The effect of extended discrimination trainingon behavioral contrast and the peak-shift

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Authors al-Dukhayyil, Abdul-Aziz Al-Abdullah, 1939-

Publisher The University of Arizona.

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THE EFFECT OF EXTENDED DISCRIMINATION TRAINING ON

BEHAVIORAL CONTRAST AND THE PEAK-SHIFT

by

A bdul-A ziz A. D ukhayyil

A T h esis Subm itted to th e F a c u lty o f th e

DEPARTMENT OF PSYCHOLOGY

In P a r t i a l F u lf i l lm e n t o f th e R equirem ents For th e Degree of

MASTER OF ARTS

In th e G raduate C ollege

THE UNIVERSITY OF ARIZONA

1 9 7 2

STATEMENT BY AUTHOR

T his th e s i s has been subm itted in p a r t i a l f u l f i l lm e n t of r e q u ir e ­ments fo r an advanced degree a t The U n iv e rs ity of A rizona and i s d ep o sited in th e U n iv e rs ity L ib ra ry to be made a v a i la b le to borrow ers under ru le s of th e L ibraryo

B rie f q u o ta tio n s from th i s th e s i s a re a llo w ab le w ith o u t s p e c ia l p e r m is s io n p r o v id e d th a t a c c u ra te acknowledgment of source i s made. R equests fo r p e rm issio n fo r extended q u o ta tio n from o r re p ro d u c tio n of t h i s m anuscrip t in whole or in p a r t may be g ran ted by th e head of th e m ajor departm ent o r th e Dean of the G raduate C ollege when in h is judgment th e proposed use of th e m a te r ia l i s in th e i n t e r e s t s of s c h o la rs h ip . In a l l o th e r in s ta n c e s , however, p e rm ission must be o b ta in ed from th e a u th o r .

SIGNED: JH » fit ■ ^

APPROVAL BY THESIS DIRECTOR

T his th e s i s has been approved on th e d a te shown below:

JOSEPH E. L A s s is ta n t P ro fe sso r Psychology

D ate

ACKNOWLEDGMENTS

Thanks a re due to Dr* Joseph Lyons f o r h i s k in d h e lp and v a lu ab le

su g g es tio n s w ith o u t which th is th e s is would n o t have come to l ig h t* The

h e lp o f D rs* T erry C* D aniel and C lin to n L. T rafto n i s a lso g re a tly

ap p rec ia ted * W» K lipec h e lp ed in s e t t i n g up the equipm ent and f ix in g

i t when needed*

This acknowledgment w i l l n o t be com plete w ith o u t m entioning the

generous f in a n c ia l a s s is ta n c e from th e Saudi A rabian Government through

th e C ollege o f Petro leum (Dhahran5 Saudi A ra b ia )»

i i i

TABLE OF CONTENTS

Page

LIST OF ILLUSTRATIONS.................................................................... ' . v

ABSTRACT .................. .... ................................................................ . v±

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . 1

METHOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

S u b jec ts . . . . . . . . . . . . . . . . . . . . . . . . 6A pparatus......................... . . . . . . . . . . . . . . . . . . . 6Procedure..... ................ 7

RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

DISCUSSION ..................... 25

LIST OF REFERENCES.......................... 33

i v

LIST OF ILLUSTRATIONS

F igu re Page

lo The mean responses to S+ fo r the b i rd s in Group 1 in5 day b lo ck s . . .......................... 11

2o . The w avelength g e n e ra l iz a t io n g ra d ie n ts fo r th e b ird sin Group 1 ♦ 13

3o The mean responses to S-+ fo r the b ird s in Group 2 in5 day b locks 15

4o The w avelength g e n e ra l iz a t io n g ra d ie n ts fo r th e s u b je c tsin Group 2 . . » . 6 , » » , 0 . ' • » . .................. 16

5» The mean responses to S+ fo r the b ird s in Group 3 in5 day b l o c k s .................................... .... . . . . . . . . . . . . 18

6, The w avelength g e n e ra l iz a t io n g ra d ie n ts fo r th e s u b je c tsin Group 3 ........................... c 20

7. The mean responses to S-f- fo r th e b i rd s in Group 4 in5 day b lo ck s 0 • • • • • « • • • • • o • 21

8o The w avelength g e n e ra l iz a t io n g ra d ie n ts fo r the s u b je c tsin Group 4............................................................... -..................................... 23

9 o The w avelength g e n e ra l iz a t io n g ra d ie n ts fo r th e s u b je c tsin Group 5 . . . . . . . . . . . . . . . . . . . . . . . 24

v

ABSTRACT

\ ■Five groups of p igeons (5 Ss p e r group) were employed to t e s t

T e rra c e ’s (1966a ,-b ) h y p o th e s is th a t b e h a v io ra l c o n tr a s t and th e peak-

s h i f t d isap p e a r as a consequence o f ex tended d is c r im in a tio n t r a in in g .

I n i t i a l l y , a l l f iv e groups re c e iv e d th e same d is c r im in a tio n t r a in in g

betw een 555 nm (S i) and 538 nm (S -). Follow ing m astery o f th i s ta s k ,

s u b je c ts were given a g e n e ra l iz a t io n t e s t a long the w avelength dim ension.

S u b seq u en tly , Group 1 was o v e r tra in e d w ith th e o r ig in a l s t im u l i . Group 2

was o v e r tra in e d on the o r ig in a l S i (555 nm) and a new S- (a w h ite v e r t i c a l

l in e ) . Group 3 con tinued t r a in in g on th e o r ig in a l S~ (538 nm) and a new

S i ( th e w h ite l in e ) , . Group 4 re c e iv e d b o th a new S i ( th e w h ite l in e ) and

a new S- (60° white* l in e ) . Group 5 r e s te d . This ex p e rim en ta l design

p e rm itte d us to r e p l i c a t e T e rra c e ’s (1966a) study as w e ll as determ ine

w hether the S i , the S - , d is c r im in a tio n t r a in in g p e r s e , o r sim ply the

passage o f tim e i s c r i t i c a l in p ro ducing the o v e r tr a in in g e f f e c t . F o llo w ­

in g each 15 days o f o v e r tr a in in g o r r e s t in g , each s u b je c t was given an

a d d i t io n a l w avelength g e n e ra l iz a t io n t e s t . The r e s u l t s f a i l e d to show,■ ■ <

fo r any o f th e f iv e groups , th e e f f e c t p re d ic te d by th e o v e r tr a in in g

h y p o th e s is . In f a c t , in many cases th e tre n d s were o p p o s ite to the

e x p e c ta tio n o f th i s h y p o th e s is . I t was concluded th a t th e o v e r tr a in in g

h y p o th e s is i s a t b e s t l im ite d and needs s e r io u s r e v is io n s .

INTRODUCTION

Two b y -p ro d u cts o f t r a d i t i o n a l d is c r im in a tio n le a rn in g ,

b e h a v io ra l c o n tra s t and the p e a k - s h i f t , have rece iv ed a g re a t dea l of

a t te n t io n in re c e n t y ears because o f the th e o r e t ic a l co n tro v e rsy over

the n ecessa ry and s u f f i c i e n t c o n d itio n s fo r producing th e se two phenomena.

B eh av io ra l c o n tra s t i s the in c re a s e in resp o n se r a te to one s tim u lu s

(S-f, SI) th a t accompanies the re d u c tio n of response r a te to an o th er

s tim u lu s (S -, S2) as a r e s u l t of e x t in c t io n o r o th e r r e l a t i v e ly

"u n fav o rab le11 co n tin g en c ie s (Freeman 1971), E lev a tio n of p o s t d isc r im in a ­

t io n g e n e ra l iz a t io n g ra d ie n ts r e l a t i v e to th a t o b ta in ed fo llo w in g s in g le

s tim u lu s t r a in in g i s a lso taken as ev idence o f b e h a v io ra l c o n tra s t

(T errace 1972), The d isp lacem ent o f the maximum p o in t (mode) of the

p o s t d is c r im in a tio n g e n e ra l iz a t io n g ra d ie n t beyond the S-f away from the

S- i s g e n e ra lly r e f e r r e d to as the p e a k - s h if t (Hanson 1959) •

The f i r s t dem onstra tion of th e se two phenomena fo llo w in g d is ­

c rim in a tio n t r a in in g was re p o rte d by Hanson (1959) , This au th o r used

the g e n e ra l iz a t io n t e s t in g p rocedure developed by Guttman and K alish

(1956) which made i t p o s s ib le to o b ta in r e l i a b l e g e n e ra l iz a t io n g ra d ie n ts

from in d iv id u a l s u b je c ts w ith in a s in g le t e s t s e s s io n . S ince then o th e r

re s e a rc h e rs have shown th a t b e h a v io ra l c o n tr a s t and th e p e a k - s h if t a re

r e l i a b l e phenomena and occur under a wide v a r ie ty of t r a in in g and t e s t in g

c o n d itio n s (Reynolds 1961; Honig, Thomas and Guttman 1959; T errace 1964;

Lyons and K lipec 1972), See a ls o g e n e ra l review s by T errace (1966a, 1972)

and Freeman (1971).

2

T errace (1966a) has r e la te d h is work on e r r o r l e s s d is c r im in a tio n

le a rn in g to the s tan d a rd e r r o r le a rn in g d a ta to conclude th a t bo th

b e h a v io ra l c o n tra s t and the p e a k - s h if t a re the r e s u l t o f em otional e f f e c t s

which accompany the S- as a r e s u l t o f n o n -re in fo rc e d respond ing (e r ro r s )

in i t s presenceo I f such e r ro r s do n o t o c c u r9 as w ith e r r o r l e s s t r a in in g ,

n e i th e r b e h a v io ra l c o n tra s t no r the p e a k - s h if t occurs (T errace 1966a)•

The p resen ce o f em otional e f f e c t s d u rin g S- were in f e r r e d by T errace

(1966a, 19 72) as a r e s u l t o f h is o b se rv a tio n o f the b i r d s 1 f la p p in g

wings and tu rn in g away from th e key in the p resen ce o f S -, T errace (1971)

has a lso shown th a t p igeons w i l l work to escape from an e r r o r S- b u t n o t

from an e r r o r l e s s one. S ince th e p re sen ce o r absence o f th e se em otional

e f f e c t s , and in tu rn of b e h a v io ra l c o n tr a s t and the p e a k - s h i f t , a re

c o r r e la te d w ith the p resen ce o r absence o f n o n -re in fo re e d respond ing .

T errace concluded th a t th e se p ro cesses a re fu n c tio n a lly r e la te d to each

o th e r (T errace 1966b, p . 613). T errace a lso concluded th a t b e h a v io ra l

c o n tra s t and the p e a k - s h if t w i l l in v a r ia b ly occur to g e th e r i f the

em otional p ro p e r t ie s of S- a re p re s e n t .■ ‘ ■ ' ' .

T errace (1966a,-b ) f u r th e r argues th a t i f b e h a v io ra l c o n tra s t and

the p e a k - s h if t a re "a m a n ife s ta tio n of *em otional* resp o n ses gen era ted by

the av e rs iv en ess o f re c e iv in g no re in fo rce m e n t, one would e x p e c t 'th a t

a f t e r p ro longed exposure to S4- and S- in a d i f f e r e n t i a l re in fo rcem en t

p rocedure [both b e h a v io ra l] c o n tra s t [and the p e a k - s h if t ] would d isap p ea r"

(1966a, p . 322; see a lso T errace 1966b, p . 613).

To t e s t th i s h y p o th e s is . T errace perform ed fo u r r e la te d e x p e r i­

ments . The f i r s t two were p i l o t s tu d ie s and were re p o r te d in p a ss in g

(T errace 1966a, p . 322 and pp. 328-330). The second two experim ents were

re p o r te d in somewhat more d e ta i l s (T errace 1966b)* The l a s t two

experim ents a re e s s e n t i a l ly s im ila r in p rocedu re ex cep t th a t in one

experim ent re p e a te d g e n e ra l iz a t io n te s t in g was a d m in is te red . The over­

t r a in in g was con tinued in bo th s tu d ie s fo r 60 d ay s . The e f f e c t of

o v e r tr a in in g on b e h a v io ra l c o n tra s t was m onitored co n tin u o u sly th rough­

o u t t r a in in g through changes in r a te o f response to S-K The rep ea ted

g e n e ra l iz a t io n t e s t in g , on the o th e r hand, p e rm itte d th e m o n ito rin g o f

the e f f e c t o f such o v e r tr a in in g on th e p e a k - s h i f t . The c o rre c t io n

p rocedu re was used in th e se e x p e rim en ts . This p rocedu re in su re d th a t

no le s s than 30 sec e lap se d between the l a s t response to S- (e r ro r ) and

the te rm in a tio n o f th a t s tim u lu s and thus p rev en ted a d v e n ti t io u s r e in ­

forcem ent of S- respond ing by th e subsequen t appearance o f th e S-K

The r e s u l t s showed th a t b o th b e h a v io ra l c o n tra s t and th e peak-

s h i f t d isap p ea red by the end o f the 60 days o f t r a in in g . T errace

concluded th a t th e se r e s u l t s a re c o n s is te n t w ith h is h y p o th e s is re g a rd ­

in g the fu n c tio n a l r e la t io n s h ip between th e p resen ce o f em otional e f f e c t s

and th e i r e f f e c t on b o th b e h a v io ra l c o n tr a s t and the p e a k - s h i f t .

However, s e v e ra l p ro c e d u ra l in ad eq u ac ies p re s e n t in t h i s study

made co n c lusions re g a rd in g th e o v e r tr a in in g e f f e c t d i f f i c u l t . F i r s t ,

T errace f a i l e d to in c lu d e c o n tro l groups in th i s s tu d y . S ince su cc e ss iv e

r e v e r s a ls o f th e main v a r ia b le s i s n o t p o s s ib le in th i s c a se , and hence

b e h a v io ra l c o n tra s t and the p e a k - s h if t could n o t be re p e a te d ly induced

and e lim in a te d , the fu n c tio n a l r e la t io n s h ip between th e independen t and

dependent v a r ia b le s in th e se experim ents could n o t have been c o n c lu s iv e ly

dem onstrated w ith o u t the use o f c o n tro l g ro u p s„ F u r th e r , i f th e em otional

responses th a t cause b e h a v io ra l c o n tra s t and th e p e a k - s h i f t occur to

the S- 5 over exposure to S- m ight in i t s e l f be a s u f f i c i e n t f a c to r fo r

p roducing the o v e r tr a in in g e f f e c t . A lso , th e re may be some c o n tr ib u tio n

o f ex tended exposure to the S-f- in p roducing the o v e r tr a in in g e f f e c t and

in a d d i t io n , d is c r im in a tio n t r a in in g p e r s e , even to a com pletely

d i f f e r e n t s e t o f s t im u li m ight le a d to the d is s ip a t io n o f th e p e a k - s h if t

o b ta in ed from the o r ig in a l t e s t dim ension. The in f lu e n c e o f the passage

o f tim e in the d is s ip a t io n o f em otional e f f e c t s and th e i r m a n ife s ta tio n s

was a lso ig n o red . F in a l ly , T errace s topped the experim ent when both

b e h a v io ra l c o n tra s t and the p e a k - s h if t d isap p ea red . A pparently th e i r

d isap pearance was assumed to be perm anent. However, th is assum ption i s

p a r t of th e o v e r tra in in g h y p o th e s is which the study was supposed to

v e r i f y „

The purpose o f the p re s e n t s tudy was f i r s t , to r e p l i c a t e

T e rra c e 1s (1966a,~b) f in d in g and second, to ex tend th e se r e s u l t s by

in c lu d in g the f a c to r s m entioned above. The p rocedu re fo r Group 1 i s

s im i la r to th a t used by T e rrace , excep t th a t the c o r re c t io n p rocedure

was n o t used . T h is , how ever, shou ld n o t be s ig n i f i c a n t d e p a r tu re as

the c o r re c t io n p rocedure would be used p r im a r i ly in th e e a r ly p a r t of

the t r a in in g . A lso , T e rra c e ’s h y p o th esis re g a rd in g the o v e r tr a in in g

e f f e c t was o ffe re d as b e in g a p p lic a b le to a l l types o f su c c e ss iv e

d is c r im in a tio n t r a in in g .

Four a d d it io n a l groups were employed. Group 2 was o v e r tra in e d

on a d is c r im in a tio n ta sk em ploying the same S+ (555 nm) used in the

i n i t i a l t r a in in g and a new S- taken from a d i f f e r e n t dim ension (a w h ite

v e r t i c a l l i n e ) . The s tim u lu s c o n tro l l i t e r a t u r e in d ic a te s th a t such

in te rd im e n s io n a l t r a in in g s teep en s the p o s t d is c r im in a tio n g e n e ra l iz a t io n

. . : 5

g ra d ie n ts around the S+o T h ere fo re , t h i s t r a in in g shou ld work a g a in s t

the tendency fo r the b ird s in Group 2 to show the p e a k - s h if t a long the

w avelength dim ension (Lyons 1969). Group 3 was o v e r tra in e d on the

o r ig in a l S~ (538 nm) and a new S+ (th e w h ite l in e ) . I f th e em otional

e f f e c t s th a t produce b e h a v io ra l c o n tra s t and the p e a k - s h i f t a re a s s o c ia te d

w ith S -, then i t would fo llow th a t ex tended exposure to th e S- in i t s e l f

shou ld produce th e o v e r tr a in in g e f f e c t . However, T errace (1966b)

in d ic a te d th a t the o v e r tr a in in g e f f e c t i s o b ta in ed w ith p ro longed

exposure to b o th ,fS+ and S- in a d i f f e r e n t i a l re in fo rcem en t p ro ced u re”

(1966b? p . 322). How th i s recommendation would fo llow from h is over­

t r a in in g h y p o th e s is i s n o t c le a r . However, Groups 2 and 3 from the

p re s e n t s tudy allow ed us to determ ine the s p e c i f ic ro le o f b o th the S-f

and S- in the o v e r tr a in in g e f f e c t . Group 4 was o v e r tra in e d on a new s e t

o f s t im u li th a t were on a dim ension d i f f e r e n t from th a t o f th e o r ig in a l

s t im u l i . This group p e rm itte d us to. in v e s t ig a te th e in f lu e n c e o f

d is c r im in a tio n t r a in in g p e r se on the p e a k - s h if t o b ta in ed from the o r ig in a l

d im ension . Group 5 re c e iv e d no f u r th e r d is c r im in a tio n t r a in in g fo llo w in g

the i n i t i a l t r a in in g . This group was employed to determ ine i f the passage

o f tim e i s c r i t i c a l in e lim in a tin g the p e a k - s h i f t . R epeated g e n e ra liz a ­

tio n te s t in g on the w avelength dim ension was given to a l l groups every

15 days.

A lso, in o rd e r to determ ine th e permenance o f th e lo s s o f

b e h a v io ra l c o n tra s t and th e p e a k - s h i f t , o v e r tr a in in g was con tinued fo r a

p red e term in ed p e rio d o f tim e re g a rd le s s o f w hether o r n o t b e h a v io ra l

c o n tra s t and the p e a k - s h if t d isap p ea red .

METHOD

S u b jec ts

The s u b je c ts (Ss) were 25 e x p e rim en ta lly n a iv e a d u l t p igeons

(mixed s t r a in s ) o b ta in ed from a lo c a l s u p p l ie r . A ll Ss w ere m ain ta ined

a t 70-75 p e r cen t ad l ib w eight th roughou t the ex p erim en t»

A pparatus

The ap p ara tu s c o n s is te d o f two s ta n d a rd key peck ing champers

(G ra so n -S tad le r Model IIQOPB), The i n t e r n a l dim ensions o f the champers

were as fo llo w s: w id th 11 in ch es 9 depth 11 in c h e s , h e ig h t 13 1 /2 in ch es

(279 X 279 X 343 mm)• A ll su rfa c e s o th e r than the f r o n t p an e l were grey;

th e f r o n t panel was unpain ted aluminum. F loo rs were composed o f w ire mesh

1 /2 in ch (12 .7 mm) sq u a re . The Ss peck ing key o f tr a n s p a re n t p l a s t i c was

p exposed through a 3/4 inch (19 .0 mm) c i r c u la r opening^ p la c e d 6 inches

(154 mm) above th e f lo o r on the f r o n t w a ll of. the box. A 2 by 1 3/4 in ch

(50 .8 X 44 .4 mm) a p e r tu re , lo c a te d 3 in ch es (76 .2 mm) below th e pecking

key p e rm itte d Ss access to food on a p red e term in ed sch e d u le . Between

magazine c y c le s , food may be low ered beyond the Ss re a c h . The food

magazine was i l lu m in a te d by a 10 w a tt bulb which was l ig h te d whenever

the food magazine was r a is e d . A 10 w a tt bu lb (house l i g h t ) s i tu a te d in

the f r o n t p an e l was used to i l lu m in a te th e e n t i r e box. In l i n e d isp lay

c e l l s ( I n d u s t r i a l E le c tro n ic s E ngineers Model E 4580-104) p re se n te d th e

s t im u li which were n in e w avelengths (501 nm, 511 nm, 538 nm9 548 nms

555 nm9 566 nm, 576 nm? 589 nm5 and 606 nm) . The d isp la y c e l l s could

. 6 . . . •

a lso produce two d i f f e r e n t o r ie n ta t io n s (90° and 60°) o f a w h ite l in e on

a b la c k background. Masking n o is e was su p p lie d f o r the d u ra tio n o f the

experim ent by a n o ise g e n e ra to r (G ra so n -S tad le r Model 901B) „

Procedure

Upon a r r iv a l a t the la b o ra to ry , S_s were in d iv id u a l ly caged and

a llow ed f re e access to food , w a te r , and g r i t u n t i l a s ta b le w eigh t le v e l

was o b ta in e d . Each b i r d was then reduced to 70-75 p e r cen t of t h e i r

f r e e fe ed in g w eigh t a t which tim e t r a in in g began.

A ll s u b je c ts were magazine and key-peck tr a in e d and allow ed to

o b ta in 50 continuous re in fo rcem en ts (CRF) fo r key-peck ing on th e f i r s t

day. R einforcem ent c o n s is te d o f a th re e sec access to the food hopper

which co n ta in ed a mixed g ra in p igeon feed . On Days 2 and 3 each b i r d was

given an a d d i t io n a l 50 CRF fo r k ey -p eck in g . During the n e x t two s e s s io n s

the CRF sch edu le was changed to a v a r ia b le i n t e r v a l (VI) 15 sec (Day 4)

and VI 30 sec (Day 5 ) . The s tim u lu s-o n p e rio d s were 50 sec in d u ra tio n

and each was se p a ra te d from the n e x t by a ten sec b la c k o u t o f the

s tim u lu s and "house l i g h t . " F if te e n such p e rio d s were p re se n te d du rin g

the fo u r th and f i f t h s e s s io n s . Throughout th is p re lim in a ry t r a in in g

the s tim u lu s on th e peck ing key was the 555 nm l i g h t .

On. Day 6 the number of s tim u lu s-o n p e rio d s was in c re a s e d to

30 and the re in fo rcem en t sch edu le was changed to VI one m in. For 15 o f

th e se p e rio d s th e s tim u lu s on the key was the 555 nm l i g h t w h ile , fo r

th e rem ain ing 15 p e rio d s th e s tim u lu s on the key was a 538 nm l i g h t .

The s t im u li were a l te r n a te d in a q u as i random sequence w ith the r e s t r i c ­

t io n th a t no more than two S+ o r S- p e r io d s could occur in su cc e ss io n and

8

VI one min re in fo rcem en t was in e f f e c t in th e p resen ce o f b o th s t im u l i»

This n o n d i f f e r e n t ia l t r a in in g con tinued fo r f iv e s e s s io n s and p rov ided

the b a s e l in e response r a t e to th e 555 nm s tim u lu s a g a in s t which the

e f f e c t o f d is c r im in a tio n t r a in in g between th e 555 nm and the 538 nm could

be judged .

D isc r im in a tio n t r a in in g then began w ith responses in the p resen ce

of the 555 nm stim u lu s (SI) r e in fo rc e d on the VI one min sch ed u le and

e x t in c t io n in e f f e c t in the p resen ce o f the 5 3 8 nm (S -) . F if te e n SJr

p e rio d s were randomly a l te r n a te d w ith the above m entioned r e s t r i c t i o n

w ith 15 S- p e rio d s d u rin g each t r a in in g s e s s io n . S tim ulus-on p e rio d s

con tinued to be 50 sec in len g th and each was s e p a ra te d from the n ex t by

the 10 sec b la c k o u t. T ra in in g con tinued in th i s manner u n t i l a c r i te r io n ,

o f ten responses to S+ fo r each response to S- was o b ta in e d .

On the day fo llo w in g c r i t e r io n perform ance each b i r d was given a

g e n e ra l iz a t io n t e s t a long th e w avelength dim ension. The t e s t s t im u li

c o n s is te d o f the nine, w avelengths p re v io u s ly m entioned. The n in e t e s t

s t im u li were random ized w ith in a s e r ie s and f iv e d i f f e r e n t random /

sequences w ere p re se n te d to each s u b je c t . A ll t e s t in g was conducted in

e x t in c t io n and each t e s t was proceeded by a f iv e m inute warm-up c o n s is t in g

o f th re e S+ p e rio d s a l te r n a te d w ith two S - p e r io d s .

F ollow ing the f i r s t g e n e ra l iz a t io n t e s t . Phase 2 was begun. In

th is phase S_s were randomly a ss ig n ed to one o f f iv e g roups, 5 Ss p e r

group. A ll Ss s excep t Ss in Group 5 which r e s te d , re c e iv e d 105 days o f

f u r th e r t r a in in g u sin g th e 50 sec s tim u lu s-o n tim e-10 sec b la ck o u t

p ro ced u re . Group 1 re c e iv e d the same c o n d itio n as b e fo re . Group 2 was *

given a new S~ (90° l in e ) , the S-f- (555 nm) rem ain ing th e same. Group 3

was given a new S+ (90° l in e ) b u t the S- rem ained the same. Group 4 was

t r a in e d to d is c r im in a te between a new s e t o f s t im u l i : S+ 90° and S~ 60°

l in e s . In th is phase a l l groups were on a VI one min sch ed u le o f r e in ­

forcem ent in the p resen ce o f S+ and e x t in c t io n c o r re la te d w ith S- (m ult

VI 1 EXT). A fte r every 15 days o f Phase 2 t r a in in g , o r in the case o f

Group 5 r e s t in g , a w avelength g e n e ra l iz a t io n t e s t s im i la r to T est 1 was

given to a l l Ss, p receded by th e f iv e min warm-up to the o r ig in a l s t im u l i .

Each S_ re c e iv e d a t o t a l of e ig h t t e s t s .

RESULTS

I t shou ld be no ted a t the o u ts e t th a t a s u f f i c i e n t ly long b a s e l in e

resp o n se r a te to the S4- was n o t o b ta in ed in the p re s e n t s tu d y „ The

i n t e r e s t in th i s study i s focused on w hether o r n o t response r a te to the

S-f would change s y s te m a tic a l ly as a fu n c tio n o f ex tended d is c r im in a tio n

tra in in g * Hence, i t was f e l t th a t b e h a v io ra l c o n tra s t d a ta could be

e v a lu a te d w ith o u t re fe re n c e to a b a s e lin e measure s in c e s p e c i f ic changes

in the r a te to S-1- would be p re d ic te d by T e rra c e fs th e o ry . T h e re fo re s the

average response r a te to S-f fo r th e f i r s t f iv e days of d is c r im in a tio n

t r a in in g i s taken as the re fe re n c e p o in t so th a t subsequen t le v e ls of

responses th a t f a l l above i t in d ic a te the p resen ce o f b e h a v io ra l c o n tr a s t

and the le v e ls o f responses th a t f a l l below i t in d ic a te th e absence of

b e h a v io ra l c o n tr a s t . This d e f in i t io n o f b e h a v io ra l c o n tr a s t i s 5 in e f f e c t ,

more s t r in g e n t than the ones th a t use as a re fe re n c e p o in t b a s e lin e s th a t

were o b ta in e d du rin g e i t h e r s in g le s tim u lu s t r a in in g (T errace 1966a?~b) .

o r non d i f f e r e n t i a l t r a in in g (Reynolds 1961) «, because i t has been re p e a te d ly

shown th a t b e h a v io ra l c o n tr a s t occurs e a r ly in th is type o f t r a in in g

( c . f . Reynolds 1961, B loom field 1969).

F ig u re 1 p re s e n ts the mean responses to the Sf fo r th e b ird s in

Group 1 in f iv e day b lo c k . I t i s c le a r from th i s f ig u re th a t a t the end

o f th e s tudy b e h a v io ra l c o n tr a s t , as d e fin ed above, f a i l e d to d isap p ea r in

th i s g roup , only S u b jec t A6 showed a c le a r p ro g re s s iv e d isappearance o f

b e h a v io ra l c o n tr a s t . B ird A7 showed a c o n tra ry tre n d ; th e r a te o f

respond ing to S-f- g ra d u a lly in c re a se d as the t r a in in g co n tin u ed .

• ■ . 10 .

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AY

Sun

hu

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GROUP I

A 19

18-16-14-12-10-8 -

20

A20

14-12-

10-8 -

20

A6

20

A8

28-26-24-22 -

20-

' A20

A7

16-14-12-10-8 -

20

NO. OF 5 DAY BLOCKS

F igure 1 . The mean responses to S+ fo r the b ird s in Group 1 in5 day b lo c k s .

. . i . ; ■ 12

S u b jec t AS a lso showed a p ro g re s s iv e in c re a s e in response r a te to Sf

th roughou t most o f the t r a in in g b u t the response r a te to S+ d ec lin ed

a b ru p tly a t the end o f the study* At th i s p o in t , the d if fe re n c e between

the averages of such respond ing fo r th e f i r s t f iv e days and the l a s t

f iv e days i s n o t pronounced,. More s u r p r is in g were th e d a ta from

S u b jec t A19. A c le a r d isap p earan ce o f b e h a v io ra l c o n tr a s t o ccu rred a t

f i r s t b u t in about th e l a s t month o f the s tu d y the r a te o f respond ing to

S*f in c re a s e d g re a tly and more p e r s i s t e n t ly than in the b e g in n in g . On

the o th e r hand, b e h a v io ra l c o n tr a s t f a i l e d to d isap p e a r a t a l l in

S u b je c t A20, In f a c t , in the l a s t f iv e days the average response rate-

in c re a se d g re a t ly .

F ig u re 2, which p re s e n ts the g e n e ra l iz a t io n g ra d ie n ts fo r th e

b ird s in Group 1, in d ic a te s th a t a l l f iv e s u b je c ts in t h i s group showed

th e p e a k - s h if t in T est 1 , fo u r in T est 2 , two in T est 3, fo u r in Test 4 ,

th re e in T est 5 , two in T ests 6 and 7, and f in a l ly , , th re e o u t of f iv e

b ird s showed the p e a k - s h i f t in T est 8.

The g e n e ra l iz a t io n t e s t r e s u l t s o f th e in d iv id u a l s u b je c ts in

th is group showed th a t w h ile th e p e a k - s h i f t m ight d isap p e a r in one t e s t

i t u s u a lly reap p eared in a l a t e r t e s t . Note th a t in fo u r s u b je c ts (A19,

A20, A7, and A8) , l a t e r p e a k - s h if ts were s t ro n g e r , i . e » , th e d if fe re n c e

between the numbers o f responses to the S4- and to the p e a k - s h i f t s tim u lu s

were la rg e r , than e a r l i e r o n e s . S u b jec t A7, fo r in s ta n c e , showed a

g ra d ie n t on T est 4 th a t was sym m etrical around the S-K However, even

though the p e a k - s h if t was n o t o b ta in ed in the n ex t t e s t (T es t 5 ) , the

p e a k - s h if t was n e v e r th e le s s o b ta in ed in th e n e x t th re e t e s t s (6 , 7, and 8) ,

NUM

BER

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13

GROUP I GENERALIZATION TESTS 3 4 5 6

800-700-600-500-400-

200 -

800-700-600-1500-400-

200 -

400-300-200 -

100-

900-600-700-600—

400-300-

WAVELENGTH1 —501 n m 6 - 566 n m2 — 511 n m 7 - 576 n m3 —538nmS- 8—589nm4 —548nm 9 -6 0 8n m5 — 555 n m S 4-

1100-1000 -

900-

700-

400-

11111-| 1 i~n' i 1 111; | T ) 111| 11 1 1 r r t T T Tr r T ' i » r r r r r i ■ i i ■ i 1 r i 11 1I 3 5 7 9 I 3 5 7 9 I 3 5 7 9 I 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9

TEST STIMULI

Figure 2. The w avelength g e n e r a l iz a t io n g rad ien ts fo r the b ird s in Group 1.

14

and in a s tro n g e r form. A s im i la r p a t te r n was o b ta in ed from S u b jec t A19.

The p e a k - s h if t d isap p ea red in T ests 5 and 6 b u t reap p eared l a t e r in

s tro n g e r form in T ests 7 and 8.

The p resen ce o f th e p e a k - s h if t was n o t n e c e s s a r i ly accompanied

by the p resen ce o f b e h a v io ra l c o n t r a s t . For in s ta n c e , the p e a k - s h if t

was n o t observed in S u b jec t A8 in T est 7 even though b e h a v io ra l c o n tra s t

was p re s e n t in the f iv e day b lo ck (Block 20) th a t im m ediately p receded

th i s t e s t . C onversely , S u b jec t A19 showed a p e a k - s h if t in T est 2 y e t

b e h a v io ra l c o n tra s t was n o t p re s e n t in th e b lo ck p reced in g i t . A lso ,

w h ile S u b jec t A6 showed a p e a k - s h if t in b o th T ests 4 and 5 no b e h a v io ra l

c o n tr a s t was p re s e n t in the b lo ck im m ediately p reced in g th e se t e s t s .

F ig u re 3 depects the mean o f responses to th e S-f o f each f iv e days

o f t r a in in g f o r the b ird s in Group 2. This group was o v e r tra in e d on th e

o r ig in a l S4- w ith a new S- (a w h ite v e r t i c a l l in e ) . As F ig u re 3 in d ic a te s ,

two s u b je c ts (A ll and A21) showed a p ro g re s s iv e d e c lin e in t h e i r response

r a te to th e S-F so th a t the average response r a te fo r th e l a s t f iv e days

o f th e study fo r bo th s u b je c ts was w e ll below the average r a t e fo r the

f i r s t f iv e days o f d is c r im in a tio n t r a in in g . There was a ls o a g re a t d ea l

o f o s c i l l a t i o n in the response r a te o f S-F by S u b jec t A ll . C onverse ly ,

S u b jec t A10 showed f i r s t a p ro g re s s iv e in c re a s e in th e resp o n se r a t e t e s t

th a t l a t e r s t a b i l i z e d a t a l e v e l th a t was h ig h e r than th a t of th e f i r s t

f iv e days. However, S u b jec t A10 *s response r a te tended to o s c i l l a t e to o .

S u b jec ts A9 and A22 d id n o t show a d e f in i t e tre n d and t h e i r responses

o s c i l l a t e d m arkedly .

F igu re 4 , which re v e a ls the g e n e ra l iz a t io n t e s t d a ta fo r Group 2 ,

in d ic a te s th a t the p e a k - s h if t was p re s e n t in fo u r s u b je c ts in T est 1.

AV

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GROUP 2

12- A21 I I- />10- I9 - /8 —

7 - 6 - 5 -

o L20

A22

14-

12- I I - 10- 9 - 8 7

20

13- AIO 12- II - 10- 9 -

l / J0 4 -r -r

20

All14-

12-

10-9 -8 -

o i0 10 20

A9

14-13-12-

0 10 20

NO. OF 5 DAY BLOCKS

Figure 3. The mean resp on ses to S+ fo r the b ird s in Group 2 in5 day b lo c k s .

NU

MBE

R OF

R

ESP

ON

SES

16

GROUP 2 GENERALIZATION TESTS 3 4 5 6

700-

500-

I OO-

WAVELENGTH1 - 501n m2 — 511 n m3 - 538nm S-4 —543nm5 —555 nmS +

6 — 566 n m7 - 576 n m 8-5 89 n m

606 n m

700-

400-

700-

400-300-200-

100-

800-700-

500-400-

200-

00-

700-

40 0 -300-

TEST STIMULI

F igure 4 . The w avelength g e n e r a liz a t io n gra d ien ts fo r the su b je c tsin Group 2.

17

This t e s t was given a t the end of the f i r s t phase in which 555 nm and

538 nm were the S4- and S - , r e s p e c t i v e l y » In T es t 2 only one p e a k - s h i f t

was o b ta in ed , no p e a k - s h i f t s were o b ta in ed i n Test 3, and on ly one p eak -

s h i f t was o b ta in ed in T ests 4, 5 , and 6 (from S ub jec ts A9, A21, and A10,

r e s p e c t iv e ly ) o However, in l a t e r t e s t s th e number of p e a k - s h i f t s

ob ta in ed increased* Three p e a k - s h i f t s were observed in T es t 7 and two

p e a k - s h i f t s in Test 8, w ith fo u r o f th e f i v e s u b je c t s showing a peak-

s h i f t i n a t l e a s t one o f th e se two t e s t s .

The g e n e r a l iz a t io n t e s t r e s u l t s o f the in d iv id u a l s u b je c ts

d is c lo s e d th a t bo th S ub jec ts A20 and A21 showed p e a k - s h i f t s only once in

the second phase , A20 in Test 5 , and A21 in T es t 7. S u b jec t A9 f a i l e d

to show a p e a k - s h i f t i n the f i r s t t e s t which fo llow ed the in t ra d im e n s io n a l

t r a in in g . Yet th i s s u b je c t e x h ib i te d a p e a k - s h i f t i n T es t 4 which

followed 45 days of i n t e r d im ensional t r a i n i n g , and again in T ests 7 and 8.

A lso , S ub jec t AID showed a p e a k - s h i f t i n T es ts 2 and 6 t h a t were s t ro n g e r

than the one o b ta in e d in Test 1. S ub jec t A ll showed the p e a k - s h i f t in

the f i r s t t e s t and in the l a s t t e s t .

The d a ta from t h i s group in d i c a t e t h a t b e h a v io ra l c o n t r a s t i s n o t

a n ece ssa ry p re c o n d i t io n f o r occurrence o f the p e a k - s h i f t . For in s t a n c e ,

S u b jec t A21 showed a p e a k - s h i f t on Test 5 and Sub jec t A ll on Test 8, y e t

by t h a t time b e h a v io ra l c o n t r a s t had a lread y d isappeared i n b o th s u b j e c t s .

Converse ly , S ub jec t A10 did n o t show p e a k - s h i f t s on Tests 2 , 3 , 4, and 8

in s p i t e o f the continuous and s t ro n g p resen ce of b e h a v io ra l c o n t r a s t .

The S+ t r a i n i n g d a ta fo r Group 3 i s p re se n te d i n F igu re 5. Note

t h a t a l l b i r d s showed an i n i t i a l in c re a s e i n t h e i r response r a t e to the

newly in tro d u ce d S+ in the e a r ly p a r t o f Phase 2, b u t th e response p a t t e r n

AV

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GROUP 3

A 2316-15-14-13-12-

10-9-,

20

A24

13-12 -

10-9 -

h20

AI430-28-26-24-22 -

2 0 -

18-16-

0 20

AI315- 14- 13- I 2 —

10-

8 -

7 A20

AI212-

10- 9- 8 -

7- . 6 -

5-

o k20

NO. OF 5 DAY BLOCKS

Figure 5 . The mean resp on ses to S+ fo r the b ird s in Group 3 in5 day b lo c k s .

19

i n subsequent s e s s io n s v a r ie d from one s u b je c t to a n o th e r . S ub jec ts A23

and A24 showed a p ro g re s s iv e d e c l in e in t h e i r response r a t e w ith t r a i n ­

in g , S ub jec ts A12 and A13 showed a s i m i l a r t r e n d , excep t t h a t a t about

the end o f th e s tudy the response r a t e began to in c re a s e ag a in . In

S ub jec t A14 the i n i t i a l c o n t r a s t f a i l e d to d isap p e a r .

The g e n e r a l iz a t io n t e s t r e s u l t s fo r t h i s group (F igure 6)

i n d i c a t e th a t over-exposure to the S- d id n o t r e s u l t i n th e permanent

d isappearance o f the p e a k - s h i f t , In f a c t , th ese r e s u l t s su g g es t the

c o n tra ry as ev idenced by the f a c t t h a t in the l a s t t e s t fo u r ou t o f the

f iv e s u b je c ts showed the p e a k - s h i f t .

S u b jec t A13 came c lo s e s t to s u p p o r t in g T e r r a c e Ts o v e r t r a in in g

h y p o th es is in th a t th e re was a p ro g re s s iv e s h i f t i n g o f the g ra d ie n t peak

back to th e S+, so t h a t on Test 7 the g ra d ie n t was approxim ately

sym m etrical around the S-K However, in T es t 8 o f t h i s s u b je c t the peak -

s h i f t r e tu rn e d . S u b jec t A14 showed a somewhat s i m i l a r p a t t e r n b u t by

T est 8 the p e a k - s h i f t re tu rn e d a l s o , even though in Tests 6 and 7 no

p e a k - s h i f t s appeared .

In genera l the number o f p e a k - s h i f t s observed in each t e s t o f

t h i s group was the same throughout excep t in Test 4 , where 3 p e a k - s h i f t s

were observed , and Test 7 in which only one p e a k - s h i f t was o b ta in ed .

The b e h a v io ra l c o n t r a s t d a ta fo r the s u b je c ts i n Group 4 a re

d ep ic ted in F igure 7, Note t h a t no d e f i n i t e response p a t t e r n emerged fo r

S ub jec ts A15 o r A17, There was g re a t d e a l o f o s c i l l a t i o n in th e se

s u b je c ts response r a t e to S-f, However, i t i s c le a r th a t i n th ese two

s u b je c t b e h a v io ra l c o n t r a s t d id n o t a c tu a l ly d is a p p e a r , a t l e a s t no t

p e rm an en tly , The response r a t e o f S ub jec ts A25, A26, and A16 d id no t

NUM

BER

OF

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SP

ON

SE

S

20

GROUP 3 GENERALIZATION TESTS

800-700-600-500-400-300-200-

100-0-

400-300-200-

100-0-

WAVELENGTH1—50lnm 6 —566 n m2 - 5 1 1 n m 7-5 76n m3 —538nmS— 8—589 nm4 —548nm 9 —606nm5 -5 5 5 n m S +

1000-

700-600-

400-

L200-

100-

800- 700- 600- 500- 400- 300- 200-

100- 0-

900- 800- 700- 600- 500- 40 0- 300— 200 -

100—

0 - i»i11111111111111 ■ i1111 ■I t i 1 i 1 i 11 m 1 i 1 i 1 i 'tTH V r t1111 * i1 r l 111 rVi M1 i'iI 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 I 3 5 7 9 1 3 5 7 9

T E S T STIMULI

Figure 6 . The w avelength g e n e r a liz a t io n g rad ien ts fo r the su b je c tsin Group 3.

AV

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GROUP 4

A25

10-9-8 -

7 -6-

5 -4 -

0 20

1 7 - 1

16-15-14-13-

A26

9 -6 -

2010

AI622 -

20 -

18 — I 6 - 14- 12 -

8 -

20

AI5

12-

II - 10 —

9 - 8 -

7 -

o i0 2010

AI714-13-12-

10-9 -8 -

7 -6—

20

NO. OF 5 DAY BLOCKS

F igure 7. The mean resp on ses to S+ fo r the b ird s in Group 4 in5 day b lo c k s .

: ■ ; - 22

d im inish below the response, l e v e l o f the i n i t i a l f iv e days o f Phase 2.

In S u b jec t A16 9 response r a t e to S4- du ring Phase 2 con tinued to in c re a s e

and then s t a b i l i z e d to a l e v e l w e l l above the l e v e l o f the f i r s t f iv e

days in Phase 2. This group was o v e r t r a in e d on a new s e t o f s t im u l i

(90° and 75° l i n e s ) » This type o f d i s c r im in a t io n ta sk i s ty p i c a l ly

d i f f i c u l t f o r p igeons to m as te r , and t h a t p robab ly e x p la in s the marked

o s c i l l a t i o n in the response r a t e o f th i s group (T errace 1963),

The g e n e r a l iz a t io n t e s t r e s u l t s from Group 4 were i n c o n s i s t e n t ,

as. shown in F igure 8. Only two ou t o f the f iv e b i rd s i n th i s group show

a p e a k - s h i f t in the f i r s t t e s t . Only one p e a k - s h i f t was o b ta in e d in the

l a s t t e s t . However, none of the two s u b je c ts showing the p e a k - s h i f t i n

the f i r s t t e s t showed i t i n any of the l a s t f iv e t e s t s .

The g e n e r a l iz a t io n t e s t r e s u l t s from Group 5 (F igure 9) a re

s i m i l a r to t h a t o b ta in e d from Group 4 excep t t h a t in the e a r ly t e s t s (1-5)

the number o f p e a k - s h i f t s was l a r g e r than in Group 4. However, the

number o f p e a k - s h i f t s in the l a s t th re e t e s t s was a lso low fo r t h i s group.

S ince t h i s group re c e iv e d no f u r th e r t r a i n i n g a f t e r Test 1 , those s u b je c t s

showing the p e a k - s h i f t s i n the f i r s t t e s t sh o u ld , acco rd ing to the ov e r­

t r a i n i n g h y p o th e s i s , con tinue to show i t i n the rem ain ing t e s t s . Yet

only One o f the s u b je c ts showing the p e a k - s h i f t in the f i r s t t e s t (A18,

A27, A29) showed i t i n the l a s t t e s t (S u b jec t A29).

NU

MBE

R OF

R

ESP

ON

SES

23

GROUP 4

GENERALIZATION TESTS 2 3 4 5 8

600—500-400-300-200-

10004

600-500-400-300-2 0 0100-

0-

A25

A26

AI5 WAVELENGTH1 — 501 n m 6 — 566 n m2 — 511 n m 7 — 5 76 n m3 —538nm S- 6— 509 n m4 — 548 n m 9 - 6 0 6 n m5 —555nm S +

600—500-

100-

700-

500-400-

100-

AI7

400-

00-

n9 13 5 7I ' l ' i ' i ' r i ' i ' i ' i ' n ' i ' p i ' r r p p p r i ' i T T r i ' i ' i '1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1

T E S T STIMULI

F igure 8 . The w avelength g e n e r a liz a t io n grad ien ts fo r the su b je c tsin Group 4 .

NUM

BER

OF

RE

SPO

NS

24

UJ

500-400300-1200100

o-400-300-2 0 0 -

10004

1000-

900- 800- 700-

" % 400- 300 2004 100

0—

700-600-500-400-300200-

100-

0-

800-700-600-500-400-300-200-

100-0-

GROUP 5 GENERALIZATION TESTS

1 4 5 6 8A27

AI9 b WAVELENGTH1 —50l nm 6-5 66 nm 2-511 nm 7 - 5 7 6 n m3 — 538 nm S- 8 - 5 8 9 nm4 — 548 n m 9 — 606 n m 5— 555 n mS+

A18

A 2 0 b

• ■ j | ► I — w | I ■ ^ I | » I ' 1 r | » • I a # ■ # # m I ■

n I 'l Tm n-' i»h i 11 i 11' 11 n i h iTl ' i »t i |-p t »i11 i 11rl >M r i 111111n i »Ml»p II 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 J 3 5 7 9

TEST STIMULI

Figure 9 . The w avelength g e n e r a liz a t io n g rad ien ts fo r the su b je c tsin Group 5 .

DISCUSSION

This experim ent p re s e n ts no ev idence th a t b e h a v io ra l c o n t r a s t and

the. p e a k - s h i f t d isappeared as a r e s u l t o f extended d is c r im in a t io n t r a i n ­

ing* There was no evidence o f any sy s te m a tic e f f e c t of p ro longed

d is c r im in a t io n t r a in in g on the course of b e h a v io ra l c o n t r a s t . Only one

s u b je c t in Group 1 9 two in Group 2, and th re e in Group 3 showed a c le a r

d isappearance of b e h a v io ra l c o n t r a s t a t the end of the t r a i n i n g s the o th e r

s u b je c ts did n o t . None o f the s u b je c ts in Group 4 showed a permanent

b e h a v io ra l c o n t r a s t d isap p ea ran ce . In some o f the su b je c ts ? in f a c t 9

th e re was a p ro g re s s iv e in c re a s e in the response r a t e to S-f- w ith t r a in in g .

I t i s i n t e r e s t i n g to n o te th a t the b e h a v io ra l c o n t r a s t r e s u l t s

ob ta in ed from the Wo in t r a d im e n s io n a l groups (Groups 1 and 4) were

s i m i l a r in a t l e a s t two r e s p e c t s „ F i r s t 5 most of the s u b je c t s in both

groups showed an in c re a s e in t h e i r response r a t e s to S-f w ith t r a i n i n g .

The d i f f e r e n c e in b e h a v io ra l c o n t r a s t r e s u l t s between th ese two groups

was l im i te d to the marked o s c i l l a t i o n i n the response r a t e o f s u b je c ts

in Group 4 9 which was a t t r i b u t e d above to the p o s s i b i l i t y t h a t l i n e

angle d is c r im in a t io n i s d i f f i c u l t f o r the p igeons to a c q u i r e . There was? .

on the o th e r hand? a g re a t d ea l o f d i f f e r e n c e between the b e h a v io ra l

c o n t r a s t r e s u l t of the in t r a d im e n s io n a l groups and the in te rd im e n s io n a l

groups in th a t the number o f s u b je c ts showing a d isappearance o f

b e h a v io ra l c o n t r a s t a t the end of the t r a i n i n g was much l e s s in the

in t ra d im e n s io n a l groups than in the in t e r dim ensional groups (1 s u b je c t

. " ' ' 25 :

' 26

v s • 5 , r e s p e c t i v e l y ) . F u r therm ore? th e re were a lso d i f f e r e n c e s in

b e h a v io ra l c o n t r a s t r e s u l t s between th e two in t e r dimens io n a l groups

th e m se lv e s . F i r s t , th e re was marked o s c i l l a t i o n s in the p a t t e r n s of

responses to the S+ in four of the f iv e s u b je c ts in Group 2, a lthough

th e tren d s in th e se responses a re c l e a r in many c a se s . These

o s c i l l a t i o n s in responses may be r e l a t e d to the a d m in is t r a t io n of the

g e n e r a l iz a t io n t e s t s which were on the dimension o f . the • S-f and p re se n te d

i n e x t i n c t i o n . The n a tu re o f th i s r e l a t i o n s h ip 9 i f any 9 i s u n c le a r and

could n o t be determ ined r e a d i ly from the d a ta . Another d i f f e r e n c e in

r e s u l t s between the two. groups i s t h a t in Group 3 th e re was almost

in v a r ia b ly a sharp in c re a s e in the response r a t e s in the e a r ly p a r t of

Phase 2 t h a t was e i t h e r fo llow ed by a p ro g re s s iv e drop in th e se r a te s

o r $ in the case o f S ub jec t A14, by a sharp drop in the r a t e fo llowed by a

p ro g re s s iv e in c re a s e in t h a t r a t e . A p p a ren t ly s the i n i t i a l sharp

in c re a s e i s r e l a t e d to the in t r o d u c t io n of the new S-f which had a

d i s r u p t iv e e f f e c t on the perform ance o f most o f the s u b j e c t s , which then

was im m ediately fo llow ed by a s t ro n g b e h a v io ra l c o n t r a s t as evidenced

by the sharp in c re a s e i n response r a t e . This d i s ru p t io n e f f e c t was

l im i t e d mostly to the f i r s t two days in Phase 2 and was thus masked in

the graphs (F igure 5) by the subsequent in c re a s e i n the response r a t e .

S u b jec t A24 i s a c l e a r e x c e p t io n „ I n c i d e n t a l l y , the same d is ru p t iv e

e f f e c t was a lso observed in a l l of the s u b je c ts o f Group 4 fo llow ing the

in t r o d u c t io n o f the new s e t o f s t i m u l i . However, i n t h i s group 9 th i s

d i s r u p t io n con tinued lo n g e r in some of the s u b je c ts ( e . g . . S ub jec t A17)

because o f the d i f f i c u l t y of the new d is c r im in a t io n ta s k . A lso, the

27

marked o s c i l l a t i o n s in subsequent s e s s io n s s which probab ly r e f l e c t -a

s e r i e s o f " d is ru p t io n s 911 masked the b e h a v io ra l c o n t r a s t t h a t followed

the i n i t i a l d i s r u p t io n .

In the p re s e n t s tu d y s as p o in te d ou t above> no b a s e l in e measure

was o b ta in e d f o r the response, to S4- because i t was n o t f e l t to be

n e c e s sa ry . The d a ta show the d e c is io n to have been v a l i d . The

b e h a v io ra l c o n t r a s t r e s u l t s a re c le a r enough to p rec lu d e the need fo r a

b a s e l in e d a ta . For i n s t a n c e s the r e s u l t s from th re e ou t o f f iv e s u b je c ts

in Group 1 a re c l e a r ly co n tra ry to the e x p e c ta t io n of the o v e r t r a in in g

h y p o th e s is . The response r a t e to S+ e i t h e r con tinued to in c re a s e

throughout the t r a i n i n g o r , i n the case o f S ub jec t A19, in c re a s e d

sh a rp ly and. more p e r s i s t e n t l y in the l a s t month o f t r a i n i n g . These

r e s u l t s a re c e r t a in l y more d e f i n i t i v e than the d a ta t h a t can be

e v a lu a te d s o le ly on the b a s i s o f i t s r e l a t i o n to the b a s e l i n e , e s p e c ia l ly

when i t has been shown th a t the s t a b i l i t y o f a VI b a s e l in e i s . n o t

a c tu a l ly achieved b e fo re the 20th o r 30th s e s s io n of s in g le s t im ulus

t r a in in g (H earst 1971; Freeman 1971).

Regarding the p e a k - s h i f t d a ta , the r e s u l t s c l e a r ly i n d ic a te th a t

p ro longed t r a i n i n g d id n o t le a d to i t s permanent d isappea rance . The

a n a ly s is of v a r ia n ce showed a s i g n i f i c a n t d i f f e r e n c e between the f iv e

groups on the number of p e a k - s h i f t s observed in Tests 2-8 [.F(4,20) =

3.23 P<o05], b u t f u r th e r ana lyses v ia in d iv id u a l groups comparisons

re v e a le d t h a t such a d i f f e r e n c e i s in the o p p o s i te d i r e c t io n of T e r r a c e 's

p r e d i c t i o n s , in t h a t o v e r t r a in in g in the absence o f the o r i g i n a l S- has

a g r e a te r tendency to. reduce the p e a k - s h i f t than does ex tended t r a in in g

w ith the S- (see Table 1 ) .

28

Table 1. The an a ly ses o f v a r ian ce v ia in d iv id u a l groups com parisons.

s - P re se n t S- Absent

F(1 ,20 ) PGroup No.No. o f

P e a k - s h i f t s Group No.No. of

P e a k - s h i f t s

1 21 2 9 6.19 <.05

3 24 2 9 9 .6 7 <.05

1 21 4 12 3.45 >.05

3 24 4 12 7.27 <.05

The p e a k - s h i f t d a ta ac ro ss t e s t s were a lso c o n tra ry to T e r r a c e ’s

e x p ec ta t io n s and i n c o n s i s t e n t w ith h i s r e s u l t s . Four ou t o f f iv e

s u b je c ts in Group 1 showed s t ro n g e r p e a k - s h i f t s in l a t e r t e s t s than in

e a r l i e r ones, as in d ic a te d i n the R esu lts s e c t i o n . A lso , even when the

t r a i n i n g makes the occurrence o f the p e a k - s h i f t h ig h ly u n l i k e l y , more

so , in f a c t , i n l a t e r t e s t s (T ests 7 and 8) than in the second t e s t

which was ad m in is te red a f t e r only 15 days of in te rd im e n s io n a l t r a in in g .

From the r e s u l t s of Groups 1 and 2 i t looks as though o v e r t r a in in g

r e s u l t s n o t in the d i s s ip a t i o n of the p e a k - s h i f t b u t in the in c re a s e

in i t s s t r e n g th and f req u en cy .

On the o th e r hand, the p e a k - s h i f t in Group 3 con tinued to be as

f req u e n t in the l a s t t e s t as in the f i r s t two t e s t s . S ince t h i s group

was overexposed to the S - , i t i s p r e d ic te d , on the b a s i s o f o v e r t r a in in g

h y p o th e s i s , th a t the em otional responses th a t accompany the S- should

adap t ou t and t h e i r m a n ife s ta t io n s d isap p ea r as a r e s u l t . I t i s c l e a r

t h a t the r e s u l t s from th i s group did no t b e a r th i s o u t .

29

Conversely ? of the f iv e s u b je c ts in Groups 4 and 5 showing the

p e a k - s h i f t in the f i r s t t e s t , four d id n o t show i t i n the l a s t fou r t e s t s ,

even though n e i t h e r o f th ese two groups were o v e r t r a in e d on the o r i g i n a l

s t im u l i fo llow ing Test 1* In f a c t , the t o t a l number o f p e a k - s h i f t s<

o b ta in e d in Tests 2 through 8 from the s u b je c ts showing the p e a k - s h i f t i n

the f i r s t t e s t , was co n s id e rab ly l e s s than th e number o f p e a k - s h i f t s

o b ta in ed from the s u b je c ts t h a t d id n o t show the p e a k - s h i f t i n the f i r s t

t e s t (10 p e a k - s h i f t s vs ; 18, r e s p e c t i v e l y ; average of 2 v s , 3*6 peak-i

s h i f t s p e r s u b je c t across the seven te s t s ) * These groups were n o t over­

t r a in e d on the o r i g i n a l s t i m u l i , and on the b a s i s o f T e r r a c e vs over­

t r a i n i n g h y p o th e s i s , th e re would have been no reason f o r the p e a k - s h i f t

to d isap p ea r in the s u b je c ts t h a t showed i t i n i t i a l l y , e s p e c ia l l y from

the s u b je c ts in Group 5 , which r e s t e d du ring Phase 2*

Terrace has re p e a te d ly m ain ta ined ( e . g . , 1966, p * 615) th a t

b e h a v io ra l c o n t r a s t and the p e a k - s h i f t covary . However, the p re s e n t

r e s u l t s in d i c a t e th a t th i s i s n o t n e c e s s a r i ly the case * The p e a k - s h i f t

might appear in a t e s t even though b e h a v io ra l c o n t r a s t was n o t ev id en t

i n the p e r io d immediately p reced in g the t e s t . On the o th e r hand, the

p e a k - s h i f t may f a i l to appear i n a t e s t in s p i t e o f the f a c t t h a t

b e h a v io r a l c o n t r a s t was s t ro n g ly e v id e n t i n the t r a i n i n g p e r io d

immediately p reced in g the t e s t .

A ls o , T errace a p p a re n t ly assumed on the b a s i s o f bo th the over­

t r a i n i n g h y p o th es is and the seemingly g radua l d isappearance o f b e h a v io ra l

c o n t r a s t and the p e a k - s h i f t t h a t such d isappearance was permanent* Hence,

he d id n o t con tinue w ith the experim ent a f t e r the two phenomena d i s ­

appeared , However, as was in d ic a te d in the R esu lts s e c t i o n o f t h i s p a p e r .

30

some o f our s u b je c ts gave a p a t t e r n of r e s u l t s t h a t were s i m i l a r to those

ob ta in ed by T errace ( e . g , , b e h a v io ra l c o n t r a s t and /o r the p e a k - s h i f t

d isappeared) , b u t because the experim ent was continued f u r t h e r i t was

found th a t a lm ost in v a r ia b ly the two phenomena did r e tu r n w ith more

t r a i n i n g . The permanence o f the d isappearance of b e h a v io ra l c o n t r a s t

and the p e a k - s h i f t i s d e f i n i t e l y p a r t o f th e o v e r t r a in in g h y p o th es is and

i t should no t have been merely assumed,■■ b u t , r a t h e r , e x p e r im en ta l ly

v e r i f i e d .

The p re s e n t r e s u l t s a re n o t w ith o u t p re c e d e n ts , H ea rs t (1971)

showed th a t b e h a v io ra l c o n t r a s t d id n o t d isap p ea r a f t e r 64 days o f

t r a i n i n g . The p e a k - s h i f t, on the o th e r hand, f a i l e d to d isap p ea r in one

s u b je c t out o f th r e e . I t took th i s s u b je c t lo n g e r time than the o th e r

two to l e a r n the d is c r im in a t io n ta s k . H ea rs t u n fo r tu n a te ly gave only

one g e n e r a l iz a t io n t e s t a t the end of the s tu d y . Had re p e a te d t e s t i n g

been p re s e n te d , the p e a k - s h i f t r e s u l t s might have been d i f f e r e n t and

more in fo rm a t iv e . At any r a t e . H ea rs t emphasized t h a t i t would be

unw arranted to conclude t h a t the absence o f the p e a k - s h i f t in the

g ra d ie n ts o f the o th e r two s u b je c ts i s the r e s u l t of o v e r t r a in in g . The

absence of the p e a k - s h i f t could a lso be a t t r i b u t e d to the f a c t th a t the

two s u b je c ts le a rn ed the d is c r im in a t io n ta s k q u ick ly .

H ears t r e p o r te d t h a t in 1970 Selekman nfound no c o n s i s te n t

decrease in the l e v e l of c o n t r a s t even a f t e r 70 days o f wavelength t r a i n ­

in g w ith a c o r r e c t io n p rocedure analogous to T e r ra c e ’s " (H earst 1971,

p. 361).

■■ . 31

R i l l i n g e t al» (1969) found th a t t h e f l e v e l of c o n t r a s t decreased

l i t t l e o r n o t a t a l l over 60 to 64 days o f t r a i n i n g e R i l l i n g e t a l . d id

n o t use the c o r r e c t io n p rocedure th a t Terrace used. However5, i t should

be no ted th a t the in c lu s io n or n o n - in c lu s io n o f the c o r r e c t io n procedure

should n o t be im p o rtan t as f a r as the o v e r t r a in in g h y p o th es is i s concerned.

For one9 w ith o r w ith o u t the c o r r e c t io n p ro c e d u re 9: the S- i s a v e r s iv e s

and th i s i s more im p o r tan t to the o v e r t r a in in g h y p o th es is • In f a c t , i t

i s p o s s ib le th a t the c o r r e c t io n procedure i s a p u n ish in g e v e n t , thus

ren d e r in g the S- more a v e rs iv e (Bloomfield 1966)« Second, the c o r r e c t io n

p rocedure w i l l more l i k e l y be used in the f i r s t few s e s s io n s o n ly ,

T ra in in g in l a t e r s e s s io n s should thus be s im i l a r to t r a i n i n g w ith o u t the.

c o r re c t io n p rocedure .

T e r r a c e fs (1966a ,-b ) own r e s u l t s re g a rd in g the p e a k - s h i f t c a s t ,

i n f a c t , doubt on the o v e r t r a in in g h y p o th e s i s . Judging by the - g e n e r a l iz a ­

t io n g ra d ie n t g ra p h s , the d isappearance o f the p e a k - s h i f t was n o t as

g radual as Terrace concluded, and as th e o v e r t r a in in g h y p o th e s is p r e d i c t s „

Most n o ta b le i s the g ra d ie n ts o b ta in ed from S ub jec t G 339 (1966b, p , 616),

In T est 2 the number o f responses to the S i and to the p e a k - s h i f t s t im u lus

were about e q u a l» However, i n T est 3 the number of responses to the same

p e a k - s h i f t s t im u lus was co n s id e rab ly l a r g e r than the number o f responses

to S i , the o p p o s ite o f what T errace would p r e d i c t , A lso , th e p e a k - s h i f t

i n the l a s t t e s t f o r S ub jec t G 355 (p« 616) did n o t d e f i n i t e l y d isappear

because the number o f responses to the p e a k - s h i f t s t im u lu s was about the

same as the number of responses to the Si» The g e n e r a l iz a t io n t e s t

r e s u l t s from S u b jec ts G 301 and G 305 (T errace 1966a, p „ 330) a re a lso

n o t q u i t e c o n s i s t e n t w ith the e x p e c ta t io n o f th e o v e r t r a in in g h y p o th e s is .

■ " ■ 32 In bo th su b jec t 's , the p e a k - s h i f t d id no t q u i te d isap p ea r i n th a t the

number of responses to the p e a k - s h i f t s t im u lu s equals the number of

responses to the S+.

In co n c lu s io n , our r e s u l t s c l e a r ly i n d ic a te t h a t bo th b e h a v io ra l

c o n t r a s t and the p e a k - s h i f t a re ephemeral phenomena in t h a t th e re was no

c o n s i s t e n t p a t t e r n d e te c te d in t h e i r p resence o r absence e i t h e r from one

day to the o th e r , from one t e s t to the o th e r , from one s u b je c t to the

o th e r , o r from one group to another* In f a c t , some o f th e se r e s u l t s ,

as n o ted above, were o p p o s i te to the e x p e c ta t io n o f the o v e r t r a in in g

h y p o th e s is . These r e s u l t s , th u s , s t ro n g ly sugges t th a t the o v e r t r a in in g

hy p o th es is i s a t b e s t l im i t e d e s p e c ia l l y in l i g h t o f the f a c t th a t in the

p r e s e n t s tudy d is c r im in a t io n t r a in in g was con tinued fo r con s id e rab ly

lo n g e r time than in T e r r a c e !s s tu d y .

LIST OF REFERENCES

B loom fie ld , T* M» Two types o f b e h a v io ra l c o n t r a s t i n d is c r im in a t io nle a r n in g . Jo u rn a l of ' the Experim ental "Analysis o f B ehavior, 1966 s 2 , 155-161.

B loom fie ld , T. M. B ehav io ra l c o n t r a s t and the p e a k - s h i f t . In Re M.G u ilb e r t and N. S. S u th e rlan d (Eds. ) , Animal D isc r im in a tio n

' L e a rn in g . New York: Academic P r e s s , 1969, pp. 215-241.

Freeman, B etty J» B ehav io ra l c o n t r a s t : Reinforcem ent frequency or■' response suppress ion? P sy c h o lo g ica l B u l l e t i n , 1971, 75_s 347-356,

Guttman, N*, • and K a l i s h 9 H. I , D i s c r im in a b i l l ty and s tim u lu s g e n e r a l iz a ­t io n = Jo u rn a l o f Experim ental Psychology , 1956, 51, 79-88.

' Hanson, H. M. E f fe c ts o f d is c r im in a t io n t r a i n i n g on s t im u lu s g e n e r a l iz a ­t io n . Jo u rn a l o f Experim ental Psycho logy , 1959, \58, 321-334.

H e a r s t , E. C o n tra s t and s t im u lu s g e n e r a l iz a t io n fo l low ing pro longedd is c r im in a t io n t r a i n i n g . Jo u rn a l o f ' the Experim enta l Analys i s o f .B e h a v io r , 1971, 15 , 355-363.

Honig, W. K . , Thomas, D. R. , and Guttman, N. D i f f e r e n t i a l e f f e c t s ofmassed e x t in c t i o n and d i s c r im in a t io n t r a i n i n g on the g e n e r a l iz a ­t io n g ra d ie n t . Jo u rn a l o f E xperim enta l P sychology , 1959, 58 , 145-152.

Lyons, J . Stimulus g e n e r a l iz a t io n a long the dimension o f S-f as a fu n c t io n o f d is c r im in a t io n le a r n in g w ith and w ith o u t e r r o r . ' Jo u rn a l o f

' Experim enta l Psychology , 1969, 81, 95-100.

L yons, J . , and K lip ec , W. The e f f e c t of chlorprom azine on the p e a k - s h i f t . Subm itted to Psychonomic S c ie n c e , 1972.

Reynolds, G. S. B ehav io ra l c o n t r a s t . Jo u rn a l o f the Experim ental A nalysis o f B eh av io r , 1961, 4_, 57-71.

R i l l i n g , M. ,' Askew, H. R. , Ahlskog, J . E. , and Kramer, T. J . Aversivep r o p e r t i e s o f the n e g a t iv e s t im u lu s in su cc e ss iv e d i s c r im in a t io n . Jo u rn a l o f the Experim ental A nalysis o f B eh av io r , 1969, 1 2 ,917-932.

T e rrac e , H. S. E r ro r le s s t r a n s f e r o f d is c r im in a t io n ac ro ss two c o n t in u e .Jo u rn a l o f the Experim ental A nalysis o f B eh av io r , 1963, 6^ 223-232.

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, Ho S. Stimulus c o n t ro l . In W* K. Honig (Ed.) 9 Operant Behavior Areas o f Research and A p p l ic a t io n . New York - A ppleton-C entury- C ro f ts , 1966a, pp. 271-344.

, Ho S. B ehav io ra l c o n t r a s t and the p e a k - s h i f t . Jo u rn a l o f the Experim ental A nalysis o f B ehav io r , 1966b, 9^ 613-617.

, H. S . Escape from L earn ing and M o tiv a t io n s 1971, 2, 148-163.

s, Ho Se By-products o f d i s c r im in a t io n learn ing* In G; H„ Bower and J . Spence (Eds.) 5 The Psychology o f Learning and M o tiv a tio n . New York: Academic P ress , 1972.

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