An experimental investigation of the effect of changes in the delay of reinforcement upon level of performance of an instrumental response

Citation preview

AM EXPEEI1HMAE XHVESTXGATIOil OF THE EFFECf-QF CHA»IS X3S THE DELAY OF EEIHFORCEMKMT UPOH EE?EE OF PERFORMABCE OF AH XM3THUMEMTAL RESPONSE

by Georg© S ta n le y B arker

A t h e s i s subm itted In p a r t ia l f u l f i l l m e n t o f th e req u irem en ts f o r th e d eg ree o f O ootor o f P hilosophy* in th e Departm ent o f Psychology* in th e Graduate C o lle g e o f th e S ta te U n iv e r s ity o f Iowa August 1950 State University of Tow& U8RARY

ProQuest Number: 10598591

All rights reserv ed INFORMATION TO ALL USERS The quality o f this rep rod u ction is d e p e n d e n t u p o n th e quality o f th e c o p y su b m itted . In th e unlikely e v e n t th a t t h e au thor did n o t s e n d a c o m p le t e m anuscript a n d th e r e a re m issing p a g e s , t h e s e will b e n o te d . Also, if m aterial h a d to b e r e m o v e d , a n o t e will in d ic a te th e d e le tio n .

uest P roQ uest 10598591 Published by ProQ uest LLC (2017). C opyright o f th e Dissertation is h eld by th e Author. All rights reserved . This work is p r o te c te d a g a in st unau th orized c o p y in g u n d er Title 17, U nited S ta te s C o d e M icroform Edition © P roQ uest LLC. ProQ uest LLC. 789 East E isenhow er Parkway P.O. Box 1346 Ann Arbor, Ml 48106 - 1346

AOK&otii. f h e w r i t e r w is h e s t o e x p r e s s h i s s i n c e r e a p p r e c i a t i o n t o Or* K enneth a# S p ence f o r f o r * m u la tln g th e p ro b lem and f o r h i s s t i m u l a t i n g c r i t i c i s m d u r in g th e p r e p a r a t i o n o f th e man* u a o rip t* ^

11

TABLEOF C0BJTEM T3

P age

I n tro d u c tio n T h e o r e t i c a l Background

1

E x p e rim e n ta l B ackground # * * * * • « * « * *

3

S ta te m e n t o f th e P r o b l e m ...................... * » • * «

6

E x p e rim e n ta l Method S u b je c ts

• • « « • « « • # • • * « * * • • *

A p p a ra tu s « * . • • • * • • * P r e lim in a r y T r a in in g

............................

» t

6 *

6

•

9

E x p e rim e n ta l D e sig n • • • * * • * « • « * • •

10

P ro c e d u re i n T r a in in g s e r i e s

11

E x tin c tio n

• • • # • • • «

* « * • « * « « *

# * 13

D is c u s s io n and R e s u lts E x p e rim e n ta l D a ta • » • * « • * « • * • • • • A c q u is itio n and P erfo rm an c e L ev e l a s a F u n c tio n o f D elay o f Reward

13

* * * 14

E f f e c t o f Changes i n D elay o f Reward on « * . 1? L ev e l o f p e rfo rm a n c e E f f e c t o f F a i l u r e o f R e in fo rc e m e n t T h e o r e ti c a l D is c u s s io n

. • « • • 22

» « • # » * « » * » •

Summary

24 27

B ib lio g ra p h y • * » * # • « * « » « » • • * * « A ppendix il

.*29

• • * • • 3 0

A ppendix B ..........................................

35

A ppendix C * • * * « • *

43

• ................... • • • « * » * ill

SABLE OF TABLES T able I

Pag® * * ..............................................

* » * »

20

*

* * • *

20

iv

BLISS

1 XSTHOBU0MOM

y h s o r a t l o a l B a o te ro u o a vi1t h i n th e fram ew ork o f H ull* h a b i t s t r e n g t h h a s t h e p r o p e r ty o f b e in g b u i l t up a s a r e l a t i v e l y p e rm a n e n t s t a t e w i t h i n t h e organism * I n d i s c u s s i n g th e c o n c e p t o f h a b i t H u ll s t a t e s 3 ” « # * th e im m ed iate oauae o f h a b i t- m e d ia te d a c t i o n e v o c a tio n m u st b e a c o m b in a tio n o f (1 ) t h e s tim ­ u l u s e v e n t an d (2 ) a r e l a t i v e l y p e rm a n e n t c o n d i­ t i o n o r o r g a n i s a t i o n l e f t by th e r e in f o r c e m e n t w i t h i n th e n e rv o u s sy ste m o f th e a n im a l! t h i s l a s t i s w hat I® m eant by th e t e n s h a b i t * * ( 2 # p* 109) w ith r e g a r d t o th e a c q u i s i t i o n o f h a b i t s and th e l i m i t i n g v a lu e s o f h a b i t s t r e n g t h t h a t w i l l be re a c h e d u n d e r p a r t i c u l a r e x p e rim e n ta l c o n d itio n s * two p a r a l l e l h y p o th e s e s hav e b een f o rm u la te d by H u lls , one in v o lv e s th e m ag n itu d e o r q u a l i t y o f rew ard and th e o t h e r th e tim e o f d e la y o f re in fo rc e m e n t*

T hese h y p o th e s e s a r e :

rtH a b it s t r e n g t h a t th e l i m i t o f p r a c t i c e (m) w i l l v a ry w ith th e q u a l ity * a s w e ll a s th e q u a n tity * o f th e r e i n f o r c i n g a g e n t from a minimum o f a e ro t o a p h y s i o l o g i c a l maximum#*1 (2* p . 1 2 9 ) **The maximum h a b i t s t r e n g t h (m*) a t t a i n a b l e w ith a g iv e n am ount and q u a l i t y o f r e in f o r c e m e n t c l o s e ly a p p ro x im a te s a n e g a tiv e g ro w th f u n c t i o n o f th e tim e ( t ) s e p a r a t i n g th e r e a c t i o n from th e r e i n f o r c i n g s t a t e o f a f f a i r s * •*'* (2* p* 14b) Two f u r t h e r s ta te m e n ts h av e b een made by H u ll c o n c e rn in g th e e f f e c t o f ch an g es i n th e v a lu e o f th e r e i n ­ f o r c i n g a g e n t upon th e maximum o f h a b i t s tr e n g th #

A lth o u g h

th e s e s ta te m e n ts r e f e r r e d s p e c i f i c a l l y t o m a g n itu d e o r d u a l ­ i t y o f rew ard* i n th e c o n t e x t o f h i e f o r m u la tio n , th e y may he c o n s id e r e d t o a p p ly t o d e la y o f r e in f o r c e m e n t a ls o * Thus H u ll s t a t e s t rt* * .a c c o r d in g t o th e p r e s e n t h y p o th e s is a n I n c r e a s e i n th e am ount o f th e r e i n f o r c i n g a g e n t s h o u ld he fo llo w e d by a m a ile d i n c r e a s e I n th© r a t e o f h a b i t s t r e n g t h a c q u i s i t i o n s t h i s * how ever* w ould g r a d u a lly l e s s e n a® th© new l i m i t i s ap p ro ach ed * i n a c c o rd a n c e w ith th e n a tu r e o f th© sim p le g ro w th f u n c tio n * 11 (2* p* 130) w ith r e s p e c t t o th e c o n v e rs e o f th© ab o v e c o n d i­ tio n * t h a t o f a r e d u c t io n i n th e m ag n itu d e o f r e in f o r c e m e n t a f t e r t r a i n i n g h a s p r o g r e s s e d f o r a s p e c i f i e d num ber o f t r i a l s , B u l l f a s ta te m e n t 1 s t 11** .i g n o r i n g se c o n d a ry r e i n f o r c i n g e f f e c t s , i t i s t o be e x p e c te d t h a t s u c c e s s iv e r e in f o r c e m e n ts w ould r e s u l t i n a p r o g r e s s iv e w eak en in g o f th© h a b i t * ” ( 2 , p# 131} The a p p a r e n t c o n t r a d i c t i o n i n th© p r o p e r t i e s a s c r ib e d t o h a b i t s t r e n g t h i s o b v io u s#

H a b it s t r e n g t h c a n ­

n o t be a n e s s e n t i a l l y p erm a n e n t c o n d i tio n o r o r g a n i z a t i o n t h a t d o es n o t w eaken o r d e c r e a s e a t one moment and b© c a l l e d upon to d e c r e a s e i n am ount w ith a d e c r e a s e i n th e m a g n itu d e o f r e in f o r c e m e n t a t th e n ex t* More r e c e n tly * H u ll ( 3 ) i n r e f o r m u l a tin g h i s p r i n ­ c i p l e s h a s changed h i s c o n c e p tio n o f th© r o l e o f m ag n itu d e and d e la y o f r e in f o r c e m e n t i n d e te r m in in g r e s p o n s e s tr e n g th * T hese two v a r i a b l e s a r e now assum ed t o d e te r m in e

h y p o t h e t i c a l in c e n ti v e f a c t o r s w h ich a c t th r o u g h a m u l t i ­ p l i c a t i v e r e l a t i o n s h i p w ith h a b i t t o p ro d u c e th® e x c i t a t o r y p o t e n t i a l o f w hich th e r e s p o n s e i s t h e d i r e c t l y o b s e r v a b le co n seq u en t*

T h is new f o r m u la tio n o b v ia te s th® c o n t r a d i c t i o n

o f th® e a r l i e r f o r m u la tio n and p r o v id e s f o r th e d e r i v a t i o n o f r a t h e r a b r u p t and e x t e n s i v e s h i f t s i n th e l e v e l o f r e ­ sp o n se s t r e n g t h f o llo w in g e i t h e r a n i n c r e a s e o r a d e c r e a s e I n t h e m ag n itu d e o r d e la y o f rew ard#

The m ost r e l e v a n t s t u d i e s t h a t b e a r upon th e s ta te m e n ts n o te d a r e th o s e o f G re s p i (1 ) and zeam an (6 )# T hese s t u d i e s g iv e d a t a on a c q u i s i t i o n and th® a s y m p to tic p e rfo rm a n c e v a lu e s f o r a n im a ls t r a i n e d u n d e r d i f f e r e n t m a g n itu d e s o f fo o d rew ard* and th e e f f e c t on l e v e l o f p e r ­ form ance o f ch a n g in g th e m a g n itu d e o f th e fo o d rew ard*

In

b o th e x p e rim e n ts th® re s p o n s e c o n s is te d i n ru n n in g down a s h o r t* e l e v a t e d maze p a th i n t o a g o a l box#

G re sp i u se d

sp e e d o f ru n n in g w h ile Seaman u s e d s t a r t i n g tim e and sp e ed o f ru n n in g a s m e asu res o f p erfo rm an ce#

The rang© o f mag­

n itu d e o f rew ard i n b o th s t u d i e s c o v e re d a n a p p r e c ia b l e p o r t i o n o f th e d a i l y r a t i o n o f th e an im als#

T r a in in g was

c a r r i e d o u t u n d e r a p ro c e d u re o f one t r i a l p e r day* th u s p r o v id in g f o r a d e q u a te c o n t r o l o f m o tiv a tio n # The r e s u l t s o f b o th o f t h e s e s t u d i e s i n d i c a t e d

4 t h a t th e p e rfo rm a n c e a s y m p to te s f o r d i f f e r e n t am ounts o f rew ard wears s i g n i f i c a n t l y d i f f e r e n t and t h a t s i g n i f i c a n t ch an g es i n p e rfo rm a n c e r e s u l t e d from b o th i n c r e a s e s and d e ­ c r e a s e s i n th® am ount o f fo o d rew ard*

The e f f e c t o f ch a n g es

i n th e m ag n itu d e o f r e in f o r c e m e n t was s t u d i e d by in t e r c h a n g ­ i n g th e am ount o f th e rew ard f o r two e x tre m e g ro u p s a f t e r a n a p p r o p r i a t e d e g re e o f t r a i n i n g h ad b e e n a t ta i n e d *

in a d d i­

t i o n , Zeaman d iv id e d a g ro u p o f 40 a n im a ls t r a i n e d o n a n in te r m e d ia te am ount o f fo o d I n t o f i v e s u b -g ro u p s o f e i g h t a n im a ls e a c h and c o n tin u e d t h e i r t r a i n i n g w ith m a g n itu d e s o f rew ard d i s t r i b u t e d two above and two below th e o r i g i n a l v a lu e # th e f i f t h g ro u p b e in g c o n tin u e d on t h e o r i g i n a l v a lu e o f rew ard a s a c o n tr o l*

The r e s u lt® i n ea c h c a s e showed a

prom pt s h i f t i n re s p o n s e la t e n c y I n k e e p in g w ith th e ch an g e i n rew ard#

i n th e c a s e o f Zeeman*s f i v e su b -g ro u p s # th®

o r d e r o f th e mean lo g l a t e n c i e s r a n from low t o h ig h co n ­ s i s t e n t w ith th e o r d e r from h ig h to low o f th® am ount o f re in fo rc e m e n t* H u ll* s new er f o r m u la tio n l a i n a c c o rd w ith th e s e d a t a a s to m ag n itu d e o f rew ard#

Th© q u e s t i o n rem ain s# how­

ev er# a® to w h e th e r th e e f f e c t s o f d e la y o f r e in f o r c e m e n t p a r a l l e l th o s e o f m ag n itu d e o f r e in f o r c e m e n t.

Th© e x p e r i ­

m e n ta l e v id e n c e on t h i s p o i n t I s l i m i t e d t o s t u d i e s o f th e e f f e c t s p ro d u ced by v a r y in g th® d e la y o f rew ard*

Ho s t u d i e s

known to th© w r i t e r d e a l w ith t h e e f f e c t s o f s h i f t s I n th®

5 d e la y o f re in fo rc e m e n t# E x p e rim e n ta l d a t a I s a v a i l a b l e I n P e r l n 's s tu d y ( 5 ) o f b a r p r e s s i n g I n r a t s w h ieh s u p p o r ts H u ll* a assum p­ t i o n , n o te d e a r l i e r , t h a t d i f f e r e n t l i m i t s o f h& M t s t r e n g t h w i l l he a t t a i n e d w ith d i f f e r e n t d e la y s o f r e in f o r c e m e n t. F e r ln f i r s t gave h i s a n im a ls 120 p r e s e n t a t i o n s o f fo o d by m a n u ally o p e r a t i n g th e fo o d -d © llv © iy m echanslm i n a S k in n e r box*

T h is s e rv e d t o e s t a b l i s h th e se c o n d a ry r e i n f o r c i n g

p r o p e r t i e s o f th e sound o f th e d e l i v e r y mechanism*

Four

group© o f a n im a ls w ere th e n t r a i n e d t o p r e s s th e b a r , t h e fo o d rew ard b e in g d e la y e d e i t h e r 0 , 2 , 5 , o r 10 see#

F ifty

t r i a l s w ere g iv e n w ith a n e i g h t- m in u te i n t e r - t r i a l i n t e r v a l * Th© a n im a ls w ere h a n d le d b e tw e e n t r i a l s # e a c h s u b j e c t b e in g r e tu r n e d t o th e home cage d u r in g th e i n t e r - t r i a l i n t e r v a l * Th© 50 t r i a l s r e q u ir e d th e b e t t e r p a r t o f an e i g h t - h o u r day f o r any on© anim al* F e r ln r e p o r te d f i n d i n g d i f f e r e n t a s y m p to te s f o r ea c h o f t h e d e l a y I n t e r v a l s * g ro u p s ( 0 ,

The a s y m p to te s f o r t h e f o u r

5 , & 10 s e c * ) w ere r e s p e c t i v e l y 1 * 8 5 , 2 * 7 5 ,

4*10 and 7*45 sec*

A 3 0 -se c * g ro u p (N « 16} t h a t was ru n

a s a n a f t e r - t h o u g h t showed no le a r n in g ^ w i t h p e rfo rm a n c e becom ing p r o g r e s s i v e l y p o o r e r on e a c h t r i a l *

6 S ta te m e n t o f th e Problem Th© p r e s e n t e x p e rim e n t was d e s ig n e d (1 ) t o s tu d y th e c o u rs e o f a c q u i s i t i o n o f a n I n s tr u m e n ta l r e s p o n s e a c ­ q u ir e d u n d e r d i f f e r e n t d e l a y s o f rew ard and ( 2 ) t o s tu d y th e e f f e c t on p e rfo rm a n c e o f s h i f t i n g t h e d e la y o f r e i n ­ fo rc e m e n t from a s h o r t e r t o a lo n g e r p e r io d and v i c e v e r s a . JBX PERIM E»$A L METHOD

The s u b j e c t s w ere 141 n a iv e hooded fe m a le r a t s from th e co lo n y o f th e D e p a rtm e n t o f P sy ch o lo g y o f th e S t a t e U n iv e r s it y o f Iowa*

T h e ir a g e s ra n g e d from 90 to

100 d a y s a t th e s t a r t o f t r a i n i n g * m&m&m The a p p a r a tu s was a m o d ifie d S k in n e r box I n w h ich th e re s p o n s e t o be le a r n e d was th e d e p r e s s io n o f a b a r p r o ­ j e c t i n g i n t o th e re s p o n s e chamber*

The b a r was r o t a t e d i n t o

th e a p p a r a tu s by th e e x p e r im e n te r th ro u g h a s l o t i n th® f r o n t w a ll and r o t a t e d o u t by t h e a n im a l* s re s p o n s e th ro u g h a s l o t b e s id e th e food cup* ( l i f t i n g ) o f th e b ar*

k r a t c h e t p r e v e n te d r e v e r s e r o t a t i o n P r o v is io n was made f o r th e e n h a n c e ­

m ent o f t h e a u d i t o r y cu e s accom panying r e in f o r c e m e n t by t h e d e l i v e r y o f a s m a ll le a d s h o t i n c o m b in a tio n w ith t h e fo o d p e lle t#

( t h i s s h o t s t r u c k a g a i n s t th© u n d e r s id e o f th® fo o d

7 ©up and th e n f e l l I n t o a r e t a i n i n g hose below}*

a 7 - w a tt

b u lb l o c a t e d 10 In* from th e f l o o r above th e s l o t th ro u g h w hich th e b a r was p r e s e n te d s e rv e d a s a s tim u lu s and t r i a l lig h t.

T h is l i g h t came on when t h e b a r was r o t a t e d i n t o

th e box bar th e e x p e r im e n te r and w en t o f f 50 sec* a f t e r th e re s p o n s e was made*

A re a d y s i g n a l was p ro v id e d by t h e f a c t

t h a t t h e e x p e rim e n te r h ad to cock th e b a r p r e p a r a t o r y t o r o t a t i n g i t i n t o th e box*

T h is c o o k in g o f th e b a r p ro d u ced

th e c h a r a c t e r i s t i c sound o f a r a t c h e t w h ich was p r e s e n t any tim e th e b a r was moved*

The e x c lu s io n o f I r r e l e v a n t

s t i m u l i was a c c o m p lish e d by th e u s e o f a m ask in g n o is e (60 c y c le sy n c h ro n o u s m o to r and g e a r t r a i n ) r a t h e r th a n by th e u s e o f a se m i-so u n d p r o o f e x t e r n a l s h e ll* th e i n s i d e d im e n s io n s o f th e box w ere 11 in* lo n g , 7*75 in# w id e , and 12 in* high*

Th© b a r e n t e r e d th e box

3*15 in* above th e f l o o r and was r o t a t e d by th e e x p e r im e n te r t o a p o s i t i o n 2 in* ab ove th e f lo o r * tr u d e d i n t o th e box one inch*

At t h i s p o in t i t p ro ­

in r e s p o n d in g , th e a n im a l had

to p r e s s th e b a r v e r t i c a l l y downward *45 in*

a t w hich p o i n t

a m o d e ra te s p r i n g a c t i o n c a r r i e d i t down and o u t o f th® box. Th® f o r c e r e q u ir e d t o d e p r e s s th© b a r was l e s s th a n one gram* The la te n c y o f th© r e s p o n s e , t h a t i s th e tim e r e ­ q u ir e d f o r th© a n im a l to a p p ro a c h and d e p r e s s th® b a r , was m easured by a s ta n d a r d E l e c t r i c c lo c k a c t u a t e d by a

8 m ic ro ~ s w itc h a p p l ie d t o a cam on th© b a r assem bly*

The

c lo c k c l u t c h was a c t u a t e d when th© b a r was p r e s e n te d and r e l e a s e d when th© a n im a l d e p r e s s e d th e b a r *15 in*

Head­

in g s w ere made t o th© n e a r e s t 1 /1 0 0 sec* t h e d e l i v e r y o f fo o d a t d e s ig n a te d I n t e r v a l s f o l ­ lo w in g th© re s p o n s e was a c c o m p lish e d by th e u se o f a d i s c w ith a p p r o p r i a t e l y sp a ced h o le s to c a r r y th e fo o d p e l l e t and le a d sh o t*

T h is d i s c was r o t a t e d by a two rpnu e l e c t r i c

c lo c k m otor*

Th© m o to r was s t a r t e d by th e a n im a l’ s re s p o n s e

and mad© on© co m p lete r o t a t i o n * d r o p p in g th© fo o d p e l l e t and l e a d s h o t i n t o a s e t o f d e l i v e r y tu b e s*

t h e minimum d e la y

p o s s i b l e . Im m ediate d e l i v e r y , was a p p ro x im a te ly one sea* b e c a u se o f th e I n i t i a l s t a r t i n g l a g o f th e m o to r and th© f a c t t h a t th e d i s c c o u ld n o t be lo a d e d a t a p o i n t c o i n c i ­ d e n t w ith th e d e l i v e r y tu b e s* Two a d d i t i o n a l b o x es 8*5 in* lo n g , 5 in* w ide and 10 in* h ig h w ere u se d i n th e p r e lim in a r y t r a i n i n g *

The

f i r s t o f th e s e was a f e e d in g box w ith wooden a i d e s , s c r e e n to p and f l o o r , w a te r b o t t l e and fo o d p la tfo rm *

The seco n d

had a s o l i d f l o o r , no w a te r b o t t l e , and was e q u ip p e d w ith u a f e e d in g d i s c and fo o d d e l i v e r y tu b e s s i m i l a r to th o s e o f th e e x p e r im e n ta l box.

The f e e d in g d i s c was a d j u s te d so t h a t a

fo o d p e l l e t and a s h o t w ore d e l i v e r e d e v e ry t h i r t y s e c o n d s . The s h o t was p e r m itte d t o s t r i k e a g a i n s t th© u n d e r s id e o f

9 th e fo o d p la tf o r m and d ro p i n t o a r e t a i n i n g box. was p e r m itte d t o f a l l on th e p la tfo rm #

The fo o d

T h ese b o x es w ere

d i f f e r e n t i a t e d from th e e x p e rim e n ta l box i n t h a t th e y w ere u n p a in te d arid c o n s id e r a b ly s m a lle r ,

A ll b o x es w ere d u p l i ­

c a te d i n o r d e r t o p e r m it t h e ru n n in g o f two s u b j e c t s a t th e same tim e . P re lim in ary .. The a n im a ls w ere t r a i n e d i n d i v i d u a l l y u n d e r 2 J - h r . fo o d d e p r iv a tio n #

A minimum o f se v e n d a y s was a llo w e d f o r

h a b i t u a t i o n to th e e x p e rim e n ta l an im a l room and t o e s t a b l i s h th e 2 3 - h r . d r i v e ih y th m .

P r e - t r a i n i n g was c a r r i e d o u t i n

two p h a s e s o v e r a p e r io d o f f i v e d a y s .

Each s u b j e c t was a l ­

low ed t o e a t (d ry P u r in a Bog Ghow p e l l e t s ) i n th e f i r s t o f th e t r a i n i n g boxes f o r a n h o u r on th e f i r s t th r e e day s# th e n was g iv e n se c o n d a ry '“r e in f o r c e m e n t t r a i n i n g i n th© box e q u ip ­ ped t o d e l i v e r fo o d p e l l e t s i n c o m b in a tio n w ith l e a d s h o t on th e f o llo w in g two d a y s .

T h is t r a i n i n g c o n s is te d o f 60 com­

b i n a t i o n s o f s h o t and p e l l e t g iv e n i n two g ro u p s o f 30 e a c h . Th© se c o n d a ry r e i n f o r c i n g p r o p e r t i e s o f t h e sound o f th e d e l i v e r y o f th e s h o t and p e l l e t w ere e s t a b l i s h e d to a s s u r e Im m ediate r e in f o r c e m e n t even th o u g h th® a n im a l m ig h t e x p e r ­ ie n c e some d e la y i n l o c a t i n g th© p e l l e t on t h e f i r s t t r i a l s i n th© e x p e r im e n ta l box*

10

F iv e g ro u p s o f animal® w ore t r a i n e d u n d e r f i v e d i f f e r e n t c o n d itio n ® . f o r th e o t h e r th re e *

X|M» o f th e g ro u p a s e rv e d a® c o n t r o l s F o r thee® c o n tro l® (G roups I & I t )

th e tim e o f d e l i v e r y o f fo o d f o llo w in g a re s p o n s e was h e ld c o n s ta n t a t one and 10 sec# r e s p e c t i v e l y th ro u g h o u t th e c o u rs e o f th e ex p e rim en t#

E x p e rim e n ta l G roups i l l and 1?

w ere t r a i n e d on im m ediate d e l i v e r y o f fo o d and E x p e rim e n ta l Group v was t r a i n e d w ith 1 0 - sec* d e la y f a r th e i n i t i a l p e r io d o f th e ex p e rim en t*

a f t e r M rty iaifc^.-iJQ on Day 1 and 10 on

Day 2# th e c o n d itio n s f o r th e s e g ro u p s w ere changed# th e c o n d itio n s f o r G roups I I I and V b e in g in te r - c h a n g e d and Group IV b e in g e x tin g u is h e d * The e x p e rim e n ta l c o n d i tio n s i n te rm s o f t r i a l s # e x p e rim e n ta l days# and th© s p e c i f i c g ro u p d e s ig n a ti o n s i s g iv e n b e lo w tDay 1 T r i a l s D elay

Day 3 T r i a l s D elay

I

1 -se c . Gont#

30

1

sec.

30

1

sec.

30

1

II

10-aeo* Cent*

30

10 s e c .

30

10 s e c .

30

10 s e c .

ill

1 -sec . Exper*

30

1

sec.

fOM oo

Day 2 T r i a l s D elay

1 sec. 10 sec*

30

10 s e c .

IV

1 -aec . E x p er.

30

1

see.

10 20

1 see. In fin ite

30

in fin ite

V

1 0 -se c. Exper*

30

10 s e c .

fOi-* OO

a ro u p

10 s e c . 1 sec.

30

1

sec.

sea.

11 P ro c e d u re i n T r a in in g s e r i e s Th® d a t a o f th e e x p e rim e n t w ere c o l l e c t e d d u r in g on© -hour se ssio n © on ©ach o f th® thro© d a y s f o llo w in g th® c o m p le tio n o f th© se co n d ary r e in f o r c e m e n t t r a i n i n g . l i g h t e d e x p e r tm e n ta l d a r k room was need*

4 d im ly

The i l l u m i n a t i o n

was p ro v id e d by two 1 0 0 -w a tt b u lb s , one b e in g l o c a t e d o n th e o u ts i d e o f e a c h e x p e r im e n ta l box and s h ie ld e d so t h a t o n ly i n d i r e c t l i g h t e n t e r e d th© boxesOn th e f i r s t day* th e a n im a ls w ere i n d i v i d u a l l y in tr o d u c e d i n t o t h e i r e x p e rim e n ta l boxes w ith th e s tim u lu s l i g h t on and w ere p e r m it te d t o s e c u r e f i v e p e l l e t s o f f o o d , t h r e e from th® s l o t th r o u g h w h ich th© b a r was s u b s e q u e n tly p r e s e n t e d , and two from th® f l o o r o f th e box i n th® v a c l n i t y o f th e fo o d cup*

One© th e a n im a l had s e c u re d th e f i v e p e l ­

l e t s , th© s tim u lu s l i g h t was tu r n e d o f f and th e t r a i n i n g s e r i e s begun* Th© p r o c e d u r e i n th© t r a i n i n g s e r i e s was a s f o l ­ lows*

The e x p e r im e n te r s e t th e fo o d m echanism f o r th e

a p p r o p r ia te d e l a y , cooked th e b a r , r o t a t e d th e b a r i n t o th e bo x , th e n w a ite d th e 9 0 - s e c . i n t e r - t r i a l i n t e r v a l b e f o r e r e p e a t i n g th e se q u e n c e .

I f a r e s p o n s e d id n o t o c c u r i n

30 s e e * , i t was e l i c i t e d by h o ld in g a p e l l e t o f fo o d i n th e s l o t above th e b a r .

When t h i s was n e c e s s a r y , th© 9 0 - s e o .

i n t e r - t r i a l i n t e r v a l was a p p ro x im a te d a s c l o s e l y a s th®

12 a n im a l *a re s p o n s e w ould p e rm it# T ills p r o c e d u r e was c o n tin u e d th ro u g h o u t th e t h r e e d a y s o f th e t r a i n i n g a e r ie s * e a c h a n im a l b e in g con* tin n e d i n t h e box t o w hich I t wa© a s s ig n e d on t h e f i r s t day w ith no s p e c i a l r e * i n t r o d u o t i o n p ro c e d u re on Days 3 an d 3*

One e x c e p tio n t o th® above se q u e n c e was made f o r

th o s e a n im a ls t h a t worn e x tin g u is h e d #

D u rin g e x t in c t io n *

t h e M r was r o t a t e d o u t o f th® box by th e e x p e rim e n te r a t th e end o f th© 3 w here th e p erfo rm a n ce m easu re i s IQ/me&Ian la t e n c y i n sec* Mean le a n Mean Mean P erfo rm an c e P erfo rm an c e G ain G ain T r i a l s 31*41 T r i a l s 4 2 -6 0 D iff* Group I 1- s e c . C o n tro l

27*10

34*11

7*01 1 .6 3

Group I I I 1 -1 0 -se c . Sxper#

25*51

3 0 .8 9

**UM p

3*38

*784

*44

21 1ay 10) o f th e I n d i v i d u a l m ed ian r e s p o n s e m e a su re s i n se c o n d s f o r t r i a l s 61 t o 90 w ere 24*43 f o r th e 1 0 -sea * c o n t r o l g ro u p ( I I ) and 33*79 f o r t h e 1 0 -1 -s e c * e x p e r im e n ta l g ro u p (V) t h a t w as now b e in g rew ard ed a f t e r one sec*

The d i f f e r e n c e , 9 * 3 6,

was s i g n i f i c a n t a t t h e 0*6 p e r c e n t, l e v e l o f c o n fid e n c e < t * 2*77)* The r e s u l t s f o r th e s h i f t i n th e o p p o s ite d i r e c ­ t i o n from a o n e - s e c . to a 10-@ec* d e la y a r e shown i n th e u p p e r p a r t o f Fig* 2*

C o n tra ry to th e f i n d in g s J u s t d i s c u s ­

sed and a l s o t o th e r e s u l t s o f com p arab le e x p e rim e n ts i n w hich th e m a g n itu d e o f rew ard was s h i f t e d from a more f a v o r ­ a b le t o a l e s s f a v o r a b le c o n d i tio n , th e s h i f t had l i t t l e o r no e f f e c t *

The means o f th e I n d iv id u a l p e rfo rm a n c e m easu res

f o r th e 1 -1 0 -se c * e x p e r im e n ta l g ro u p ( I I I ) and f o r th e o n e sec* c o n t r o l g ro u p ( I ) f o r th e 11 p r e - s h i f t t r i a l s and th e 19 p o s t - s h i f t t r i a l s a r e shown i n T ab le I I*

I t w i l l be

s e e n from t h i s t a b l e and a l s o from F ig* 2 t h a t th e gro u p ( I I I ) s h i f t e d t o 1 0 -aec* d e la y a c t u a l l y c o n tin u e d to im prove* T h is Im provem ent c o n tin u e d ev e n i n t o bay 3* on w hich th e mean p e rfo rm a n c e m easu re was 33*70*

W hile th e g a in (5 * 3 6 )

from p r e - s h i f t to th e p o s t - s h i f t p e r io d shown by th e e x p e r i ­ m e n ta l g ro u p was n o t a s l a r g e a s t h a t (7 * 0 1 ) mad© by th e c o n t r o l g ro u p ( I ) c o n tin u e d on o n e -se c * d e l a y , th e d i f f e r ­ e n c e ( 1 .6 3 ) i s n e g lig a b le *

s i m i l a r l y th© d i f f e r e n c e (3*55)

22 b etw een t h e s e two g ro u p s on d ay th r e e was n o t l a r g e and a g a in was n o t s i g n i f i c a n t ( t * *88)# #

* 4 s t h e c o n d i tio n o f h o m o g en eity o f v a r ia n c e was n o t s a t i s f i e d i n t h e e a s e o f th e d i s t r i b u t i o n s o f g a in s o f th e s e two g ro u p s# th e t - t e s t c o u ld n o t be used* The a p ­ p l i c a t i o n o f th e M a n n -? h itn ey U - t e s t (4 ) I n d ic a te d t h a t th e d i f f e r e n c e was n o t s i g n i f i c a n t (P * #44)*

E f f e c t o f F a i l u r e o f R e in fo rc e m e n t I n o r d e r to a s c e r t a i n th e e f f e c t o f s h i f t i n g t o no rew ard ( i n f i n i t e d e la y ) # rew ard was d is c o n tin u e d I n one g ro u p a f t e r 40 t r i a l s u n d e r th e o n e -se c # d e la y c o n d itio n * The p e rfo rm a n c e o f t h i s g ro u p (XV) I s shown I n Pig* 5 I n w nioh th e c u rv e f o r th e one seco n d c o n t r o l group i s a l s o g iv e n f o r co m p ariso n p u rp o se s#

I t w i l l be se e n t h a t d e s p i t e

d is c o n tin u a n c e o f th e rew ard# p e rfo rm a n c e a c t u a l l y c o n tin u e d t o Im prove f o r th e n e x t tw e lv e t r i a l s * / e x t i n c t i o n to o k p la c e f a i r l y

F o llo w in g th is #

r a p id ly a lth oi u g h th e m a jo r d ro p

o o cu red a t th e b e g in n in g o f Bay 3*

T hese f i n d i n g s i n d i c a t e

t h a t th e r e s p o n s e was h ig h ly r e a l s t e n t t o e x p e rim e n ta l ex** tln e tio n *

U ndoubtedly one o f th e f a c t o r s r e s p o n s i b le f o r

t h i s r e s i s t a n c e was th e f a c t t h a t th e am ount o f f o r c e r e ­ q u ir e d t o d e p r e s s th e b a r was e x tre m e ly sm a ll ( l e s s th a n one gm)#

The sm a ll am ount o f w ork In v o lv e d I n e x e r t i n g

su c h a f o r c e com bined w ith th e 9 0 - s e c . i n t e r - t r i a l i n t e r v a l

o oo /C . 00 O ao W 0

OC

*rH

5 O

0

xi P

XI

P •H 6

0 -P « a o

o

_co

ca,o rH 0 *04 •H f4 P J§ P cf •rl o

O £O 3 rr-t H