Response Rate, Latency, and Resistance to Change

Western Michigan University ScholarWorks at WMU Dissertations Graduate College 4-1981 Response Rate, Latency, and Resistance to Change Stephen Joseph Fath Western Michigan University Follow this and additional works at: https://scholarworks.wmich.edu/dissertations Part of the Experimental Analysis of Behavior Commons Recommended Citation Fath, Stephen Joseph, "Response Rate, Latency, and Resistance to Change" (1981). Dissertations. 2589. https://scholarworks.wmich.edu/dissertations/2589 This Dissertation-Open Access is brought to you for free and open access by the Graduate College at ScholarWorks at WMU. It has been accepted for inclusion in Dissertations by an authorized administrator of ScholarWorks at WMU. For more information, please contact maira.bundza@wmich.edu.

RESPONSE RATE, LATENCY, AND RESISTANCE TO CHANGE by Stephen Joseph F ath A D is s e r ta tio n S ubm itted to th e F a c u lty o f The G raduate C o lleg e in p a r t i a l f u lf i llm e n t o f th e re q u ire m e n ts f o r th e D egree o f D octor o f P h ilo so p h y D epartm ent o f Psychology W estern M ichigan U n iv e rs ity K alam azoo, M ichigan A p ril 1981

RESPONSE RATE, LATENCY, AND RESISTANCE TO CHANGE S tephen Joseph F a th, Ph.D. W estern M ichigan U n iv e r s ity, 1981 R esponse r a t e h as been c r i t i c i z e d a s an a d e q u a te m easure o f re sp o n se s tr e n g t h on th e b a s is t h a t r a t e r e f l e c t s th e a d v e n titio u s re in fo rc e m e n t o f in te r r e s p o n s e tim e s. Nevin (1974, 1979) p ro p o sed r e l a t i v e r e s is ta n c e to change a s an a l t e r n a t i v e m easure. N evin (1974) employed m u ltip le - p a c in g sc h e d u le s in w hich e i t h e r h ig h - o r lo w - r a te re q u ire m e n ts w ere p la c e d in tandem w ith e i t h e r VI 1 min o r VI 3 min s c h e d u le s o f re in fo rc e m e n t. The r e s u l t s su g g ested t h a t lo w - r a te resp o n d in g may be m ore r e s i s t a n t to change when sch e d u le s a r e e q u a te d f o r re in fo rc e m e n t fre q u e n c y. F a th and M a lo tt (1979) r e p l i c a t e d N e v in 's e x p erim en t, b u t found no ev id en ce th a t c o n tin g e n c ie s on re s p o n s e r a t e a f f e c t r e l a t i v e r e s i s t a n c e to change. T hat N evin o b serv ed d if f e r e n c e s in re sp o n se s tr e n g t h u nder s im ila r c o n d itio n s in h i s s tu d y, may be due to d if f e r e n c e s in th e programming o f h ig h - and lo w -re sp o n se r a t e c o n tin g e n c ie s. In th e p re s e n t s tu d y, re fin e m e n ts o f th e p ro ced u re used by N evin (1974) and F a th and M alo tt (1979) w ere u sed, and a p a ra m e tric in v e s t ig a t io n o f th e e f f e c t s o f re sp o n se -in d e p e n d e n t food on b e h a v io r m a in ta in e d by a m u ltip le -p a c in g s c h e d u le was co n d u cted. The r e s u l t s su p p o rt th e fin d in g s o f F a th and M alo tt (1 9 7 9 ), th a t re sp o n se r a t e c o n tin g e n c ie s do n o t a f f e c t r e l a t i v e r e s i s t a n c e to change. Both re s p o n s e r a t e s and la te n c i e s to resp o n d v a r ie d s y s te m a tic a lly w ith in c r e a s e s in th e m agnitude o f re sp o n se -in d e p e n d e n t food p r e s e n ta tio n s. R esponse r a t e s d e c re a se d, w h ile l a t e n c i e s in c re a s e d. T hese r e s u l t s

a r e c o n s is te n t w ith N evin*s s u g g e s tio n t h a t r e l a t i v e r e s is ta n c e to change i s a fu n c tio n o f re in fo rc e m e n t fre q u e n c y, b u t n o t w ith th e n o tio n t h a t re sp o n se r a t e c o n tin g e n c ie s a f f e c t re sp o n se s tr e n g th, The r e l a t i o n betw een N evin*s co n cep t o f re sp o n s e s tr e n g t h and p re v io u s e x p e rim e n ta l fin d in g s i s d is c u s s e d.

ACKNOWLEDGEMENTS I would lik e to th ank D rs. M. Kay M a lo tt, John L. M ichael, D avid 0. Lyon and A rth u r G. Snapper f o r t h e i r g u id a n c e, e x p e r t is e, and frie n d s h ip d u rin g th e c o u rse o f my g ra d u a te s tu d ie s. In a d d itio n, th anks a re due Dr. C la ren ce G oodnight f o r s e rv in g as th e o u ts id e member o f my d is s e r t a t i o n com m ittee, and to D eborah G ro s s e tt fo r a s s is ta n c e in programming and co n d u c tin g th e e a r ly p a r t o f th i s in v e s tig a tio n. I would a l s o l i k e to thank th e D epartm ent o f Psychology and The G raduate C o lle g e f o r t h e i r s u p p o rt, w ith o u t w hich t h i s stu d y would n o t have b een p o s s ib le. S tephen Joseph F ath i i

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8116613 Fath, Stephen Jo seph RESPONSE RATE, LATENCY, AND RESISTANCE TO CHANGE Western Michigan University PH.D. 1! University Microfilms International 300 N. Zeeb Road, Ann Arbor, MI 48106

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TABLE OF CONTENTS ACKNOWLEDGEMENTS...i i LIST OF FIGURES... iv C hapter I. INTRODUCTION... 1 I I. METHOD...15 S u b je c ts... 15 A p p a ra tu s...15 P ro c e d u re... 16 M agazine t r a i n i n g...16 Keypeck t r a i n i n g...16 B a s e lin e s c h e d u le s... 17 T e s tin g... 22 I I I. RESULTS...24 B a s e lin e A ssessm en t... 24 E f f e c ts o f R esp o n se-in d ep en d en t Food...28 IV. DISCUSSION...44 BIBLIOGRAPHY...54 i i i

I LIST OF FIGURES F ig u re 1. S ta te d iagram o f c o n tin g e n c ie s on re sp o n se r a t e u sed by N evin (1974) and F a th and M a lo tt (1 9 7 9 )... 1 F ig u re 2. S ta te diagram o f te rm in a l b a s e lin e p ro c e d u re...18 F ig u re 3. F ig u re 4. F ig u re 5. F ig u re 6. F ig u re 7. F ig u re 8. Mean in te r - r e s p o n s e tim e p e r o p p o rtu n ity a s a fu n c tio n o f IRT i n seconds f o r in d iv id u a l s u b j e c t s... <25 Mean re s p o n s e r a t e and mean la te n c y a s a fu n c tio n o f re s p o n se-in d e p e n d e n t food magn itu d e in seconds f o r in d iv id u a l s u b je c t s... 30 Mean re s p o n s e r a t e and mean la te n c y a s a fu n c tio n o f re sp o n se-in d e p e n d e n t food magn itu d e i n seco n d s f o r in d iv id u a l s u b je c t s...33 L aten cy a s a fu n c tio n o f t r i a l s w ith in s e s s io n s o f re sp o n se -in d e p e n d e n t food p re s e n ta tio n (S u b je c ts 1 and 2 )... 37 L atency a s a fu n c tio n o f t r i a l s w ith in s e s s io n s o f re s p o n se-in d e p e n d e n t food p re s e n ta tio n (S u b je c ts 3 and 4 )...39 L atency a s a fu n c tio n o f t r i a l s w ith in s e s s io n s o f re s p o n se-in d e p e n d e n t food p re s e n ta tio n (S u b je c ts 5 and 6 )...41 iv

INTRODUCTION In th e f i e l d o f o p e ra n t c o n d itio n in g, re in fo rc e m e n t i s d e fin e d a s th e p r e s e n ta tio n o f an e v e n t fo llo w in g a re s p o n s e, w hich in c r e a s e s th e f u tu r e p r o b a b ility, o r r a t e, o f th e re sp o n se. I t i s o f te n s t a t e d t h a t re in fo rc e m e n t in c re a s e s th e s tr e n g th o f a re sp o n se ( c f. H e r m s te in, 1970; S m ith, 1974). The te rm "re sp o n se s tr e n g th " im p lie s t h a t s e v e r a l p r o p e r tie s o f b e h a v io r c o v a ry. Each p ro p e rty i s ta k e n a s a m easure o f s tr e n g th, b u t no one p r o p e r ty i s synonymous w ith t h i s q u a l ity o f b e h a v io r. A lthough th e n o tio n o f re sp o n se s tr e n g th has a p p e a re d i n th e l i t e r a t u r e s in c e th e e a r l y days o f re fle x o lo g y (W hytt, 1751;. S echenov, 1863; S h e rrin g to n, 1906; P a v lo v, 1927; T h o rn d ik e, 1911; and H u ll, 1943), no one method o f a s s e s s in g th e s tr e n g th o f a re sp o n se h as come in t o common u sag e. R esponse r a t e, la te n c y, a m p litu d e, and r e s i s t a n c e to e x tin c tio n have a l l f a i l e d to g a in g e n e ra l su p p o rt b ecause o r d e r ly d a ta w ith q u a n t i t a t i v e and g e n e ra l s ig n if ic a n c e have n o t b een fo rth co m in g ( H e rm s te in, 1970). S k in n er (1938) n o te d t h a t th e r e a re two e f f e c t s o f re in fo rc e m e n t; one i s th e im m ediate in c r e a s e in re sp o n se r a t e, th e second i s in c re a s e d r e s is ta n c e to e x t i n c t i o n w ith th e u se o f a d d itio n a l r e i n f o r c e r s. He n o te d, how ever, t h a t th e s e two m e asu re s, re sp o n se r a t e and r e s i s t a n c e to e x tin c tio n, a r e n o t w e ll c o r r e l a te d, and s e t t l e d on re sp o n se r a t e a s h is m easure o f re s p o n s e s tr e n g t h. The la c k o f c o r r e l a t i o n betw een re sp o n se r a t e and r e s i s t a n c e to e x tin c tio n i s e x e m p lifie d i n a stu d y by W ilson (1954) in v o lv in g f ix e d - i n t e r v a l (F I) re in fo rc e m e n t s c h e d u le s. W ilson tr a in e d d i f f e r e n t groups o f r a t s a t d i f f e r e n t FI v a lu e s, and o b ta in e d a d e c re a s in g 1

2 m onotonic f u n c tio n r e l a t i n g av erage re sp o n se r a t e s to th e le n g th o f th e f i x e d - i n t e r v a l. When th e s u b je c ts were exposed to an e x t in c tio n p ro c e d u re, a non-m onotonic r e la tio n s h ip betw een th e mean number o f re sp o n se s d u rin g e x t i n c t i o n and th e v a lu e o f th e FI sc h e d u le em ployed d u rin g tr a i n in g was fo u n d ; maximum resp o n d in g was o b serv ed a t an FI v a lu e o f one m in u te. Response r a t e does n o t a p p e a r to be a good g e n e ra l m easure of re sp o n se s tr e n g t h. Such in d e p en d en t v a r ia b le s as m agnitude and d e la y o f re in fo rc e m e n t have been shown to have l i t t l e e f f e c t on re sp o n se r a t e (C a ta n ia, 1963; N e u rin g e r, 1967; R ic h a rd s, 1973). R ate o f re sp o n se may a ls o be i n s e n s i t i v e to r a t e o f re in fo rc e m e n t, e s p e c ia lly a t h ig h re in fo rc e m e n t r a t e s (C a ta n ia and R eynolds, 1968). More im p o rta n tly, how ever, re sp o n se r a t e may be b o th in c re a s e d by re in fo rc e m e n t r a t e and shaped by th e c o n tin g e n c ie s w hich r e l a t e re sp o n d in g to re in fo rc e m e n t (M orse, 1966). As su c h, re sp o n se r a t e can n o t be i n t e r p r e te d unam biguously i n r e l a t i o n to th e co n cept o f s tr e n g th (N evin 1977, 1979). M oderate re sp o n se r a t e s may be m a in ta in e d on i n t e r v a l sch e d u le s b ecause th ey s e l e c t i v e l y r e in f o r c e lo n g in te r - r e s p o n s e tim es (IRTs) (see Shimp, 1974). In r a t i o s c h e d u le s, how ever, h ig h re sp o n se r a te s may be m a in ta in e d b ecau se th e y le a d to h ig h e r av era g e r a t e s o f re in fo rc e m e n t. A lthough th e s tre n g th e n in g e f f e c t o f re in fo rc e m e n t presum ably o p e ra te s i n th e same way u nder a l l s c h e d u le s, th e s tre n g th e n in g and r a te - s h a p in g e f f e c t s can n o t be e a s i l y d is e n ta n g le d. The o b je c tio n s t a t e d above i s th a t th e r o le o f th e d i s t r i b u t i o n o f re in f o r c e d IRTs i n d e te rm in in g resp o n se r a t e i s n e g le c te d. The mean r a t e o f re sp o n se i s th e r e c ip r o c a l o f th e mean o f th e d i s t r i b u t i o n o f

3 IRTs, w hich i s i n tu r n d e te rm in e d by th e d i s t r i b u t i o n o f re in fo rc e m e n t f o r th o s e IRTs. The s u g g e s tio n i s t h a t a s u b j e c t 's IRTs a r e d i s t r i b u t e d a c c o rd in g to th e freq u en cy w ith w hich each i s r e in f o r c e d r e l a t i v e to th e o th e r s. From t h i s p e r s p e c tiv e, th e b a s ic re sp o n se u n it in c lu d e s th e p a u ses betw een s u c c e s s iv e re s p o n s e s, r a t h e r th a n th e sim p le sw itc h c lo s u r e. The p o in t i s th a t re sp o n se r a t e i s a c o n d itio n a b le dim ension o f b e h a v io r. T hat i s, c o n tin g e n c ie s on re s p o n s e r a t e, sch ed u led o r s p u rio u s, can r e s u l t in a b ia se d d ependent v a r i a b l e. T his c o n te n tio n i s su p p o rte d by numerous s tu d e is ( c f. A nger, 1956, 1973; B lo u g h, 1963: B lough an d B lo u g h, 1968; M a lo tt and Cumming, 1965; Shimp, 1967, 1968; S tad d o n, 1968; W illiam s, 1968; and W ilk ie and P e a r, 1972). N evin (1974, 1977, 1979) has su g g ested t h a t a co n cept o f re sp o n s e s tr e n g th, p h rased i n te rm s o f r e s is ta n c e to ch an g e, may b e u sed to sum m arize th e e f f e c t s o f d iv e rs e p ro c e d u re s. Changes i n re s p o n s e r a t e s, r e l a t i v e to t h e i r own b a s e lin e s, a r e o b serv ed when some o p e ra tio n i s used to d is r u p t ongoing re sp o n d in g. Under t h i s p ro c e d u re, tw o, o r m ore, p erfo rm ances a r e compared u nder i d e n t i c a l c o n d itio n s th a t d is r u p t a t l e a s t one o f them. I t i s th e n p o s s ib le to make o r d in a l com p ariso n s. A c o n v e n ie n t way to a rra n g e t h i s s t a t e o f a f f a i r s i s th ro u g h th e u s e o f a m u ltip le sc h e d u le in w hich d i f f e r e n t re in fo rc e m e n t s c h e d u le s, each c o r r e l a te d w ith d i s t i n c t i v e s t i m u l i, a r e p re s e n te d s u c c e s s iv e ly. In t h i s way i t i s p o s s ib le to a s s e s s th e e f f e c t s o f a t h i r d v a r ia b le on in d iv id u a l p erfo rm ances. Exam ples o f th e d is r u p tiv e o p e ra tio n in c lu d e m a n ip u la tio n s o f d e p r iv a tio n s c h e d u le s o r th e in tr o d u c tio n o f re sp o n se-in d e p e n d e n t food.

In a s e r i e s o f ex p erim en ts by Nevin (1 9 7 4 ), p ig e o n s w ere tr a in e d w ith, one sc h e d u le o f food re in fo rc e m e n t f o r p eck in g i n th e p re s e n c e o f a lig h te d re s p o n s e key a s s o c ia te d w ith one com ponent o f a th r e e - component m u ltip le s c h e d u le, and a d i f f e r e n t s c h e d u le in th e p re se n c e o f a second key c o lo r. A fte r resp o n d in g in b o th s c h e d u le com ponents s t a b i l i z e d, re sp o n s e -in d e p e n d e n t food was p re s e n te d i n th e p re se n c e o f an u n illu m in a te d key w hich in te rv e n e d betw een c o lo r com ponents. The re s p o n s e r a t e s, r e l a t i v e to t h e i r own b a s e l i n e s, in b o th sch e d u le com ponents d e c re a se d a s a fu n c tio n o f re sp o n se -in d e p e n d e n t food freq u en cy d u rin g d a rk -k e y p e rio d s. The r e l a t i v e d e c re a s e s in re sp o n d in g w ere r e l a t e d to th e fre q u e n c y, d e la y, o r m agnitu d e o f re in fo rc e m e n t a s s o c ia te d w ith each com ponent, a s w e ll a s to re s p o n se r a te - c o n tin g e n c ie s. N evin (1979) p ro v id e s an e l a b o r a tio n, and a d d itio n a l e v id e n c e, which, s u g g e s ts th e u t i l i t y o f a c o n c e p t o f re s p o n s e s tr e n g th b ased on r e s i s t a n c e to change. E xperim ent I o f N ev in s (1974) stu d y was d e sig n e d to show changes in re s p o n s e r a t e d u rin g a th ree-com ponent m u ltip le sc h e d u le w here p eck in g was r e in f o r c e d w ith food a t d i f f e r e n t c o n s ta n t f re q u e n c ie s, w h ile th e fre q u e n c y o f re sp o n se -in d e p e n d e n t food i n th e t h i r d component was v a r ie d s y s te m a tic a lly. The r e s u l t s w ere c o n s is te n t w ith th e common fin d in g t h a t resp o n d in g in one sc h e d u le component depends on th e r e l a t i v e fre q u e n c y o f re in fo rc e m e n t produced by re sp o n d in g in th a t com ponent, and t h a t th e so u rc e o f re in fo rc e m e n t and th e c o n tin g e n c ie s in th e o th e r component do n o t a l t e r t h a t r e la tio n s h ip (H e r r n s te ln, 1961, 1970, 1973; N evin, 1968; R a c h lin and Baum, 1972). In E xperim ent I, th e r e l a t i v e re in fo rc e m e n t r a t e was alw ays h ig h e r

5 i n th e p re se n c e o f a g reen s tim u lu s, and r e l a t i v e re sp o n se r a t e was l e s s a f f e c te d by th e in tr o d u c tio n o f re s p o n s e -in d e p e n d e n t food. I t h as a lre a d y been n o te d t h a t th e e v a lu a tio n o f re s p o n se s tr e n g th i s co m p lic a te d by th e f a c t t h a t re sp o n s e r a t e i s a c o n d itio n a b le d im ension o f b e h a v io r, and t h a t th e sc h e d u le em ployed in c o n d itio n in g re s p o n s e r a t e may have th e e f f e c t o f e s ta b l is h in g q u a l i t a t i v e l y d i f f e r e n t perform ances w hich can n o t b e e a s i l y o rd e re d w ith r e s p e c t to s tr e n g t h. E xperim ent V o f N e v in 's (1974) s tu d y e v a lu a te d th e p o s s i b i l i t y t h a t re s p o n s e s tr e n g th may b e m e an in g fu l o n ly w here p erform ances m a in ta in e d by s im ila r c o n tin g e n c ie s a r e com pared. As in E xperim ent I, d e s c rib e d above, a three-co m p o n en t m u ltip le sc h e d u le was u se d. Red and g re e n k e y lig h t p r e s e n ta tio n s, each o f 60 s e c d u r a tio n, w ere i n i t i a l l y c o r r e l a te d w ith v a r i a b l e - i n t e r v a l (VI) 1 min o r VI 3 min s c h e d u le s o f re in fo rc e m e n t. The sc h e d u le com ponents a l t e r n a t e d r e g u la r ly w ith 3 0 -sec d a rk -k e y p e rio d s in te r v e n in g. D ark-key p e rio d s w ere c o r r e la te d w ith e x tin c tio n d u rin g th e b a s e lin e p h ase o f th e e x p e rim e n t. N ext, c o n tin g e n c ie s on th e r a t e o f re sp o n se n e c e ssa ry to c o l l e c t re in fo rc e m e n t w ere p la c e d in tandem w ith th e VI sch e d u le re q u ire m e n ts. In a tandem s c h e d u le, two c o n tin g e n c ie s m ust b e met s u c c e s s iv e ly i n o rd e r to c o l l e c t a sch ed u le d r e in f o r c e r. No s tim u lu s changes a r e d i f f e r e n t i a l l y c o r r e la te d w ith th e d i f f e r e n t com ponents o f th e re in fo rc e m e n t sc h e d u le in a tandem a rran g em en t. A d if f e r e n tia l - r e in f o r c e m e n t- o f - l o w - r a t e (DRL) c o n tin g e n c y was p la c e d in tandem w ith e i t h e r th e VI 1 min o r VI 3 min s c h e d u le, and a d if f e r e n tia l - r e in f o r c e m e n t- o f - h i g h - r a te (DRH) re q u ire m e n t was p la c e d in tandem w ith th e o th e r VI s c h e d u le. The e n t i r e arrangem ent d e s c rib e d h e re i s c a lle d a " m u ltip le -p a c in g sc h e d u le " o f re in fo rc e m e n t.

6 F ig u re 1 i s a S ta te Diagram (S n ap p er, Knapp and K ushner, 1970) Which i l l u s t r a t e s th e e s s e n t i a l s o f th e te rm in a l b a s e lin e c o n tin g e n c ie s o f re in fo rc e m e n t. The f ig u r e i s o rg a n iz e d in te rm s o f " s t a t e s e t s, " w hich d e s c r ib e p o rtio n s o f th e e x p e rim e n ta l p ro c e d u re, and " s t a t e s, " (S#) w hich a r e d e fin e d by th e s tim u lu s c o n d itio n s and re sp o n se c o n tin g e n c ie s a c t iv e a t a g iv en moment in th e e x p e rim e n ta l environm ent. R equirem ents f o r t r a n s i t i o n from one s t a t e to a n o th e r ap p ear on th e t r a n s i t i o n v e c to r s (a rro w s). The two s t a t e s e t s d e p ic te d in F ig u re 1 a r e, o f c o u rs e, m u tu a lly e x c lu s iv e, s in c e a m u ltip le sch e d u le was em ployed. Only one s e t o f c o n tin g e n c ie s was i n e f f e c t a t a given moment. The u p p er p o rtio n o f F ig u re 1 d e s c r ib e s th e tandem V I, DRL c o n tin g e n c y employed by Nevin (1974, Exp V) arid F a th and M alo tt (1979) i n t h e i r r e p l i c a t i o n o f N e v in 's p ro c e d u re. At th e o n se t o f each re d s tim u lu s com ponent, an in d epen d en t VI tim e r began tim in g (S 2 ). A fte r th e tim e r had tim e d -o u t, s u b je c ts w ere r e q u ir e d to make a re sp o n se (S 3 ), w a it a t l e a s t th r e e se c (S 4 ), and th e n em it a second re sp o n se (S5) i n o rd e r to c o l l e c t re in fo rc e m e n t. R esponses w hich w ere e m itte d p r io r to th e tim in g -o u t o f th e th r e e sec tim e r in S4 r e s e t th e tim e r. In t h i s way, o n ly re sp o n se s te rm in a tih g IRTs o f a t l e a s t th r e e sec w ere r e in f o r c e d. R ein fo rcem en ts n o t c o l le c t e d a t th e end o f t h i s component w ere c a n c e lle d. The lo w er p o rtio n o f F ig u re 1 d e p ic ts th e tandem V I, DRH co n tin g en cy u sed in b o th e x p e rim e n ts, in th e p re s e n c e o f a g re e n k e y lig h t. An in d e p en d en t VI tim e r was a c tiv a te d a t th e tim e o f component o n se t (S 2 ). Once th e VI tim e r has tim e d -o u t, s u b je c ts w ere re q u ire d to em it th r e e re s p o n ses w ith in th r e e sec (S3) in o rd e r to c o l l e c t re in fo rc e m e n t.

F ig u re 1 S ta te d iagram o f c o n tin g e n c ie s on re sp o n se r a t e u sed by N evin (1974) and F a th and M a lo tt (1 9 7 9 ).

F ig u re 1 TANDEM V I, DHL component o ffset ENT O N SE T -^J^) V I S -* @ IES/ ^ l l K ^ j ------NO----------<CaKPOMIMT>«---- 5"«OFF sr----- rjurom vj» PRg CCHPOHB1T OFFSET COMPONENT ONS: NO IX S cckpohhrr">5,:o rr sj NEVIN, 1974, E rp. V PATH AND MALOTT, 1979

9 T here w ere no s p e c if i c IRT re q u ire m e n ts on th e s e re s p o n s e s. In o th e r w o rd s, re in fo rc e m e n t was p re s e n te d no m a tte r w hat th e p a r t i c u l a r IRTs, so lo n g a s th e r a t i o o f th r e e re s p o n s e s was com pleted b e fo re th e th r e e s e c tim e r (S3) had tim e d -o u t. I f th e r e in f o r c e r w ere n o t c o lle c te d w ith in th e s p e c if ie d tim e l i m i t, i t was c a n c e lle d. For b o th th e re d and g re e n com ponents, th e n e x t VI began tim in g a f t e r re in fo rc e m e n t d e liv e r y (S6 f o r DRL and S4 f o r DRH) p ro v id ed t h a t th e same s tim u lu s was a c t iv e. I f e i t h e r sc h e d u le component had tim e d -o u t d u rin g th e c o u rse o f re in fo rc e m e n t d e l iv e r y, th e food p r e s e n ta tio n was n o t in t e r r u p te d, r a t h e r th e s t a t e s e t was d e a c tiv a te d ' fo llo w in g re in fo rc e m e n t d e liv e r y. Component o f f s e t p r io r to th e co m p letio n o f th e re sp o n se r a t e c o n tin g e n c ie s r e s u lte d in th e lo s s o f re in fo rc e m e n t in th e c a s e o f b o th c o n tin g e n c ie s. N evin used two v a lu e s o f th e in d e p e n d e n t v a r ia b le, r a t e o f re sp o n se-in d e p e n d e n t food p r e s e n ta tio n d u rin g d a rk -k e y p e rio d s (60 o r 360 p e r h o u r), to a s s e s s d i f f e r e n t i a l r e s i s t a n c e to change. The f i r s t ex p o su re to 60 re sp o n se -in d e p e n d e n t food p r e s e n ta tio n s p e r h o u r la s t e d f o r 14 s e s s io n s. T h e r e a f te r, p r e s e n ta tio n s w ere lim ite d to one s e s s io n (The o b ta in e d r a t e s o f re in fo rc e m e n t changed s u b s t a n t i a l l y u n d er th e sc h e d u le d c o n tin g e n c ie s, and N evin re g a rd e d th e s e d a ta as u n i n t e r p r e t a b l e ). F ollo w in g th e second t e s t (360 re s p o n s e -in d e p e n d e n t food p r e s e n ta tio n s p e r h o u r), b a s e lin e s w ere re c o v e re d, and th e n e x tin g u is h e d by w ith o ld in g food re in fo rc e m e n t f o r seven s e s s io n s. The b a s e lin e c o n d itio n s w ere th e n re v e rs e d. T hat i s, i f th e DRL c o n tin g e n c y had been in tandem w ith th e VI 1 min sc h e d u le, i t was p la c e d i n tandem w ith th e VI 3 min sc h e d u le, and th e DRH c o n tin g en cy was p la c e d in tandem w ith th e o th e r VI s c h e d u le. B a se lin e s w ere th e n e s ta b lis h e d f o r th e n e x t s e r i e s o f

10 t e s t s e s s io n s w ith re sp o n se -in d e p e n d e n t fo o d. N evinfs dep en d ent v a r i a b l e was r e l a t i v e re sp o n se r a t e. In t h i s c a s e, th e o b serv ed re s p o n s e r a t e f o r each component d u rin g t e s t s e s s io n s was e x p re sse d a s a p ro p o rtio n o f i t s a s s o c ia te d b a s e lin e re sp o n se r a t e. B a s e lin e re sp o n se r a t e s w ere e s ta b lis h e d by a v e ra g in g th e d a ta f o r each com ponent a c ro s s th e th r e e s e s s io n s p r i o r to each t e s t s e s s io n. The d a ta from N e v in 's (1974, Exp V) stu d y su g g e st t h a t when c o n tin g e n c ie s on re s p o n s e r a t e a r e th e same (DRL o r DRH), p erfo rm ances m a in ta in e d by VI 1 min re in fo rc e m e n t a r e s tr o n g e r ( le s s changed from b a s e lin e ) th a n th o s e m a in ta in e d by VI 3 min re in fo rc e m e n t. In a d d itio n, th e d a ta f o r a t l e a s t two s u b je c ts p ro v id ed some s u g g e s tio n t h a t p erform ances m a in ta in e d by th e DRL c o n tin g e n c y a r e s tr o n g e r th a n th o s e m a in ta in e d u nder th e DRH c o n tin g e n c y. However, b e c a u se th e s e r e s u l t s w ere u n e x p ected, th e ex p erim en t was n o t d esig n ed to i s o l a t e th e e f f e c t s o f th e DRL and DRH c o n tin g e n c ie s. N evin s ta t e d t h a t to do s o, i t would b e b e s t to a rra n g e i d e n t i c a l re in fo rc e m e n t fre q u e n c ie s i n c o n ju n c tio n w ith th e d i f f e r e n t re s p o n s e r a t e c o n tin g e n c ie s in th e two c o lo r com ponents o f a m u ltip le s c h e d u le. T h is arrangem ent would a llo w com parison o f th e e f f e c t s o f th e re sp o n s e r a t e c o n tin g e n c ie s w ith o u t th e v a r i a b i l i t y in tro d u c e d by th e i n t e r v a l s o f n e a r ly th r e e m onths w hich e la p se d betw een com parisons in h is stu d y. N e v e rth e le s s, Nevin s ta t e d th a t h i s r e s u l t s, a lth o u g h p e rm ittin g o n ly weak c o n c lu s io n s, in c o n ju n c tio n w ith th o s e o f o th e rs (Blackman, 1 968), i n d i c a t e t h a t h ig h - r a t e re q u ire m e n ts g e n e ra te w eaker p erfo rm ances th a n lo w -ra te re q u ire m e n ts. F a th and M a lo tt (1979) p ro v id ed s y ste m a tic r e p l i c a t i o n o f N ev in s

11 (1974, Exp V) p ro c e d u re. In o rd e r to a llo w f o r t h e a p p r o p r ia te com parisons o f th e e f f e c t s o f h ig h - and lo w - r a te c o n tin g e n c ie s, as su g g e ste d by N evin, two s u b je c ts w ere exposed to a M u ltip le VI 1 m in, DRL/VI 1 m in, DRH c o n d itio n, and two s u b je c ts w ere exposed to th e same d i f f e r e n t i a l - r a t e c o n tin g e n c ie s i n tandem w ith VI 3 min sch e d u le s o f re in fo rc e m e n t. In a d d itio n, fo u r s u b je c ts w ere exposed to th e c o n d itio n s employed by N evin. The r e s u l t s o f F a th and M a lo tt (1979) su p p o rt N ev in s (1974, 1977, 1979) f in d in g s t h a t re in fo rc e m e n t freq u en cy i s a s tro n g d e te rm in a n t o f r e l a t i v e r e s i s t a n c e to ch an g e, r e g a r d le s s o f th e o b serv ed b a s e lin e re sp o n se r a t e s. However, N ev in s (1974) t e n t a t i v e c o n c lu s io n, t h a t c o n tin g e n c ie s on re sp o n se r a t e a f f e c t r e s i s t a n c e to change, was n e i th e r confirm ed n o r d is c o n firm e d. The a v e ra g e r e s u l t s f o r th e p ig e o n s exposed to th o s e c o n d itio n s employed by N evin (1974, Exp V) showed s im ila r e f f e c t s. However, when th e sc h e d u le com ponents w ere eq u ated f o r re in fo rc e m e n t fre q u e n c y, th e r e w ere no c o n s is te n t d if f e r e n c e s betw een resp o n d in g m a in ta in e d u n d er th e DRL and DRH c o n tin g e n c ie s. N evin (1974, 1977, 1979) h as d em o n strated t h a t r e l a t i v e r e s is ta n c e to change i s a v ia b le re sp o n se m easure w hich v a r i e s in a c o n s is te n t m anner w ith v a rio u s p a ra m e te rs o f re in fo rc e m e n t ( e.g. fre q u e n c y and d e la y ). To th e e x te n t w hich t h i s i s t r u e, th e a s s o c ia te d co n cept o f re sp o n se s tr e n g th i s su p p o rte d a s p o t e n t i a l l y u s e f u l. F a th and M a lo tt (1979) co n firm ed N evin s appro ach to th e q u a n t if ic a tio n o f re sp o n se s tr e n g th by d e m o n stra tin g t h a t r e l a t i v e r e s i s t a n c e to change v a r ie s w ith re in fo rc e m e n t fre q u e n c y in th e ex p ected m anner. The f a i l u r e to su p p o rt th e s u g g e s tio n t h a t low - and h ig h - r a t e

re q u ire m e n ts p roduce d if f e r e n c e s in r e s i s t a n c e to change, o f c o u rse, i n no way in v a lid a t e s N evin s approach to th e q u a n t i f i c a t i o n o f re sp o n se s tr e n g t h ; r a t h e r th e fin d in g su g g e s t t h a t su ch c o n tin g e n c ie s on th e te m p o ra l d i s t r i b u t i o n, and num ber, o f re s p o n s e s have l i t t l e o r no e f f e c t on r e s is ta n c e to change. T hat N evin o b serv ed d if f e r e n c e s in s tr e n g th betw een b e h a v io rs m a in tain ed by h ig h - and lo w -ra te c o n tin g e n c ie s, w hich le d him to th e t e n t a t i v e c o n c lu sio n t h a t su c h p erfo rm ances a r e q u a l i t a t i v e l y d i f f e r e n t, may be a t t r i b u t e d to d if f e r e n c e s in th e program m ing o f th e re s p o n se r a t e c o n tin g e n c ie s, w hich d i f f e r e n t i a l l y a f f e c t e d th e a v a i l a b i l i t y of re in fo rc e m e n t f o r h ig h - and lo w -ra te b e h a v io r s. I n s p e c tio n o f F ig u re 1 s u g g e s ts t h a t th e c o n tin g e n c ie s used by N evin (1974, Exp V) and F ath and M alo tt (1979) a r e e s s e n t i a l l y in e q u iv a le n t w ith r e s p e c t to th e d is p o s itio n o f u n c o lle c te d r e i n f o r c e r s. R ein fo rcem en t f o r DRL re sp o n d in g was n o t c a n c e lle d u n t i l th e end o f a g iv e n s c h e d u le com ponent, b u t th a t f o r DRH re sp o n d in g was c a n c e lle d w ith in th r e e se c o f s e t- u p, u n le ss th e s u b je c t e m itte d th e a p p ro p ria te number o f re sp o n ses w ith in th e s p e c if ie d tim e l i m i t. In a d d i tio n, th e DRL c o n tin g e n c y i s o p en-ended. Any IRT o f th r e e o r more seconds d u r a tio n can be re in f o r c e d under t h i s p ro c e d u re. The n e t e f f e c t o f th e s e d if f e r e n c e s i s on th e a v a i l a b i l i t y of re in fo rc e m e n t f o r resp o n ses w hich o c c u r d u rin g th e c o u rse o f t e s t i n g. The program m ing o f r a t e c o n tin g e n c ie s i n th e m anner d e s c rib e d in F ig u re 1 c r e a te s a b ia s in fa v o r o f re sp o n d in g m a in ta in e d by th e DRL c o n tin g e n c y. A s u b je c t s ta n d s a b e t t e r chance o f b ein g re in f o r c e d even a f t e r long p auses in re sp o n d in g u n d er t h i s c o n d itio n, w hereas u n d er th e DRH c o n tin g en cy

re in fo rc e m e n t i s n o t l i k e l y u n le s s th e an im al i s re sp o n d in g a s th e VI tim e r re a c h e s th e end o f i t s c y c le. Long p a u se s r e s u l t i n a d e c re a se d lik lih o o d o f re in fo rc e m e n t. When re in fo rc e m e n t i s more l i k e l y in one c o n d itio n th a n i n a n o th e r, more re s p o n d in g, and th u s g r e a te r r e s is ta n c e to ch an g e, i s to b e ex p e c te d. When th e r a t e o f re in fo rc e m e n t i s h e ld c o n s ta n t, th e r a t e a t w hich re sp o n d in g o c c u rs can b e a l t e r e d by p la c in g c o n tin g e n c ie s on re sp o n se r a t e i n tandem w ith th e sc h e d u le o f re in fo rc e m e n t. S in ce re sp o n se r a t e i s c o n d itio n a b le in t h i s way, t h e r e i s, a s N evin (1979) p o in ts o u t, l i t t l e sen se in id e n tif y in g re s p o n s e s tr e n g t h w ith re sp o n s e r a t e. R a th e r, th e q u e s tio n o f w hether d i f f e r e n t i a l re in fo rc e m e n t o f re sp o n se r a t e s e s ta b l is h e s perfo rm ances w hich d i f f e r i n r e s i s t a n c e to change becomes m e a n in g fu l. been fo rth c o m in g. As y e t, a c l e a r answ er to t h i s q u e s tio n h as n o t The m ethods w hich h av e b een u sed to e s t a b l i s h d i f f e r e n t re sp o n se r a t e s w h ile h o ld in g re in fo rc e m e n t r a t e s c o n s ta n t a r e in e q u iv a le n t. When th e c o n tin g e n c ie s o f re in fo rc e m e n t a r e n o t e q u iv a le n t, i t i s s a f e to assume t h a t th e p erfo rm ances w hich th e y m a in ta in w i l l d i f f e r. In th e fo llo w in g ex p erim en t, s i x p ig e o n s a r e exposed to an a l t e r n a t i v e s e t o f c o n tin g e n c ie s w hich i s d e sig n e d to red u ce th e d if f e r e n c e s d is c u s s e d above. Under t h i s p ro c e d u re, o n ly re sp o n se s w hich te rm in a te IRTs w hich f a l l w ith in s p e c i f i c bandw idths a r e r e in f o r c e d. For exam ple, in o rd e r to c o l l e c t a sch ed u le d r e i n f o r c e r, th e s u b je c t m ust em it a re sp o n se w hich te rm in a te s an IRT o f a t l e a s t 2.5 s e c, b u t no lo n g e r th a n 3.5 seco n d s (2.5 sec <. IRT < 3. 5 s e c ). R esponses w hich te rm in a te s h o r te r IRTs r e s e t th e tim e r a s s o c ia te d w ith th e low er l i m i t o f th e re q u ire d IRT, w h ile th o s e w hich a r e lo n g e r with permission of the copyright owner. Further reproduction prohibited without permission.

14 r e s u l t i n r e c y c lin g to e n su re t h a t re in fo rc e m e n t i s p re s e n te d o n ly f o r re s p o n s e s w hich te rm in a te th e a p p r o p r ia te IRTs. I n a d d itio n, re in fo rc e m e n t, once a v a i la b l e, rem ains s e t- u p u n t i l i t i s c o l le c t e d. T hus, d u rin g t e s t i n g re in fo rc e m e n t i s a v a i la b l e f o r a p p r o p r ia te p a tte r n s o f re sp o n se d e s p ite th e f a c t t h a t lo n g p au ses may o c c u r.

METHOD Subj e c ts S ix n a iv e, b a rre n -h e n W hite C am eaux p ig e o n s, a p p ro x im a te ly seven y e a rs o ld a t th e b e g in n in g o f th e s tu d y, serv e d a s s u b je c ts. The b ir d s w ere o b ta in e d from th e P a lm e tto P igeon P la n t, Sum ter, South C a ro lin a. The s u b je c ts w ere m a in ta in e d a t 80%, + 5 %, o f t h e i r f r e e - f e e d in g w e ig h ts, and w ere allo w ed f r e e a c c e s s to g r i t and w a te r i n t h e i r home cag es th ro u g h o u t th e e x p e rim e n t. A pparatus T h ree, tw o-key L ehigh V a lle y E le c tr o n ic s pig eon t e s t i n g cham bers w ere u sed. The i n t e l l i g e n c e p a n e l in each cham ber was ap p ro x im a te ly 3 2.5 cm s q u a re, w ith th e rem ovable f lo o r in p la c e. The re sp o n se k e y s, tr a n s lu s c e n t p a n e ls b eh in d 2.5 cm d ia m e te r h o le s, w ere lo c a te d 23 cm from th e bottom o f th e i n t e l l i g e n c e p a n e l and 8.8 cm from e i t h e r edge. The r i g h t key rem ained u n illu m in a te d and in o p e ra tiv e th ro u g h o u t th e ex p erim en t. A minimum f o r c e o f 0.2 N was re q u ir e d to o p e ra te th e k e y, which, was illu m in a te d from b eh in d by an I n d u s t r i a l E le c tr o n ic s E n g in e e rs, o n e -p la n e re a d o u t p r o je c to r. used to p ro v id e re d and g re e n s t i m u l i. Kodak w ra tte n f i l t e r s w ere A ccess to g r a in was th ro u g h a 5 cm by 6 cm opening c e n te re d on th e i n t e l l i g e n c e p a n e l 11 cm above th e chamber f lo o r. The g ra in a p e r tu r e was illu m in a te d by a G en eral E l e c t r i c #1819 bulb w henever th e fe e d e r was o p e ra te d. Chamber illu m in a tio n was p ro v id ed by a 7.5 w a tt G en eral E l e c tr i c b u lb c e n te re d on th e i n t e l l i g e n c e p a n e l 5.5 cm above th e re sp o n se k e y s. The h o u s e lig h t rem ained illu m in a te d th ro u g h o u t th e d a i ly s e s s io n s. 15

16 W hite n o is e was p ro v id ed th ro u g h u se o f a G ra s o n -S ta d le r, Model 901-B w h ite n o is e g e n e ra to r co n n ected to a 7.5 cm s p e a k e r lo c a te d 13.5 cm from th e chamber f l o o r, and 5 cm from th e r i g h t edge o f th e i n t e l l i g e n c e p a n e l. The th r e e cham bers w ere in te r f a c e d ( S ta te System s, In c, K alam azoo, MI) w ith a PDP 8 - f ( D ig ita l Equipm ent C orp, M aynard, MA) m in i-co m p u ter, lo c a te d in an a d ja c e n t room. S ch ed u lin g o f s tim u lu s e v e n ts, re in fo rc e m e n t c o n tin g e n c ie s, and d a ta c o l l e c t i o n w ere accom plished th ro u g h u s e o f T im e-share SuperSked s o ftw a re ( S ta t e S ystem s, I n c ). P ro ced u re M agazine t r a i n i n g. D uring th e f i r s t s e s s io n, th e s u b je c ts w ere tr a i n e d to e a t from th e food h o p p e r. Each b i r d was m anually h e ld in p o s itio n in f r o n t o f th e o p e ra te d m agazine u n t i l i t a t e f o r ap p ro x im a te ly 3 s e c, a t w hich tim e th e hopper was low ered f o r a p e rio d o f ab o u t 15 seco n d s. T h is p ro ced u re was r e p e a te d u n t i l th e s u b je c t a t e from th e hopper f i v e tim es in s u c c e s s io n. The cham ber was th e n c lo s e d, and an a u to m a tic program s t a r t e d. The rem a in d er o f th e m agazine tr a i n i n g s e s s io n c o n s is te d o f 30 f iv e - s e c hopper p r e s e n ta tio n s w hich o c c u rre d on a V a ria b le Time (VT) 1 min sc h e d u le. The h o u s e lig h ts and w h ite n o is e w ere b o th tu rn e d on d u rin g t h i s t r a i n i n g s e s s io n, b u t th e re sp o n se key rem ained u n illu m in a te d. Keypeck t r a i n i n g. D uring th e n e x t th r e e s e s s io n s, th e subj e c ts w ere exposed to a n o n - d i f f e r e n t i a l a u to sh a p in g p ro c e d u re, in w hich e ig h t- s e c p r e s e n ta tio n s o f e i t h e r th e re d o r th e g reen k e y lig h t w ere fo llo w ed by f iv e - s e c re sp o n se -in d e p e n d e n t food p r e s e n ta tio n s. These e v e n ts w ere sched u led to o ccu r on a VT 1 min sc h e d u le. The i n i t i a l stim u lu s c o lo r f o r each, o f th e s e s e s s io n s was s e le c te d random ly. T h e r e a f te r, th e

17 re d and g re e n s tim u li a l t e r n a t e d r e g u la r ly on a t r i a l - b y - t r i a l b a s is u n t i l 40 food p r e s e n ta tio n s had been made. B a s e lin e s c h e d u le s. A f te r th e t h i r d s e s s io n u n d er th e a u to sh a p in g p ro c e d u re, th e p ro c e d u re was changed to a re s p o n s e -c o n tin g e n t arran g em en t. V a ria b le I n t e r v a l 1 min (VI 1 m in) sc h e d u le s w ere a s s o c ia te d w ith each o f th e two key c o lo r s. T h is i n i t i a l p ro c e d u re i s b e s t d e s c rib e d a s a M u ltip le V a ria b le I n te r v a l/e x tin c tio n /V a r ia b le I n te r v a l (MULT VI/EXT/VI) sc h e d u le o f re in fo rc e m e n t. The d u r a tio n o f each VI sc h e d u le component was 60 se c o n d s. The e x tin c tio n sc h e d u le was c o r r e la te d w ith a d a rk re sp o n se -k e y, p r e s e n ta tio n s o f w hich la s t e d 30 seco n d s. The i n t e r v a l v a lu e s f o r th e VI sch e d u le s w ere s e le c te d random ly w ith in each s e s s io n from in d e p e n d e n t a r ith m e tic s e r i e s a s s o c ia te d w ith each s tim u lu s c o n d itio n. As i n th e a u to sh a p in g p ro ced u re d e s c rib e d above, th e s e le c tio n o f th e i n i t i a l s tim u lu s c o lo r was random fo llo w in g th e f i r s t d a rk -k e y p e rio d. T h e r e a f te r, th e VI sch e d u le com ponents a l te r n a t e d r e g u la r ly w ith d a rk -k e y p e rio d s in te r v e n in g. S e ssio n s te rm in a te d fo llo w in g th e f o r t i e t h VI s c h e d u le com ponent. C o n tin g e n c ie s on th e r a t e o f re sp o n se n e c e s s a ry to c o l l e c t a sch ed u led r e in f o r c e r w ere in tro d u c e d i n th e f i f t y - f i r s t s e s s io n. F ig u re 2 i s a S ta te Diagram o f th e te rm in a l b a s e lin e p ro c e d u re. R e c a ll th a t a s t a t e (S#) i s d e fin e d by th e s tim u lu s c o n d itio n s and re sp o n se c o n tin g e n c ie s a c t iv e a t a g iv e n moment i n th e e x p e rim e n ta l en vironm ent. R equirem ents f o r t r a n s i t i o n from one s t a t e to a n o th e r ap p ear on th e t r a n s i t i o n v e c to r s (arro w s) alo n g w ith any stim u lu s changes c o r r e la te d w ith th e t r a n s i t i o n re q u ire m e n t. A s t a t e s e t ( S. S. i f ) r e p r e s e n ts a c o l le c t io n o f c o n d itio n s w hich d e s c r ib e a l l, o r a p o r tio n

F ig u re 2. S ta t e D iagram o f th e te rm in a l b a s e lin e p ro c e d u re.

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20 o f, th e e x p e rim e n ta l p ro c e d u re. In f i g u r e 2, p a r a l l e l s t a t e s e t s a r e u sed to d e s c r ib e th e stim u lu s c o n d itio n s (S.S. 1) and t h e i r a s s o c ia te d re in fo rc e m e n t c o n tin g e n c ie s (S.S. 2 and S.S. 3 ), As th e term im p lie s, o p e r a tio n s i n p a r a l l e l s t a t e s e t s a r e u s u a lly, b u t n o t alw ay s, d ep en d ent upon c o n d itio n s in o th e r s t a t e s e t s. In o rd e r to sy n c h ro n iz e th e o p e r a tio n s i n p a r a l l e l s t a t e s e t s, Z p u ls e s a r e u se d. For exam ple, when th e re d s tim u lu s i s tu rn e d on (S3 o f S.S. 1 ), a Z1 p u ls e i s produced a s an o u tp u t. The Z1 i s u se d, i n t u r n, a s an in p u t s ig n a l to a c t i v a t e S.S. 2, w hich c o n tro ls th e c o n tin g e n c ie s o f re in fo rc e m e n t a s s o c ia te d w ith th e red k e y l ig h t. S im ila r ly, a n o th e r Z1 i s o u tp u t when t h e component d u ra tio n tim e r a s s o c ia te d w ith th e re d s tim u lu s tim e s - o u t. T h is Z1 p u ls e d e - a c tiv a t e s S ta t e S et tw o. S ta te S et th r e e i s a c t i v e when th e g reen s tim u lu s l i g h t i s tu rn e d on (S4 o f S.S. 1 ), and S.S. 4 shows t h a t th e s e s s io n i s te rm in a te d fo llo w in g th e f o r t i e t h sc h e d u le component p r e s e n ta tio n. The re d and g reen s tim u lu s c o n d itio n s w ere each c o r r e l a te d w ith a d i f f e r e n t tandem sc h e d u le o f re in fo rc e m e n t. In a tandem sc h e d u le, a s you w i l l rem em ber, two c o n tin g e n c ie s m ust b e met s u c c e s s iv e ly in o rd e r to c o l l e c t a r e i n f o r c e r. No stim u lu s changes a r e d i f f e r e n t i a l l y a s s o c ia te d w ith th e two com ponents o f th e re in fo rc e m e n t sc h e d u le in a tandem a rran g em en t. In th e p re s e n t p ro c e d u re, two tandem sch e d u le s o f re in fo rc e m e n t a l t e r n a t e d r e g u la r ly w ith 3 0 -se c d a rk -k e y p e rio d s in te r v e n in g. T hroughout th e b a s e lin e p h ase o f th e p ro c e d u re, th e d a rk -k e y rem ained c o r r e l a te d w ith an e x tin c tio n (EXT) s c h e d u le. The c o n tin g e n c ie s w hich w ere in e f f e c t i n th e p re s e n c e o f th e re d

21 s tim u lu s (S3 o f S,S. 1) a r e d e s c rib e d in S.S. 2, and th e c o n tin g e n c ie s a s s o c ia te d w ith th e g reen s tim u lu s (S4 o f S,S. 1) a r e d e s c rib e d in S.S. 3. The c r i t i c i s m re g a rd in g th e p ro c e d u re s o f N evin (1974, Exp V) and F a th and M alo tt (1979) w hich was r a is e d in th e in tr o d u c tio n, i s a d d re sse d by u s e o f re sp o n se r a t e c o n tin g e n c ie s in w hich s u b je c ts a r e r e in f o r c e d f o r re sp o n s e s w hich te rm in a te IRTs w ith in s p e c if ie d b andw idths (T l" ^ IR T ^.T 2 " ). The u se o f t h i s co n tin g e n c y a llo w s th e e x p e rim e n te r to e q u a te th e h ig h - and lo w - r a te c o n tin g e n c ie s f o r th e number o f re q u ire d re s p o n s e s. In a d d i tio n, th e c o n tin g e n c ie s em ployed i n th e p re s e n t experim ent in c lu d e sa v in g u n c o lle c te d r e in f o r c e r s a c ro s s s c h e d u le com ponents, th u s e q u a tin g th e two sch e d u le s f o r th e a v a i l a b i l i t y o f re in fo rc e m e n t. The c o n tin g e n c ie s w hich w ere i n e f f e c t i n th e p re se n c e o f th e re d s tim u lu s a r e d e sc rib e d i n S.S. 2 : When th e re d s tim u lu s was tu rn e d o n, an in d e p en d en t VI tim e r a s s o c ia te d w ith t h a t component (S3) began tim in g. A fte r th e i n t e r v a l had tim e d -o u t (S 4 ), th e s u b je c t was r e q u ir e d to em it one re s p o n s e, w a it a t l e a s t 2.5 sec (S 5 ), and th e n em it a second re sp o n se (S6) w ith in one sec in o rd e r to c o l l e c t th e sch ed u le d r e in f o r c e r (S 7 ). R esponses w hich w ere e m itte d p r i o r to th e end o f th e re q u ire d 2.5 sec p au se r e s e t th e tim e r a s s o c ia te d w ith S5. F a ilu r e to em it th e second re s p o n s e w ith in th e one sec tim e l i m i t r e s e t th e IRT re q u ire m en t ( r e tu r n to S 4 ). rem ained a v a i la b l e u n t i l i t was c o l le c t e d. Once sc h e d u le d, re in fo rc e m e n t I f th e 6 0 -sec re d com ponent tim e r had tim ed o u t p r io r to re in fo rc e m e n t c o l l e c t i o n, th e o p p o rtu n ity f o r re in fo rc e m e n t was saved (S8) u n t i l th e n e x t re d stim u lu s a p p e a re d. When th e n e x t re d s tim u lu s was tu rn e d on, S4 o f S.S. 2 was th e

22 e f f e c t i v e c o n d itio n. The s u b je c t, once a g a in, had to m eet th e IRT req u ire m e n t in o rd e r to c o l l e c t th e sched u led r e i n f o r c e r. T his p ro c e d u re c o n s t i t u t e s v a r i a b l e - i n t e r v a l re in fo rc e m e n t f o r d i f f e r e n t i a l l y - l o w - r a t e s o f re s p o n s e, in a tandem (TAND) sc h e d u le o f re in fo rc e m e n t (TAND VI 1 m in, 2.5 sec < IRT < 3.5 s e c ). The p ro c e d u re f o r v a r i a b l e - i n t e r v a l re in fo rc e m e n t f o r d i f f e r e n t i a l l y - h ig h r r a te s o f re sp o n d in g (TAND VI 1 m in, 0.5 se c < IRT ^ 1. 5 s e c ) i s d e s c rib e d in S.S. 3 o f F ig u re 2. The c o n tin g e n c ie s d e s c rib e d in t h i s p o r tio n o f th e S ta t e D iagram a r e e s s e n t i a l l y th e same as th o s e d e s c rib e d above f o r th e re d s tim u lu s com ponent. S ta te S et t h r e e, how ever, was a c t iv e when th e g re e n s tim u lu s was tu rn e d on (S4 o f S.S. 1 ), and th e re q u ire d IRT was d i f f e r e n t. In t h i s c o n d itio n, once th e VI tim e r had tim e d -o u t, th e s u b je c t was re q u ire d to w a it o n ly 0.5 sec (S5) b e fo re e m ittin g a second re s p o n s e w ith in one se c (S 6 ). N ote t h a t, f o r th e two sc h e d u le com ponents, th e re q u ire d IRTs d i f f e r, b u t th e bandw idths rem ained c o n s ta n t a t one second. T e s tin g. A f te r 50 s e s s io n s w ith th e m u ltip le -p a c in g sc h e d u le s in e f f e c t, th e t e s t i n g p h ase o f th e ex p erim en t b eg an. On t e s t d a y s, re sp o n se-in d e p e n d e n t food p r e s e n ta tio n s w ere made d u rin g d a rk -k e y p e rio d s. The o n s e t o f th e re sp o n se -in d e p e n d e n t food p r e s e n ta tio n alw ays o c c u rre d 10 sec a f t e r th e o n s e t o f th e d a rk -k e y p e rio d. The d u ra tio n o f th e hopper p r e s e n ta tio n s was v a r ie d. S ix le v e l s o f th e in d e p en d en t v a r i a b l e (m agnitude o f re s p o n s e -in d e p e n d e n t food p r e s e n ta tio n ) w ere u se d : 2.5 s e c, 5.0 s e c, 7.5 s e c, 10.0 s e c, 12.5 s e c, and 15.0 s e c. M agnitude o f re s p o n s e -in d e p e n d e n t re in fo rc e m e n t, r a t h e r th a n fre q u e n c y, was u sed, s in c e in a p re v io u s experim ent (F a th and M a lo tt, 1979)