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A failure to find schedule-induced grit and water consumption in the pigeon Whalen, Thomas Eric 1975

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A FAILURE TO FIND SCHEDULE-INDUCED GRIT AND WATER CONSUMPTION IN THE PIGEON by THOMAS ERIC WHALEN B.A. U n i v e r s i t y Of C a l i f o r n i a , San Diego, 1973 A THESIS SUBMITTED IN PARTIAL FUFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS i n the Department of Psychology He accept t h i s t h e s i s as conforming t o the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA August 1975 In presenting th i s thes is in pa r t i a l fu l f i lment of the requirements for an advanced degree at the Un ivers i ty of B r i t i s h Columbia, I agree that the L ibrary sha l l make it f ree l y ava i l ab le for reference and study. I fur ther agree that permission for extensive copying of th i s thes is for scho lar ly purposes may be granted by the Head of my Department or by his representat ives. It is understood that copying or pub l i ca t ion of th is thes is for f inanc ia l gain sha l l not be allowed without my wr i t ten permission. Depa rtment The Univers i ty of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date / f A-csfcj*-ABSTRACT I n t h e f i r s t e xperiment two hungry, but o t h e r w i s e u n d e p r i v e d , pigeons were exposed t o v a r i o u s f i x e d i n t e r v a l f o o d r e i n f o r c e m e n t s c h e d u l e s f o r k e y p e c k i n g w h i l e e i t h e r water o r g r i t was c o n c u r r e n t l y , f r e e l y a v a i l a b l e . The i n t e r - r e i n f o r c e m e n t i n t e r v a l was v a r i e d from 30 s e c t o 16 min i n d i f f e r e n t phases of the e x p e r i m e n t . Both s u b j e c t s consumed g r i t , but n e i t h e r s u b j e c t drank water. The n e x t f o u r e x p e r i m e n t s attempted t o r e p l i c a t e the g r i t consumption t h a t o c c u r r e d i n the f i r s t e xperiment or t o produce water consumption. In t h e s e e x p e r i m e n t s the g r i t and water c o n t a i n e r s were moved t o v a r i o u s l o c a t i o n s w i t h i n the e x p e r i m e n t a l chamber, the p r o t e i n c o n t e n t o f t h e s u b j e c t ' s d i e t was v a r i e d , and t h e r e f l e c t i v e windows i n the chamber were c o v e r e d t o e l i m i n a t e the p o s s i b i l i t y t h a t a t t a c k s a t t h e i r own r e f l e c t i o n s were competing w i t h t h e s u b j e c t ' s tendency t o consume g r i t o r water. The s u b j e c t s d i d not consume g r i t o r water i n any o f t h e s e e x p e r i m e n t s . The i m p l i c a t i o n s o f t h i s l a c k of c o n s i s t e n t water and g r i t consumption b e h a v i o u r i n the pigeon f o r v a r i o u s t h e o r i e s o f the d e t e r m i n a n t s of b e h a v i o u r a r e examined. i i TABLE OF CONTENTS A b s t r a c t - - i L i s t o f T a b l e s . - i i v L i s t o f F i g u r e s ;v I n t r o d u c t i o n 1 G e n e r a l Method 8 S u b j e c t s ......................................... 8 Apparatus 9 Procedure ................................ .-..-..-11 Experiment One ...-...-.........-...........---.------12 Method - .- .-..12 R e s u l t s and D i s c u s s i o n ...........................12 Experiment Two - ................18 Method .- 19 R e s u l t s and D i s c u s s i o n ...........................19 Expe r i m e n t Three -.--.22 Method 23 R e s u l t s and D i s c u s s i o n -.24 Experiment Four - -.24 Method - - - 27 R e s u l t s and D i s c u s s i o n 27 Experiment F i v e ......28 Method ... ....31 i i i R e s u l t s and D i s c u s s i o n 3 1 Experiment S i x 32 Method ...... 32 R e s u l t s and D i s c u s s i o n 33 G e n e r a l D i s c u s s i o n 35 R e f e r e n c e s ...........................................51 •: i v LIST OF TABLES C o n d i t i o n s and R e s u l t s f o r Experiment One .....13 C o n d i t i o n s and R e s u l t s f o r Experiment Two .......20 C o n d i t i o n s and R e s u l t s f o r Experiment Three ...23 C o n d i t i o n s and R e s u l t s f o r Experiment Four ........... 28 C o n d i t i o n s and R e s u l t s f o r Experiment F i v e ...........32 R e s u l t s f o r C o n d i t i o n One of Experiment S i x ..........34 R e s u l t s f o r C o n d i t i o n Two o f Experiment S i x ..........34 R e s u l t s f o r C o n d i t i o n Three o f Experiment S i x ........35 LIST OF FIGURES F i g u r e 1 - - . . . . . . - . - . . . - . - - - 1 5 F i g u r e 2 . - - 1 6 F i g u r e 3 .......17 F i g u r e <l . . . . . . . . . . . . . . . . . . . . . . . 2 1 F i g u r e 5 . . . . . . . . . - . . . . - - . - - - - . . - - - . - • - • - • - - • * - • - - • « - » 2 5 1 INTRODUCTION Du r i n g the p a s t f i f t e e n y e a r s , many s t u d i e s , p r i m a r i l y w i t h r a t s , have shown t h a t when food r e i n f o r c e r s 1 a r e d i s t r i b u t e d over t i m e , t h e r a t e of o c c u r r e n c e o f some non-operant b e h a v i o u r s d u r i n g t h e i n t e r - r e i n f o r c e m e n t i n t e r v a l i s a f f e c t e d . F a l k (1969, 1971) has c a l l e d t h e s e b e h a v i o u r s a d j u n c t i v e b e h a v i o u r s and has shown t h a t t h e p r o b a b i l i t y of the o c c u r r e n c e o f t h e s e b e h a v i o u r s depends upon the degree o f d e p r i v a t i o n of the r e i n f o r c e r , the magnitude of t h e r e i n f o r c e r , and t h e d e n s i t y o f t h e s c h e d u l e o f r e i n f o r c e m e n t . To q u a l i f y as a d j u n c t i v e , as F a l k (1971) uses t h e term, a b e h a v i o u r must d i s p l a y c e r t a i n c h a r a c t e r i s t i c s . F i r s t , t h e r a t e of o c c u r r e n c e of t h e b e h a v i o u r d u r i n g i n t e r - s t i m u l u s i n t e r v a l s must i n c r e a s e t o an e x c e s s i v e l e v e l when a s t i m u l u s i s p r e s e n t e d r e p e a t e d l y over a p e r i o d of t i m e . Second, t h e s t i m u l u s must not a c t e i t h e r as an u n c o n d i t i o n e d o r c o n d i t i o n e d s t i m u l u s i n e l i c i t i n g t h e b e h a v i o u r and i t must n o t r e i n f o r c e t h e b e h a v i o u r i n any o b v i o u s f a s h i o n . T h i r d , t h i s i n c r e a s e d r a t e must be s t a b l e o ver t i m e . F o u r t h , the r a t e a t which t h e b e h a v i o u r o c c u r s s h o u l d be a b i t o n i c f u n c t i o n o f t h e r a t e a t which t h i s s t i m u l u s i s d e l i v e r e d . F i n a l l y , t h e b e h a v i o u r s h o u l d o c c u r w i t h t h e h i g h e s t p r o b a b i l i t y j u s t a f t e r t h i s s t i m u l u s has been d e l i v e r e d -The d r i n k i n g b e h a v i o u r of f o o d - d e p r i v e d but w a t e r - s a t e d r a t s has been t h e most e x t e n s i v e l y s t u d i e d example o f b e h a v i o u r which 1 F o r t h e sake o f c o n v e n i e n c e i n t h i s paper s t i m u l i such as f o o d p r e s e n t a t i o n s w i l l be c a l l e d r e i n f o r c i n g s t i m u l i , even though i n some o f the e x p e r i m e n t s c i t e d , they are not r e i n f o r c e r s , b e i n g d e l i v e r e d i n d e p e n d e n t l y of the s u b j e c t ' s b e h a v i o u r . 2 o c c u r s a d j u n c t i v e l y t o food r e i n f o r c e m e n t . F a l k (1966) found t h a t t h e amount of water t h a t a f o o d - d e p r i v e d r a t d r i n k s d u r i n g i n t e r - f o o d i n t e r v a l s i s a b i t o n i c f u n c t i o n o f t h e d e n s i t y o f the f e e d i n g s c h e d u l e , w i t h the maximum amount o f water consumption o c c u r r i n g on s c h e d u l e s w i t h an i n t e r - f o o d i n t e r v a l o f about two minutes. At t h i s peak, a r a t w i l l sometimes consume more t h a n t h r e e t i m e s h i s normal d a i l y water i n t a k e i n a 3.17 h r s e s s i o n ( F a l k , 1967). T h i s p o l y d i p s i a has been r e p o r t e d t o o c c u r i n a number of s p e c i e s o f a n i m a l s , o t h e r t h a n r a t s , i n c l u d i n g mice ( K u t s c h e r , 1971; P a l f a i , K u t s c h e r , and Symons, 1971), monkeys (Shuster and Woods, 1966; M e l l o and Mendelson, 1971) and, i n one s t u d y , p i g e o n s (Shanab and P e t e r s o n , 1969). B e s i d e s water d r i n k i n g , v a r i o u s o t h e r b e h a v i o u r s seem t o s a t i s f y many of F a l k • s c h a r a c t e r i s t i c s f o r a d j u n c t i v e b e h a v i o u r : a g g r e s s i o n i n s q u i r r e l monkeys (Hutcheson, A z r i n and Hunt, 1968) and p i g e o n s ( G e n t r y , 1968), p i c a i n r h e s u s monkeys ( V i l l a r r e a l , 1967) and r a t s (Freed and Hymowitz, 1969), a i r l i c k i n g i n r a t s (Mendelson and C h i l l a g , 1970) and n i t r o g e n l i c k i n g i n r a t s ( T a y l o r and L e s t e r , 1969), wheel r u n n i n g i n r a t s ( L e v i t s k y , 1967; S e g a l , 1969; and S k i n n e r and Morse, 1957), and t a i l gnawing i n r a t s ( L a t i e s , Weiss, C l a r k , and R e y n o l d s , 1965). D r i n k i n g i s t h e most commonly s t u d i e d a d j u n c t i v e b e h a v i o u r and t h e pigeon i s one o f the most common e x p e r i m e n t a l s u b j e c t s i n p s y c h o l o g i c a l r e s e a r c h on o p e r a n t b e h a v i o u r . I t i s t h e r e f o r e s u r p r i s i n g t h a t the one r e p o r t o f s c h e d u l e - i n d u c e d p o l y d i p s i a i n the p i g e o n has never been r e p l i c a t e d . Even a d i r e c t r e p l i c a t i o n o f t h i s d a ta would be 3 i n t e r e s t i n g , as t h e s t u d y by Shanab and P e t e r s o n was not a p a r t i c u l a r l y r i g o r o u s d e m o n s t r a t i o n of p o l y d i p s i a i n t h e p i g e o n . Only one s u b j e c t was used, and p o l y d i p s i a was found w i t h o n l y two food s c h e d u l e s , both o f which had mean i n t e r - r e i n f o r c e m e n t i n t e r v a l s of 2 min. The f i r s t s c h e d u l e p r o v i d e d a r e i n f o r c e r f o r the f i r s t response t h a t o c c u r r e d a f t e r at l e a s t 2 min had passed s i n c e the p r e v i o u s r e i n f o r c e m e n t had been d e l i v e r e d (FI 2 min s c h e d u l e ) . The second s c h e d u l e p r o v i d e d a r e i n f o r c e r f o r t h e f i r s t r e s p o n s e t h a t o c c u r r e d a f t e r a v a r i a b l e i n t e r v a l , a v e r a g i n g 2 min, had passed s i n c e t h e p r e v i o u s r e i n f o r c e m e n t (VT 2 min). The s u b j e c t was exposed t o t h e s e two s c h e d u l e s f o r a t o t a l o f 44 s e s s i o n s and t o f i x e d i n t e r v a l s c h e d u l e s o f f o o d r e i n f o r c e m e n t w i t h i n t e r - r e i n f o r c e m e n t i n t e r v a l s o f 30, 60 and 180 sec f o r 2, 3 and 4 s e s s i o n s , r e s p e c t i v e l y . The d r i n k i n g which was o b t a i n e d w i t h s c h e d u l e s of foo d r e i n f o r c e m e n t w i t h a mean i n t e r - r e i n f o r c e m e n t i n t e r v a l o f 2 min d i d not o c c u r d u r i n g the s c h e d u l e s w i t h o t h e r i n t e r - r e i n f o r c e m e n t i n t e r v a l s . The p o s s i b i l i t y o f such a s h a r p g r a d i e n t o f d r i n k i n g as a f u n c t i o n o f s c h e d u l e d e n s i t y s u g g ested by t h i s d a t a i s i n t r i g u i n g and was one o f t h e phenomena t h a t t h e p r e s e n t s e r i e s o f e x p e r i m e n t s was i n i t i a l l y d e s i g n e d t o examine. A c l o s e e x a m i n a t i o n of Shanab and P e t e r s o n ' s d a t a , however, r e v e a l s t h a t t h e i r e x p e r i m e n t d i d not u n e q u i v o c a l l y demonstrate p o l y d i p s i c water consumption. The q u e s t i o n must be r a i s e d as t o whether t h e amounts of water consumption t h a t Shanab and P e t e r s o n r e p o r t e d were e x c e s s i v e . A s u b j e c t might be expected t o d r i n k a t some time when water i s f r e e l y a v a i l a b l e d u r i n g an e x p e r i m e n t a l s e s s i o n which l a s t s f o r more th a n t h r e e hours. To 4 c a l l t h e s u b j e c t ' s water consumption p o l y d i p s i c , one must demonstrate t h a t the amount o f water consumed i s e x c e s s i v e i n some way. T h i s r e q u i r e s comparing the s u b j e c t ' s consumption under t h e e x p e r i m e n t a l c o n d i t i o n s w i t h some c r i t e r i o n o r e x p e c t a t i o n of the s u b j e c t ' s consumption d e r i v e d from some o t h e r s i t u a t i o n . One of t h e most o b v i o u s c r i t e r i a t o use i n d e t e r m i n i n g i f a s u b j e c t ' s water consumption d u r i n g a p a r t i c u l a r s c h e d u l e i s e x c e s s i v e i s t o compare i t t o the water consumption d u r i n g a n o t h e r s c h e d u l e which does not produce e x c e s s i v e water consumption. S p e c i f i c a l l y , the amount o f water consumed d u r i n g t h e F I 2 min s c h e d u l e o f r e i n f o r c e m e n t c o u l d be compared t o the amount o f water consumed d u r i n g a s c h e d u l e i n which each operant response d e l i v e r s a r e i n f o r c e r (CHF s c h e d u l e ) . In t h e r a t , a comparison between a p o l y d i p s i a - g e n e r a t i n g FI 2 min s c h e d u l e and a CRF s c h e d u l e , i n which the r a t i s f r e e t o e a t a l l o f the r e i n f o r c e r s i n a s h o r t p e r i o d o f t i m e , shows t h e r a t d r i n k s t e n t i m e s as much water under the former as under the l a t t e r ( F a l k , 1967). Shanab and P e t e r s o n d i d r e p o r t data from a CRF s c h e d u l e t o compare t o the o t h e r s c h e d u l e s i n t h e i r e x p e r i m e n t , and co n c l u d e d f o r some re a s o n t h a t t h e i r s u b j e c t s had consumed an e x c e s s i v e amount o f water. When a l l o t h e r c o n d i t i o n s b e s i d e s the s c h e d u l e were e q u a l , however, no d i f f e r e n c e i n the amounts o f water consumption on t h e CRF s c h e d u l e and the F I 2 min s c h e d u l e e x i s t e d . With t h e F I 2 min s c h e d u l e o f r e i n f o r c e m e n t i n e f f e c t , t h e e x p e r i m e n t e r s moved the water c o n t a i n e r w i t h o u t c h a n g i n g t h e food s c h e d u l e . The q u a n t i t y o f water consumed d u r i n g an e x p e r i m e n t a l s e s s i o n doubled as a r e s u l t . They never exposed t h e 5 s u b j e c t t o the CEF s c h e d u l e w i t h the water c o n t a i n e r i n t h i s new l o c a t i o n , even though they l e f t the water t h e r e d u r i n g a l l of the o t h e r s c h e d u l e s t h a t t hey used. R a t h e r , they compared the s u b j e c t ' s water consumption d u r i n g t h e s e o t h e r s c h e d u l e s t o the s u b j e c t ' s water consumption d u r i n g t h e CRF s c h e d u l e w i t h the water c o n t a i n e r i n the f i r s t l o c a t i o n and c o n c l u d e d t h a t e x c e s s i v e consumption had o c c u r r e d . Because t h e l o c a t i o n of t h e water c o n t a i n e r was shown t o make such a l a r g e d i f f e r e n c e , Shanab and P e t e r s o n a r e i n c o r r e c t i n making a comparison which confounds t h e water l o c a t i o n w i t h the type of s c h e d u l e . One cannot d e c i d e whether t h e i r s u b j e c t showed e x c e s s i v e water consumption o r not from t h e i r d a t a u s i n g t h i s c r i t e r i o n . Another p o s s i b l e c r i t e r i o n f o r c o n c l u d i n g t h a t water consumption i n a s u b j e c t i s e x c e s s i v e i s t o compare the water consumption of the s u b j e c t d u r i n g t h e e x p e r i m e n t a l s e s s i o n t o the s u b j e c t ' s normal d a i l y water i n t a k e . T h i s i s not s t r i c t l y an e x p e r i m e n t a l c o m p a r i s o n , but r a t h e r s i m p l y a s c a l e by which t o e v a l u a t e the amount of water t h a t a s u b j e c t consumes. For example, i n the f i r s t d e m o n s t r a t i o n of s c h e d u l e - i n d u c e d p o l y d i p s i a ( F a l k , 1961), r a t s drank an average o f 91.55 ml of water d u r i n g a 3.17 h r s e s s i o n on a VI 1 min s c h e d u l e of f o o d r e i n f o r c e m e n t . W h i l e t h i s d a t a has v e r y l i t t l e meaning by i t s e l f , i t i s c l e a r t h a t t h i s q u a n t i t y i s e x c e s s i v e when one c o n s i d e r s t h a t t h e s e r a t s o n l y drank a mean of 26.96 ml per day when t h e y were not b e i n g exposed t o t h e e x p e r i m e n t a l c o n d i t i o n s . D u r i n g t h e 3.17 hr s e s s i o n t h e s e r a t s consumed 3.4 t i m e s t h e i r normal d a i l y water i n t a k e . 6 Shanab and P e t e r s o n ' s s u b j e c t drank an amount t h a t o n l y sometimes exceeded i t s normal d a i l y water i n t a k e . Two v a l u e s a r e r e p o r t e d as t h e s u b j e c t ' s normal d a i l y water i n t a k e . The f i r s t q u a n t i t y i s t h e amount of water t h a t t h e s u b j e c t drank w h i l e w e i g h i n g 80% of i t s ad l i b w e i g h t , and t h e second i s the amount of water t h a t t h e s u b j e c t drank w h i l e a t i t s ad l i b weight. I n comparison w i t h t h e q u a n t i t y of water t h a t the s u b j e c t drank a t 80% of i t s ad l i b w e i g h t , consumption l e v e l s d u r i n g the F I 2 min s c h e d u l e w i t h t h e water c o n t a i n e r i n the f i r s t l o c a t i o n i s l e s s than the s u b j e c t ' s normal d a i l y water i n t a k e , b e i n g o n l y 68% o f i t s mean d a i l y water i n t a k e w h i l e consumption l e v e l s d u r i n g t h e o t h e r F I 2 min s c h e d u l e and the two VI 2 min s c h e d u l e s w i t h t h e water c o n t a i n e r i n t h e second l o c a t i o n exceeded the s u b j e c t ' s normal d a i l y water i n t a k e by 154, 159, and 236%, r e s p e c t i v e l y . In comparison w i t h t h e s u b j e c t ' s ad l i b mean d a i l y water i n t a k e , however, a l l f o u r s c h e d u l e s r e s u l t e d i n l e s s than t h e s u b j e c t ' s normal d a i l y water i n t a k e , t h e amounts of water consumed on the s e s c h e d u l e s b e i n g 65, 67 and 98% o f t h e s u b j e c t ' s ad l i b mean d a i l y water i n t a k e , r e s p e c t i v e l y . These r e s u l t s a r e Shanab and P e t e r s o n ' s s t r o n g e s t argument t h a t t h e i r s u b j e c t ' s water i n t a k e d u r i n g t h i s e x periment was e x c e s s i v e . However, w h i l e t h r e e o f t h e s e e i g h t v a l u e s d i d exceed t h e pigeon's mean d a i l y water i n t a k e , r a t s consume much more than t h e i r mean d a i l y i n t a k e o f water measured a t e i t h e r 80 o r 100% of t h e i r ad l i b body weight ( F a l k , 1964 and F a l k , 1967). By t h i s c r i t e r i o n , t h e n , the argument t h a t t h e pig e o n ' s consumption of water i s e x c e s s i v e under t h e s e s c h e d u l e s i s not n e a r l y as s t r o n g as t h e argument t h a t the r a t ' s consumption of water i s 7 e x c e s s i v e . Another c r i t e r i o n which has been used t o g i v e a sense o f s c a l e t o t h e amount of water t h a t a s u b j e c t consumes under t h e s e c o n d i t i o n s i s a comparison o f the weight o f the water consumed w i t h the t o t a l body weight of t h e s u b j e c t . B a t s have been found t o d r i n k about one h a l f t h e i r body weight i n water d u r i n g a 3.17 h r s e s s i o n ( F a l k , 1961). While Shanab and P e t e r s o n do not r e p o r t t h e weight of t h e i r s u b j e c t , b e i n g a White Carneau p i g e o n , i t p r o b a b l y weighed between 350 and 500 g. Assuming t h a t t h e s u b j e c t weighed o n l y 350 g, then d u r i n g t h e second VI 2 min s c h e d u l e c o n d i t i o n t h e s u b j e c t consumed a mean o f 14.8% of h i s §.<! l i f e body weight i n water and d u r i n g t h e o t h e r s c h e d u l e s , t h e s u b j e c t consumed 4.3, 9.7, and 10.0% o f h i s ad l i b body weight i n water i n 3.5 h r . C l e a r l y one cannot argue t h a t t h e p i g e o n was consuming an e x c e s s i v e amount of water i n r e l a t i o n t o the r a t ' s consumption u s i n g t h i s c r i t e r i o n . C o n s i d e r i n g t h i s a n a l y s i s , i t seemed w o r t h w h i l e t o conduct t h e p r e s e n t s e r i e s o f e x p e r i m e n t s t o s y s t e m a t i c a l l y r e p l i c a t e Shanab and P e t e r s o n ' s experiment and d i s c o v e r I f o t h e r p i g e o n s , a t some o t h e r s c h e d u l e d e n s i t y , would show water consumption which was u n e q u i v o c a l l y e x c e s s i v e a c c o r d i n g t o a t l e a s t some of the c r i t e r i a commonly used. B e s i d e s a t t e m p t i n g t o g a t h e r data on the magnitude o f water consumption i n t h e p i g e o n a t d i f f e r e n t f o o d s c h e d u l e p a r a m e t e r s , t h i s experiment a l s o s e a r c h e d f o r a d j u n c t i v e g r i t consumption i n t h e p i g e o n . I n a d d i t i o n t o f o o d and water, p i g e o n s and o t h e r t y p e s of b i r d s a l s o e a t g r i t , o r s m a l l p i e c e s of rock and sand, which h e l p s d i g e s t i o n by g r i n d i n g 8 a g a i n s t the g r a i n i n the c r o p . Because o f t h e o b v i o u s r e l a t i o n s h i p i n t h e pigeon between e a t i n g g r a i n and e a t i n g g r i t , i t seemed p o s s i b l e t h a t p i g eons would show a d j u n c t i v e g r i t c onsumption i n a d d i t i o n t o a d j u n c t i v e water consumption d u r i n g v a r i o u s s c h e d u l e s of g r a i n r e i n f o r c e m e n t . GENERAL METHOD S u b j e c t s The s u b j e c t s were f i v e White K i n g p i g e o n s , c a l l e d WK7, HK10, «K17, HK28, and WK32. Each of the s u b j e c t s had p r i o r e x p e r i e n c e i n v a r i o u s o perant c o n d i t i o n i n g e x p e r i m e n t s , but none of t h e s u b j e c t s had e v e r r e c e i v e d e i t h e r water o r g r i t o u t s i d e of t h e i r home cages. The s u b j e c t s were m a i n t a i n e d a t about 80% of t h e i r ad l i b body weight throughout the experiment by g r a i n o b t a i n e d d u r i n g and a f t e r t h e e x p e r i m e n t a l s e s s i o n s . The food g i v e n i n t h e i r i n d i v i d u a l home cages a t t h e end of each e x p e r i m e n t a l s e s s i o n and on days when t h e s u b j e c t s d i d not r e c e i v e a s e s s i o n was always mixed g r a i n , c o n s i s t i n g o f a p p r o x i m a t e l y 44% wheat, 26% c o r n , 18% k a f i r and 12% maple peas. T r a c e s of b a r l e y and w i l d o a t s were p r e s e n t but co m p r i s e d l e s s than 1% o f the m i x t u r e . During a l l o f t h e e x p e r i m e n t a l s e s s i o n s and d u r i n g p o s t - s e s s i o n f e e d i n g s i n t h e f i r s t and f o u r t h e x p e r i m e n t s t h e peas were not i n c l u d e d i n t h e f e e d m i x t u r e . The p r o p o r t i o n s o f o t h e r g r a i n s remained the same, however, so t h a t t h e g r a i n m i x t u r e c o n s i s t e d o f a p p r o x i m a t e l y 50% wheat, 30% c o r n 9 and 20% k a f i r w i t h t r a c e s o f b a r l e y and w i l d o a t s s t i l l p r e s e n t -There was always g r i t and water i n t h e home cag e s . G r a n i t e g r i t was used i n both t h e e x p e r i m e n t a l s e s s i o n s and i n t h e home cages. The average weight of one p i e c e o f g r i t was 0.004 g when dry and 0.005 g when m o i s t , as i t was d u r i n g t h e s e e x p e r i m e n t s . A p p a r a t u s Two BSB/LVE c o n d i t i o n i n g chambers f o r p i g e o n s were used. The chamber used f o r s u b j e c t s WK7 and WK10 was 35 cm h i g h , 35 cm wide and 50 cm l o n g . The chamber used f o r s u b j e c t s WK17, »K28 and WK32 was 35 cm h i g h , 30 cm wide, and 30 cm l o n g . Both chambers were i n s u l a t e d t o a t t e n u a t e e x t r a n e o u s sounds. Any such sounds were f a r t h e r masked by v e n t i l a t i o n f a n s . The windows on both chambers were c o v e r e d from the o u t s i d e w i t h c a r d b o a r d t o pr e v e n t t h e b i r d s from being d i s t r a c t e d by e v e n t s i n t h e room i n which t h e e x p e r i m e n t a l chambers were l o c a t e d . Both e x p e r i m e n t a l chambers were i l l u m i n a t e d w i t h a 7 W h o u s e l i g h t . I n a l l e x p e r i m e n t s t h e r e s p o n s e keys were i l l u m i n a t e d w i t h red l i g h t from I n d u s t r i a l E l e c t r o n i c s S e r i e s 10 p r o j e c t o r s . Pecks on t h e response keys which exceeded about 0.2 N f o r c e o p e r a t e d t h e p e c k - s e n s i n g m i c r o s w i t c h . A s o l e n o i d - o p e r a t e d g r a i n hopper was l o c a t e d d i r e c t l y below the response key i n each chamber. D u r i n g r e i n f o r c e m e n t t h e f o o d hopper was i l l u m i n a t e d by a 7 I l i g h t and the key l i g h t was t u r n e d o f f . A r e c t a n g u l a r g l a s s c o n t a i n e r , 6 cm h i g h , 8 cm deep, and 10 cm wide c o n t a i n i n g e i t h e r water o r g r i t , was p l a c e d i n t h e chambers i n a c o r n e r f u r t h e s t from the re s p o n s e keys and t h e 10 f e e d e r . Pecks by t h e s u b j e c t s which c o n t a c t e d t h e water or g r i t were d e t e c t e d by a d r i n k o m e t e r c i r c u i t . When g r i t was p l a c e d i n the c o n t a i n e r , i t was dampened i n o r d e r t h a t t h e c u r r e n t from the d r i n k o m e t e r c o u l d pass through i t . T h i s s h o u l d not have i n t e r f e r e d w i t h the s u b j e c t s consumption o f t h e g r i t , as p i g e o n s have been r e p o r t e d t o p r e f e r damp g r i t t o dry g r i t ( L e v i , 1974, page 504). T h i s c o n t a i n e r was weighed t o t h e n e a r e s t gram b o t h b e f o r e and a f t e r each s e s s i o n . D u r i n g a two hour s e s s i o n between 0.5 and 1.5 g of m o i s t u r e e v a p o r a t e d from e i t h e r t h e g r i t o r the water i n the WK7 and WKlO's chamber, and between 2.5 and 3.5 g ev a p o r a t e d i n t h e o t h e r chamber. T h i s d i f f e r e n c e was p r o b a b l y caused by the d i f f e r e n c e i n the s i z e o f t h e chambers and i n t h e l o c a t i o n of t h e v e n t i l a t i o n f a n . Dampened paper t o w e l s were p l a c e d on t h e f l o o r o f t h e chambers about the g l a s s c o n t a i n e r t o ensure t h a t t h e s u b j e c t ' s f e e t would p r o v i d e a good e l e c t r i c a l c o n t a c t f o r the d r i n k o m e t e r c i r c u i t . The paper t o w e l s a l s o p r o v i d e d an easy way t o check f o r p o s s i b l e s p i l l a g e of t h e g r i t from t h e c o n t a i n e r . P e r i o d i c a l l y they were l e f t dry t o check f o r p o s s i b l e water s p i l l a g e , a l t h o u g h i t t u r n e d out t h a t s p i l l a g e was never a problem f o r e i t h e r t h e g r i t o r t h e water. The i n t e r - r e i n f o r c e m e n t i n t e r v a l was d i v i d e d i n t o t h i r d s f o r t he purpose o f c o l l e c t i n g the d a t a . I n t h i s manner, t h e average d i s t r i b u t i o n of keypecks and c o n t a c t s w i t h e i t h e r t h e water or the g r i t d u r i n g the i n t e r - r e i n f o r c e m e n t i n t e r v a l was o b t a i n e d . 1 1 S c h e d u l e s were programmed and data were r e c o r d e d w i t h BES/LVE s o l i d - s t a t e and e l e c t r o m e c h a n i c a l equipment. Proc e d u r e E x p e r i m e n t a l s e s s i o n s were a r r a n g e d f i v e days a week. Dur i n g t h e f i r s t f i v e c o n d i t i o n s o f Experiment One t h e s e s s i o n s were conducted i n the l a t e a f t e r n o o n b e g i n n i n g between 15:00 and 18:00 h r . D u r i n g t h e remainder of t h e e x p e r i m e n t s the s e s s i o n s were conducted i n t h e l a t e e v e n i n g b e g i n n i n g between 21:00 and 24:00 h r . S u b j e c t s WK7, HK10 and WK32 were p l a c e d i n t h e a p p a r a t u s f o r 2 hr each day. The o t h e r s u b j e c t s were p l a c e d i n t h e a p p a r a t u s f o r 1 hr each day. For a l l e x p e r i m e n t s , e x c e p t t h e f i f t h , t h e s u b j e c t s were exposed to F I s c h e d u l e s such t h a t t h e f i r s t key peck t o o c c u r a f t e r a f i x e d p e r i o d o f time had passed s i n c e the s t a r t of t h e s e s s i o n or t h e p r e v i o u s r e i n f o r c e m e n t produced a 5 sec p r e s e n t a t i o n of mixed g r a i n i n the l i g h t e d f o o d hopper. The s u b j e c t s were always p e r m i t t e d f r e e a c c e s s t o e i t h e r g r i t or water throughout the s e s s i o n . E x p e r i m e n t a l c o n d i t i o n s were n o r m a l l y changed when a s u b j e c t ' s b e h a v i o u r had been s t a b l e as determined by v i s u a l i n s p e c t i o n f o r at l e a s t 5 days and t h e s u b j e c t had been exposed t o an e x p e r i m e n t a l c o n d i t i o n f o r a t l e a s t 7 days. The d a t a p r e s e n t e d f o r each o f t h e e x p e r i m e n t s i s the a r i t h m e t i c mean o v e r t h e s e l a s t f i v e days o f each c o n d i t i o n . The l a s t f i v e e x p e r i m e n t s f o l l o w e d d i r e c t l y a f t e r one a n o t h e r , such t h a t each experiment began on t h e s e s s i o n f o l l o w i n g t h e s e s s i o n i n which t h e p r e c e e d i n g experiment ended. 12 EXPERIMENT ONE T h i s experiment s i m p l y measured t h e amount of water and g r i t consumed by s u b j e c t s w h i l e t h e y \ e r e exposed t o v a r i o u s f i x e d i n t e r v a l food r e i n f o r c e m e n t s c h e d u l e s f o r key p e c k i n g . I n t e r - r e i n f o r c m e n t i n t e r v a l s were v a r i e d from 1 min (FI 1 min) t o 16 min (FI 16 min). Method S u b j e c t s WK7 and WK10 s e r v e d as s u b j e c t s . The o r d e r o f t h e s c h e d u l e s , whether water o r g r i t was a v a i l a b l e , and the number of s e s s i o n s d u r i n g each of these c o n d i t i o n s are l i s t e d i n T a b l e 1. B a s i c a l l y , t h e f i x e d i n t e r v a l s c h e d u l e v a l u e was i n c r e a s e d i n an a s c e n d i n g s e r i e s from a F I 2 min t o a F I 16 min by d o u b l i n g t h e i n t e r - r e i n f o r c m e n t i n t e r v a l . The s c h e d u l e s were then d e c r e a s e d i n a d e scending s e r i e s by h a l v i n g t h e i n t e r - r e i n f o r c m e n t i n t e r v a l . The s u b j e c t was g i v e n an o p p o r t u n i t y t o e a t g r i t d u r i n g each of t h e d i f f e r e n t s c h e d u l e s and an o p p o r t u n i t y t o d r i n k water a t each of the s c h e d u l e s , e x c e p t f o r the F I 4 min and t h e F I 8 min v a l u e s on t h e a s c e n d i n g s e r i e s of s c h e d u l e s . R e s u l t s and D i s c u s s i o n The l a s t t h r e e columns of T a b l e 1 show the a r i t h m e t i c mean ( f o r the l a s t f i v e days o f each c o n d i t i o n ) o f the number of grams of water or g r i t consumed, the number o f t i m e s the b i r d came i n c o n t a c t w i t h t h e g r i t o r the number of seconds t h a t t h e 13 TABLE 1 The o r d e r o f the c o n d i t i o n s and t h e r e s u l t s f o r each o f t h e s u b j e c t s i n Experiment One- The f i r s t column l i s t s the number of the s u b j e c t . The second and t h i r d columns l i s t t h e i n t e r -r e i n f o r c e m e n t i n t e r v a l and the c o n t e n t s of the g l a s s c o n t a i n e r . The f o u r t h column l i s t s t h e number o f s e s s i o n s i n each c o n d i t i o n . The l a s t t h r e e columns l i s t t h e a r i t h m e t i c mean of the p e r c e n t o f i n t e r v a l s d u r i n g which t h e s u b j e c t came i n t o c o n t a c t w i t h t h e g r i t a t l e a s t once, the number of c o n t a c t s w i t h the g r i t o r number o f seconds t h a t t h e s u b j e c t was i n c o n t a c t w i t h t h e water and t h e t o t a l w e i g h t , i n grams, of the water o r g r i t t h a t was removed from the c o n t a i n e r . Each o f t h e s e v a l u e s was averaged over the l a s t f i v e s e s s i o n s of each c o n d i t i o n . S u b j e c t FI C o n t a i n e r Number P e r c e n t C o n t a c t s Weight Number Value C o n t e n t s Of Of With The Of The S e s s i o n s I n t e r v a l s G r i t Or G r i t Or With G r i t Water Water E a t i n g Consumed WK7 2 Min Water 14 2 Min G r i t 18 2 Min Water 7 4 Min G r i t 10 8 Min G r i t 10 16 Min G r i t 10 16 Min Water 7 8 Min Water 7 8 Min G r i t 10 4 Min Water 8 WK10 2 Min Water 12 2 Min G r i t 17 2 Min Water 7 4 Min 1 G r i t 10 8 Min G r i t 10 16 Min G r i t 10 16 Min Water 7 8 Min Water 7 8 Min G r i t 10 4 Min Water 8 4 Min G r i t 13 2 Min Water 7 2 Min G r i t 10 1 Min Water 7 1 Min G r i t 10 0. 0. 38.3 1077.8 7.25 1.8 0. 34.8 1188.6 5.6 55.6 384.0 3.8 87.5 636.6 5.7 0. .4 0. 0. 35.7 215.4 2. 8 0. 0. 0. 0. 52.7 1049.8 15.0 2.2 0. 76,0 1678.2 16.2 98.7 2470.4 26.6 100. 752.2 9. 6 0. 0. .2 0. 86.5 470.6 4. 0. 0. 33.5 439.0 5. 8 0. 0. 85.7 893.2 10.4 1.0 2. 8 61.0 1295-8 14.2 14 b i r d was i n c o n t a c t w i t h the water, and, f o r t h o s e c o n d i t i o n s where g r i t was a v a i l a b l e , t h e p e r c e n t of the i n t e r - r e i n f o r c e m e n t i n t e r v a l s d u r i n g which some g r i t consumption o c c u r r e d . I n no c o n d i t i o n was t h e r e an amount of water m i s s i n g from the c o n t a i n e r which was i n excess o f t h e amount which would be ex p e c t e d from normal e v a p o r a t i o n . F u r t h e r m o r e , d u r i n g the whole e x p e r i m e n t , t h e s u b j e c t s had almost no c o n t a c t w i t h t h e water as measured by t h e d r i n k o m e t e r c i r c u i t . The g r e a t e s t amount of c o n t a c t w i t h the water was shown by WK10 on a F I 2 min s c h e d u l e , and t h i s o n l y amounted t o a mean o f 2.2 sec of c o n t a c t w i t h the water over the l a s t f i v e days o f t h i s c o n d i t i o n . I t i s t h e r e f o r e i m p o s s i b l e t o c o n c l u d e t h a t t h e s e s u b j e c t s were showing any d r i n k i n g a t a l l . C e r t a i n l y , they were showing nowhere near the amount of d r i n k i n g t h a t Shanab and P e t e r s o n (1969) had found under s i m i l a r c o n d i t i o n s . Both b i r d s , however, showed a c o n s i d e r a b l e amount o f g r i t consumption. The mean amount o f g r i t consumed by HK7 v a r i e d from 7.25 g d u r i n g t h e FI 2 min s c h e d u l e on t h e a s c e n d i n g s e r i e s t o 2.8 g per day on the F I 8 min s c h e d u l e on t h e d e s c e n d i n g s e r i e s . The mean amount of g r i t consumed by WK10 v a r i e d from 26.6 g d u r i n g t h e F I 8 min s c h e d u l e on the a s c e n d i n g s e r i e s t o 4.0 g per day on the F I 8 min s c h e d u l e on t h e de s c e n d i n g s e r i e s . These means a r e shown i n F i g 1. The d a t a f o r WK10 c l e a r l y shows t h a t both the amount of g r i t consumed and t h e number of t i m e s t h a t the s u b j e c t came i n t o c o n t a c t w i t h t h e g r i t a r e b i t o n i c f u n c t i o n s of t h e d u r a t i o n s of t h e i n t e r - r e i n f o r c e m e n t i n t e r v a l f o r the a s c e n d i n g s e r i e s , w i t h t h e maximum amount of g r i t 15 F i g u r e 1. The number of c o n t a c t s w i t h the g r i t and the amount of g r i t consumed by each of the s u b j e c t s as a f u n c t i o n of t h e i n t e r - r e i n f o r c e m e n t i n t e r v a l s f o r each of the c o n d i t i o n s d u r i n g which g r i t was a v a i l a b l e d u r i n g Experiment One. The d o t t e d l i n e r e p r e s e n t s the number o f c o n t a c t s t h a t the s u b j e c t made w i t h the g r i t . The s c a l e f o r t h i s i s on the l e f t s i d e of each graph. The s o l i d l i n e r e p r e s e n t s the weight, i n grams, o f t h e g r i t t h a t the s u b j e c t removed from t h e c o n t a i n e r . The s c a l e f o r t h e s e d a t a a r e on the r i g h t s i d e of each graph. The l i n e s double back on th e m s e l v e s f o r those s c h e d u l e d e n s i t i e s t h a t were p r e s e n t i n the de s c e n d i n g s e r i e s as w e l l as t h e a s c e n d i n g s e r i e s . Each p o i n t i s the a r i t h m e t i c mean of the l a s t f i v e s e s s i o n s of t h a t c o n d i t i o n . consumption o c c u r r i n g d u r i n g the F I 8 min s c h e d u l e . For the de s c e n d i n g s e r i e s f o r WK10, the g r a d i e n t i s much f l a t t e r and shows an i n c r e a s e toward the s h o r t e r i n t e r - r e i n f o r c e m e n t i n t e r v a l s . The d a t a f o r WK7 are l e s s c l e a r l y a b i t o n i c f u n c t i o n , but do show a peak i n the amount of r e s p o n d i n g at the FI 2 min s c h e d u l e . For the one s c h e d u l e i n the descending s e r i e s f o r which g r i t was a v a i l a b l e , t h e r e i s a l s o a decrease i n the r e s p o n d i n g f o r t h i s s u b j e c t . 16 CQo i n . m w M i l SUBJECT V K 7 3?K get INTER-RElNFORCEflENT INTERVAL 0IV1DED INTO THIRDS i 55T 3 II IP lis a SUBJECT. W K 1 0 u. •CO [NT£R-RE1NFDRCE>IENT INTERVAL DIVIDED INTO THIRDS F i g u r e 2. The number of c o n t a c t s w i t h the g r i t and the number of keypecks t h a t were e m i t t e d by each of t h e s u b j e c t s d u r i n g each t h i r d o f the i n t e r - r e i n f o r c e m e n t i n t e r v a l i n the f i r s t e x p e r i m e n t . The l e f t , dark bar o f each p a i r r e p r e s e n t s the number o f c o n t a c t s t h a t the s u b j e c t made w i t h the g r i t and the r i g h t , l i g h t bar o f each p a i r r e p r e s e n t s t h e number o f keypecks t h a t was e m i t t e d by each s u b j e c t . Each of t h e s e v a l u e s r e p r e s e n t s the a r i t h m e t i c mean o f t h e r e s p e c t i v e t h i r d s of a l l of t h e i n t e r - r e i n f o r c e m e n t i n t e r v a l s d u r i n g the l a s t , f i v e s e s s i o n s of a l l c o n d i t i o n s i n Experiment One f o r which g r i t was a v a i l a b l e . The a r i t h m e t i c mean of the number of c o n t a c t s each s u b j e c t made w i t h t h e g r i t d u r i n g s u c c e s i v e t h i r d s o f the i n t e r -r e i n f o r c e m e n t i n t e r v a l , averaged over the l a s t f i v e s e s s i o n s of a l l the c o n d i t i o n s where g r i t was p r e s e n t , as w e l l as the a r i t h m e t i c mean of t h e number of key pecks f o r each s u b j e c t d u r i n g t h e s e same p e r i o d s i s shown i n F i g . 2. T h i s d i s t r i b u t i o n 17 F i g u r e 3. The c u m u l a t i v e r e c o r d of the r e s p o n s e s of WK10 d u r i n g one s e s s i o n when g r i t was c o n c u r r e n t l y a v a i l a b l e w i t h a FI 2 min s c h e d u l e of r e i n f o r c e m e n t d u r i n g the a s c e n d i n g s e r i e s of s c h e d u l e s i n Experiment One. The pen was r e s e t a f t e r e v e r y r e i n f o r c e r was d e l i v e r e d . Downward d e f l e c t i o n s of the pen r e p r e s e n t c o n t a c t s w i t h the g r i t . i s r e p r e s e n t a t i v e of t h e mean d i s t r i b u t i o n f o r each of the i n d i v i d u a l c o n d i t i o n s which comprise i t . These data show t h a t the s u b j e c t ' s c o n t a c t s w i t h t h e g r i t o c c u r r e d most f r e q u e n t l y d u r i n g t h e f i r s t t h i r d of the i n t e r - r e i n f o r c e m e n t i n t e r v a l , and l e a s t f r e q u e n t l y d u r i n g the l a s t t h i r d of the i n t e r -r e i n f o r c e m e n t i n t e r v a l . G r i t consumption o c c u r r e d d u r i n g the p o s t - r e i n f o r c e m e n t pause b e f o r e the s u b j e c t began t o respond on the key f o r the next food r e i n f o r c e m e n t , as shown i n the c u m u l a t i v e r e c o r d i n F i g . 3, which i s r e p r e s e n t a t i v e of the o t h e r s e s s i o n s i n t h i s experiment where g r i t consumption o c c u r r e d . T h i s i s how an a d j u n c t i v e b e h a v i o u r would be expected t o be d i s t r i b u t e d ( F a l k , 1969). 18 I t i s u n c l e a r why p o l y d i p s i a d i d not o c c u r i n t h i s e x periment w h i l e g r i t consumption d i d occur- When Shanab and P e t e r s o n moved t h e i r c o n t a i n e r o f water t o a n o t h e r p o s i t i o n i n the chamber t o i n c r e a s e t h e i r s u b j e c t ' s d r i n k i n g , t h e y r e p o r t e d t h a t the s u b j e c t had a " s u p e r s t i t i o u s t u r n i n g b i a s " away from t h a t p o r t i o n o f t h e chamber i n which the c o n t a i n e r had f i r s t been p l a c e d . Because both s u b j e c t s i n the p r e s e n t e xperiment a t e g r i t under the same c o n d i t i o n s and from th e same c o n t a i n e r i n the same p o s i t i o n i n t h e e x p e r i m e n t a l chamber as when water was a v a i l a b l e , i t cannot be e a s i l y argued t h a t the c o n t a i n e r l o c a t i o n o r response b i a s was r e s p o n s i b l e f o r the f a i l u r e to o b t a i n d r i n k i n g . EXPERIMENT T¥0 The r e s u l t s of t h e f i r s t e xperiment were u n u s u a l , p r i m a r i l y because they f a i l e d t o r e p l i c a t e a p r e v i o u s f i n d i n g o f p o l y d i p s i a i n the p i g e o n and, t o a l e s s e r e x t e n t , because one of the s u b j e c t s d i d not c l e a r l y show the b i t o n i c f u n c t i o n i n g r i t e a t i n g as the i n t e r - r e i n f o r c e m e n t i n t e r v a l was v a r i e d . The l a t t e r would have been p r e d i c t e d from p r e v i o u s r e s e a r c h on a d j u n c t i v e b e h a v i o u r w i t h m i r r o r a t t a c k i n g i n p i g e o n s and w i t h a d j u n c t i v e water consumption i n o t h e r s p e c i e s o f s u b j e c t s (Cohen and Looney, 1973; F a l k , 1966). To check th e r e l i a b i l i t y of t h e s e r e s u l t s . Experiment Two was i n t e n d e d as a s i m p l e r e p l i c a t i o n of Experiment One u s i n g more s u b j e c t s , u s i n g a s l i g h t l y d i f f e r e n t o r d e r o f c o n d i t i o n s and e x p o s i n g t h e s u b j e c t s t o each c o n d i t i o n 19 f o r more s e s s i o n s than i n the f i r s t e x p e r i m e n t . Method One o f t h e s u b j e c t s from t h e f i r s t e x p e r i m e n t , WK10, was a l s o used i n t h i s experiment as w e l l as t h r e e new s u b j e c t s (WK17, SK28 and WK32) . The procedure i s summarized i n Table 2. S u b j e c t WK10 was p r e s e n t e d w i t h a s h o r t e r a s c e n d i n g s e r i e s of s c h e d u l e s than i n Experiment One. S u b j e c t s RK17 and WK28 were g i v e n a descending s e r i e s and s u b j e c t WK32 was g i v e n b o t h an as c e n d i n g and a de s c e n d i n g s e r i e s of s c h e d u l e s . The i n t e r -r e i n f o r c m e n t i n t e r v a l s were v a r i e d i n the same manner as i n Experiment One. S u b j e c t WK10 spent one month a t ad l i b body weight between Experiment One and Experiment Two. R e s u l t s and D i s c u s s i o n The l a s t two columns o f T a b l e 2, i n d i c a t e t h e weight o f e i t h e r water o r g r i t consumed, i n grams, and t h e number of t i m e s t h a t t h e s u b j e c t came i n t o c o n t a c t w i t h e i t h e r t h e water o r the g r i t . T a k i n g e v a p o r a t i o n i n t o a c c o u n t , i t can be seen t h a t none of the s u b j e c t s e i t h e r drank a n o t i c e a b l e amount of water o r a t e a n o t i c e a b l e amount o f g r i t . D u r i n g most of t h e c o n d i t i o n s t h e s u b j e c t s r a r e l y came i n t o c o n t a c t w i t h e i t h e r t h e g r i t o r t h e water. There were t h r e e e x c e p t i o n s t o t h i s . S u b j e c t WK32 came i n t o c o n t a c t w i t h the g r i t a mean o f 102 t i m e s on the F I 4 min s c h e d u l e on the a s c e n d i n g 20 TABLE 2 The o r d e r of the c o n d i t i o n s and the r e s u l t s f o r Experiment Two. The f i r s t column l i s t s t h e number o f the s u b j e c t . The second and t h i r d columns l i s t t h e i n t e r - r e i n f o r c e m e n t i n t e r v a l and t h e c o n t e n t s o f the g l a s s c o n t a i n e r . The f o u r t h column l i s t s t h e number o f s e s s i o n s f o r which each c o n d i t i o n l a s t e d . The l a s t two columns l i s t t h e a r i t h m e t i c mean o f the number of c o n t a c t s w i t h the g r i t or w i t h the water and t h e t o t a l w e i g h t , i n grams, of the water or g r i t t h a t was removed from the c o n t a i n e r , each averaged over the l a s t f i v e s e s s i o n s o f each c o n d i t i o n . S u b j e c t FI C o n t a i n e r Number C o n t a c t s Weight 01 Number Value C o n t e n t s Of With G r i t Or S e s s i o n s G r i t Or Water Water Consumed WK10 2 Min Mater 10 0. 0.4 2 Min G r i t 23 0. 0. 4 Min G r i t 28 0. 1. 8 Min G r i t 14 0. 1. WK32 2 Min Water 28 0, 3.2 2 Min G r i t 10 8. 2.6 4 Min G r i t 14 102.0 3. 4 Min Water 9 .8 2-8 8 Min G r i t 8 .2 2.6 16 Min G r i t 5 .4 3. 4 Min G r i t 9 0. 2.8 4 Min Water 8 0. 3.6 2 Min Water 7 0. 2.4 WK17 8 Min G r i t 18 .6 1. 8 Min Water 8 107. 2.4 4 Min Water 11 0. 1.8 4 Min G r i t 11 199.4 1.2 WK28 8 Min G r i t 12 0. 1. 8 Min Water 7 . 8 1.2 4 Min Water 13 0. 1.4 4 Min G r i t 11 0. 1. s e r i e s , and WK17 came i n t o c o n t a c t w i t h the water a mean o f 107 t i m e s on the F I 8 min s c h e d u l e and w i t h t h e g r i t a mean o f 199.4 t i m e s on t h e F I 4 min s c h e d u l e , even though n e i t h e r s u b j e c t consumed an a p p r e c i a b l e amount o f e i t h e r t h e g r i t o r water as the change i n the weight o f the g r i t and water d u r i n g t h e s e s s i o n s shows. The mean d i s t r i b u t i o n d u r i n g t h e average i n t e r -21 WK32 - FI 4 MIN - GRIT P I W I f m it VK17 - FI 8 MIN - WRTER ISTtR-KlMrOSCTKEST I.VlERVRL ClVlOtO INTO TH1SCS rtftf 17 - FI 4 KIN - GRIT '<1 > ; !«I£R-RCIIirsSasE»I !S'T£RV=L OWOED IK'J THICS F i g u r e 4. The d i s t r i b u t i o n s of the c o n t a c t s w i t h t h e g r i t or water and t h e number o f keypecks d u r i n g each t h i r d of the i n t e r -r e i n f o r c e m e n t i n t e r v a l f o r WK32 when g r i t was a v a i l a b l e d u r i n g an FI 4 min s c h e d u l e and f o r WK17 when water was a v a i l a b l e d u r i n g an FI 8 min s c h e d u l e and when g r i t was a v a i l a b l e d u r i n g an FI '4 min s c h e d u l e i n Experiment Three. The l e f t , dark bar of each p a i r r e p r e s e n t s the number o f c o n t a c t s t h a t t he s u b j e c t made w i t h t h e g r i t or water and the r i g h t , l i g h t , bar of each p a i r r e p r e s e n t s the number of keypecks t h a t was e m i t t e d by each s u b j e c t . Each of the s e v a l u e s r e p r e s e n t s the. a r i t h m e t i c mean of the r e s p e c t i v e t h i r d s of a l l of t h e i n t e r - r e i n f o r c e m e n t i n t e r v a l s d u r i n g t h e l a s t f i v e s e s s i o n s o f each of these c o n d i t i o n s . Note the d i f f e r e n c e s i n t h e s c a l e s . r e i n f o r c e m e n t i n t e r v a l of the s u b j e c t ' s c o n t a c t s w i t h the water o r g r i t and t h e s u b j e c t ' s key pecks i n each o f t h e s e t h r e e c a s e s i s shown i n F i g . 4. Rather than b e i n g e v i d e n c e of the e x i s t e n c e o f a d j u n c t i v e consummatory b e h a v i o u r , c o n t a c t s with the g r i t and water w i t h o u t consumption s u g g e s t s t h a t the open c o n t a i n e r was g e t t i n g i n the 22 way o f the s u b j e c t w h i l e he was e m i t t i n g some o t h e r b e h a v i o u r . K i l l e e n (1975) has shown t h a t t h e r a t e a t which a pigeon moves about t h e e x p e r i m e n t a l chamber when f o o d i s d e l i v e r e d a t r e g u l a r i n t e r v a l s i n d e p e n d e n t l y of h i s b e h a v i o u r i n c r e a s e s t o a peak s h o r t l y a f t e r r e i n f o r c e m e n t and then d e c r e a s e s thoughout t h e r e s t o f t h e i n t e r v a l . Thus, K i l l e e n * s p i g e o n ' s g e n e r a l a c t i v i t y f o l l o w s the same d i s t r i b u t i o n t h r o u g h o u t t h e i n t e r - r e i n f o r c r a m e n t i n t e r v a l as the c o n t a c t s w i t h t h e g r i t and water do i n t h e p r e s e n t e x p e r i m e n t . I f t h e s e s u b j e c t s were showing the same i n c r e a s e d a c t i v i t y d u r i n g t h e i n t e r - r e i n f o r c e m e n t i n t e r v a l as K i l l e e n ' s s u b j e c t s , then i t would be r e a s o n a b l e t o e xpect t h a t t h e more the b i r d moves about the chamber the more l i k e l y i t i s t o come i n t o c o n t a c t w i t h the g r i t . The d a t a o f t h e p r e s e n t e x p e r i m e n t thu s c o u l d be accounted f o r by such a phenomenon. EXPERIMENT THREE Although none of t h e f i v e s u b j e c t s d i s p l a y e d a d j u n c t i v e d r i n k i n g i n e i t h e r of the f i r s t two e x p e r i m e n t s , s c h e d u l e -i n d u c e d g r i t consumption was shown by s u b j e c t SK10 i n t h e f i r s t e x p e r i m e n t , but not i n the second e x p e r i m e n t . The p r e s e n t e x p e r i m e n t a t t e m p t e d t o r e c o v e r t h e a d j u n c t i v e g r i t consumption i n t h i s s u b j e c t . The g r i t c o n t a i n e r was moved t o r u l e out t h e p o s s i b i l i t y t h a t t h e b i r d had d e v e l o p e d some k i n d o f s p a t i a l s u p e r s t i t i o u s response o r had f o r g o t t e n t h a t t h e g r i t was a v a i l a b l e i n t h e chamber d u r i n g t h e month t h a t had passed between Experiment One and Experiment Two. Such a change i n Shanab and P e t e r s o n ' s experiment had had the e f f e c t of 23 a p p r o x i m a t e l y d o u b l i n g the q u a n t i t y of water consumed by t h e i r s u b j e c t . Method The s u b j e c t was p l a c e d i n t h e chamber f o r 12 s e s s i o n s w i t h the c o n t a i n e r o f g r i t moved d i r e c t l y f o r w a r d from t h e c o r n e r f u r t h e s t from t h e f e e d e r and response key to t h e c o r n e r next t o the r e s p o n s e key. D u r i n g t h e next 7 s e s s i o n s t h e g r i t was moved t o a l o c a t i o n h a l f w a y between t h e s e , d i r e c t l y under the window. The o r d e r of the c o n d i t i o n s i s l i s t e d i n T a b l e 3. D u r i n g both c o n d i t i o n s an F I 8 min s c h e d u l e o f r e i n f o r c e m e n t was i n e f f e c t on t h e r e s p o n s e key. T h i s s c h e d u l e v a l u e was chosen s i n c e WK10 had consumed t h e maximum amount of g r i t under t h i s s c h e d u l e i n Experiment One. TABLE 3 The o r d e r of c o n d i t i o n s and t h e r e s u l t s f o r Experiment Three. The f i r s t column l i s t s the number o f t h e s u b j e c t . The second, t h i r d and f o u r t h columns l i s t t h e i n t e r - r e i n f o r c e m e n t i n t e r v a l and the c o n t e n t s and p o s i t i o n of t h e g l a s s c o n t a i n e r . The f i f t h column l i s t s t h e number of s e s s i o n s f o r which t h a t t h e s u b j e c t spent i n each c o n d i t i o n . The l a s t two columns l i s t t h e a r i t h m e t i c mean of t h e number of c o n t a c t s w i t h t h e g r i t and the t o t a l w e i g h t , i n grams, of the g r i t t h a t was removed from the c o n t a i n e r , each averaged over the l a s t f i v e s e s s i o n s o f each c o n d i t i o n . S u b j e c t FI C o n t a i n e r C o n t a i n e r Number Number Weight Number Value C o n t e n t s L o c a t i o n Of Of Consumed S e s s i o n s C o n t a c t s WK10 8 Min G r i t By Feeder 12 144.4 3.4 8 Min G r i t By Window 7 29.4 2. 2 24 Results and Discussion There was no g r i t consumption i n either condition as shown in Table 3. When the g r i t container was placed next to the feeder there was a r e l a t i v e l y large number of contacts with the g r i t . Examination of the d i s t r i b u t i o n of the number of contacts with the g r i t shows that, rather than being negatively correlated with the responses on the Key, as adjunctive behaviour should be, the number of contacts with the g r i t i n these situations was distributed throughout the i n t e r -reinforcement i n t e r v a l i n the same way that the key pecks were. Fig. 5 shows t h i s d i s t r i b u t i o n of the contacts with the g r i t and the pecks on the response key averaged over the l a s t f i v e sessions of t h i s condition. Observation of the subject revealed that t h i s occurred because the subject often stood on the g r i t while responding on the key. This happened to a l e s s e r extent when the g r i t container was by the window. EXPERIMENT FOUR Because schedule-induced g r i t eating occurred in the f i r s t experiment, but not i n the second experiment, the obvious strategy to use i n attacking t h i s problem was to examine any differences i n the two experiments. The only apparent difference was that the diet of the subjects had been changed afte r the f i r s t experiment by the addition of maple peas. This change in diet had been necessary because some of the pigeons in the colony were in poor health because of a lack of 25 SUBJECT WK10 - GRIT BY. FEEDER DC <S> UJ a. Ira i-2-01°. cr. CJ OLD" a: UJ DO MS ; ••i-'-'-n -co-. o ° U J ID Li_ O o; UJ INTER-REINFORCEMENT INTERVAL OIVIDED INTO THIRDS F i g u r e 5. The a r i t h m e t i c mean of t h e number of c o n t a c t s w i t h the g r i t and the number of keypecks t h a t o c c u r r e d d u r i n g each t h i r d of t h e i n t e r - r e i n f o r c e m e n t i n t e r v a l averaged over the l a s t f i v e s e s s i o n s o f the f i r s t c o n d i t i o n i n Experiment Three. The l e f t , dark bar of each p a i r r e p r e s e n t s t h e number of c o n t a c t s t h a t WK10 made w i t h t h e g r i t and the r i g h t , l i g h t bar of each p a i r r e p r e s e n t s the number o f keypecks. 26 p r o t e i n i n t h e i r d i e t . L e v i (1971, page 490) s t a t e s t h a t p i g e ons r e q u i r e legumes f o r t h e h i g h p r o t e i n c o n t e n t . Other g r a i n s have between 9 and 12% p r o t e i n , but p i g e o n s r e q u i r e between 13 and 14% p r o t e i n i n t h e i r d i e t s . Peas, c o n t a i n i n g between 23 and 25% p r o t e i n a r e t h e r e f o r e n e c e s s a r y t o g i v e t h e p i g e o n s the p r o t e i n t h a t they r e q u i r e . I t seemed p o s s i b l e , because t h e f o o d t h a t t h e s u b j e c t s were e a t i n g was d e f i c i e n t , t h a t they might be s e a r c h i n g f o r a n o t h e r s o u r c e o f n u t r i m e n t s by e a t i n g the g r i t . I n e f f e c t , they would be t r y i n g t o b a l a n c e t h e i r d i e t by consuming a v a r i e t y of f o o d s . B a t s have shown t h i s t y p e o f s t r a t e g y when they were made d e f i c i e n t i n some n u t r i m e n t (see r e v i e w by B o z i n and K a l a t , 1971) . That p i g e o n s might eat e x t r a g r i t t o s a t i s f y t h e i r n u t r i t i o n a l r e q u i r e m e n t s i s not as u n l i k e l y as i t seems, as g r i t does appear t o p r o v i d e a c e r t a i n amount of n u t r i t i o n , e s p e c i a l l y c a l c i u m , a s w e l l as s i m p l y p r o v i d i n g a way f o r the pigeon to g r i n d g r a i n i n i t s c r o p ( L e v i , 1974, page 405). Peas a l s o have l a r g e amounts of c a l c i u m , r e l a t i v e t o t h e o t h e r g r a i n s i n t h e s e pigeon's d i e t . S p e c i f i c a l l y , peas a r e 0.07% c a l c i u m , as compared t o 0.03% i n wheat, 0.01% i n c o r n and 0.04% i n k a f i r g r a i n ( M o r r i s o n , 1936). P o s s i b l y , t h e n , t h e s u b j e c t s i n Experiment One were e a t i n g g r i t t o compensate f o r a c a l c i u m o r p r o t e i n d e f i c i e n c y . Because i t seems r e a s o n a b l e t h a t t h e pigeons c o u l d have been t r y i n g t o compensate f o r a n u t r i t i o n a l d e f i c i e n c y by consuming e x t r a amounts of g r i t , f o u r p i g e ons were p l a c e d on t h e 27 d i e t w i t h o u t maple peas f o r a under a v a r i e t y o f f i x e d i n t e r v a l f o r water and g r i t consumption. p e r i o d of ti m e and were t e s t e d food r e i n f o r c e m e n t s c h e d u l e s Method Maple peas were e l i m i n a t e d from t h e d i e t of s u b j e c t WK10 f o r 133 days and from the d i e t s o f s u b j e c t s 8K17, BK28 and WK32 f o r 115 days each, ft summary o f t h e c o n d i t i o n s f o r each o f these s u b j e c t s d u r i n g t h i s experiment i s p r e s e n t e d i n T a b l e 4. S u b j e c t WK10 was exposed t o an FI 2 min s c h e d u l e of r e i n f o r c e m e n t w i t h g r i t a v a i l a b l e t h r o u g h o u t t h i s p e r i o d . S u b j e c t s MK17 and HK28 were each p r e s e n t e d w i t h a s e r i e s o f s c h e d u l e s d e s c e n d i n g from F I 2 min t o F I 30 s e c and then a s c e n d i n g back t o F I 2 min, w i t h g r i t a v a i l a b l e d u r i n g a l l c o n d i t i o n s . S u b j e c t WK32 was p r e s e n t e d w i t h a des c e n d i n g s e r i e s o f s c h e d u l e s from FI 2 min t o F I 30 s e c , w i t h g r i t a v a i l a b l e , and then an F I 30 sec s c h e d u l e w i t h water a v a i l a b l e . R e s u l t s and D i s c u s s i o n No s u b j e c t showed any e v i d e n c e o f consumption o f the g r i t o r water as shown i n T a b l e 4. A l l o f t h e l o s s i n weight from t h e c o n t a i n e r s d u r i n g t h e s e s s i o n s can be accounted f o r by e v a p o r a t i o n . The g r e a t e s t mean number o f c o n t a c t s w i t h t h e g r i t was shown by WK10 which had a t o t a l o f 159 c o n t a c t s o v e r the l a s t f i v e days o f t h i s c o n d i t i o n . T h i s cannot be t a k e n as ev i d e n c e o f consumption of the g r i t , because 92% o f th e s e c o n t a c t s o c c u r r e d i n a s i n g l e day, w h i l e t h e r e was no e v i d e n c e 28 TABLE 4 The o r d e r of the c o n d i t i o n s and t h e r e s u l t s f o r Experiment Four. Each o f t h e columns i n t h i s t a b l e c o n t a i n t h e same type of d a t a as the columns o f Tab l e 2. S u b j e c t FI C o n t a i n e r Number C o n t a c t s Weight Of Number Value C o n t e n t s Of With G r i t Or S e s s i o n s G r i t Or Water Water Consumed WK10 2 B i n G r i t 107 31.8 3.2 WK17 2 Min G r i t 11 0. 1. 1 Hin G r i t 10 11. 1. 30 Sec G r i t 14 3.4 1.4 1 Min G r i t 18 .2 1.6 2 Min G r i t 12 16.6 1. WK28 2 Min G r i t 12 0. 1. 1 Min G r i t 10 0. 1.4 30 Sec G r i t 14 0. 1.4 1 Min G r i t 24 0. 1.4 2 Min G r i t 14 .2 1. WK32 2 Min G r i t 12 .2 2.6 1 Min G r i t 10 7. 8 3.8 30 Sec G r i t 8 5. 2.6 30 Sec Water 5 .7 3.2 of any more l o s s of t h e g r i t by weight d u r i n g t h a t day d u r i n g any o t h e r day i n t h i s e x p e r i m e n t . These d a t a suggest a p r o t e i n - c a l c i u m d e f i c i e n c y was not r e s p o n s i b l e f o r t h e e a t i n g found i n Experiment One. I t i s p o s s i b l e , however, g r i t e a t i n g o c c u r s o n l y a f t e r a p r o l o n g e d p e r i o d of maple d e p r i v a t i o n . t h a n t h a t g r i t t h a t pea EXPERIMENT FIVE The r e p e a t e d f a i l u r e s t o f i n d e i t h e r s c h e d u l e - i n d u c e d p o l y d i p s i a or g r i t consumption c o u l d have been t h e r e s u l t of of some o t h e r competing a d j u n c t i v e b e h a v i o u r b e i n g e m i t t e d a t a 29 h i g h r a t e d u r i n g the e x p e r i m e n t a l s e s s i o n s . Freed and Hyraowitz (1969) have shown t h a t one a d j u n c t i v e b e h a v i o u r may be e m i t t e d t o t h e complete e x c l u s i o n of a n o t h e r b e h a v i o u r when two a r e p o s s i b l e . They found t h a t r a t s d i d not show any p o l y d i p s i a when a b l e t o chew on t h e c e l l u l o s e between t h e b a r s of t h e f l o o r o f t h e i r e x p e r i m e n t a l chamber. The p o s s i b i l i t y of some type of competing a d j u n c t i v e b e h a v i o u r i s a l s o p r e d i c t e d by the a r o u s a l t h e o r y (Wayner, 1974) c o n c e r n i n g t h e s o u r c e o f s c h e d u l e - i n d u c e d b e h a v i o u r s . T h i s t y p e of t h e o r y h y p o t h e s i z e s t h a t an a n i m a l exposed t o a s c h e d u l e under which food i s d i s t r i b u t e d over time becomes aroused and e m i t s some b e h a v i o u r a t a much h i g h e r r a t e than would be normal. Which o f t h e s e v e r a l p o s s i b l e b e h a v i o u r s i s e m i t t e d depends on what the most l i k e l y b e h a v i o u r i s i n t h a t p a r t i c u l a r s i t u a t i o n . T h i s , o f c o u r s e , depends upon t h e p h y s i c a l c h a r a c t e r i s t i c s o f the environment. With t h i s i n mind, t h e e x p e r i m e n t a l chambers were examined t o determine i f t h e s u b j e c t s had any o p p o r t u n i t y t o e m i t any type of a d j u n c t i v e b e h a v i o u r o t h e r t h a n water or g r i t consumption. The o n l y apparent p o s s i b i l i t y was t h a t t h e s u b j e c t s might be showing some k i n d of a t t a c k toward t h e windows. These s u r f a c e s were somewhat r e f l e c t i v e n o r m a l l y and the c a r d b o a r d which had been taped t o the o u t s i d e o f the windows t o e l i m i n a t e the p o s s i b i l i t y o f v i s u a l d i s t r a c t i o n s f o r the b i r d s from o u t s i d e t h e chambers r e n d e r e d the windows even more r e f l e c t i v e . I t has f r e q u e n t l y been shown t h a t p i g eons w i l l a t t a c k o t h e r p i g e o n s o r images o f pigeons both d u r i n g e x t i n c t i o n and d u r i n g ft 30 t h e p o s t - r e i n f o r c e m e n t pause on s c h e d u l e s under which r e i n f o r c e r s a r e d i s t r i b u t e d o v er time- F l o r y (1969) and Webbe, DeWeese and M a l a g o d i (1974) have shown t h a t p i g eons i n t h i s t y p e of s i t u a t i o n w i l l a t t a c k o t h e r p i g e o n s , Cohen and Looney (1974) have shown t h a t p i g e o n s on f i x e d r a t i o s c h e d u l e s w i l l a t t a c k p i c t u r e s o f o t h e r p i g e o n s , and Looney and Cohen (1973) have shown t h a t p i g e o n s on v a r i o u s f i x e d r a t i o s c h e d u l e s w i l l a t t a c k t h e i r own images i n m i r r o r s . These l a t t e r d a t a suggest t h a t p i g e ons on v a r i o u s t y p e s of s c h e d u l e s may a t t a c k v a r i o u s r e f l e c t i v e s u r f a c e s i n the s t a n d a r d operant c o n d i t i o n i n g chamber d u r i n g t h e p o s t - r e i n f o r c e m e n t pause. The o n l y s u r f a c e i n the e x p e r i m e n t a l chambers used i n t h e p r e s e n t s e r i e s o f e x p e r i m e n t s which would r e f l e c t the image o f the s u b j e c t s was the i n s i d e o f the window. In t h e s e e x p e r i m e n t s , t h e s u b j e c t s had not been s y s t e m a t i c a l l y observed by the e x p e r i m e n t e r t o see i f any o t h e r a d j u n c t i v e b e h a v i o u r was o c c u r r i n g because e v e r y t i m e t h a t t h e c a r d b o a r d was removed from t h e o u t s i d e o f t h e windows so t h a t the e x p e r i m e n t e r c o u l d l o o k i n t o the chambers, i t was observed t h a t t h e s u b j e c t s , when they were not o c c u p i e d w i t h k e y p e c k i n g , spent t h e i r t i m e l o o k i n g i n t h e d i r e c t i o n o f the e x p e r i m e n t e r . T h i s was i n t e r p r e t e d t o mean t h a t t h e s u b j e c t s c o u l d l o o k back out of the windows and were b e i n g d i s t r a c t e d by the presence o f the e x p e r i m e n t e r . Another p o s s i b i l i t y , however, was t h a t the pigeons were a t t a c k i n g t h e i r own images i n t h e r e f l e c t i v e window. When t h e c a r d b o a r d was removed from the windows so t h a t the e x p e r i m e n t e r c o u l d l o o k i n , t h e i n s i d e o f the windows were not as r e f l e c t i v e as when t h e c a r d b o a r d had been t h e r e . 31 C o n s e q u e n t l y , t h e s u b j e c t s were not s e e i n g t h e i r images as c l e a r l y as normal and were not a t t a c k i n g t h e windows. Thus t h e o b s e r v e r saw o n l y t h e s u b j e c t l o o k i n g i n h i s d i r e c t i o n , but saw no s i g n Of s c h e d u l e - i n d u c e d a t t a c k . In o r d e r t o e l i m i n a t e t h e s e r e f l e c t i o n s , t h e windows were co v e r e d on the i n s i d e w i t h p l a i n w h i t e paper. I n a d d i t i o n , because t h e f i x e d r a t i o (FR) s c h e d u l e s were e f f e c t i v e i n p r o d u c i n g s c h e d u l e - i n d u c e d a g g r e s s i o n i n Looney and Cohen's s u b j e c t s , one s u b j e c t was exposed t o a f i x e d r a t i o s c h e d u l e i n t h i s e x p e r i m e n t . Method A summary of t h e c o n d i t i o n s o f t h i s experiment appear i n T a b l e 5. D u r i n g a l l s e s s i o n s the windows were c o v e r e d on t h e i n s i d e w i t h p l a i n w h i t e paper. S u b j e c t WK10 was p l a c e d i n the e x p e r i m e n t a l chamber f o r 10 s e s s i o n s w i t h g r i t a v a i l a b l e . T h i s s u b j e c t was r e q u i r e d t o emit 100 responses on the key t o r e c i e v e f o o d r e i n f o r c e m e n t (FR 100). A F I 2 min s c h e d u l e was i n e f f e c t f o r 9 s e s s i o n s f o r WK17 and f o r 9 s e s s i o n s f o r WK28. G r i t was a v a i l a b l e t o both t h e s e s u b j e c t s . For WK32 a FI 30 sec s c h e d u l e was i n e f f e c t f o r 5 s e s s i o n s and water was a v a i l a b l e . R e s u l t s and D i s c u s s i o n The r e s u l t s of t h i s e x p e r i m e n t , shown i n T a b l e 5, a r e t h a t none o f t h e s u b j e c t s showed any g r i t o r water consumption. 32 TABLE 5 The o r d e r of t h e c o n d i t i o n s and t h e r e s u l t s f o r Experiment F i v e . Each o f the columns i n t h i s t a b l e c o n t a i n s t h e same ty p e o f d a t a as t h e columns o f T a b l e 2 and Ta b l e 4. S u b j e c t Schedule C o n t a i n e r Number C o n t a c t s H e i g h t Of Number Va l u e C o n t e n t s Of S e s s i o n s With G r i t Or Water G r i t Or Water Consumed WK10 FR 100 G r i t 15 2. 1. WK17 FI 2 Min G r i t 10 7. 1. WK28 FI 2 Min G r i t 10 1.8 1. WK32 FI 30 Sec Water 5 1.2 2.6 EXPERIMENT SIX Measurments were made o f the amount o f g r i t consumed d u r i n g e x p e r i m e n t a l s e s s i o n s when f o o d was f r e e l y a v a i l a b l e , t h e amount of g r i t and water consumed d u r i n g 5 days i n the home ca g e s , and the p a t t e r n o f water consumption d u r i n g a 12 hr p e r i o d . These were determined i n o r d e r t o make comparisons w i t h t h e p r e c e e d i n g e x p e r i m e n t s . Method F o r 6 s e s s i o n s , s u b j e c t s WK10, WK17 and WK28 were exposed t o t h e c o n d i t i o n s d e s c r i b e d i n Experiment F i v e but w i t h f o o d f r e e l y a v a i l a b l e i n t h e c o r n e r of t h e e x p e r i m e n t a l chamber i n the same type of me t a l food cup as i n the s u b j e c t ' s home cages. F o l l o w i n g t h i s , s u b j e c t s WK10, WK17, WK28, and WK32 remained i n t h e i r home cages f o r 5 days w i t h u n l i m i t e d a c c e s s t o f o o d , water 33 and g r i t . The water and g r i t was weighed t o t h e n e a r e s t gram a t the same time each day. A f t e r t h i s , the depth of t h e water i n each cup was measured each hour over a 15 hr p e r i o d from 9:00 hr t o 24:00 hr and was measured a t 9:00 hr the f o l l o w i n g day. R e s u l t s and D i s c u s s i o n The r e s u l t s of t h e s e c o n d i t i o n s a r e shown i n T a b l e s 6, 7 and 8. None of t h e s u b j e c t s consumed g r i t w i t h i n the e x p e r i m e n t a l a p p a r a t u s when f o o d was f r e e l y a v a i l a b l e o r consumed more th a n 4 g of g r i t i n 24 hr i n i t s home cage. I n comparison w i t h both o f t h e s e measures t h e amount of g r i t consumed by b o t h s u b j e c t s i n Experiment One would be c o n s i d e r e d e x c e s s i v e . U n f o r t u n a t e l y , i t i s not known i f t h e change t h a t o c c u r r e d between Experiment One and t h e s u c c e e d i n g e x p e r i m e n t s a l s o d e c r e a s e d home cage consumption and rendered t h i s c omparison i n v a l i d . Each s u b j e c t consumed more th a n 68 g of water per day. T h i s amount exceeds the g r e a t e r mean d a i l y water i n t a k e t h a t Shanab and P e t e r s o n r e p o r t e d by 36.2%, and t h e l e s s e r by 227.3%. The t h i r d c o n d i t i o n showed t h a t t h e s e p i g e o n s t e n d e d t o d r i n k o n l y i n t h e l a t e morning and e a r l y e v e n i n g . TABLE 6 The r e s u l t s f o r the f i r s t c o n d i t i o n of Experiment S i x . The f i r s t column l i s t s the s u b j e c t number. Columns two and three l i s t the a r i t h m e t i c mean of the number of c o n t a c t s each s u b j e c t made with the g r i t and the number of grams of the g r i t consumed averaged over the s i x s e s s i o n s of t h i s c o n d i t i o n . S u b j e c t Number o f Weight Number C o n t a c t s Consumed WK10 1.67 1.0 WK17 38.67 1.2 WK28 .67 1.0 T A B L E 7 The r e s u l t s f o r the second c o n d i t i o n of Experiment S i x . The f i r s t column l i s t s the s u b j e c t number. The second and t h i r d columns l i s t the a r i t h m e t i c mean of the weight of the water and the g r i t consumed to the nearest gram averaged over the f i v e days of t h i s c o n d i t i o n . These val u e s have been c o r r e c t e d f o r the estimated e v a p o r a t i o n . Subject Number Weight of The Water Consumed Weight o f The G r i t Consumed WK10 77.6 3.6 WK17 68.4 2.6 WK28 71.4 1.4 WK32 71.4 4.0 35 TABLE 8 The r e s u l t s f o r t h e t h i r d c o n d i t i o n o f Experiment S i x . The f i r s t column l i s t the time t h a t each measurement was t a k e n . The o t h e r f o u r columns l i s t t h e amount of water t h a t was consumed from the d r i n k i n g cups t o t h e n e a r e s t m i l l i m e t e r s i n c e t h e p r e c e e d i n g measurement. E v a p o r a t i o n was n e g l e g i b l e . Time MM Hater Consummed WK10 WK17 HK28 HK32 10:00 0 0 0 0 11:00 2 6 1 0 12:00 1 2 1 0 13:00 1 2 6 3 14:00 1 1 8 2 15: 00 1 1 0 1 16:00 1 0 0 1 17:00 0 0 0 1 18:00 0 0 0 1 19:00 2 0 0 1 20:00 0 1 4 0 21: 00 2 2 2 2 22:00 0 1 0 3 23:00 0 0 0 0 24:00 0 0 0 0 9: 00 2 1 1 0 GENERAL DISCUSSION In t h i s s e r i e s o f e x p e r i m e n t s , i n a t o t a l o f 1303 hours of e x p e r i m e n t a l s e s s i o n s , o n l y two out o f f i v e p i g e o n s showed any i n g e s t i o n of g r i t . T h i s was not r e p l i c a t e d i n one o f t h e s u b j e c t s . At no t i m e d i d any of t h e s u b j e c t s show any water consumption. S c h e d u l e - i n d u c e d consummatory b e h a v i o u r d i d not o c c u r d e s p i t e r e p e a t e d exposures t o a wide range o f f i x e d i n t e r v a l s c h e d u l e s ; exposure t o a f i x e d r a t i o s c h e d u l e ; placement of the c o n t a i n e r o f g r i t i n d i f f e r e n t l o c a t i o n s i n t h e e x p e r i m e n t a l chamber; and the removal o f any o p p o r t u n i t y t o show s c h e d u l e - i n d u c e d a t t a c k t h a t may have i n t e r f e r e d w i t h t h e 36 e m i s s i o n o f the s c h e d u l e - i n d u c e d consummatory b e h a v i o u r s . I t i s u n c l e a r why some g r i t consumption o c c u r r e d d u r i n g the f i r s t e x periment but not d u r i n g t h e s u c c e e d i n g e x p e r i m e n t s . I t i s c l e a r , however, t h a t t h e e x p e r i m e n t s were as i d e n t i c a l as p o s s i b l e , so t h a t t h e d i f f e r e n c e which would have caused one r e s u l t i n t h e f i r s t e xperiment and a d i f f e r e n t r e s u l t i n t h e o t h e r e x p e r i m e n t s must have been a v e r y s m a l l one. I t i s o b v i o u s t h a t s c h e d u l e - i n d u c e d g r i t e a t i n g i n p i g e o n s i s by no means the r o b u s t phenomenon t h a t s c h e d u l e - i n d u c e d p o l y d i p s i a i s i n r a t s . S c h e d u l e - i n d u c e d p o l y d i p s i a i n r a t s has been shown t o o c c u r i n many d i f f e r e n t l a b o r a t o r i e s under many d i f f e r e n t c o n d i t i o n s . I t seems u n l i k e l y t h a t t h e s e p i g e o n ' s p r i o r e x p e r i m e n t a l h i s t o r i e s i n h i b i t e d t h e i r water consumption. B a t s which have been exposed t o s c h e d u l e s of food r e i n f o r c e m e n t w i t h o u t water p r e s e n t i n the a p p a r a t u s consume as much water as th o s e r a t s which were e x p e r i m e n t a l l y n a i v e ( G i l b e r t , 1974). W h i l e a n e g a t i v e f i n d i n g , the f a i l u r e t o d i s c o v e r r o b u s t s c h e d u l e - i n d u c e d consummatory b e h a v i o u r s i n t h e pigeon has i n t e r e s t i n g i m p l i c a t i o n s - I n the f i r s t p l a c e , t h e s e d a t a are a f a i l u r e t o r e p l i c a t e p r e v i o u s l y r e p o r t e d f i n d i n g s . The c o n d i t i o n s i n t h i s s e r i e s o f e x p e r i m e n t s were made as s i m i l a r as p o s s i b l e t o the c o n d i t i o n s i n t h e e x p e r i m e n t a l s i t u a t i o n r e p o r t e d by Shanab and P e t e r s o n (1969). These r e s e a r c h e r s r e c o r d e d the consumption of l a r g e amounts o f water. D u r i n g the average 3.5 hr s e s s i o n i n t h e i r e x p e r i m e n t , t h e i r s u b j e c t drank about 30 g o f water on an F I 2 min s c h e d u l e , which i s a mean of 9 g of water consumed per hour. D u r i n g a VI 2 min s c h e d u l e of 37 r e i n f o r c e m e n t an average of more th a n 50 g of water was consumed i n a 3.5 hr s e s s i o n , which i s a mean o f 14-29 g o f water per h r . The f i v e s u b j e c t s i n t h e p r e s e n t s e r i e s o f e x p e r i m e n t s , however, never consumed a measurable amount o f water. I t i s not c l e a r where the d i f f e r e n c e between t h e s e two e x p e r i m e n t s l i e s . The o n l y o b v i o u s d i f f e r e n c e s i n procedure a r e t h a t the e x p e r i m e n t a l s e s s i o n s i n t h e p r e s e n t experiment l a s t e d f o r 2 r a t h e r than 3.5 h r , and the d u r a t i o n of the g r a i n p r e s e n t a t i o n was 5.0 sec r a t h e r t h a n 2.0 sec-I t does not seem l i k e l y t h a t t h e d i f f e r e n c e s i n the r e i n f o r c e r d u r a t i o n s h o u l d have p r e v e n t e d the s u b j e c t s i n t h e p r e s e n t experiment from d r i n k i n g . I t has been demonstrated w i t h r a t s t h a t i n c r e a s e s i n r e i n f o r c e r magnitude have the e f f e c t of d e c r e a s i n g t h e q u a n t i t y o f water consumed t o a c e r t a i n degree, but does not e l i m i n a t e d r i n k i n g even when t h e r e i n f o r c e r magnitude i s i n c r e a s e d as much as twenty t i m e s ( L o t t e r , Woods and V a s s e l l i , 1973; R e y n i e r s e , 1966). There i s no o b v i o u s r e a s o n why t h e d i f f e r e n c e s i n t h e s e s s i o n d u r a t i o n s h o u l d cause a d i f f e r e n c e i n the q u a n t i t y t h a t the s u b j e c t s d r i n k per hour- I t i s p o s s i b l e , however, t h a t t h e s u b j e c t s may t e n d not t o d r i n k d u r i n g t h e f i r s t p a r t of the e x p e r i m e n t a l s e s s i o n s because, though t h e y a r e food d e p r i v e d , t h e y are not water d e p r i v e d - I n t h e l a s t p a r t of the 3.5 hr s e s s i o n , a f t e r not d r i n k i n g f o r two h o u r s , they may be becoming s l i g h t l y water d e p r i v e d and b e g i n t o d r i n k . The s h o r t e r s e s s i o n s i n t h e p r e s e n t s e r i e s o f e x p e r i m e n t s may have ended b e f o r e t h i s p o i n t i s r e a c h e d . The p a t t e r n of d r i n k i n g t h a t o c c u r r e d i n 38 Experiment S i x s u p p o r t s t h i s h y p o t h e s i s . P i g e o n s do not d r i n k s t e a d i l y , but d r i n k l a r g e amounts o f water two o r t h r e e t i m e s d u r i n g t h e day. I t i s q u i t e p o s s i b l e t h a t Shanab and P e t e r s o n happened t o i n c l u d e one o r p o s s i b l y two d r i n k i n g p e r i o d s i n t h e i r e x p e r i m e n t a l s e s s i o n , w h i l e t h e a f t e r n o o n and l a t e e v e n i n g s e s s i o n s the p r e s e n t s e r i e s o f e x p e r i m e n t s never happened t o i n c l u d e a d r i n k i n g p e r i o d . U n f o r t u n a t e l y , Shanab and P e t e r s o n do not r e p o r t whether t h e i r s u b j e c t was d r i n k i n g t hroughout t h e s e s s i o n o r o n l y d u r i n g the l a s t p o r t i o n . Nor do they r e p o r t t h e time o f day of t h e i r s e s s i o n s . T a k i n g i n t o c o n s i d e r a t i o n t h e d i f f i c u l t y i n showing t h a t Shanab and P e t e r s o n ' s s u b j e c t ' s water consumption was e x c e s s i v e w i t h t h e f a i l u r e t o f i n d any water consumption i n t h e p r e s e n t s e r i e s of e x p e r i m e n t s , i t i s d i f f i c u l t t o argue t h a t pigeons show s c h e d u l e - i n d u c e d p o l y d i p s i a . One must c o n c l u d e t h a t t h e d r i n k i n g found i n p i g e o n s i s not t h e same s t r o n g phenomena t h a t s c h e d u l e - i n d u c e d p o l y d i p s i a i s i n r a t s , and may v e r y w e l l be a d i f f e r e n t phenomena a l t o g e t h e r . In f a i l i n g t o r e p l i c a t e Shanab and P e t e r s o n ' s r e s u l t s , the r e s u l t s o f the p r e s e n t experiment must then q u e s t i o n the g e n e r a l i t y o f t h e phenomena of s c h e d u l e -i n d u c e d consummatory b e h a v i o u r . These f i n d i n g s must a l s o have i m p l i c a t i o n s f o r t h e t h e o r i e s which have been c r e a t e d t o e x p l a i n t h e phenomena o f s c h e d u l e -i n d u c e d p o l y d i p s i a . Each of the f o l l o w i n g t h r e e b e h a v i o u r a l o r p h y s i o l o g i c a l t h e o r i e s has not been s u p p o r t e d by some of t h e e x i s t i n g d a t a from r a t s and o t h e r mammals ( F a l k , 1969). The p r e s e n t s e r i e s of e x p e r i m e n t s p r o v i d e s even more e v i d e n c e t o 39 r a i s e doubts about some o f them. One t h e o r y t o e x p l a i n the phenomena of s c h e d u l e - i n d u c e d p o l y d i p s i a was t h e t h e o r y t h a t i t i s a t y p e o f s u p e r s t i t i o u s b e h a v i o u r which was a d v e n t i t i o u s l y r e i n f o r c e d by f o o d i n some way ( C l a r k , 1962). Bond, Blackman and S c r u t o n (1973) r e c e n t l y demonstrated t h a t s c h e d u l e - i n d u c e d water consumption i n the r a t c e a s e s t o o c c u r when i t i s punished by e l e c t r i c shock and does not o c c u r d u r i n g the p r e s e n t a t i o n of a tone which r e l i a b l y preceeds shock. They c o n c l u d e d t h a t s c h e d u l e - i n d u c e d p o l y d i p s i a i s an o p e r a n t . T h i s i s i n c o n c l u s i v e , however, because t h e i r argument c o n t a i n s a l o g i c a l f a l l a c y . They argued t h a t because p o l y d i p s i a i n r a t s can be punished and i s s u b j e c t t o c o n d i t i o n e d s u p p r e s s i o n , and because operant b e h a v i o u r i n r a t s such as l e v e r p r e s s i n g can be punished and i s s u b j e c t t o c o n d i t i o n e d s u p p r e s s i o n , then p o l y d i p s i a must be an operant b e h a v i o u r . . T h i s i s no more t r u e than s a y i n g t h a t because f r u i t s can be eaten and because meat can be e a t e n , then meat i s a f r u i t . The f i n d i n g s of t h e p r e s e n t s e r i e s o f e x p e r i m e n t s seem t o c o n t r a d i c t t h i s t h e o r y , as one may argue t h a t a pigeon as l i k e l y t o d e v e l o p s u p e r s t i t i o u s d r i n k i n g as a r a t . The l a c k o f water consumption when f o o d was c o n t i n u o u s l y a v a i l a b l e i n Experiment S i x , however, p r o v i d e s e v i d e n c e a g a i n s t t h i s argument. I t i s p o s s i b l e t h a t i f t h e pigeon never drank water d u r i n g t h e e x p e r i m e n t a l s e s s i o n , then i t would never be a d v e n t i t i o u s l y r e i n f o r c e d . Thus one must r e l y upon the e v i d e n c e d i s c u s s e d by F a l k (1971) t o e l i m i n a t e t h i s t h e o r y . & second t h e o r y which has been proposed i s t h a t because of 40 the a c t i v i t y i n which t h e s u b j e c t i s engaged, i t s i n t r a c r a n i a l t e m p e r a t u r e r i s e s and i t d r i n k s t o c o o l i t s e l f to i t s p r o p e r temperature ( C a r l i s l e , 1971). There does not seem to be any reason why t h e r a t s and monkeys s h o u l d become o v e r h e a t e d , however, and not p i g e o n s . K i l l e e n (1975) has shown t h a t p i g e o n s i n t h i s t y pe o f s i t u a t i o n a r e v e r y a c t i v e , and t h e r e f o r e s h o u l d g e n e r a t e as much heat as o t h e r s p e c i e s o f s u b j e c t s and be as w i l l i n g t o d r i n k the water t o c o o l t h e m s e l v e s . I t would have t o be shown t h a t p i g eons e i t h e r have a b e t t e r method of d i s s i p a t i n g e x c e s s heat t h a n d r i n k i n g o r do not g e n e r a t e as much body h e a t , t o c o n t i n u e t o use t h i s t h e o r y to e x p l a i n p o l y d i p s i a i n t h e f a c e o f t h e l a c k o f s c h e d u l e - i n d u c e d p o l y d i p s i a found i n p i g e o n s . Another t h e o r y t h a t has been proposed t o e x p l a i n s c h e d u l e -i n d u c e d p o l y d i p s i a i s t h a t i t s e r v e s as a m e d i a t i n g b e h a v i o u r . I t has been h y p o t h e s i z e d t h a t d r i n k i n g f o r a c e r t a i n amount of t i m e a f t e r a r e i n f o r c e r has been d e l i v e r e d h e l p s a r a t o r a monkey p r e d i c t t h e a r r i v a l o f t h e n e x t r e i n f o r c e r ( S e g a l , 1965). A g a i n , t h e r e i s no r e a s o n why a pigeon would not need t o t i m e t h i s i n t e r v a l when o t h e r s u b j e c t s do. I f t h i s were t h e c a s e , a pigeon would be f a r more e f f i c i e n t on f i x e d i n t e r v a l s c h e d u l e s and would emit f a r fewer r e s p o n s e s d u r i n g t h e i n t e r -r e i n f o r c e m e n t i n t e r v a l than they a c t u a l l y do. Though t h e s e l a s t t h r e e t h e o r i e s c o u l d be m o d i f i e d t o account f o r t h e f a i l u r e o f p i g e o n s t o d e v e l o p s c h e d u l e - i n d u c e d consummatory b e h a v i o u r , c o n s i d e r i n g t h e o t h e r arguments t h a t have a l r e a d y been r a i s e d a g a i n s t them ( F a l k , 1971), such ad hoc m o d i f i c a t i o n s h a r d l y seem w o r t h w h i l e . One must c o n s i d e r the 41 p o s s i b i l i t y t h a t i f a t h e o r y has t r o u b l e p r e d i c t i n g t h e da t a of the p r e s e n t e x p e r i m e n t s which a r e r e l a t i v e l y s i m p l e and s t r a i g h t f o r w a r d , then i t might never p r e d i c t any d a t a , but would have t o be m o d i f i e d e v e r y time a d i f f e r e n t t y p e o f s u b j e c t was ru n . A v e r y g e n e r a l t h e o r e t i c a l framework t h a t has been proposed t o encompass a wide range o f data i s t h e c o n c e p t o f a d j u n c t i v e b e h a v i o u r by F a l k (1971). F a l k ' s t h e o r y i s b a s i c a l l y an attempt t o show c e r t a i n common c h a r a c t e r i s t i c s between a number of phenomena by c r e a t i n g a c l a s s o f b e h a v i o u r c a l l e d a d j u n c t i v e b e h a v i o u r . There i s no f u r t h e r d e s c r i p t i o n of t h i s c l a s s of b e h a v i o u r than t h e s e common c h a r a c t e r i s t i c s , however, so t h e p r e d i c t i o n s g e n e r a t e d by t h i s t h e o r y a r e mainly l i m i t e d t o p r e d i c t i n g t h e g e n e r a l i t y of the o c c u r r e n c e o f e x c e s s i v e b e h a v i o u r s d u r i n g t h e p o s t - r e i n f o r c e m e n t pause on an i n t e r m i t t e n t s c h e d u l e of r e i n f o r c e m e n t a c r o s s s p e c i e s , r e i n f o r c e r s and c e r t a i n t y p e s o f b e h a v i o u r s . From t h i s t h e o r e t i c a l framework, one would e x p e c t t h a t p i g e o n s would be as l i k e l y t o show a d j u n c t i v e d r i n k i n g as any o t h e r s p e c i e s when the environment does n ot p r o v i d e o p p o r t u n i t i e s f o r the s u b j e c t t o emit o t h e r t y p e s of a d j u n c t i v e b e h a v i o u r s . I t i s c e r t a i n l y not the case t h a t F a l k ' s t h e o r y would p r e d i c t t h a t p i g e o n s would f a i l t o show s c h e d u l e - i n d u c e d p o l y d i p s i a or g r i t consumption. F a l k r e l a t e s a d j u n c t i v e b e h a v i o u r t o t h e d i s p l a c e m e n t activity t h a t e t h o l o g i s t s have r e p o r t e d . He argues t h a t by e m i t t i n g a d i f f e r e n t b e h a v i o u r t h a n t h a t s p e c i f i e d by t h e r e i n f o r c e m e n t c o n t i n g e n c y the s u b j e c t i s l i k e l y t o c o l l e c t o t h e r 42 r e i n f o r c e r s from t h e environment. Thus, d i s p l a y i n g a d j u n c t i v e b e h a v i o u r s would be a d a p t i v e . I f t h i s were t h e c a s e , then the p r o b a b i l i t y o f t h e p i g e o n ' s s u r v i v a l s h o u l d be i n c r e a s e d as much as t h e p r o b a b i l i t y o f the r a t ' s s u r v i v a l by t h i s i n c r e a s e d v a r i a t i o n i n t h e t y p e s of b e h a v i o u r d i s p l a y e d . Thus th e pigeon s h o u l d be as l i k e l y t o have developed a d j u n c t i v e consummatory b e h a v i o u r s as the r a t o r monkey. F u r t h e r m o r e , i f s c h e d u l e -i n d u c e d b e h a v i o u r i s a type of d i s p l a c e m e n t a c t i v i t y , t h e n one would expect t h a t pigeons would be as l i k e l y t o show the s e b e h a v i o u r s as r a t s , as most of the t y p e s o f d i s p l a c e m e n t a c t i v i t i e s t h a t e t h o l o g i s t s have observed have been e m i t t e d by v a r i o u s t y p e s of b i r d s (Armstrong, 1950; T i n b e r g e n , 1952). Thus, i t seems unr e a s o n a b l e t o expect t h a t r a t s , mice and monkeys s h o u l d show t h i s d i s p l a c e m e n t b e h a v i o u r i n t h e l a b o r a t o r y but not p i g e o n s . Another t h e o r y which a t t e m p t s t o e x p l a i n p o l y d i p s i a and o t h e r s c h e d u l e - i n d u c e d b e h a v i o u r s i s a r o u s a l t h e o r y . T h i s t h e o r y has been most c o m p l e t e l y e x p l a i n e d by Wayner (1974) i n a paper devoted t o a d i s c u s s i o n o f d r i n k i n g i n r a t s . He h y p o t h e s i z e s t h a t , i n a r a t which has been s e v e r e l y f o o d d e p r i v e d , the d e l i v e r y of a f o o d p e l l e t i s a v e r y p o w e r f u l u n c o n d i t i o n e d s t i m u l u s which e l i c i t s a s t a t e i n t h e r a t g e n e r a l l y termed e x c i t a t i o n o r a r o u s a l . When the s u b j e c t i s e x p e r i e n c i n g t h i s s t a t e , i t w i l l be h i g h l y m o t i v a t e d t o engage i n some b e h a v i o u r w i t h a h i g h e r f r e q u e n c y than normal. T h i s s t a t e of a r o u s a l i s n o n s p e c i f i c w i t h r e s p e c t t o which b e h a v i o u r w i l l be i n c r e a s e d i n r a t e , w i t h t h e c o n s t r a i n t t h a t i t must i n v o l v e s k e l e t a l o r muscular movement o f t h e s u b j e c t i n some way. An aroused a n i m a l 4 3 would not be expected to engage i n s i t t i n g or sleeping at a higher rate than normal. For the most part, the s p e c i f i c behaviour, out of a l l the possible behaviours that the subject could engage i n , which w i l l increase in frequency i s determined by the subject's environment. If water i s available, an aroused animal w i l l drink, i f a running wheel i s available an aroused animal w i l l run or i f another animal i s available then an aroused animal w i l l attack i t . I f s t i m u l i are available which would allow more than one behaviour to occur then either a few of the behaviours w i l l occur alternately or, more l i k e l y , one of the behaviours w i l l occur at a high rate and the other behaviours w i l l not occur at a l l . Which behaviour i s most l i k e l y to occur i s unclear, but references are made to "the most probable a c t i v i t y associated with eating". The phrase "associated with eating" i s not explained and may refer to a Markovian t r a n s i t i o n p r o b a b i l i t y from the behaviour of eating, an unconditioned or conditioned behaviour e l i c i t e d by food, an unconditioned or conditioned behaviour e l i c i t e d by the lack of food aft e r i t has a l l been consumed or simply behaviour that the animal i s most l i k e l y to engage i n when food i s no longer available in that s i t u a t i o n . Possibly t h i s issue i s not dealt with at length, despite i t s central position i n the theory, because a l l of these p o s s i b i l i t i e s are l i k e l y to y i e l d the same behaviour, and i f they do not, one can fi n d out which behaviour i s going to occur by simply placing the animal in the experimental sit u a t i o n for a few sessions. No one has yet attempted to manipulate which behaviour an animal associates with eating, possibly by a 4 4 c l a s s i c a l c o n d i t i o n i n g p r o c e d u r e , so the i s s u e has not been t e s t e d e m p i r i c a l l y . Wayner a l s o shows t h a t t h e r e s u l t s of p l a c i n g a r a t on an i n t e r m i t t e n t f o o d s c h e d u l e i s s i m i l a r i n i t s e f f e c t s t o e l e c t r i c a l l y s t i m u l a t i n g i t s l a t e r a l hypothalamus, and from t h i s d e v e l o p s a p h y s i o l o g i c a l t h e o r y o f a d j u n c t i v e b e h a v i o u r . T h i s t h e o r y i s used by K i l l e e n (1975) i n h i s r e f e r e n c e s t o s c h e d u l e - i n d u c e d p o l y d i p s i a . H i s e x p e r i m e n t s showed t h a t the g e n e r a l a c t i v i t y of a pigeon (measured as t h e s u b j e c t ' s movement from one s i d e o f an e x p e r i m e n t a l chamber t o t h e o t h e r ) when the s u b j e c t i s r e c e i v i n g g r a i n a t r e g u l a r l y spaced i n t e r v a l s , i s d i s t r i b u t e d as a gamma f u n c t i o n . The s u b j e c t ' s a c t i v i t y i n c r e a s e s t o a maximum a s h o r t time a f t e r r e i n f o r c e m e n t o c c u r s and d e c r e a s e s t h r o u g h o u t the remainder of the i n t e r v a l . He a l s o g e n e r a t e d s c h e d u l e - i n d u c e d p o l y d i p s i a i n r a t s and showed t h a t t h e i r d r i n k i n g was d i s t r i b u t e d by t h e same f u n c t i o n , i m p l y i n g t h a t both g e n e r a l a c t i v i t y and d r i n k i n g a r e f u n c t i o n s of t h e a r o u s a l o f t h e s u b j e c t s by the f o o d s c h e d u l e . He does not i n d i c a t e why he s t u d i e d a c t i v i t y i n the pigeon i n a l l o f h i s e x p e r i m e n t s , and then s w i t c h e d t o r a t s t o study p o l y d i p s i a . K i l l e e n ' s e x p e r i m e n t , c o n s i d e r e d i n the l i g h t of the r e s u l t s o f the p r e s e n t s e r i e s o f e x p e r i m e n t s , have o b v i o u s i m p l i c a t o n s f o r the a r o u s a l t h e o r y of s c h e d u l e - i n d u c e d p o l y d i p s i a . K i l l e e n showed t h a t p i g e o n s were d e f i n i t e l y aroused by t h e f o o d r e i n f o r c e r s , y e t the p r e s e n t e x p e r i m e n t s show t h a t t h i s a r o u s a l does not cause t h e pigeons t o e i t h e r d r i n k o r e a t g r i t e x c e s s i v e l y , even though both o f t h e s e b e h a v i o u r s , o r a t 45 l e a s t one of them, must be s u f f i c i e n t l y s t r o n g l y a s s o c i a t e d w i t h e a t i n g t o be c o n s i d e r e d a l i k e l y s c h e d u l e - i n d u c e d b e h a v i o u r . The o n l y o t h e r p o s s i b i l i t y i s t h a t t h e s u b j e c t s i n t h e p r e s e n t experiment were not aroused by the f o o d r e i n f o r c e r s as K i l l e e n ' s s u b j e c t s were. T h i s seems v e r y u n l i k e l y when the f o o d r e i n f o r c e r s i n the p r e s e n t experiment were p o w e r f u l enough t o g e n e r a t e r a t e s of k e y p e c k i n g of more than 1500 keypecks per hour on an F I 2 min s c h e d u l e o f r e i n f o r c m e n t . The o n l y p o p u l a r t h e o r y which does a l l o w f o r t h e p o s s i b i l i t y t h a t pigeons might not show s c h e d u l e - i n d u c e d p o l y d i p s i a i s t h e t h e o r y t h a t a n i m a l s d r i n k a f t e r f o o d r e i n f o r c e m e n t s i m p l y because t h e i r mouth i s dry ( S t e i n , 1964). One then has t o e x p l a i n o t h e r s c h e d u l e - i n d u c e d b e h a v i o u r s w i t h s e p a r a t e t h e o r i e s . T h i s p r a n d i a l d r i n k i n g t h e o r y was one o f the f i r s t t h e o r i e s f o r m u l a t e d , but i t was argued a g a i n s t p r i m a r i l y because some, though f a r l e s s e r amount of d r i n k i n g , o c c u r s a f t e r l i q u i d r e i n f o r c e m e n t , such as m i l k or v e g e t a b l e o i l ( F a l k , 1967; 1969). T h i s does not n e c e s s a r i l y e l i m i n a t e t h e p r a n d i a l d r i n k i n g t h e o r y , however. I t i s v e r y p o s s i b l e t h a t t h e s u b j e c t s d r i n k water a f t e r d r i n k i n g m i l k or o i l f o r s l i g h t l y d i f f e r e n t r e a s o n s than t h e reason t h a t they d r i n k a f t e r e a t i n g d r y f o o d . Even though l i q u i d r e i n f o r c e r s may not l e a v e t h e mouth d r y , t h e y may l e a v e an a v e r s i v e s t i c k i n e s s o r a f t e r t a s t e b e h i n d which can be e l i m i n a t e d by d r i n k i n g water. For example, t h i s seems t o happen i n human e x p e r i e n c e . Many people d r i n k water a f t e r e a t i n g i c e cream because t h e i c e cream l e a v e s t h e mouth s t i c k y , even though the t a s t e i s q u i t e r e i n f o r c i n g t o many peo p l e . 46 T h i s p r a n d i a l d r i n k i n g t h e o r y of s c h e d u l e - i n d u c e d p o l y d i p s i a has been r e c e n t l y r e v i v e d by i o t t e r , Hoods and V a s s e l l i (1973). These r e s e a r c h e r s have found t h a t r a t s d r i n k a f i x e d amount a f t e r e a t i n g some f o o d . I n an environment where f o o d i s always a v a i l a b l e the r a t w i l l e a t a c e r t a i n amount and t h e n d r i n k t h i s f i x e d amount of water. When f o o d p e l l e t s a r e d e l i v e r e d at spaced i n t e r v a l s the s u b j e c t s t i l l d r i n k s the same amount as i f he had eaten the l a r g e r amount of f o o d t h a t he would have eaten i f i t had been a v a i l a b l e . There i s a decrease i n t h e amount of water consumed d u r i n g the i n t e r - p e l l e t i n t e r v a l s on s c h e d u l e s w i t h s h o r t e r i n t e r - p e l l e t i n t e r v a l s s i m p l y because t h e r a t does not have time t o d r i n k as much water as he would n o r m a l l y due t o the imminent d e l i v e r y o f t h e next food p e l l e t . I t i s h y p o t h e s i z e d t h a t t h e r e a s o n t h a t t h e r a t d r i n k s t h i s c o n s t a n t amount of water a f t e r every p e r i o d o f f e e d i n g i s t o wet h i s mouth and wash down the crumbs of t h e d r y f o o d p e l l e t . T h i s t h e o r y i s a l s o s u p p o r t e d by e v i d e n c e from second o r d e r s c h e d u l e s and from the use o f e l e c t r i c a l s t i m u l a t i o n o f t h e b r a i n as a r e i n f o r c e r . I f the a r o u s a l t h e o r y i s c o r r e c t , then one would e x p e c t t h a t any s t r o n g r e i n f o r c e r would ar o u s e t h e s u b j e c t enough t o show s c h e d u l e - i n d u c e d p o l y d i p s i a , whereas, i f the p r a n d i a l d r i n k i n g t h e o r y i s c o r r e c t one would e x p e c t t o f i n d d r i n k i n g o n l y f o l l o w i n g c e r t a i n consumable r e i n f o r c e r s . S e v e r a l r e c e n t a t t e m p t s have been made t o f i n d s c h e d u l e -i n d u c e d p o l y d i p s i a on second o r d e r or p e r c e n t a g e r e i n f o r c e m e n t s c h e d u l e s on which some i n t e r v a l s t e r m i n a t e i n f o o d 47 r e i n f o r c e m e n t and some i n o n l y c o n d i t i o n e d r e i n f o r c e r s , such as the f e e d e r l i g h t b e i n g i l l u m i n a t e d b r i e f l y . These e x p e r i m e n t s have f a i l e d t o f i n d an amount of d r i n k i n g f o l l o w i n g t h e c o n d i t i o n e d r e i n f o r c e r s which was even c l o s e t o t h e amount of d r i n k i n g t h a t o c c u r r e d f o l l o w i n g the f o o d r e i n f o r c e r s ( A l l e n , P o r t e r and I r a z i e , 1975; F a l k , 1971). Experiments i n which r a t s r e c e i v e d f o o d r e i n f o r c e m e n t d u r i n g some s e s s i o n s and e l e c t r i c a l s t i m u l a t i o n of the hypothalamus d u r i n g o t h e r s e s s i o n s found t h a t the f o o d r e i n f o r c e r s produced p o l y d i p s i a , but t h e b r a i n s t i m u l a t i o n d i d not (Earner and C l o u s t o n , 1974; Earner and H i l k i e , 1975). Thus t h e r e s u l t s o f e x p e r i m e n t s w i t h c o n d i t i o n e d r e i n f o r c e r s and e l e c t r i c a l b r a i n s t i m u l a t i o n r e i n f o r c e m e n t f a v o r the p r a n d i a l d r i n k i n g t h e o r y over the a r o u s a l t y p e of t h e o r y . In a d d i t i o n , the r e s u l t s of t h e p r e s e n t experiment which f a i l e d t o f i n d s t r o n g d r i n k i n g or g r i t e a t i n g i n the p i g e o n f o l l o w i n g food r e i n f o r c e m e n t f a v o r s the p r a n d i a l d r i n k i n g t h e o r y over the a r o u s a l t h e o r y . P i g e o n s have been shown t o become ar o u s e d i n terms of t h e i r g e n e r a l a c t i v i t y d u r i n g i n t e r m i t t e n t s c h e d u l e s of f o o d d e l i v e r y , but i t i s v e r y p o s s i b l e t h a t e a t i n g g r a i n does not g i v e a p i g e o n a d r y mouth. G r a i n i s not as d r y as r a t p e l l e t s , and a p i g e o n ' s method of e a t i n g i s d i f f e r e n t from t h e way t h a t a r a t o r a monkey e a t s . The p igeon does not chew the g r a i n i n i t s mouth, but r a t h e r s i m p l y p i c k s t h e p i e c e o f g r a i n up i n i t s beak and t o s s e s i t down i t s t h r o a t . The g r a i n i s not ground up u n t i l i t r eaches t h e p igeon's c r o p where i t i s mixed w i t h t h e g r i t t h a t i s a l r e a d y t h e r e and i s ground up by muscular 48 c o n t r a c t i o n s . Thus t h e pigeon need not d r i n k i m m e d i a t e l y a f t e r e a t i n g , as the r a t does, because t h e m o i s t u r e i n the mouth would not have been absorbed by the presence o f t h e dry f o o d . N e i t h e r i s i t c l e a r t h a t the pigeon need e a t g r i t a f t e r e a t i n g g r a i n , as t h e same g r i t c o u l d remain i n t h e b i r d ' s c r o p f o r a c o n s i d e r a b l e t i m e . The a d o p t i o n of the p r a n d i a l d r i n k i n g t h e o r y would r e q u i r e t h a t o t h e r t h e o r i e s be c r e a t e d t o handle t h e o t h e r phenomena which have been grouped under the l a b e l o f a d j u n c t i v e b e h a v i o u r . T h i s would not be as d i f f i c u l t as i t seems. Much of t h e s e phenomena c o u l d be e x p l a i n e d by e x i s t i n g t h e o r i e s of a n i m a l b e h a v i o u r . U n l e s s t h e a n i m a l i s dead, i t must be p o s s i b l e t o d e f i n e the a n i m a l ' s a c t i v i t y o r l a c k of a c t i v i t y a t any g i v e n time as a type o f b e h a v i o u r . T h e r e f o r e , t h a t t h e a n i m a l i s engaged i n some b e h a v i o u r d u r i n g t h e p o s t - r e i n f o r c e m e n t i n t e r y a l i s not u n u s u a l , and does not r e q u i r e any e x p l a n a t i o n . What does r e q u i r e an e x p l a n a t i o n i s the s p e c i f i c b e h a v i o u r t h a t the a n i m a l i s engaged i n , and any unusual a s p e c t s o f t h i s b e h a v i o u r , where the term unusual i s used r a t h e r l o o s e l y t o i n d i c a t e a n y t h i n g t h a t an e x p e r i m e n t e r would not have e x p e c t e d t o happen, or t h a t i n t e r e s t s him enough t o conduct f u r t h e r r e s e a r c h on i t . C o n s i d e r i n g t h e u n c o n d i t i o n e d e f f e c t s o f t h e r e i n f o r c e r upon the a n i m a l and the f a c t t h a t t h i s p e r i o d i n any f i x e d i n t e r v a l o r f i x e d r a t i o s c h e d u l e i s when a r e i n f o r c e m e n t i s l e a s t l i k e l y t o o c c u r , i t i s p o s s i b l e t o g e n e r a t e t h e o r i e s which e x p l a i n most of the phenomena observed d u r i n g t h e p o s t - r e i n f o r c e m e n t i n t e r v a l w i t h i n t h e c o n t e x t o f e x i s t i n g t h e o r i e s o f a n i m a l b e h a v i o u r w i t h o u t r e c o u r s e t o the lumping a l l of t h e s e b e h a v i o u r s t o g e t h e r 49 as a s i n g l e phenomena. For example, i t i s not s u r p r i s i n g t h a t a p i g e o n w i l l a t t a c k a n o t h e r pigeon o r an image of a n o t h e r pigeon when one c o n s i d e r s t h a t i t has been shown t h a t a p i g e o n a t t a c k s o t h e r b i r d s d u r i n g p e r i o d s of n o n - r e i n f o r c e m e n t a v a i l a b i l i t y and t h a t t h e post r e i n f o r c e m e n t - p a u s e p r e d i c t s t h a t no f o o d w i l l be d e l i v e r e d t o the s u b j e c t f o r a f i x e d amount of t i m e . Staddon and Simelhag (1971) r a i s e the f o l l o w i n g i s s u e : A r e v i s i o n of the c o n c e p t u a l f o u n d a t i o n s of o p e r a n t b e h a v i o u r , which w i l l d e a l n a t u r a l l y w i t h t h e s e [ a d j u n c t i v e ] b e h a v i o r s , as w e l l as g u i d e r e s e a r c h i n t o more p r o f i t a b l e c h a n n e l s , seems c a l l e d f o r . The q u e s t i o n i s , what i s t h e n a t u r e o f t h e s e r e v i s i o n s ? I s t h e r e a s i n g l e massive change t h a t can be made t o t h e t h e o r y of a n i m a l b e h a v i o u r which w i l l t ake i n t o account e v e r y t h i n g t h a t anyone w i l l want t o c a l l an a d j u n c t i v e b e h a v i o u r , or s h o u l d each o f t h e s e b e h a v i o u r s be t r e a t e d by i t s e l f , and a s m a l l adjustment be made which w i l l accomodate each p a r t i c u l a r c a s e . A d j u n c t i v e b e h a v i o u r s do not seem t o have enough i n common w i t h each o t h e r t o be i n c l u d e d under a s i n g l e r e v i s i o n of t h e t h e o r i e s of a n i m a l b e h a v i o u r . I t might be b e s t , a t t h i s p o i n t t o s i m p l y t a k e each f i n d i n g as i t comes and f i t i t i n as b e s t as p o s s i b l e . One t h i n g t h a t i s c l e a r from t h e d a t a from t h i s s e r i e s of e x p e r i m e n t s i s t h a t t h e phenomena of s c h e d u l e - i n d u c e d p o l y d i p s i a v a r i e s from one s p e c i e s t o t h e n e x t . T h i s means t h a t whatever t h e o r y i s used t o e x p l a i n t h e phenomena of a d j u n c t i v e b e h a v i o u r i s g o i n g t o have t o somehow t a k e t h e s p e c i e s i n t o a c c o u n t . T h i s c o u l d be a n y t h i n g from b l a t a n t l y s p e c i f y i n g t h a t the t h e o r y o n l y a p p l i e s t o a s i n g l e s p e c i e s t o s u b t l y making t h e r e s u l t s dependent upon t h e o p e r a n t l e v e l of some b e h a v i o u r t h a t i s emitted with d i f f e r e n t frequencies by d i f f e r e n t s p e c i e s . 51 REFERENCES A l l e n , J . D., P o r t e r , J . H. , and A r a z i e , R. S c h e d u l e - i n d u c e d d r i n k i n g as a f u n c t i o n of pe r c e n t a g e r e i n f o r c m e n t . J o u r n a l o f th e E x p e r i m e n t a l A n a l y s i s of B e h a v i o r , 1975, 23, 223-232. Armstrong, E. A. The n a t u r e and f u n c t i o n o f d i s p l a c e m e n t a c t i v i t i e s . Symposia of t h e Society; f o r E x p e r i m e n t a l Biolog_y_, 1950, 4, 361-384. Bond, N. W., Blackman, D. E., and S c r u t o n , P. S u p p r e s s i o n of op e r a n t b e h a v i o r and s c h e d u l e - i n d u c e d l i c k i n g i n r a t s . J o u r n a l of t h e E x p e r i m e n t a l A n a l y s i s o f B e h a v i o r , 1973, 20, 375-383. C h i l l a g , D., and Mendelson, J . H. S c h e d u l e - i n d u c e d a i r l i c k i n g as a f u n c t i o n of body-weight d e f i c i t i n r a t s . P h y s i o l o g y , and B e h a v i o r , 1971, 6, 603-605. C l a r k , F. C. Some o b s e r v a t i o n s on t h e a d v e n t i t i o u s r e i n f o r c e m e n t of d r i n k i n g under f o o d r e i n f o r c e m e n t . J o u r n a l of t h e E x p e r i m e n t a l A n a l y s i s o f B e h a v i o r , 1962, 5, 61-66. Cohen, P. S., and Looney, T. A. S c h e d u l e - i n d u c e d m i r r o r r e s p o n d i n g i n t h e pi g e o n . J o u r n a l o f t h e E x p e r i m e n t a l A n a l y s i s of B e h a v i o r , 1973, 19, 395-408. F a l k , J . L. P r o d u c t i o n of p o l y d i p s i a i n normal r a t s by an i n t e r m i t t e n t f o o d s c h e d u l e . S c i e n c e , 1961, J.33, 195-196. F a l k , J . L. S t u d i e s on s c h e d u l e - i n d u c e d p o l y d i p s i a . I n T h i r s t y F i r s t I n t e r n a t i o n a l Symposium on T h i r s t i n t h e R e g u l a t i o n of Body; Water, Ed. W. J . Wayner, Pergamon P r e s s : New Yo r k , 1964. F a l k , J . L. S c h e d u l e - i n d u c e d p o l y d i p s i a as a f u n c t i o n of f i x e d i n t e r v a l l e n g t h s . J o u r n a l o f the E x p e r i m e n t a l A n a l y s i s of B e h a v i o r , 1966, 9, 37-3 9. F a l k , J . L. C o n t r o l of s c h e d u l e - i n d u c e d p o l y d i p s i a : t y p e , s i z e and s p a c i n g o f meals. J o u r n a l of t h e E x p e r i m e n t a l A n a l y s i s of B e h a v i o r , 1967, JO , 199-206. F a l k , J . L. C o n d i t i o n s p r o d u c i n g p s y c h o g e n i c p o l y d i p s i a i n a n i m a l s . A n n a l s o f t h e New York Academy o f S c i e n c e s , 1969, 157, 569-593. F a l k , J . L. The n a t u r e and d e t e r m i n a n t s o f a d j u n c t i v e b e h a v i o u r . P h y s i o l o g y and B e h a v i o r , 1971, 6, 577-587. F l o r y , R. K., A t t a c k b e h a v i o r as a f u n c t i o n o f minimum i n t e r -f ood i n t e r v a l . 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