Rewards cause eddies in the stream of time

Behavioural Processes, 30 (1993) 259-272 259 1993 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Else vie r Sc ie nc e Pub lishe rs B.V All rig hts re se rve d 0376-6357/ 93/ $06.00 BEPROC 00498 C ng ing te s o f re info rc e me nt p e rturb s the flo w o f time Laura Morgan a Department b Indiana a, Peter R Killeen a and J Cregor Fetterman b of Psychology, Arizona State University, Tempe, Arizona, USA, and University, Purdue University at Indianapolis, Indiana, USA (Ac c e p te d 13 Ma y 1993) Abstract This experiment tested the hypothesis that changes in rate of reinforcement affect the rate of an internal pacemaker as suggested by the Behavioral Theory of Timing (BeT: Killeen and Fetterman, 1988) Pigeons were trained to discriminate durations of 10 s and 20 s, and then exposed to higher or lower rates of fre e ly d e live re d re info rc e rs Whe n re turne d to the ’ d isc rimina tio n ta sk, jud g me nts we re re lia b ly b ia se d in the p re d ic te d d ire c tio ns: tho se re turning tha n d id tho se re turning Be T, fro m a ric he r c o nte xt jud g e d sta nd a rd d ura tio ns to b e lo ng e r fro m a p o o re r c o nte xt The se a nd p ro vid e a n e xp la na tio n re sults va lid a te a ke y a ssump tio n o f o f ho w c ng ing te mp o s o f life b ia s the p e rc e p tio n o f time Key words: Time p e rc e p tio n; Pa c e ma ke r sp e e d ; Be vio l The o ry o f Timing (Be T); Temporal discrimination; Reinforcement rate; Response bias; Choose-short effect; Pigeon Introduction Who fre ne tic s no t e xp e rie nc e d the p a c e o f a m a jo r me tro p o lis slo w p a ssa g e o f time d uring a rura l va c a tio n, o r the o ne is ne wly a rrive d a t? This se nse o f b e ing “ o ut o f sync ” with the c o nte xt fa d e s q uic kly, as our sense of time acclimates to the tempo environment What is the origin of these perceptions and adjustments? Correspondence to: P Killeen, Department of a new of Psychology, ASU, Tempe, AZ 85287-l 104, USA 260 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA The o rie s o f time p e rc e p tio n usua lly invo ke a p a c e ma ke r-c o unte r mo d e l no t unlike tho se fo und in mo st c lo c ks: a c e ntra l o sc illa to r, o r p a c e ma ke r, e mits p ulse s whic h a re a c c umu- la te d b y so me typ e o f c o unte r (e g G ib b o n a nd C hurc h, 1990; 1963) simp le De p e nd ing Ro b e rts, 1981; Tre isma n, o n the kind s o f e rro r a sso c ia te d with e a c h o f the c o mp o ne nts, suc h syste ms c a n p ro vid e a c c ura te me a sure me nts o f time d e sp ite sub sta ntia l fluc tua tio ns in the inte rva ls b e twe e n suc c e ssive p ulse s (Kille e n, 1992; Kille e n a nd We iss, 1987) But suc h syste ms a re una b le to d e a l with shifts in the a ve g e sp e e d o f the p a c e ma ke r, a nd it is to suc h shifts e nviro nme nt tha t we a ttrib ute the tra nsie nt b ia se s o b se rve d whe n the te mp o o f the c ng e s In a typ ic a l time d isc rimina tio n e xp e rime nt the o nse t o f o ne stimulus sig na ls the sta rt o f a n inte rva l to b e time d , a nd the o nse t o f a no the r sig na ls the e nd o f the inte rva l a nd the o c c a sio n fo r the sub je c t to ind ic a te the d ura tio n o f the sig na l If the inte rva l w a s sho rt, re sp o nse s to o ne switc h mig ht b e re info rc e d , whe re a s if it w a s lo ng , re sp o nse s to the o the r switc h mig ht b e re info rc e d (e g Stub b s, 1968) p a c e ma ke r in suc h situa tio ns ? Sinc e Wha t c o rre sp o nd s to the c o unte r a nd the va rio us a d junc tive b e vio rs (e g p a c ing , turning , p e c king , e tc ) g e ne lly o c c ur d uring d istinc t p o rtio ns o f the inte rva l, Kille e n a nd Fe tte rma n (1988) hyp o the size d a d junc tive tha t the y mig ht c o nstitute w a s ‘ lo ng ’ (12 s) o r ‘ sho rt’ (4 s) The inte rva l; the c o unte r Fig ure sho w s d istrib utio ns re sp o nse s in o ne p ig e o n w ho w a s re q uire d to d isc rimina te sinc e re sp o nse s to the se tte r’ (Ho lla nd , 1980) b ird w a s usua lly c ro uc hing a t the e nd o f the sho rt ‘ sho rt’ c o rre c t c ho ic e re sp o nse , a nd sho uld of whe the r a n inte rva l ke y a re the n re info rc e d , the re fo re c ro uc hing b e c o me e sta b lishe d p re d ic ts the a s a c ue , o r ‘ o c c a sio n fo r the c o rre c t c ho ic e C o nve rse ly, if the p ig e o n w a s e xte nd ing its those behaviors, being predictors of the correct ‘long’ response, may b e c o me c o nd itio ne d a s d isc rimina tive stimuli fo r it ne c k o r p a c ing when the interval ended, The nature of the pacemaker that drives transition from one adjunctive behavior to the next is less certain Indeed, it is not necessary to have a periodic pacemaker at all: a Poisson emitter that moves the organism from one state to the next with constant probability will suffice (Killeen and Fetterman, 1993) If the period of the pacemaker (or the time constant of the Poisson emitter) is proportional to the interval being timed, then A Crouching + Neck Extension + Pacing 6 Time (s) 10 12 14 Fig The time course of three adjunctive responsesemitted by one subject in a timing experiment The data are from Fetterman and Killeen (1991) 261 adjunctive behaviors should accordion to fill the interval They (e.g Killeen, 1975) If temporal discriminations are based on them, then discriminative accuracy should be proportional to the length of the interval being timed It is - or at least it is a linear function of - the interval being timed (e.g Gibbon, 1977; Killeen and Weiss, 1987) This is Weber’s Law, which, in this context, is also called scalar timing In their behavioral theory of timing (BeT) Killeen and Fetterman (1988) assumed that the speed of the pacemaker was proportional to the rate of reinforcement in the experimental context Under normal circumstances this is highly - but not perfectly correlated with the duration of the intervals to be timed Their theory tied pacemaker speed to reinforcement rate because reinforcers are more biologically potent events than arbitrary stimuli By constructing BeT in this manner, many other phenomena such as contrast effects and foraging strategies might be accommodated (Killeen, 1991) Furthermore, distributions of adjunctive behaviors such as those shown in Fig zyxwvutsrqponmlkjihgfedcbaZY zyxwvutsrqponmlkjihgfedcbaZYX ve b e e n fo und to e xp a nd a nd c o ntra c t in w a ys tha t a re c o nsiste nt with shifts in the p a c e ma ke r sp e e d a s a func tio n o f c ng e s in re info rc e me nt te , e ve n whe n the d ura tio n o f the inte rva l in whic h the y o c c ur is he ld c o nsta nt (Ha ig ht a nd Kille e n, If te o f re info rc e me nt re info rc e me nt e stima te s while 1991) d rive s the sp e e d o f the p a c e ma ke r, the n c ng ing the te o f le a ving the inte rva l to b e d isc rimina te d In p a rtic ula r, the ir te s o f re info rc e me nt d o w n: the d istrib utio ns inta c t sho uld b ia s te mp o l if we ta ke ‘ c ity p ig e o ns’ o ut to the c o untry fo r a we e k in the e xp e rime nta l in Fig sho uld shift to the rig ht Whe n we e ve ntua lly to the ‘ c ity’ a nd te st the ir d isc rimina tio ns, re d uc e c mb e r - the ir p a c e ma ke rs sho uld slo w the y sho uld b e b ia se d to se e time re turn the m p a ssing mo re q uic kly tha n b e fo re the va c a tio n: b ia se d to c a ll lo ng inte rva ls ‘ sho rt’ (b e c a use the b e vio rs suc h a s c ro uc hing tha t me d ia te the ‘ sho rt’ re sp o nse ve no w e xp a nd e d into the time tha t d p re vio usly b e e n o c c up ie d b y ne c k e xte nsio n) e xp o se the m to a m a jo r me tro p o lis, C o nve rse ly, if we ta ke c ity b ird s a nd the y sho uld re turn ho me to find a c ity tha t s se e me d to slo w d o w n Ho w e ve r we b ia s the a nima ls, we e xp e c t the m to e ve ntua lly a d a p t: up o n re turn to the b a se line re info rc e me nt mig te b a c k c o nte xt the a d junc tive b e vio rs sho uld to the ir ‘ p ro p e r p la c e s’ a nd te mp o l p e rc e p tio n will re turn to the sta tus q uo a nte If re info rc e me nt will re ma in te within ske w e d fro m b e c o me re c o nd itio ne d le ve ls Thus, d istrib utio ns the te sting c o nte xt itse lf is shifte d , the a d junc tive b a se line The to the a lte rna tive b e vio l c ue s tha t re ma in re sp o nse b e vio rs misle a d ing must b e fo re a c c ura c y c a n re turn to b a se line if in Fig a hig he r te o f re info rc e me nt in the te sting c o nte xt shifte d the to the le ft fro m the ir b a se line p o sitio n, p a c ing will b e c o me a mo re re lia b le c ue fo r the ‘ lo ng ’ re sp o nse tha n ne c k e xte nsio n, d isc rimina tive stimulus whic h, b e ing e q uivo c a l, ma y e xting uish a s a We c a ll suc h re c o nd itio ning o f the c ue s tha t c o nstitute the c o unte r ‘ re c a lib tio n’ Both adjustment of the pacemaker speed and compensatory recalibration of the counter to maintain accuracy are continual processes; the rate at which they will occur is not predicted by the present theory, but s b e e n a d d re sse d e lse whe re (Fe tte rma n a nd Kille e n, 1991; Kille e n, 1984) In p c tic e , the a d justme nt o f the p a c e ma ke r b e g ins imme d ia te ly c o unte r a nd is virtua lly d e p e nd s o n the c o mp le te c o nting e nc ie s within 100 tha t sha p e re info rc e me nts a c c ura te Re c a lib tio n re sp o nd ing o f the a nd thus the se le c tio n o f d iffe re nt c o unts a s c rite ria c ue s, a nd o n the a va ila b ility a nd p re vio us histo ry o f re info rc e me nt re info rc e me nts o f tho se p o te ntia l c ue s In p c tic e the re c a lib tio n ma y la g o nly a c o up le o f b e hind le a ving d isc rimina tio ns The the a d justing p a c e ma ke r - o r re c a lib tio n sho w ing a p e rma ne nt hyste re sis e ffe c t p re se nt e xp e rime nt p ro vid e d a te st o f the se id e a s To in time p e rc e p tio n we c o nd itio ne d a te mp o l d isc rimina tio n, ma y ne ve r o c c ur, e xa mine the p re d ic te d shifts the n shifte d the a nima ls to a 262 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA hig he r (o r lo we r) d isc rimina tio n d uring te o f fre e re info rc e me nt, te sting to a sse ss p e rfo rma nc e Fina lly, d uring re turne d the a nima ls to the re info rc e me nt a nd a fte r re a d justme nt to the te sting c o nte xt we inc re a se d te o f re info rc e me nt Ma te ria ls a nd the n ta sk We me a sure d b ia s e a rly in the shift p e rio d a nd withhe ld within the e xp e rime nta l c o nte xt itse lf zyxwvutsrqponmlkjihgf a nd Me tho ds Subjects Eig ht ma le ma inta ine d p ig e o ns (C o lumb a a t 80-85% livia ) with p re vio us histo rie s o f e xp e rime nta tio n we re o f the ir fre e -fe e d ing we ig hts Apparatus The e xp e rime nt w a s c o nd uc te d in thre e id e ntic a l Le hig h Va lle y p ig e o n b o xe s ving a c mb e r o f 31 x 36 x 37 c m fo r the sub je c ts The re o n the fro nt wa ll 24 c m a b o ve the flo o r The we re thre e G e rb nd s re sp o nse ke ys c e nte r ke y c o uld b e illumina te d with a re d lig ht to sig na l the o nse t o f the inte rva l to b e time d The sid e ke ys c o uld b e illumina te d white lig ht to sig na l a c ho ic e o p p o rtunity, a nd re sp o nse s to the rig ht sig nifying ‘ lo ng ’ The c o uld b e o b ta ine d thro ug h a c e ntra lly White with re sp o nse s to the le ft ke y sig nifying re info rc e r (2.3 s o f a c c e ss to mixe d g in) lo c a te d a p e rture , situa te d no ise a t 40 d B w a s c o ntinuo usly with ‘ sho rt’ , 11 cm above the flo o r p re se nt At the ve ry to p o f the fro nt wa ll a sma ll b ulb p ro vid e d g e ne l c mb e r illumina tio n Procedure Pretraining Tria ls c o nsiste d o f illumina tio n s (the lo ng stimulus) fo llo we d o f the c e nte r ke y fo r e ithe r 10 s (the sho rt stimulus) b y illumina tio n w a s c o rre c t a fte r the 10 s stimulus s stimulus Fo r the first IO w a s in e ffe c t d uring re p e titio n this a nd a re sp o nse o n the rig ht ke y w a s c o rre c t a fte r the 20 se ssio ns inc o rre c t re sp o nse s we re fo llo we d c o rre c t re sp o nse s we re a lwa ys fo llo we d b y fo o d ; b y a s b la c ko ut o f a ll lig hts A c o rre c tio n p ro c e d ure p a rt o f p re tra ining , o f the tria l The re a fte r o r 20 o f the c ho ic e ke ys A re sp o nse o n the le ft ke y no c o rre c tio n with inc o rre c t re sp o nse s fo llo we d by a p ro c e d ure w a s use d Afte r 10 a d d itio na l se ssio ns the p ro b a b ility o f re info rc e me nt fo r a c o rre c t re sp o nse w a s re d uc e d to 0.5 Sho rt a nd lo ng tria ls o c c urre d q ua si-ra nd o mly with e q ua l fre q ue nc y d uring Re sp o nse s o n unre info rc e d re info rc e me nts, tria ls we re fo llo we d a nd p re tra ining e a c h g -tria l b lo c k b y a s b la c ko ut Se ssio ns e nd e d a fte r 60 a fte r a to ta l o f 40 se ssio ns Baseline The p ro b a b ility o f re info rc e me nt for correct responses was decreased to 0.25 The short (IO s) and long (20 s) durations were presented on 75% of the trials, with the trials equally divided between the two training durations A 14-s probe duration was presented on the remaining (25%) trials The probe was used to evaluate temporal discrimination near the 263 p o int o f sub je c tive e q ua lity whe re we e xp e c te d g re a te st se nsitivity re sp o nse s o n the p ro b e tria ls we re b la c ko ut, a s we re sc he d ule d ne ve r re info rc e d , zyxwvutsrqponmlk to shifts in b ia s C ho ic e b ut we re a lwa ys fo llo we d by a s inc o rre c t c ho ic e re sp o nse s a nd c o rre c t c ho ic e re sp o nse s o n tria ls no t fo r re info rc e me nt The me a n inte rfo o d inte rva l d uring b a se line te sting wa s b e twe e n 60 s a nd 70 s, d e p e nd ing o n a c c ura c y Se ssio ns e nd e d a fte r 60 re info rc e me nts, a nd the b a se line c o nd itio n a fte r a to ta l o f 20 se ssio ns Initial adjustment of the pacemaker The m a jo r ma nip ula tio n c o nsiste d o f fe e d ing the a nima ls a t sho rte r o r lo ng e r inte rfo o d inte rva ls tha n the y e xp e rie nc e d fre e re info rc e rs re ma ining d uring the b a se line c o nd itio n a t a hig he r te tha n tha t e xp e rie nc e d Ha lf o f the b ird s re c e ive d d uring b a se line the illumina tio n o f the re d c e nte r ke y lig ht Und e r the fa st b ia s c o nd itio n, re ma ine d o n fo r 10 s a nd with a p ro b a b ility o f 0.5 w a s fo llo we d a nd o the rwise b y a s b la c ko ut The we re no t illumina te d , b y 2.3 s a c c e ss to g in, o n fo r 60 s a nd with a p ro b a b ility b y 2.3 s a c c e ss to g in, a nd o the rwise the re fo re , b e g a n with the ke y lig ht p ro c e d ure w a s simila r und e r the slo w b ia s c o nd itio n e xc e p t tha t the ke y lig ht sig na l re ma ine d fo llo we d (fa st b ia s); the b ird s re c e ive d the fre e re info rc e rs a t a lo we r te (slo w b ia s) Tria ls a nd re sp o nse s we re b y a s b la c ko ut The no t re q uire d o f 0.5 w a s c ho ic e ke y lig hts fo r re info rc e me nt (te c hnic a lly, sc he d ule s) zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJ Se ssio ns e nde d a fte r 60 re info rc e me nts, a nd the se a re Fixe d -Time this c o nd itio n a fte r se ssio ns First test Afte r the e ig ht se ssio ns te mp o l d isc rimina tio n o f fre e ly-d e live re d ta sk, with re info rc e rs, lf the tria ls e ithe r 10 s o r 20 s No re info rc e me nt la sting sub je c ts we re 14 s, a nd the re turne d w a s g ive n o n a ny tria l, i.e the te sting w a s d o ne in e xtinc tio n The te sting p ro c e d ure w a s use d to me a sure the e ffe c ts o f p rio r e xp o sure hig h a nd lo w re info rc e me nt te to the o the r lf la sting c o nte xts Se ssio ns e nde d a fte r 112 tria ls, to the a nd this c o nd itio n a fte r se ssio ns Fast testing context (1) Whe n the first te st w a s c o mp le te d , c ho ic e re sp o nse s we re a g a in e lig ib le me nt O ne se ssio n w a s g ive n imme d ia te ly a fte r the te st p se d uring re sp o nse s to the sho rt (IO s> a nd lo ng (20 s) stimuli o n p ro b e (14 s) tria ls we re no t re info rc e d This me nt in the c o nte xt fro m ze ro d e p e nd ing o n a c c ura c y The c ng e s in re info rc e me nt (e xtinc tio n) ma nip ula tio n o n p ig e o ns’ timing d e nsity o f fo o d o c c urre d within the te sting fo r re info rc e - whic h a ll c o rre c t we re re info rc e d As b e fo re , re sp o nse s p ro c e d ure e le va te d the te o f re info rc e - to a p p ro xima te ly re info rc e rs p e r minute , p ro vid e d a no the r a sse ssme nt o f the e ffe c ts o f b e vio r, b ut o ne in whic h the c ng e in the c o nte xt Se ssio ns e nd e d a fte r 60 re info rc e rs, a nd this c o nd itio n a fte r se ssio n Baseline Afte r the te st with e le va te d te s o f re info rc e me nt, b a se line c o nd itio n fo r 25 se ssio ns, 60 re info rc e rs a ll sub je c ts we re re turne d to the p e r se ssio n Readjustment of the pacemaker The n the b ia s ma nip ula tio ns we re re ve rse d Sub je c ts tha t initia lly e xp e rie nc e d the hig h te o f fre e -re info rc e me nt (fa st b ia s) we re e xp o se d to the lo w te (slo w b ia s), a nd vic e ve rsa As b e fo re , this p se la ste d fo r e ig ht se ssio ns, e a c h c o nsisting o f 60 re info rc e me nts 264 Second test zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Afte r the e ig ht se ssio ns o f fre e ly-d e live re d re info rc e rs, sub je c ts we re re turne d to the te mp o l d isc rimina tio n ta sk, with lf the tria ls la sting 14 s, a nd the o the r lf la sting e ithe r zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 10 s o r 20 s No re info rc e me nt w a s g ive n o n a ny tria l, i.e the te sting w a s d o ne in e xtinc tio n Se ssio ns e nd e d a fte r 112 tria ls, a nd this c o nd itio n a fte r se ssio ns Fast testing context (2) Whe n the se c o nd te st w a s c o mp le te d , c ho ic e re sp o nse s we re a g a in e lig ib le fo rc e me nt: fo r re in- a ll c o rre c t re sp o nse s to the sho rt (IO s) a nd lo ng (20 s) stimuli we re re info rc e d As b e fo re , re sp o nse s o n p ro b e (14 s) tria ls we re no t re info rc e d Se ssio ns e nd e d a fte r 60 re info rc e rs, a nd this c o nd itio n a fte r se ssio n In a ll c a se s, the p rima ry me a sure o f p e rfo rma nc e c o nsiste d o f the p ro b a b ility o f ma king a ‘ lo ng ’ c ho ic e re sp o nse This p ro b a b ility w a s c a lc ula te d se p a te ly o n sho rt (IO s), lo ng (20 s), a nd p ro b e (14 s) tria ls This me a sure w a s use d b e c a use it p e rfo rms a s well as other of bias suc h a s / 3, a nd is e a sy to inte rp re t (Ma c Milla n measures Whe re a s tra ining re sp o nse s to the p ro b e stimuli stimuli p ro b a b ilitie s sho uld a nd C re e lma n, sho w the g re a te st shifts, sho uld a lso b e a ffe c te d b y o ur b ia sing ma nip ula tio ns, 1991) re sp o nse s to the a nd so the re sp o nse ma y a lso b e a ve g e d o ve r a ll thre e typ e s o f tria l Results Fig ure sho w s d a ta fro m the fina l 15 b a se line se ssio ns p o o le d a c ro ss sub je c ts a nd a c ro ss the first a nd se c o nd b a se line c o nd itio ns The fig ure d isp la ys the p ro b a b ility o f re sp o nd ing ‘ lo ng ’ a fte r the IO s (c irc le s), 14 s (sq ua re s), a nd 20 s (tria ng le s) stimuli; sho w s the me a n p ro b a b ility o ve r a ll typ e s o f tria ls The the to p c e ntra l line ve rtic a l ma rks ind ic a te sta nd a rd e rro rs a c ro ss sub je c ts The a ve g e p ro b a b ility o f b e ing c o rre c t whe n p re se nte d with o ne o f the tra ining stimuli w a s 89%, c o rre sp o nd ing (c o e ffic ie nt o f va ria tio n) o f 0.27 Stub b s, to a d’ o f 1.25, a nd a We b e r Fra c tio n This is c o mp a b le to va lue s fo und in o the r stud ie s (e g 1979), a ltho ug h it is so me wha t la rg e r tha n tha t o b ta ina b le fo r p ig e o ns und e r the Fe tte rma n a nd Kille e n, 1992) The p re se nc e o f unre info rc e d tria ls o f inte rme d ia te d ura tio n ma y b e o ne re a so n fo r the le ss tha n p e rfe c t b e st o f c irc umsta nc e s (0.22; p ro b e d isc rimina tio n The se d a ta sho w tha t d isc rimina tio n the c e nte r ke y stimulus, Fig ure d isp la ys the p ro p o rtio n p ro b e -tria l p ro b e w a s: (1) c o ntro lle d o f ‘ lo ng ’ re sp o nse s to the 14 s p ro b e stimulus b lo c ks (i.e e a c h d a ta p o int summa rize s stimulus) fo r the b y the d ura tio n o f a nd (2) ve ry sta b le a c ro ss ind ivid ua ls a nd b a se line te st se ssio ns two c o nse c utive te sting re sp o nse s to p re se nta tio ns se ssio ns The in o f the d a ta a re a ve g e d o ve r sub je c ts a nd o ve r the o rig ina l (first te st) a nd re ve rse d (se c o nd te st) c o nd itio ns, a ll o f whic h sho w e d the sa me e ffe c ts whe n a na lyse d se p a te ly So me a nima ls sto p p e d re sp o nd ing d uring the la st b lo c k o f tria ls, a nd so the fig ure p o rtra ys o nly the d a ta fro m the first 13 tria l b lo c ks We se e tha t the p ro p o rtio n hig h te o f re info rc e me nt re info rc e me nt (slo w b ia s): o f ‘ lo ng ’ c ho ic e s w a s hig he r a fte r sub je c ts e xp e rie nc e d the (fa st in the b ia s), tha n first a fte r the y e xp e rie nc e d fe w b lo c ks o f tria ls the the sta nd a rd lo w te of e rro r b a rs fo r p ro p o rtio n o f ‘ lo ng ’ re sp o nse s d o no t o ve rla p This is e xa c tly the re sult p re d ic te d und e r o ur a ssump tio n tha t te o f re info rc e me nt a ffe c ts the sp e e d o f the p a c e ma ke r The inte rc e p ts o f the re g re ssio n line s te ll us ho w muc h the w a rp ing ma nip ula tio ns the e xtinc tio n c ng e d the b ia s b e fo re c o nd itio ns d a c nc e to w a sh o ut the e ffe c t Fo r the fa st b ia s c o nd itio n, 265 _ : - I 0.0 I ; ZOSEC I I , I I 012345676 I , I I I I 10 11 12 13 14 15 DAYS zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJI Fig Ave g e p ro b a b ility o f re sp o nd ing ‘ lo ng ’ d uring b a se line Pro b a b ilitie s se c o nd b a se line s w e re p o o le d C irc le s, sq ua re s, a nd tria ng le s re p re se nt p ro b a b ility fro m the first a nd m e a sure s o n sho rt, p ro b e , a nd lo ng d ura tio n tria ls, re sp e c tive ly The line w itho ut symb o ls re p re se nts the a ve g e o ve r a ll tria ls The ve rtic a l line s ind ic a te sta nd a rd e rro rs o f the m e a n a c ro ss e ig ht p ig e o ns the intercept was 0.55, a nd for the slow bias condition it wa s 0.27 The 95% confidence intervals for these intercepts not overlap (the lower limit for the fast bias is 0.46, w he re a s the up p e r lim it for the slow bias is 0.39) This provides strong confirmation of the shift predicted by BeT, the primary claim tested in this experiment BeT further predicts that under the extinction in the testing context the rate of the pacemaker will slow, leading to a ‘choose short’ bias, and the distributions of adjunctive behaviors will flatten, leading to poorer discrimination This also happened The slope for the fast bias condition is -0.018, which is significantly less than zero: t(1 I) = 3.522, I n 0.8 l Fast Bias y = - 0.018x + 0.55 SlowBias y = + 0.007x + 27 Blocks Fig Pro b a b ility o f re sp o nd ing of Probe ‘ lo ng ’ to the p ro b e (14 sub je c ts, re p lic a tio ns, Trials s) stim ulus d uring a nd b lo c ks o f e ig ht re sp o nse s te sting , a ve g e d o ve r 266 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA P < 0.05 The slo p e fo r slo w b ia s, 0.007, P > 0.05 012, b a se line (0.47) to 0.36, o f re info rc e me nt No te d o e s no t d iffe r sig nific a ntly fro m ze ro : t(ll> = The o ve ll p ro b a b ility o f sa ying ‘ lo ng ’ d e c re a se d fro m tha t fo und und e r c o nsiste nt with a d e c re a se in p a c e ma ke r sp e e d d ue to the a b se nc e in this c o nd itio n tha t Fig d isp la ys the d a ta fro m two se ssio ns, with so me d isc o ntinuity visib le b e twe e n the la st b lo c k o f the first d a y o f te sting (7) a nd the first b lo c k o f the se c o nd d a y o f te sting (8) If we a na lyse the se d a ys se p a te ly, fo r the first d a y we find a hig he r inte rc e p t for the fast bias condition (0.641, a nd a g re a te r d e c re a se in the p ro b a b ility o f a ‘ lo ng ’ c ho ic e thro ug h the c o urse o f the se ssio n The slo w b ia s c o nd itio n inte rc e p ts the o rd ina te a t 0.24, a nd sho w s no c ng e thro ug h the se ssio n O n the se c o nd d a y the a ve g e p ro b a b ility o f a ‘ lo ng ’ re sp o nse sig nific a ntly re ma ins re la tive ly c o nsta nt fo r b o th g ro up s a t a me a n va lue o f 0.36, found under baseline (t(5) = 5.25, 2.92 for fast and slow; both P’s < ,051 Afte r the te st se ssio ns, a ll sub je c ts we re e xp o se d to a ‘ fa st te sting c o nte xt’ , a n e le va te d lower than te o f re info rc e me nt a p p ro xima te ly we re o the rwise tra ining (a ll c o rre c t re sp o nse s to sho rt a nd lo ng stimuli re info rc e rs p e r minute ) re info rc e d , yie ld ing Exc e p t fo r the hig h d e nsity o f re w a rd , c o nd itio ns the sa me a s to tho se d uring te st se ssio ns (i.e the mixture o f p ro b e a nd tria ls w a s the sa me ) Fig ure sho w s d a ta fro m the fa st te sting c o nte xt (I) a c ro ss b lo c ks o f 16 tria ls to a ll stimulus p lo tte d Fo r e c o no my o f p re se nta tio n, the se d a ta a re b a se d o n re sp o nse s typ e s (sho rt, p ro b e , a nd lo ng d ura tio ns) Diffe re nt symb o ls sho w whe the r a sub je c t d b e e n in the fa st b ia s o r slo w b ia s c o nd itio ns p rio r to the te st The ind ic a te s the a ve g e p ro b a b ility o f re sp o nd ing ‘ lo ng ’ fo r a ll stimuli d a she d line fo r the fina l se ssio n o f the first b a se line c o nd itio n; the ve rtic a l b a rs g ive s the sta nd a rd e rro r o ve r the e ntire se ssio n, a nd fo r e a c h b lo c k ‘0 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 08 0.6 II_~ _ n Slow Bias Fa st Bias - Average 00 BLOCKS OF 16 RESPONSES Fig Probability of responding ‘long’ across blocks of 16 responses averaged stimuli during the first exposure to the fast testing context previously received the slow bias treatment received the fast bias treatment testing and unfilled circles indicate subjects who had previously The dashed line indicates probability The vertical over subjects and Filled squares indicate subjects who had lines indicate standard for the last session of baseline errors of the mean 267 Whe n shifte d to the e le va te d te s o f re info rc e me nt in the fa st te sting zyxwvutsrqponmlk c o nte xt (I), a ll sub je c ts sho w e d the p re d ic te d inc re a se in the a ve g e p ro p o rtio n o f ‘ lo ng ’ re sp o nse s (fro m 0.47 to 0.65); this inc re a se w a s sig nific a nt, t(7) = 5.02, P < 0.05 The fig ure sho w s tha t the b ia s inc re a se d o ve r the first lf o f the se ssio n (p re suma b ly sp e e d ) a nd d e c re a se d d uring a s the p a c e ma ke r c a me up to the se c o nd lf (p re suma b ly a s the b e vio l c ue s we re re c a lib te d ) Up o n se c o nd e xp o sure to this c o nd itio n in the fa st te sting c o nte xt (21, whic h is no t sho w n in the fig ure , the inc re a se in the p ro p o rtio n o f ‘ lo ng ’ re sp o nse s (to 0.51) w a s no t sig nific a nt It is p o ssib le tha t the p rio r histo ry o f re c a lib tio n p ro c e e d mo re q uic kly und e r this se c o nd e xp o sure p e rmitte d a d justme nt to to the fa st te sting c o nte xt Discussion We ve d e mo nstra te d te sting , re lia b ly c o nsiste nt b ia s time with tha t shifts in the te o f re info rc e me nt, e stima te s in the d ire c tio n b o th b e fo re a nd d uring p re d ic te d b y Be T The se shifts a re the e ffe c ts o f e le c tric a l b in stimula tio n (Me e k, 19881, a nd with a d ministra tio ns whic h (Me e k, 1983) The y c o nsiste nt p he no me no lo g ic a l with e ithe r e xc ite o r se d a te o b se rva tio ns sub je c ts ma d e e ve ry d a y b y unto ld d rug a re numb e rs a lso of huma n o b se rve rs The c ng e s in b ia s w a she d o ut in the c o urse e xp e c te d We c ho se to run the te sts in e xtinc tio n b e vio l c ue s b y p a iring re sp o nse s ne w (shifte d ) o f o ne o r two se ssio ns to a vo id the p o ssib ility a d junc tive b e vio rs with This wa s a s o f re c a lib ting the the c o rre c t c ho ic e But we a lso re c o g nize tha t the sp e e d o f the p a c e ma ke r va rie s with the te o f re info rc e me nt in the e xp e rime nta l c o nte xt, a nd tha t it a p p ro a c he s p ro p o rtio na lity with it a s a line a r a ve g e o f its o ld me a n va lue a nd the c urre nt va lue In the te sting c o nte xt, the te o f re info rc e me nt re info rc e me nt is ze ro , so tha t we e xp e c t a c o ntinua l d e c re a se in the sub je c tive to w a rd ze ro As it d e c re a se s, the me d ia ting b e vio rs will inc re a se p ro p o rtio na te ly, me a n a nd sta nd a rd d e via tio n te o f o f the c a using the c urve s in Fig to mo ve to the rig ht a nd fla tte n As the b e vio rs tha t me d ia te the ‘ lo ng ’ re sp o nse mo ve o ut o f ng e , the p ro b a b ility o f c ho o sing ‘ lo ng ’ will d e c re a se to w a rd ze ro To ma y se t up a simp le mo d e l in whic h b e vio r tha t me d ia te s the the ‘ lo ng ’ re sp o nse me a n o f the (~~1 inc re a se s line a rly e xtinc tio n b e g ins, kb , a s a func tio n o f the time in e xtinc tio n /_L~ = pb kt The sta nd a rd d e via tio n o f the se d istrib utio ns + p ro p o rtio na lity a, = sho w ho w this w o rks, we d istrib utio n o f the fro m a d junc tive its va lue b e fo re (t): (1) is g ive n b y We b e r’ s La w , with a c o nsta nt o f (‘ We b e r c o nsta nt’ ) o f w : (2) W/At Fro m the se two e q ua tio ns we ma y fo rm a Z-sc o re : (3) 4=(x-/4)/5 C umula tive no rma l d istrib utio ns p ro vid e a g o o d fit to re sp o nse s sho w n in Fig 1, a s the y d o to a d junc tive Kille e n, 1991) We ma y the re fo re e va lua te the Z-sc o re the d istrib utio ns o f te rmina l b e vio r in g e ne l (Fe tte rma n a nd a s a no rma l d e via te In the p re se nt 268 L., zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Blocks 10 of Probe 12 14 Trials Fig The data are zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA the sa me a s tho se sho w n in Fig The smooth lines are derived from the assumption that, because the speed of the pacemaker experimental adjunctive context, its period must lengthen varies with the rate of reinforcement during extinction in the This causes the distribution of behavior that serves as the criteria1 count for the ‘long’ response to shift to the right and flatten, according to Equations 1-3 c a se , we ve a d d itio na l info rma tio n p ro b e d isc rimina tio ns a b o ut the p a me te rs: a re me a sure d , whic h x is the time is a lwa ys 14 s The a t whic h the We b e r fra c tio n fo r the is w = 0.27 The ind e p e nd e nt va ria b le t is p ro p o rtio na l to the block number, and fo r simp lic ity we use the b lo c k numb e r a s the p re d ic to r This le a ve s us two p a me te rs to e va lua te : the inte rc e p t a nd slo p e o f Eq ua tio n Fig ure sho w s tha t if we se t zyxwvutsrqponmlkjihgfe k = 0.8, p r, fo r the fa st b ia s c o nd itio n to 11 s, a nd p c Lbfo r the slo w b ia s c o nd itio n to 19 s, b a se line c o nd itio ns the p re d ic te d shifts in b ia s (c urve s) p ro vid e a g o o d summa ry o f the d a ta A mo re e la b o te mo d e l w o uld inc re me nt the p e rio d o f the p a c e ma ke r a s a n e xp o ne ntia lly-we ig hte d e xp lic it mo ving a ve g e o f the e la p sing time witho ut c o mmitme nt to the re info rc e me nt, a nd ma ke a n p o ints a t whic h up d a ting o c c urre d , a nd tre a t the c urre nc y c o e ffic ie nt se p a te ly fro m the sc a le fa c to r fo r time But it w o uld b e unlike ly to d o b e tte r with the se d a ta , a nd o ur m a jo r p o int - re c o nc ilia tio n o f the ‘ c ho o se sho rt’ b ia s with time in e xtinc tio n, a s p re d ic te d b y Be T - is se rve d a s we ll b y this simp le No te tha t the infe rre d we re shifte d c o nd itio n, the shifte d sta rting in the d ire c tio ns mo d e l va lue s fo r the me a ns o f the me d ia ting d istrib utio n, p re d ic te d b y the the o ry: pb, to sho rte r va lue s fo r the fa st b ia s a nd lo ng e r va lue s fo r the slo w b ia s c o nd itio n The shift w a s no t p ro p o rtio na l to in te s o f re info rc e me nt p ro p o rtio na lity, e xp e rime nta l und e r the b ia sing c o nd itio ns ma nip ula tio ns tha n p ro p o rtio na l c ng e (Bizo a nd White , Altho ug h Be T a ssume s suc h a s the se mo re o fte n yie ld a line a r the r 1993; Fe tte rma n a nd Kille e n, 1991) The re a re se ve l re a so ns why this ma y b e the c a se Ea rly in the shift the old values fo r the p a c e ma ke r ma y no t ve w a she d o ut A mo re e xp e rime nta l c o nte xt o f the associated with a for scores of se ssio ns Altho ug h the re ma y b e sub sta ntia l shift in Entry base rate of reinforcement into c o mmo n re a so n ma y b e the the e xp e rime nta l the sp e e d o f the p a c e ma ke r within c o nd itio ning c mb e r s been the c o urse o f a se ssio n, we e xp e c t so me sp o nta ne o us re c o ve ry o f its o ld va lue a t the b e g inning o f the ne xt se ssio n It will ta ke multip le fo r this c o nd itio ning o f the c o nte xt to re a c h a symp to te Fina lly, limits to the sp e e d o f the p a c e ma ke r If e a c h p ulse ta ke s a finite hig h te s o f re info rc e me nt so me a p p ro p ria te ‘ b lo c ke d -c o unte r’ hyp e rb o lic func tio n re info rc e me nt 1993) se ssio ns ma y b e struc tura l a mo unt o f time , the n a t p ulse s will b e b lo c ke d b y the e missio n mo d e l p re d ic ts tha t p a c e ma ke r sp e e d sho uld o f te o f re info rc e me nt (Kille e n, the re tha t a p p ro a c he s line a rity o f o the rs The inc re a se a s a o nly a t lo w te s o f 269 zyxwvutsrqponmlk Bizo a nd White c o nfirming (1993) a lso te ste d this fund a me nta l p re d ic tio n o f Be T, a nd fo und re sults the d e p e nd e nc e o f p a c e ma ke r sp e e d o n te o f re info rc e me nt The y a lso fo und e vid e nc e fo r re c a lib tio n o f the c rite ria numb e r o f c o unts o ve r the c o urse o f lf-d o ze n se ssio ns The se Ro b e rts a nd Ho ld e r zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA (1985) o b se rve d shifts in b ia s p a rtia lly c o nsiste nt o ur e ffe c ts inve stig a to rs tra ine d ts to c la ssify sig na ls a s ‘ sho rt’ o r ‘ lo ng ’ , a nd the n re p la c e d 80% o f the c ho ic e tria ls with e xtinc tio n p re se nte d fo r 15 s fo llo we d o r p a iring tria ls b y the ITI a p e lle t o f fo o d a nd the n the ITI simila r to the re sults fo llo wing During The e xtinc tio n e xtinc tio n tria ls, the sig na l w a s by tria ls p ro d uc e d a b ia s to re sp o nd ‘ sho rt’ , the slo w b ia s c o nd itio n re lia b le c ng e s in the o the r d ire c tio n, O the r fa c to rs a re kno w n During p a iring tria ls, the 15 s sig na l w a s fo llo we d The p a iring tria ls d id no t p ro d uc e ho we ve r to a ffe c t re sp o nse c o lle a g ue s (e g Sp e tc h a nd Rusa k, 1992) b ia s in timing fo und tha t fo llo wing e xp e rime nts Sp e tc h a nd a p e rio d o f tra ining witho ut d e la ys, d e la ye d c ho ic e te sts p ro d uc e a b ia s in p ig e o ns to re sp o nd ‘ sho rt’ C o nve rse ly, whe n p ig e o ns a re g ive n le ng thy d ura tio n d isc rimina tio n tra ining with a p a rtic ula r d e la y (e g s), a nd the n te ste d with sho rte r d e la ys (e g s), the y a re b ia se d to re p o rt ‘ lo ng ’ Simila r re sults a re o b ta ine d whe n inte r-tria l inte rva l is ma nip ula te d o c c ur muc h to o q uic kly - within sp e e d We As the a utho rs no te , the se a sing le tria l - to b e a ttrib ute d b e lie ve the y a re d ue to d e c re a se s in the a d junc tive ‘ lo ng ’ re sp o nse a s the c o m p a riso n stimuli e ffe c ts to c ng e s in p a c e ma ke r b e vio r me d ia ting the b e c o me o ve rd ue , o r whe n the tria l o nse t w a s o ve rd ue Until the a p p ro p ria te o b se rva tio ns a re ma d e , ho we ve r, this is me re sp e c ula tio n In a n e le g a nt se t o f e xp e rime nts, c ho o se -sho rt G nt a nd Sp e tc h (1993) e ffe c t ma y b e e limina te d c o rre la te d with the sa me c o m p a riso n (c o lo r) This a d junc tive re sp o nse s a mo re d iffic ult Fo rtuna te ly, a d junc tive ma nip ula tio n o r line tha t the o rie nta tio n) a re ma ke s te mp o lly-d rive n a nd a m b ig uo us me c nism fo r me d ia ting the d e la y b e c a use o urs is a b e vio l the o ry o f timing , it sp e c ifie s just wha t o b se rva tio ns c a n b e ma d e to c o nfirm The re d e mo nstra te d if two sa mp le s (d ura tio n o r infirm is a lo t le ft unsa id o ur hyp o the tic a l e xp la na tio n o f the se typ e s o f e ffe c ts b y o ur b e vio l the o ry o f timing b e vio r, so tha t it d o e s no t p re d ic t ho w inte rim a b se nt, the n a p p e a r a nd b e c o me inte g te d into the timing ho w muc h e xp e rie nc e with a g ive n re info rc e me nt It is no t a the o ry of b e vio rs, a t first ne c e ssa rily p ro c e ss We d o no t p re d ic t te is ne c e ssa ry to p ro d uc e ho w muc h c ng e in p a c e ma ke r te Tha t is the kind o f fa c t a b o ut b e vio r tha t is so c o nting e nt o n the histo ry o f the o rg a nism a nd e xp e rime nta l c o nte xt tha t it is unlike ly g e ne l p re d ic tio n a nd Kille e n Ho w e ve r, Eq ua tio ns 1-3 the c c te r o f tha t re la tio nship , (1984) to b e susc e p tib le to sho w ho w we c a n infe r a nd use it to o ur a d va nta g e in p re d ic ting o the r thing s It is no t a c o g nitive the o ry, so it d o e s no t sa y ho w me mo rie s a re re c ruite d wha t kind o f a lg e b the y a re c o mp a re d We d o no t think c o mp a re d : a nima ls b e ve , a nd , if it p ro ve s use ful, me mo rie s a nd a c c o rd ing to a re re c ruite d a nd le a rn to ta ke no te o f wha t the y a re d o ing a nd p re d ic a te c ho ic e b e vio r o n it A the o ry b a se d o n o b se rva b le s is mo re e a sily e a sily c lle ng e d , a nd we think tha t to b e a virtue mo re re lia b ly tha n we c a n me mo rie s; o f huma n’ s o w n me mo ria l p ro c e sse s, ma y find b e lie ve tha t the re a re c o rre sp o nd ing a nd tha t the se ma y b e use fully we c a n se e a nd c o d e b e vio r it a fa ult It is no t a ne ura l mo d e l; we c ng e s within the ne rvo us syste m a s a nima ls b e ve , sp o ke n c a sc a d e s a nd a d a p tive re so na nc e o f Be T: o the rs, p e rha p s mo re imp re sse d with the imme d ia c y o f in te rms o f te mp la te But invo c a tio n o f suc h we twa re p re d ic t the a va ila b le d a ta It is no t a the o ry o f mind ; tho se inte re ste d a s a n ind ic a to r o f a sso c ia tive p ro c e sse s - o r o f me mo ry ne ura l c o nd itio ning - will b e d isa p p o inte d Tha t’ s why we like it ma tc hing a nd b ina ry is no t ne c e ssa ry to in b e vio r p rima rily b a nks o r o f c o g nitive ma p s o r o f in o ur e mp ty o rg a nism Be T is no t muc h a t a ll 270 It ma ke s se nse tha t the sp e e d o f the p a c e ma ke r sho uld e nviro nme nt the c o unte r, suc h a d a p ta tio n ke e p s d isc rimina tio ns whic h the y will b e re q uire d (Fe tte rma n Ho usto n, c o va ry with the te mp o o f o ur G ive n na tura l limits o n the p re c isio n o f the p a c e ma ke r a nd the c a p a c ity o f But suc h fle xib ility 1987) ma xima lly a nd Kille e n, 1990; a c c ura te in the ng e fo r Kille e n, c o me s a t a p ric e : whe n shifting with d iffe re nt te mp o s, d isc rimina tio ns 1991; Mc Na ma a nd b e twe e n e nviro nme nts o f inte rva ls will b e d isto rte d with re sp e c t to d isc rim i- na tio ns o f the sa me inte rva ls in the o ld e nviro nme nt This is no t a fa ta l p ro b le m fo r se ve l re a so ns: sinc e it is re info rc e rs suc h a s fo o d a nd ma te s, a nd a ve rsive s suc h a s p re d a to rs tha t d rive the p a c e ma ke r, d isc rimina tio ns will b e o p timize d e ve nts in the a nima l’ s e nviro nme nt la te d with te s o f re info rc e me nt with re sp e c t to the se mo st sa lie nt Ac c ura te d isc rimina tio n is le ss urg e nt Whe re o f a rb itra ry d ura tio ns unc o rre d isc rimina tio ns b te d , the c rite ria c o unte r e ve nts whic h me d ia te the d isc rimina tio ns usua lly within The a sc o re o f tria ls b ia se s we fo und c o nsiste ntly in this e xp e rime nt ve a p o sitive utility Whe n a n o rg a nism e nc o unte rs re w a rd s a t a hig he r te tha n e xp e c te d , it is a use ful sig n tha t it s e nte re d a ric he r ‘ p a tc h’ in its e nviro nme nt c o nd itio ne d to d istinc tive future must b e re c a li- a re re c o nd itio ne d , The e nsuing b y ma king suc h lo c a le s mo re a ttra c tive The p ro vid e s time c ng e s in a ro usa l ma y b e c o me a sp e c ts o f tha t p a tc h, a nd thus im p ro ve fo g ing e ffic ie nc y in the fo r this c o nd itio ning la g in the a d justme nt o f the p a c e ma ke r to ta ke p la c e , while p ro vid ing a la rg e r sa mp le o f the ne w e nviro nme nt o n whic h to b a se it Sinc e suc h c a lc ula tio ns o nly ma ke se nse re la tive to the a s a who le , e nviro nme nt the a d justing sp e e d o f the p a c e ma ke r p ro vid e s a use ful inte g to r o f tha t g lo b a l va lue Anima ls c o ming fro m a ric h fo g ing e nviro nme nt ‘ hig he r e xp e c ta tio ns’ o f a ne w p a tc h within will ve it - a fa ste r p a c e ma ke r - a nd thus a sho rte r g iving -up time , tha n d it e nte re d the sa me p a tc h fro m a p o o r e nviro nme nt As is o fte n the c a se in we ll-a d a p te d o rg a nisms, c o nstra ints ma y b e me c nisms, whe n lo o ke d a t fro m the rig ht p e rsp e c tive Acknowledgements This re se a rc h c o nstitute d 9021562 L.M.‘ s Ma ste r’ s The sis fro m NSF a nd RO I MH 48359 It w a s sup p o rte d in p a rt b y G nts BNS fro m NIH References Bizo , L a nd White , G , 1993 Be vio lthe o ry o f timing : 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Exp Ana l Be v., 11: 223-238 Stub b s, D.A., (Ed ito rs), 1979 Vo l Wile y, Tre ism a n, Te m p o l d isc rim ina tio n a nd p syc ho p hysic s Ad va nc e s in the Ana lysis o f Be vio r: C hic he ste r, M., 1963 o f the “ inte rna l UK, In: M.D Ze ile r a nd P Ha rze m a nd the O rg a niza tio n o f Be vio r, p p 341-369 Te m p o l d isc rim ina tio n c lo c k” Re info rc e m e nt Psyc ho l Mo no g , a nd the ind iffe re nc e 77 (Who le # 576) inte rva l: Im p lic a tio ns fo r a m o d e l ... to the interval being timed, then A Crouching + Neck Extension + Pacing 6 Time (s) 10 12 14 Fig The time course of three adjunctive responsesemitted by one subject in a timing experiment The. .. confirmation of the shift predicted by BeT, the primary claim tested in this experiment BeT further predicts that under the extinction in the testing context the rate of the pacemaker will slow, leading... because the speed of the pacemaker experimental adjunctive context, its period must lengthen varies with the rate of reinforcement during extinction in the This causes the distribution of behavior