s o gain i n t e r e s t through the rather high  degree of consistency i n the temporal trend toward the p i l i n g up of e r r o r scores i n a rank order of frequency under each column.  Obviously,  i n view of the r e l a t i v e infrequency of cases i n the s i g n i f i c a n t categories, t h i s type of a n a l y s i s demands a very l a r g e number of subjects. While i t i s u n l i k e l y t h a t the a n a l y s i s stands or f a l l s by the comparison of i n d i v i d u a l scores, since the assumptions on which i t r e s t s are commonplace enough, i t i s r e l e v a n t t o examine the i n d i v i d u a l performance i n Table I I I .  I t must be remembered that r e s u l t s f o r i n d i v i d u a l  animals cannot p o s s i b l y be s i g n i f i c a n t owing t o the small number of u n i t s involved;  indeed, t h i s i s one o r i g i n of the controversy.  c e r t a i n i n d i c a t o r s may be sought.  However,  For example, i f the ten t r i a l s  fol-  lowing the expression of a p o s i t i o n "hypothesis" u s u a l l y contain an error score below f i v e , i t w i l l be an i n d i c a t i o n of the trend expressed i n the a n a l y s i s .  Inspection of Table I I I shows t h a t t h i s i s almost i n -  v a r i a b l y the case, p a r t i c u l a r l y beyond the f i r s t ten t r i a l s .  Subjects  ranked 9 (9M) 15 (10) and 24 (IBM.) are e s p e c i a l l y i n t e r e s t i n g i n t h i s connection since they present p o s i t i o n responses l e v e l s of ten trials.  successive  I t w i l l be seen that number 36 (1M) contradicts the expected  trend and presents a p e c u l i a r p i c t u r e generally.  Another i n d i c a t i o n i s  91  found i n the p o s i t i o n responses which occur a f t e r s o l u t i o n of the d i s crimination.  The general p a t t e r n of the a n a l y s i s i s upheld i f e r r o r  scores here f a l l i n the lowest category permitted by the p o s i t i o n l e v e l . Inspection of the t a b l e w i l l show t h a t t h i s i s the case, w i t h the notable exception of-the animal ranked 4 (3)' interest.  One further comparison i s of  From Table I I I the scores o f i n d i v i d u a l animals can be read  to determine the number of errors o c c u r r i n g at various l e v e l s of p o s i t i o n response f o r each animal.  I t would be p o s s i b l e but extremely laborious  to c a l c u l a t e the combined p r o b a b i l i t i e s f o r each animal.  On the other  hand a summation of b r i g h t and dark favouring responses would ignore the p r o b a b i l i t y weighting of s p e c i f i c values.  An approximation may be achiev-  ed by simply adding the amounts by which the e r r o r scores exceed 5 and the amounts by which the e r r o r scores are l e s s than f i v e separately f o r each animal.  This information i s contained i n the l a s t column of Table I I I  f o r p o s i t i o n l e v e l s of 9, 8 and 7'  The numerator represents amounts  above f i v e , the denominator amounts below f i v e , the c o n t i n u i t y p r e d i c t i o n being t h a t the numerator w i l l u s u a l l y be the smaller value.  The  d i s t r i b u t i o n of the scores during the successive t r i a l s can be read f o r each animal.  These r a t i o s again support the c o n t i n u i t y p o s i t i o n .  It  i s a l s o of i n t e r e s t i n i n s p e c t i n g the t a b l e to n o t i c e that the f i r s t t e n t r i a l s of Day 1 i n d i c a t e a preponderance of e i t h e r b r i g h t or dark going responses, w i t h few at the 50$ l e v e l , ^ probably i n d i c a t i n g t h a t even i n  ^ The data have not been presented by days because t h i s d i v i s i o n , beyond the p o i n t noted, o f f e r s no new f i n d i n g s , and i s more a r t i f i c i a l than t h a t adopted i n Table IV. The trend i s consistent however when the a n a l y s i s i s made.  92  these very e a r l y t r i a l s the animals were responding t o t h i s element of the stimulus complex. Summarising t h i s s e c t i o n i t i s suggested that the proper evalua t i o n of e r r o r scores accompanying high l e v e l s o f p o s i t i o n response r e s t s not w i t h the s i g n i f i c a n c e range of t e n responses but w i t h the l i m i t e d range permitted by the l e v e l o f p o s i t i o n responses. scores asks the question :  A n a l y s i s of these  When an animal departs from a h i g h l e v e l  of p o s i t i o n responses, i s t h e departure most f r e q u e n t l y t o the p o s i t i v e or to the negative stimulus of the d i s c r i m i n a t i o n problem?  Since  stimulus conditions are arranged t o provide random v a r i a t i o n between p o s i t i o n and brightness, i t f o l l o w s t h a t i f the error scores are a c t u a l l y the product of chance these departures w i l l be approximately equal toward the p o s i t i v e and negative s t i m u l i .  Highly s i g n i f i c a n t v a r i a t i o n s  from chance are found f o r p o s i t i o n l e v e l s of 7, # and 9 responses out of ten i n the d i r e c t i o n f a v o u r i n g the c o n t i n u i t y prediction.^  -  I t must be  r e a l i z e d of course t h a t t h i s a n a l y s i s i s h i g h l y a r t i f i c i a l i n t h a t i t ignores the f a c t o r of response sequence, and assumes that summated scores represent the tendency of a l l animals, a usage which i s nevertheless general i n animal l e a r n i n g experiments. I t would seem then t h a t the view which regards the l e a r n i n g of a simple d i s c r i m i n a t i o n as a process i n which the animals, when respondi n g t o p o s i t i o n aspects of the stimulus complex, are i g n o r i n g or not responding t o brightness aspects as w e l l , represents an inadequate view  x  6 and 5«  I t need h a r d l y be s a i d that t h i s i s also t r u e f o r categories  93  of such l e a r n i n g ;  and that the apparent chance l e v e l of the " c o r r e c t "  response during p o s i t i o n dominated s e r i e s of t r i a l s i s a spurious e f f e c t of the s t r u c t u r i n g of the stimulus sequences, and does not represent chance l e v e l of f u n c t i o n i n g .  The p o s s i b i l i t y remains t h a t the  a  scores  r e f l e c t the performance of those animals which were responding on the basis of two c o n f l i c t i n g hypotheses." " 1  I f t h i s i s the case, an i n s p e c t -  i o n of Table I I I would seem to i n d i c a t e t h a t very n e a r l y a l l of the animals are included i n t h i s category, and none may d e f i n i t e l y be cluded.  ex-  Further, the conditions o f the experiment were not those  which would force the animals to attend to the relevant discrirainanda from the beginning.  The question a r i s e s then, which theory  provides  the more p r e c i s e d e s c r i p t i o n of the d i s c r i m i n a t i o n l e a r n i n g process i n the s i t u a t i o n of the present experiment.  I t would seem that the theory  which p r e d i c t s the r e s u l t s obtained i s p r e f e r a b l e to t h a t which can merely be a p p l i e d a f t e r the f a c t and i n a modified form.  The  continu-  i t y theory p r e d i c t s these r e s u l t s , f o r a simple d i s c r i m i n a t i o n , without equivocation.  The foregoing a n a l y s i s , together w i t h the r a t i o n a l e on  which i t i s based, are presented therefore as demonstrating the adequacy o f the c e n t r a l p r o p o s i t i o n of c o n t i n u i t y theory f o r a simple discrimination.  brightness  I t i s suggested t h a t t h i s method of a n a l y s i s might  p r o f i t a b l y be a p p l i e d t o more complex d i s c r i m i n a t i o n s , using large groups o f subjects and meeting the requirements o u t l i n e d e a r l i e r .  I t i s the  """ I t might be noted that t h i s problem does not a r i s e i n connection with p o s i t i o n l e v e l s 8, 9 or 10, since the error scores are w i t h i n the "chance zone l i m i t " . The concern i s with the remaining trials.  94  w r i t e r ' s opinion that t h i s experiment would be p r e f e r a b l e t o the reversed p r e - t r a i n i n g experiment as a c r u c i a l t e s t o f t h e opposed theories since the problem o f d e f i n i n g an acceptable point of r e v e r s a l does not a r i s e . Before l e a v i n g these data one other p o i n t w i l l b r i e f l y be mentioned.  The c o n t i n u i t y theory describes t h e appearance o f system-  a t i c and c o n s i s t e n t responses t o the appropriate s t i m u l i as being a f u n c t i o n not only o f the gradual accumulation o f e x c i t a t o r y p o t e n t i a l t o the appropriate s t i m u l i , but a l s o as a f u n c t i o n o f the e q u a l i z a t i o n o f p o s i t i o n tendencies.  I t f o l l o w s t h a t f o r the a r b i t r a r y c r i t e r i o n chosen  here, which does not demand 100$ l e v e l o f responses, the t r i a l s o f t h e two days following, mastery of t h e c r i t e r i o n w i l l be approximately normal i n d i s t r i b u t i o n o f t h e number o f p o s i t i o n responses, w i t h t h e mean a t 5 responses t o each p o s i t i o n .  I f such a t e s t y i e l d s a d i s t r i b u t i o n pre-  ponderantly f a v o u r i n g e i t h e r r i g h t or l e f t responses the operation of a systematic f a c t o r can be assumed.  I f however t h e d i s t r i b u t i o n i s  symmetrical i t s t r o n g l y suggests t h a t p o s i t i o n responses are randomly a l l o c a t e d , s i n c e the l i k e l i h o o d o f a p r e c i s e balance between subjects r e t a i n i n g r i g h t going and l e f t going tendencies i s v e r y s l i g h t under the conditions of the experiment.  The i n t e r e s t o f the f o l l o w i n g data  derives c h i e f l y from t h e i r s t r i k i n g conformity t o the p r e d i c t e d d i s tribution.  The frequency o f 8, 7, 6, 5, 4, 3 and 2 r i g h t going  responses during the twenty t r i a l s f o l l o w i n g attainment o f the c r i t e r i o n was 0, 2, 12, 32, 12, 2, and 0, r e s p e c t i v e l y . The Spence Assumptions . One f u r t h e r area o f p o t e n t i a l i n t e r e s t i n the data concerns  95  the measure of l a t e n c y .  There i s an i m p l i c a t i o n i n Spence's t a b l e f o r  a h y p o t h e t i c a l d i s c r i m i n a t i o n l e a r n i n g s e r i e s , t h a t i f l a t e n c y be accepted as a measure of the strength o f the momentary response tendency, then the l a t e n c i e s f o r the r e s p e c t i v e stimulus element combinations w i l l be arranged i n rank order determined by the r e l a t i v e strength of each component.  For example, an animal i n a given t r i a l whose strongest  p o s i t i o n tendency was r i g h t and whose strongest tendency was t o b r i g h t ness, would, before these tendencies became evident i n systematic responses to brightness.,, present the f o l l o w i n g r e l a t i o n s h i p among latencies :  RB<cLB«c:RD«=:LD.  Thus, i f the r i g h t going tendency were  s u f f i c i e n t l y high to mask the b r i g h t going tendency the RD l a t e n c i e s when a negative card coincided with the r i g h t p o s i t i o n would be longer than the RB l a t e n c i e s i n which the p o s i t i v e card was presented on the right.  And since these tendencies are assumed t o be f a i r l y s t a b l e f o r  s e r i e s o f t r i a l s , the l a t e n c y curve f o r each animal f o r each t r i a l would contain markedly serrated portions.  The appearance of t h i s feature i n  the data c o l l e c t e d i n the present experiment i s rather frequent  and  s t r i k i n g , p a r t i c u l a r l y when combined w i t h behavioural observations i n d i c a t i n g that during the prolonged l a t e n c i e s the animals appeared t o be "exploring" "washing" e t c . , but only on those t r i a l s i n which the i n appropriate s t i m u l i were combined, the.other t r i a l s being d i r e c t .  It  would of course be h i g h l y inappropriate merely t o s e l e c t these instances as evidence, and suggest that the design was obscured f o r other subjects and t r i a l s .  The data were rather exhaustively analysed but f a i l e d t o  show s i g n i f i c a n t d i f f e r e n c e s (e.g., the p r e d i c t i o n that l a t e n c i e s f o r LB  96  and LD responses would be c o r r e l a t e d , that there would be a c o r r e l a t i o n between RB and LB responses, that the variance of the l a t e n c y measure would be greater i n the t r i a l s immediately preceding mastery than i n those on equal preceding periods, e t c . ) *  The p o s s i b i l i t y o f t e s t i n g  these and s i m i l a r p r e d i c t i o n s remains open, however, since the l a t e n c y measure here i s very crude and contains, f o r error t r i a l s , the time spent r e t u r n i n g from the i n c o r r e c t t o the correct window on the double stand.  I t i s suggested t h a t a c o n t r o l l e d study i n t h i s d i r e c t i o n might  prove i n t e r e s t i n g and that the d i f f e r e n c e s might be increased by p l a c i n g a m i l d l y charged g r i d before each window. A d i r e c t approach t o the c o n t i n u i t y assumptions concerning combination of stimulus elements was made a f t e r the conclusion of the experiment, t h e design of which w i l l be b r i e f l y described.  Fourteen  animals whose jumps t o t h e s m a l l white square were s a t i s f a c t o r y and who had had considerable o v e r t r a i n i n g t o brightness were placed i n the stand and presented w i t h two equal white squares (one and three-quarter by two and a quarter inches) on a black ground. whichever s i d e they jumped.  They were rewarded  They were then given f i v e rewarded  on trials  on t h i s s i d e a f t e r which they were t e s t e d f o r strength of the p o s i t i o n response by determining the amount o f increase i n area of white on the non p r e f e r r e d side that was necessary to induce a jump t o t h i s s i d e . T r a i n i n g was given f o r t e n t r i a l s t o an u p r i g h t as opposed to an i n v e r t e d e q u i l a t e r a l t r i a n g l e (two inches base) randomly a l t e r n a t e d to r i g h t and l e f t , the u p r i g h t t r i a n g l e being c o n s i s t e n t l y rewarded. t r i a l s responses were c o n s i s t e n t l y to the p r e f e r r e d s i d e .  During these They were  97  then t e s t e d again, h a l f the animals w i t h the upright t r i a n g l e f i r s t and i n v e r t e d t r i a n g l e second f o r any change i n area of white necessary t o induce a response t o the non p r e f e r r e d s i d e .  These s e r i e s of ten t r i a l s ,  followed by t e s t were continued. The p r e d i c t i o n of c o n t i n u i t y theory i n t h i s s i t u a t i o n i s c l e a r l y that as the number o f rewarded t r i a l s t o the upright t r i a n g l e i n creases, and before systematic responses t o brightness are evidenced, the area of white necessary t o induce the non preferred p o s i t i o n response w i t h the p o s i t i v e f i g u r e on the p r e f e r r e d side w i l l increase, while there w i l l be a decrease i n the area of white required to induce the departure i n the presence of the negative f i g u r e on the preferred s i d e .  It will  be seen t h a t the design i t s e l f i s based on c o n t i n u i t y theory.  The t e s t  f o r strength of t h e p o s i t i o n habit had p r e v i o u s l y proven efficaceous, f i v e animals r e q u i r i n g an i n c r e a s i n g amount of white on the non preferred s i d e as t r a i n i n g t o that side continued, and a decreasing amount as non reward of the preferred p o s i t i o n accumulated.  In t h i s connection i t  was observed that fewer t r i a l s were required t o produce a s t a b l e p o s i t i o n response than to t r a i n i t out. Results of t h i s procedure tended i n the d i r e c t i o n predicted. However i n view of the f a i r l y l a r g e number o f t e s t i n g t r i a l s  required  between t r a i n i n g t r i a l s t o e s t a b l i s h the r e l a t i o n s h i p s , the s i t u a t i o n was not w e l l c o n t r o l l e d .  In a d d i t i o n t o t h i s the animals again develop-  ed s p o i l e d jumps, and as the t r a i n i n g proceeded the number of animals dwindled.  For t h i s reason the a c t u a l data are not presented here.  The p r i n c i p a l i n t e r e s t of t h i s experiment was i n demonstrating the  98  r e l a t i o n s h i p between p r e v i o u s l y acquired p o s i t i o n and brightness cues as being roughly equivalent to the c o n t i n u i t y d e s c r i p t i o n .  It i s felt  that t h i s type of design,.which i s too crude here even t o j u s t i f y d i s cussion of r e s u l t s , might very e a s i l y be r e f i n e d by the use of e l e c t r i c a l l y c o n t r o l l e d continuous gradations of brightness, p o s s i b l y i n a hurdle d i s c r i m i n a t i o n , and naive subjects.  The technique would a f f o r d d i r e c t  comparisons of the r e l a t i v e strength of each stimulus component at selected points throughout the l e a r n i n g , and would not have t o be l i m i t ed t o p o s i t i o n t r a i n e d animals.  The w r i t e r believes that i f more  experiments of t h i s type were run, i n which a d e s c r i p t i v e p r e d i c t i o n i s made from theory, and the d e s c r i p t i o n e m p i r i c a l l y q u a n t i f i e d , at varyi n g l e v e l s of complexity, there would be l e s s l i k e l i h o o d of controversi a l pseudo-issues appearing i n the l i t e r a t u r e .  I t i s suggested that  non-continuity theory would b e n e f i t by t h i s type of experimentation, before f u r t h e r d i r e c t t e s t s i n v o l v i n g a c o n f l i c t o f r e s u l t s between the two t h e o r i e s are attempted.  CHAPTER VI SUMMARY AND  CONCLUSIONS  Summarising r a t h e r . b r i e f l y the foregoing m a t e r i a l the f o l l o w i n g points appear r e l e v a n t .  The c o n t i n u i t y controversy o r i g i n a l l y concerned  the i s s u e of continuous versus discontinuous l e a r n i n g of the f i n a l stimuli i n discrimination situations.  Subsequent refinements were i n -  troduced, among others the issues of awareness or a t t e n t i o n , the r o l e s of i n h i b i t i o n and g e n e r a l i z a t i o n , and the issue of successive as opposed to simultaneous hypothesis formation, p a r t i c u l a r l y as r e l a t e d t o the comp l e x i t y of the s i t u a t i o n .  Experimentally  the t e s t which was  found most  acceptable was the reversed p r e - t r a i n i n g d i s c r i m i n a t i o n which appeared to y i e l d c l e a r cut p r e d i c t i o n s but which was results.  found t o y i e l d  contradictory  P a r a l l e l i n g the refinement of theory was the i n t r o d u c t i o n of  a number of experimental issues the most important of these concerning the receptor o r i e n t a t i o n of the animals i n the e a r l y phases of l e a r n i n g , the n e c e s s i t y of p r o v i d i n g a d i s c r i m i n a t i o n s u f f i c i e n t l y d i f f i c u l t that two or more hypotheses must be t e s t e d , the avoidance of any technique which forces a t t e n t i o n t o the relevant discriminanda from the beginning of l e a r n i n g , and the n e c e s s i t y of avoiding punishment f a c t o r s i n the t r a i n i n g of the animals.  Various w r i t e r s reviewing the experimental  l i t e r a t u r e have put forward suggestions as t o i t s s i g n i f i c a n c e .  Among  the more cogent of these are the suggestions t h a t experiments using a  100  simple d i s c r i m i n a t i o n , or those using a minimum o f punishment techniques, or those i n v o l v i n g a low l e v e l o f sensory dominance and perceptual organi z a t i o n have tended r e s p e c t i v e l y t o favour the c o n t i n u i t y p r e d i c t i o n while those i n v o l v i n g the opposites of these conditions have tended t o favour the opposing view.  Among suggestions o f f e r e d as t o t h e nature  o f the controversy there has been some s t r e s s r e c e n t l y on the view that the i s s u e s have been o v e r s i m p l i f i e d , on the view that each o f the t h e o r i e s are i n r e a l i t y presenting d e s c r i p t i o n s o f i d e n t i c a l processes at d i f f e r i n g l e v e l s , and t h e view that each theory may be appropriate t o a d i s c r e t e range o f events. Consideration might a l s o be given by way of summary t o the view t h a t , as Underwood (46) suggests, t h e r o l e o f the yes-no controvers y i n psychology may represent an immature stage o f theory development. From the standpoint of Learning Theory i t would seem t h a t an answer, t o the controversy i t s e l f i s , i n a f i n a l a n a l y s i s , rather l e s s important than t h e e l a b o r a t i o n o f each theory, and the r e f e r r a l o f each theory s e p a r a t e l y t o e m p i r i c a l t e s t s appropriate t o i t s c o n s t r u c t s . t h i s process, the non-continuity theory has lagged.  In  This i s not,  however, s u f f i c i e n t ground on which t o r e j e c t i t , e s p e c i a l l y s i n c e i t contains germinal hypotheses whose f i n a l adequate acceptance or r e j e c t i o n i s extremely important f o r psychology.  That such a l a g need not  0  be t h e case i s perhaps suggested by Brunswick's treatment o f theory construction (3) i n which bases f o r extending the systematic development o f t h i s type o f theory are suggested. An experiment i s described i n which an attempt was made t o  101  t e s t the p o s s i b i l i t y that Krechevsky "s r e u l t s i n h i s o r i g i n a l reversed p r e - t r a i n i n g experiment  (24) were due t o the s p e c i f i c nature of the  f i n a l stimulus cards.  This was t o have been e f f e c t e d by c a r e f u l l y  e l i m i n a t i n g those aspects of Krechevsky's technique which were objectionable i n terms of recent statements o f c o n t i n u i t y theory.  I t was  not p o s s i b l e t o complete t h i s experiment and the suggestion i s made that i f experiments of t h i s design prove t o be inoperable, as d i d the present one, then the o p e r a t i o n a l v a l i d i t y o f the controversy must be h e l d i n question.  F a i l i n g r e s u l t s from the scheduled experiment the data of  the i n i t i a l brightness d i s c r i m i n a t i o n are analysed and are found to favour w i t h s i g n i f i c a n t d i f f e r e n c e s the p r e d i c t i o n of c o n t i n u i t y theory, f o r a simple brightness d i s c r i m i n a t i o n . A l i m i t e d number of conclusions consistent w i t h the m a t e r i a l presented may be drawn. ( l ) I t would seem t o be f a i r l y evident t h a t the o r i g i n a l statement of non-continuity theory must be modified i f i t i s t o be accepted as an adequate d e s c r i p t i o n of l e a r n i n g .  The weight of experiment-  a l evidence, i n c l u d i n g t h a t presented here, does not seem t o j u s t i f y the notion that those responses to a s i n g l e stimulus component i n a simple q u a n t i t a t i v e d i s c r i m i n a t i o n which precede systematic responses t o the r e l e v a n t stimulus components represent a p e r i o d of l e a r n i n g during which reward of the f i n a l cues i s i n e f f e c t i v e .  I t should be noted t h a t  non-continuity theory does not p r e d i c t but merely admits the p o s s i b i l i t y of, simultaneous hypotheses being formed i n l e a r n i n g such a d i s c r i m i n a t i o n , and t h a t the o b j e c t i o n t o the reversed p r e - t r a i n i n g design i n  102  simple d i s c r i m i n a t i o n s i s merely t h a t t h i s process may occur w i t h consequent r e t a r d a t i o n o f l e a r n i n g i n the reversed group. (2) -From an o p e r a t i o n a l standpoint i t must be conceded that the adequacy of a modified non-continuity theory f o r d i s c r i m i n a t i o n s i n v o l v i n g complex perceptual organizations of s t i m u l i has not been adequately t e s t e d .  I t i s suggested that the most p r o f i t a b l e re-evalu-  a t i o n of the non-continuity theory might be d i r e c t e d at t h i s range of events. (3) I t must be concluded on the basis of the present survey that an experimental t e s t which i s designed t o provide c l e a r cut and c o n f l i c t i n g r e s u l t s f o r each theory cannot be s a i d to have been performed unless i t meets the c r i t e r i a presented i n Section IV ( l ) o f t h i s study.  I f experiments which do f u l f i l these c r i t e r i a should prove, as  d i d the present one, t o be inoperable or t o give i n c o n c l u s i v e r e s u l t s i t must be concluded that the controversy as i t i s p r e s e n t l y formulated does not provide an o p e r a t i o n a l i s s u e .  REFERENCES  Blum, R.A., and Blum, J.S. Factual issues i n the " c o n t i n u i t y controversy". Psychol. Rev.. 1949, 56, 33-50. Brogden, W.J. Animal studies o f l e a r n i n g . I n Handbook o f experimental psychology (Ed., Stevens, S.S.). New York: John Wiley and Sons, Inc., 1951, 568-612. Brunswick, E. The conceptual framework o f psychology. Intern a t i o n a l Encyclopedia of U n i f i e d Science. Chicago: Universi t y o f Chicago Press, 1952. Edwards, A.L. New York:  Experimental design i n psychological Rinehart and Co. Ltd., 1950.  research.  Ehrenfreund, D.J. An experimental t e s t of the c o n t i n u i t y theory of d i s c r i m i n a t i o n l e a r n i n g w i t h pattern v i s i o n . J . comp. Psychol., 1948, 41, 408-432. Gellerman, L.W. Chance orders o f a l t e r n a t i n g s t i m u l i i n v i s u a l d i s c r i m i n a t i o n experiments. J . genet. Psychol., 1933, 42, 206-208. Grice, G.R. The a c q u i s i t i o n o f a v i s u a l d i s c r i m i n a t i o n habit f o l lowing responses t o a s i n g l e dimension. J . exp. Psychol., 1948, 38, 633-642. Haire, M. A note concerning McCulloch's discussion o f d i s c r i m i n a t ion habits. Psychol. Rev., 1939, 46, 298-303Haire, M. Some experimental data r e l a t i v e t o f i e l d and a s s o c i a t i v e theories o f d i s c r i m i n a t i o n l e a r n i n g . J . genet. Psychol., 1942, 26, 267-288. Harlow, H.F. 1949,  The formation o f l e a r n i n g s e t s .  56, 51-65-  Psychol. Rev.,  104  Harlow, H.F. Analysis o f d i s c r i m i n a t i o n l e a r n i n g by monkeys. J . exp. Psychol., 1950, 40, 26-39. H u l l , C.L., and Spence, K.W. Correction versus non-correction method of t r i a l and e r r o r l e a r n i n g i n r a t s . J . comp. Psychol., 1938, 25, 127-145-  Hull, C L . The d i s c r i m i n a t i o n o f stimulus configurations and the hypothesis o f a f f e r e n t n e u r a l i n t e r a c t i o n s . Psychol. Rev., 1945, 52, 133-142.  Hull, C L .  Simple q u a l i t a t i v e d i s c r i m i n a t i o n l e a r n i n g .  Psychol.  Rev., 1950, 57, 303-313.  Krechevsky, I .  Hypothesis i n r a t s .  Psychol. Rev., 1932, 39,  516-532.  Krechevsky, I . "Hypothesis" versus "chance" i n t h e p r e - s o l u t i o n period i n sensory d i s c r i m i n a t i o n l e a r n i n g . Univ. C a l i f . Publ. Psychol., 1932, 6, 27-44Krechevsky, I . The genesis o f hypotheses i n r a t s . Publ. Psychol., 1932, 6, 45-64-  Univ. C a l i f .  Krechevsky, I . , and Tolman, E.C Means-end readiness and hypot h e s i s - a c o n t r i b u t i o n t o comparative psychology. Psychol. Rev., 1933, 40, 60-70.  Krechevsky, I . The d o c i l e nature o f "hypothesis". Psychol., 1933, 15, 429-441-  J . comp.  Krechevsky, I . The h e r e d i t a r y nature of "hypotheses". Psychol., 1933, 16, 99-116. Krechevsky, I . Brain mechanisms and "hypotheses". Psychol., 1935, 19, 427-462. Krechevsky, I .  J . comp.  J . comp.  A note concerning "the nature o f d i s c r i m i n a t i o n  105  33*  McCulloch, T.L., and P r a t t , J.G. A study of the p r e - s o l u t i o n period i n weight d i s c r i m i n a t i o n by white r a t s . J . comp.  106  Psychol., 1934, 18, 271-290. McCulloch, T.L. Comment on the formation o f d i s c r i m i n a t i o n habits. Psychol. Rev.. 1939, 46, 75-85McCulloch, T.L. Reply t o a note on d i s c r i m i n a t i o n habits. Psychol. Rev., 1939, 46, 304-307Munn, N.L. Handbook of psychological research on the r a t . Boston: Houghton M i f f l i n Co., 1950. Prentice, W.CH.  Continuity i n human l e a r n i n g .  J . exp. Psychol.,  1949, 39, 187-194-  Rethlingschafer, A. The l e a r n i n g o f a v i s u a l d i s c r i m i n a t i o n problem under varying motivating conditions. J . comp. Psychol., 1941, 32, 583-591-  R i t c h i e , J . An experimental attack on t h e c o n t i n u i t y controversy. J . comp. Psychol., 1950, 43, 170-180. Spence, K.W. The nature o f d i s c r i m i n a t i o n l e a r n i n g i n animals. Psychol. Rev., 1936, 43, 427-449Spence, K.W. The d i f f e r e n t i a l response i n animals t o s t i m u l i varying w i t h i n a s i n g l e dimension. Psychol. Rev., 1937, 23, 77-100.  Spence, K.W. Gradual versus sudden s o l u t i o n of d i s c r i m i n a t i o n problems by chimpanzees. J . comp. Psychol., 1938, 25, 213224.  Spence, K.W. Continuity versus non-continuity i n t e r p r e t a t i o n s of discrimination learning. Psychol. Rev., 1940, 47, 271-288. Spence, K.W. An experimental t e s t o f the c o n t i n u i t y and non-cont i n u i t y interpretations of learning. J . exp. Psychol., 1945, 35, 253-266.  107  45-  Spence, K.W. Cognitive versus S-R t h e o r i e s of l e a r n i n g . Rev., 1950, 57, 159- .  Psychol.  46.  Underwood. Learning. In Annual review of psychology. Annual Reviews, Inc., 1953-  Stanford:  47'  Wherry, R.J. F a c t o r i a l a n a l y s i s of l e a r n i n g dynamics i n animals. J . comp. Psychol.. 1939, 28, 263-272.  

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