EFFECTS 0F TIMEOU AND EXTINCTAAN 0N BEHAVIORAL CONTRAST TheS'is for the Degree 6f M..A . ‘ MICHIGAN f* TAT {UNIVERSITY . - .. . 'H‘ENAYALLEA 'v-A - . ~ ' . n. , ' ' 0- . . . -- ”.2 - . _ ' ‘ " 1 ' no 00 a . o -O' ' '»‘ '.... .‘ . .‘ . . . ‘ _c-. . ., . {..'l-pa4’. .. ' o I. ‘ . n ' . -.. a ' . . . a - ~A agov '- l 0. O. - 4 - . . .. .A ,. . . ..o’|-l . . - I o - "7 par ' ' ' - . , l . - ._ . . . . . - _ c - C" r. - - . ., ¢ . ' v.‘ . . " . c . . .. .. . .. ~ .R— . . . - . v .r . u . , . v 1 Q ' o p o a) "I . . .1. — ~ - . o . to _.-.o. ‘M . . n .. '. . .n ; 5-.-. " 0 v ' -. - ' . . c ‘0..‘ . n. . I. . . o ., .g‘ - '3. n.: w ,. _ ' ' -‘- o-' . .. . . ‘ . . . .g _ 4 .l... o . . , ' O - - ' .. . f. v .-. 0" r - no .- .. .(.‘- ' - . '1 l '. .- , . u.-. . o. 4 0‘ lo. a - . .. . —.. .. .' . - I n- p .. o a o. . . .. ' -' ' H' - u .. .- - . . - " , .. -.o -- - ‘ n - ~ at . - ‘ . n‘ . o . u 1:- O.,--.,l .O.' ’- c—.01- -oc v - ‘N . -. . - ‘ . on. . - . .. .... . . 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'. :'.'.-,~,°.o‘.'.'.‘0',', .- on . 0d-_ -0~ in o-o- o-.‘(&'..“'i 33- o‘rh“°.°.'V’h‘- " ." ‘ ”\(l..f. ." . .l' (I 3 o .‘OII 170‘! 04".va tr tvo r? JfO-g-l vo-‘Itenov/o .9 50 - d, § -~v J. 5, 4.5., I.“ .(u' ..'.-.r . - .-o¢ ~l C . O I 'pgzflw’ “fo‘ 0‘- poi-“f 0"- an 'm' vupcnl . . .— vv"(-'. . ’ . O . - o 'lrfr-w 5w. -’ -~ (v 0'. -0 I 0-..- 0"- . .. :E-l ii! EI!W;-‘_llur .‘-‘_r--.r Md ‘- LIBRARY ’ ' Michigan State University r rwvvva-w— V—r—uv‘ww—v‘u— - rrvcag ABSTRACT EFFECTS OF TIMEOUT AND EXTINCTION ON BEHAVIORAL CONTRAST by Henry Allen Vieth Two theories have emerged to account for behavioral contrast. The relative reinforcement theory states that contrast in S1 is due to an increase in reinforcement den- sity in S relative to the $2 stimulus. The reSponse re- 1 duction theory states that contrast in S may be a result of 1 emotional factors resulting from unreinforced reSponding in the presence of $2. In order to test these hypotheses, a within subject design was used to compare the amount of contrast resulting from timeout(little or no unreinforced reSponding) with the amount of contrast resulting from extinction(a measureable amount of unreinforced reSponding). Relative reinforcement resulting from timeout and extinction was equivalent. Five pigeons were trained to key peck in the presence of S and S . On the eleventh session, extinction in $2, 1 2 and timeout were introduced in alternation with S . 1 After correction was made for the greater latencies to first peck after a timeout, the results showed an approxi- mately equivalent amount of sustained Contrast for the two conditions. However, transient contrast was greater follow- ing extinction than timeout. Reversal sessions showed a change in the degree of con- trast induced by extinction but little change in the degree of contrast induced by timeout. The sustained contrast results tended to support the relative reinforcement hypo- thesis. The transient contrast results tended to support the response reduction hypothesis. Dates w 70 Approved: Mark Billing, Committee Chairman EFFECTS OF TIMEOUT AND EXTINCTION ON BEHAVIORAL CONTRAST by Henry Allen Vieth A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF ARTS Department of Psychology 1970 Q, e57// F; 7' 7/ ACKNOWLEDGEMENTS I wish to extend my sincere thanks and appreciation to Dr. Mark Billing for his assistance and support, far above and beyond the call of duty, also to Dr. Glenn Hatton for his helpful criticisms and discussion, and to Dr. Ralph Levine for his helpful suggestions. I also wish to thank Thomas Kramer for his useful criticisms and advice. ii LIST OF TABLES LIST OF FIGURES LIST OF APPENDICES INTRODUCTION METHOD RESULTS DISCUSSION REFERENCES APPENDIX TABLE OF CONTENTS iii Page iv vi 10 13 33 38 1+0 LIST OF TABLES Table Page 1. Average latencies, in seconds to first 22 response following S2 or timeout. iv Figure 1. 2. 3. 7. LIST OF FIGURES Mean rates of reSponding for all subjects under all conditions, during training and discrimination sessions. Mean transients across all test sessions for all subjects during discrimination sessions. Mean rates of reSponding during the first 30 seconds of S during discrimination training, correéted for differential lat- ency to first reSponse after offset of timeout and S . Shaded portion is post timeout and ogen portion is post-extinc- 131011. Change in rate of reSponding, post-timeout and post-extinction, between last discrimin- ation session and first reversal session. Mean rates of reSponding for all subjects under all conditions during reversal ses- sions. Mean transients for all subjects during the first reversal session. Mean rates of responding, post-timeout and post-extinction, during the first revers- al session. The first 30 seconds follow- ing the offset of timeout and extinction was omitted. Shaded portion is post-time- out and Open area is post-extinction. Page 18 20 26 28 30 32 LIST OF APPENDICES Page APPENDIX: Summaries of analyses of variance. 40 vi INTRODUCTION While studying a classically conditioned salivation reSponse in dogs, Pavlov(1927, p.188) found that when he alternated reinforced trials with unreinforced trials, the amount of saliva secreted during the reinforced trials, in- creased to an amount greater than that prior to the intro- duction of the unreinforced trials. Pavlov called the incr- ease in the magnitude of the response ”positive induction”, and described it as ”inhibition leading to increased ex- citation”. In order to allay the "confusion” resulting from the use of the term induction by other theorists in other contexts, Skinner(1938, p.175) substituted the term pos- itive contrast to identify the increase in the reSponse to the reinforced stimulus which occurs when it is alternated with an unreinforced stimulus. Subsequently, Ferster(1958) studied the effects of timeout from positfie reinforcement on an Operant reSponse. A timeout is a period during which the experimental chamber is darkened and the opportunity for reinforcement is with- drawn. Unlike extinction, during which many unreinforced reSponses are characteristically observed, a timeout reduces the probability of a response to nearly zero. Ferster trained chimpanzees to reSpond for reinforcement by lever pressing on a variable interval schedule. The variable interval(VI) schedule provides reinforcement for reSponding, 1 2 at intervals varying around a mean. When Ferster alternated VI periods with timeout periods, he found an increase in the reSponse rate in the presence of a red light presented for the 30 seconds immediately preceeding and signalling the onset of the timeout. The increase in the rate of re- sponse(contrast) occurred even though reinforcement was available on the same basis as before during the red light. Two theories have been developed to explain the contrast effect. The first theory, developed by Reynolds(1961a), assumes that the rate of responding in the presence of a given stimulus is a function of the frequency of reinforce- ment in the presence of that stimulus relative to the freq- uency of reinforcement during the presence of the other stimuli controllirlg that organism's behavior. Hence con- trast is a result of an increase in the relative frequency of reinforcement during the presence of the stimulus during which the contrast occurs. Reynolds(1961a, p.60) introduced the term behavioral contrast, which he defined as "an in- crease in the rate of reSponding in one component of a mult- iple schedule when certain changes occur in the other com- ponent”. The second theory, develOped by Terrace(1963;1966;1968), states that response suppression has an excitatory as well as an inhibitory prOperty. The inhibitory prOperty appears as the reduction in reSponse rate in the unreinforced com- ponent. The excitatory prOperty appears as the increase in reSponse rate in the reinforced component. According to the 3 theory, the increase in response rate in the reinforced com- ponent, positive behavioral contrast, would occur whenever the response rate in the alternate component was reduced from a baseline level, irreSpective of relative reinforcement. Reynolds(1961a) develOped the relative reinforcement theory from a senbs of experiments in which he compared the contrast effects obtained in multiple schedules. In a mult- iple schedule, two stimuli, each correlated with a given schedule of reinforcement are presented alternately. This procedure has become the customary method of investigating behavioral contrast. To begin with, Reynolds(1961a) trained pigeons to re- Spond by key pecking on a multiple schedule until their rates of reSponding had stabilized. Reynolds found that when he introduced extinction in the second component, the rate of responding during the first component increased (be- havioral contrast). When he introduced timeout in place of the second component, he found approximately the same degree of behavioral contrast as was induced by extinction. When the VI schedule was restored to the second component in place of extinction or timeout, the rate of reSponding in the first component decreased to the baseline level. In order to de- termine if the response rate in the first component was con- trolled by relative reinforcement, Reynolds then substituted Dro 50 seconds in the second component. A Dro(Differential reinforcement of other behavior) schedile provides reinforce- ment if no reSponse has occurred for a given period of time. L; Under this procedure, relative reinforcement should have remained about the same during the VI component. As would have been predicted from Reynolds' theory, behavioral con- trast did not occur in the VI component. Further evidence for the relative reinforcement theory was presented in a study(Reynolds, 1961b) in which pigeons were trained to reSpond on mult variable interval-fixed ratio schedules(mult VI FR). In a fixed ratio schedule, the organism is reinforced for the first reSponse after a fixed number of responses have occurred. By manipulating the value of one schedule, while holding that of the other con- stant, Reynolds found that the rate of responding during the constant component was an approximate linear function of the relative frequency of reinforcement in that component. A similar study(Reynolds and Catania, 1961) obtained the same results by alternating V1 with Fixed interval(FI), In a fixed interval schedule, reinforcement is provided for the first reSponse after a given period of time has elapsed. In the same study, behavioral contrast was obtained when a mult Drl Drl schedule was changed to mult Drl ext. In the Drl(Differential reinforcement of low rates) schedule, the animal is reinforced for each reSponse, but only if a time period, t, has elapsed since the occurrence of the previous response. Even though the introduction of extinction pro- duced a higher rate of reSponding during the Drl component, and hence, a lower rate of reinforcement, relative reinforce- ment actually increased during the Drl component. The 5 results therefore, supported the relative reinforcement theory. Further support came from the results of a study by Catania(1961). Pigeons were trained to reSpond on a concur- rent mult VI VI schedule. In the concurrent mult VI VI sched- ule, the birds were presented with two keys, lit at all times. Reinforcement was available on a V13 basis for reSponding on either key. One key, the mult VI VI key, alternated be- tween green and yellow. The second key, the cone VI key, was always red. After training the birds to reSpond, Catania introduced extinction during the presence of the yellow key. Behavioral contrast was obtained during the presence of the green light on the first key and also in number of reSponses to the red key. Next, Catania doubled the number of rein- forcements available on the red(conc) key at the same time that he introduced extinction during the presence of the yellow key. This time, behavioral contrast did not occur during the presence of the green key, presumably since rela- tive reinforcement during the green key had not been in- creased. Reynolds(1961c) suggested that extinction has both an inhibitory and an excitatory pr0perty. The inhibitory prOp- erty is manifested by the reduced rate of reSponding during the presence of the stimulus correlated with extinction(S-). And the excitatory prOperty is manifested by the occurrence of behavioral contrast in the presence of the stimulus cor- related with reinforcement(S+). Terrace(1963;1966) found 6 that he could eliminate both the inhibitory and the excit- atory aSpects of extinction by means of a procedure he called errorless discrimination learning. Terrace used a procedure in which the S- stimulus was presented as a dark key for a brief period of time and then gradually increased both in intensity and in duration. Terrace concluded that a neces- sary condition for behavioral contrast seemed to be unrein- forced responding to 8-. As Dunham(1968) points out in a review of the literature, this analysis fails to account for the results obtained by Reynolds(1961a). Reynolds obtained contrast by alternating S+ with timeout, a condition during which few, if any, reSponses will occur. Terrace(1968) attempted to distinguish between the two possible explanations for behavioral contrast: 1.) Rel- ative reinforcement; and 2.) ReSponse reduction. After training pigeons to reSpond on a mult VI VI schedule, Terrace introduced electric shock contingent on reSponding during 82. This produced an increase in response rate during 81 although there was no change in relative reinforcment. Similarly, a change from mult VI VI to mult VI Drl pro- duced the same results, although for only half the subjects tested. These results led Terrace to conclude that a reduc- tion in response rate in $2 is a sufficient condition for the occurrence of behavioral contrast in 81' Reynolds and Limpo(1968) performed a similar experiment in which pigeons were trained on a mult Drl Drl schedule. After the birds' reSponse rates had stabilized, a time cue was introduced 7 during 82 which served as a signal that the Drl interval had elapsed. This decreased the reSponse rate during 82 but in- creased the number of reinforcements. The decrease in re- sponse rate in S was accompanied by an increase in reSponse 2 1 even though relative reinforcement in S1 had decreased. These results were directly Opposite to what rate during S would have been predicted from Reynolds' theory. Weisman (1970) in a study similar to Reynolds(1961a) trained birds on a mult VI VI and then changed the schedule to a mult VI Dro. Weisman found that if reinforcement density was held nearly equal in the two components by manipulating the rate of reinforcement in the Dro component, behavioral contrast occurred in the VI component. These data, and those ob- tained by Reynolds and Limpo(1968) were in agreement with the results obtained by Terrace(19633196631968) and with his conclusions. ReSponse reduction in S would seem to be 2 a sufficient condition for the occurrence of behavioral con- trast in 51' Evidence has been presented for two theoretical eXpla- nations for behavioral contrast. The first theory states that behavioral contrast is a result of an increase in rel- ative reinforcement in the component during which it occurs. This position was taken by Catania(1961), Reynolds(1961a31961b; 1961031963) and Reynolds and Catania(1961). The second theory stems from the work on errorless learn- ing by Terrace(196331966) who suggested that behavioral con- trast may be an emotional byproduct of unreinforced reSponding 8 during extinction. Terrace(1968) has suggested that re- duction in response rate in the presence of one stimulus is a sufficient condition for the occurrence of behavioral contrast in the other. This explanation was supported by results obtained by Reynolds and Limpo(1968) and Weisman(1970). The purpose of the present study was to compare, as de- terminants of behavioral contrast, timeout and extinctbn. Two possible sets of results were expected based on the theoretical explanations listed above. (a) If behavioral contrast were a function of relative reinforcement, then both conditions would produce an equivalent increase in the rate of reSponding in the presence of the stimulus cor- related with reinfircement, (b) If behavioral contrast were a result of unreinforced responding in the presence of the stimulus correlated with extinction, then contrast would occur in multiple schedule components preceeded by extinction but not in components preceeded by timeout, since reSponses during a timeout are quite rare. Nevin and Shettleworth(1966) found that the rate of re- Sponding during the presence of a stimulus correlated with reinforcement was highest in the period immediately following the offset of extinction. Nevin and Shettleworth differ- entiated the change in reSponse rate within the schedule component from the overall change in reSponse rate across schedule components. They called the change in gross reSponse rates averaged over successive components of the experi-. mental session, sustained contrast. This procedure seemed 9 to permit a more sensitive analysis of the effects of the independent variable. In the present study, the comparison of timeout and extinction as determinants of behavioral con- trast utilized an analysis of both sustained and transient contrast. 10 METHOD Subjects: Five locally obtained, female, White Carneaux pigeons, four to ten years of age, were maintained at 80% i5% of their free feeding weights for the duration of the eXperi- ment. The birds were experimentally naive at the beginning of the study. Apparatus: All subjects were run in the same standard, Lehigh Valley model 1519 test chamber, equipped with three model 1348 pecking keys. Only the center was key was used or illuminated at any time. The chamber was equipped with a blower which was used for ventilation and the masking of extraneous sounds. Standard electro-mechanical equipment located in an adjacent room was used to program the experi- ment and to record the data. Procedure: Discrimination sesgipns: After having stabilized for at least three days at 80% of their free feeding weights, the birds were placed into the test chamber and allowed to habituate to it. They were presented during this time with continued access to the raised magazine. Once the birds had become accustomed to eating from the magazine, they were shaped to peck a key illuminated from behind by a white light. The first session was terminated after the bird had received a total of 100 reinforcements. Each reinforcement 11 consisted of 3.5 seconds access to the raised magazine. 0n ten succeeding 67 minute daily sessions, each bird was train- ed to reSpond on a mult VI one minute VI one minute schedule during both S and S . During both the training and the 1 2 discrimination sessions, S1 was correlated with a green key light and S with a red key light. The S period was of 2 1 three minutes duration and the 82 period of one minute duration. The three minute S1 periods were selected to per- mit an analysis of transient contrast. The one minute length for the S2 component was selected because it permitted a shorter session length. Each training sesSiOn consisted of 17 S1 presentations and 16 S presentations. Each session 2 began with an S period in order to allow for stabilization 1 of responding. After the initial S period, S and S were 1 1 2 presented alternately. Data from the first S1 period of the session was not used in the analysis of the results of the experiment. 0n the eleventh session, each bird was introduced to both extinction during 82 and to the timeout condition. These conditions were counterbalanced in an ABBA design, i.e., presented in the following order; one S1 component (for response rate stabilization), four S1 components pre- ceeded by 52’ eight S components preceeded by timeout, four 1 S1 components preceeded by 82. This manner of presentation of the eXperimental conditions was designed to control for order and fatigue effects. These conditions were presented during the eleventh through the twentieth sessions. 12 In addition, one session was selected at random between the 13th and the 19th sessions for each bird. During this randomly selected session, latency to the first peck after the reappearance of the 81 condition was recorded with a stOpwatch. These latencies were recorded at the beginning of each 31 component following both S2 and timeout. This was done in order to evaluate the possible effects of dif- ferential latencies to first peck after the offset of timeout as compared to extinction. Reversal sessions; The same subjects and apparatus were used as in the discrimination sessions. At the beginning of the reversal sessions, the positions of S1 and $2 in the order of presentation were exchanged. During the reversal series, reinforcement was available only during 82. During the re- versal series, S was preceeded by either 8 or timeout. 2 1 The same ABBA design was used that was used during the disc- rimination sessions. All 81 components and timeout com- ponents were one minute in length and 82 components were three minutes in length. Any reinforcement made available but not collected during any component was cancelled at the end of that com- ponent. During all components associated with extinction or timeout the variable interval tape was stopped. 13 RESULTS Figure 1 shows the mean rate of responding for each ses- sion during both S1 and $2. Discrimination sessions began in session 11. The baseline consists of an average of the last five days of training sessions prior to the intro- duction of discrimination training. The increase in the rate of reSponding during Sl(behavioral contrast) which accompanied the introduction of discrimination training was not large, but was evident in four of the five birds tested. Bird #174 showed a decrease in the rate of reSponding during Sl(induction) upon the introduction of discrimination train- ing. ReSponses during the timeout were rare. Figure 1 shows that the average rate of reSponding across the three minutes of the S component was not differentially influenced 1 by the preceeding stimulus. An analysis of transient contrast is presented in Figure 2. The rate of responding within each 30 second seg- ment of the S component was averaged across the 10 sessions 1 of discrimination training. The higher response rate shown during the first 30 seconds of the S component following 1 . the termination of S2 as compared to that following the term- ination of timeout, reflects a consistent transient contrast for all subjects except #174. The slight difference shown for #174 is a result of a much higher reSponse rate following timeout during only the first session of discrimination 14 training. For all subjects, the rates during the second through sixth segments of the S component were not dif- 1 ferentially affected by the experimental conditions. Differential reSponse rates during the first 30 seconds of the $1 component could have been a result of differential latencies to the first peck. In order to determine the ex- tent of the effects of this variable, latencies to the first peck after the reappearance of S1 were recorded after both timeout and S2 for each bird during one randomly selected discrimination session. Means and standard deviations of these latency times are shown in Table 1. The latency to first peck following timeout was found to be reliably long- er than the latency following S This difference was 2. found to be statistically significant(p <.05) when sub- jected to an analysis of variance. The latency data was used to recompute the reSponse rates for the initial 30 seconds of the S components in 1 those sessions during which latency times were recorded. As shown in Figure 3, the consistently lower reSponse rate during the first 30 seconds after timeout remained even after the rates had been corrected for the differential response latencies. An analysis of variance for repeated measures showed this difference to be statistically significant(p <.001). Reversal sessions; 0n the twentyfirst session the re- inforcement contingencies were reversed so that Sl(green) was correlated with extinction and 82(red) was correlated 15 with VI one minute. A comparison was then made of the re- sponse rates during the presence of the stimulus correlated with reinforcement on the last day of discrimination train- ing(Sl) with the response rates during the presence of the stimulus correlated with reinforcement on the first day of reversal(SZ). These data,shown in Figure 4, revealed no reliable change in the rate of response during the com- ponents preceeded by timeout between the last discrimination session and the first reversal session. All the birds showed a decline in response rates during those components preceeded by extinction from the last discrimination session to the first reversal session. Even those birds that showed a decline in post-timeout rates showed a greater decline in post-extinction rates, as seen in Figure 4. Referring to Figure 5, this effect is seen in broader perSpective. Be- havioral contrast resulting from timeout remained relatively constant overall. The rate of reponding in those reinforced components preceeded by extinction declined upon reversal and then increased to prereversal levels. Figure 6 shows the mean transients during the first re- versal sessions for the S components. A consistently high- 2 er response rate was found in those components preceeded by timeout as opposed to those preceeded by extinction. Furth- ermore, the general shape of the post-timeout transients re- mained about the same as the prereversal transients, but the post-extinction transients adOpted a configuration comparable to the prereversal shape of the post-timeout transients. 16 A differential latency to first peck was found during the discrimination sessions. In view of this, the compar- ison of reSponse rates during periods following timeout and extinction in the reversal sessions was made ommitting the first 30 seconds of responding during the reinforced com- ponent. These data are shown in Figure 7. The response rate following timeout was found to be higher than that fol- lowing extinction during the first reversal session. An analysis of variance for repeated measures showed this dif- ference to be statistically significant(p <.025). 17 Figure 1. Mean rates of responding for all subjects under all conditions during training and discrimination sessions. 18 ZO_mmmm ONm.m_ t 0— m. E m. N. : ON 9 w. t L m_ i m. N. : ON m. m. N. m. m. v. m. N_ __ H 3 S d O N S I I O. Q I I I d I I I onw 8m III IVE oeN 0-0 )\ m. 0‘)\ 00.....— o\ .. mzfimmwm .0w .6 Jm¢ .0m .0 Pmmi km<4 ._.w5u_ hm”: v2 anomo DI PS. © O O O O O O O [- co to v H) N "' 3.1.0le 83:! SBSNOdSBH O (D 27 Figure 5. Mean rates of reSponding for all subjects under all conditions during reversal sessions. 28 mN ¢N mN NN _N I'll ZO_mmmm mN ¢N MN NN .N I II. )\. .v u ’ ’1 1‘“. I.- ll‘\ -‘ . _m mwhmd. mm... .OH awku—d Nmno 5.0 mm .Vt mN VN MN NN _N mmm 29 Figure 6. Mean transients for all subjects during the first reversal session. 30 onma sz_wz