Journal of Comparative and Physiological Psycholcgy1966, Vol. 62, No. 2, 208-213

EFFECTS OF TWO COUNTERCONDITIONING PROCEDURESON THE EXTINCTION OF FEAR1

FRANKLIN NELSON2

Yale University

In Experiment 1, rats were fed in a compartment in which they had beenshocked by being placed directly over a food dish. In Experiment 2, foodwas used to provide an incentive for Ss to enter the fear compartment.The results indicated that the major effect of food on fear is not one ofcounterconditioning, but rather one of decreasing or increasing the amountof exposure to the fear-producing situation.

The procedure of feeding an organismin a fear-producing situation has been tra-ditionally viewed as having a fear-reducingeffect. The interpretation of this method ofextinguishing fear, called countercondi-tioning, has been that fear is reduced byconditioning to the fear-producing stimulithe incompatible emotional responses as-sociated with eating (e.g., Miller, 1951). Inrecent studies, however, Moltz (1954)found no effect of feeding on fear, andLane (1954) obtained an effect that can-not clearly be attributed to countercondi-tioning. The present experiments weredesigned to evaluate further whethercounterconditioning extinguishes fear.

Experiment 1 had two purposes. Thefirst was to repeat Lane's (1954) study,using a measure of the effect of counter-conditioning that was less ambiguous. InLane's study, animals were first givenshock-escape training in a Miller-Mowrerapparatus, then confined in the fear com-partment with shock off; during confine-ment, food was presented intermittently toone group but not at all to the other. Thesubsequent measure of running out of thefear compartment, without food or shockpresent, showed that the group that wasfed ran out more slowly. Observationsrecorded during confinement indicated,however, that the no-food group crouchedat the escape door while the food group

1This article is based on a dissertation sub-mitted in partial fulfillment of PhD requirementsat Yale University. The author wishes to thankthe members of his committee: F. D. Sheffield, I.L. Child, and W. Kessen.

2 Now at C. W. Post College of Long IslandUniversity, Greenvale, Long Island, New York.

alternated between crouching at the doorand approaching the food tray situated atthe center of the compartment. This ini-tially suggested the possibility that thedifference in running-out times reflected aneffect of feeding in conditioning motorresponses incompatible with the measureof fear, and not an effect on the level offear. The second purpose was to determinewhether the counterconditioning effect, ifone exists, results in an extinction of fear,or only a temporary suppression of it.Studies on conflict (e.g., Miller & Krael-ing, 1952), in which animals are first fedand then shocked, show that the food-re-lated responses reappear when the fear re-sponses are extinguished. If an analogousconclusion may be drawn about counter-conditioning, these findings suggest thatextinguishing the association of food withthe fear-producing situation would resultin a reappearance of fear.

EXPERIMENT 1

In this experiment, as in Lane's (1954),the sequence was: (a) fear conditioning,(b) confinement in the fear compartmentwith or without food, (c) measurement ofresidual fear. In order, however, to obtaina less ambiguous measure of fear, escapefrom the fear to the safe compartment wasprevented during fear conditioning andwas permitted only during the last phase ofthe sequence; thus, while the present studyalso employed a running response as ameasure of fear, the level of fear was heredetermined by evaluating its strength as adrive for learning a new response. In addi-tion, in order to minimize the condition-

208

EXTINCTION OF FEAR 209

ing of approach responses to food that maybe incompatible with the measure of fear,Ss were not fed intermittently, but werefed by being placed directly over a dish offood.

Five experimental treatments were intro-duced after fear conditioning: (a) 3 trialsof confinement in the fear compartmentwith food; (6) 3 trials of confinementwith no food; (c) 3 trials of confinementwith food followed by 3 trials withoutfood; (d) 6 trials of confinement with nofood; and (e) no confinement in the fearcompartment.

The No-Confinement condition servedas a baseline for the other comparisons. TheConfinement condition, in comparisonwith the Food condition, served as a con-trol for the effects of confinement. A com-parison of the Food + Confinement con-dition with the Food condition assessedthe results of extinguishing any counter-conditioning effect. However, as these twoconditions were not equated on the totalnumber of trials, a comparison betweenthe Food + Confinement and the Con-finement + Confinement conditions alsoassessed the results of extinguishing anycounterconditioning effect.

MethodSubjects and apparatus. One hundred male al-

bino rats of the Sprague-Dawley strain, 90-120 daysold, were kept in individual cages with water al-ways available.

The apparatus was similar to one described byMiller (1948). It had two compartments, one whitewith a grid floor, the other black with a Masonitefloor. The fear compartment, measuring 12 X 8 X12 in., had a sliding Masonite top, a glass side, and amovable wall at one end which could be used toforce S out of the compartment. The grid was madeof stainless steel bars placed 3A in. apart. The safecompartment measured 21 X 6 X 11 in., had a glasstop, and a floor 1 in. higher than that of the fearcompartment; except for a l-in.-deep stationary-floor adjacent to the fear compartment, the floorwas hinged to operate a microswitch when de-pressed. The compartments were separated by aMasonite door, which, when raised, operated amicroswitch starting a Standard Electric Timer;the timer stopped when S entered the safe com-partment.

In order to prevent Ss from escaping throughthe top of the fear compartment when removingthem after fear conditioning and confinement trials,a "removing case" was used. This case measured

9 X 6 X 10 in., was painted gray, and had a glasstop and a removable Masonite floor. The case, withthe floor removed, could be lowered into the fearcompartment over S, and its floor then insertedthrough a slit in the side of the fear compartmentinto grooved inner edges of the case.

Procedure. The experiment was run in 10 repli-cations of 10 Ss each. Each replication took 6nights. Twelve nights prior to the first experimen-tal night of each replication, Ss were placed on awet mash ration of 10-gm. dry-weight groundPurina chow mixed with equal parts of water,presented in the same dish used during the experi-mental conditions. This ration was omitted com-pletely for all Ss on the eleventh and thirteenthnights of the schedule.

On Experimental Night 1, all Ss were given 4shock trials: Ss were placed on a cold grid and,after 30 sec., a 5-sec. shock of 300 v. ac was deliv-ered through a resistance of 180 K ohms in serieswith S. After each shock trial, the removing casewas used to return S to its home cage; the inter-trial interval was 78 min. Habituation trials to thesafe compartment were provided by placing Ss inthe safe compartment for a 5-min. period of con-finement between each of the 4 shock trials; thetime elapsing between a shock and a habituationtrial averaged 36 min.

On Night 2, Ss were randomly divided into ex-perimental groups. In the No-Confinement condi-tion, S was handled but not placed in the appara-tus during this stage. In the Food condition, S wasplaced in the center of the fear compartment, shockoff, directly over a dish of 15 gm. of wet mash;after 10 min., S was returned to its home cage withthe removing case. The Confinement condition wasidentical to the Food condition, except that nofood was present; in the confinement trials of theFood + Confinement group only, the dish whichhad previously contained food was also present.The Food group and the Confinement group re-ceived 2 trials of their respective conditions onNight 2 and 1 trial on Night 3. The Food + Con-finement group received 2 trials on Night 2 and 1trial on Night 3 of the Food condition and 2 trialson Night 3 and 1 trial on Night 4 of the Confine-ment condition; the trials of the Confinement +Confinement condition were spaced like those ofthe Food + Confinement group, except that alltrials were confinement trials. The Ss were observedduring all confinement trials, and on the food trialsa stopwatch was used to record the total time spenteating.

Sixty trials of running from the fear to the safecompartment were given on Nights 4 and 5 for theFood, Confinement, and No-Confinement groups,and on Nights 5 and 6 for the Food + Confinementand Confinement + Confinement groups. Withfood, dish, and shock absent, S was placed in thefear compartment, the door was opened, and afterS had left, the door was closed to prevent retracing.The time elapsing between the opening of the doorand S's entrance into the safe compartment was re-corded to the nearest .1 sec. The movable wall was

210 FRANKLIN NELSON

A Food

* Food plus conf inement

• • C o n f i n e m e n t p lusc o n f i n e m e n t

a a N o - c o n f i n e m e n t

A A l t e r n a t i n g foodand conf inement

30 40

TRIALS

FIG. 1. Mean, speeds of the running responsereflecting the level of fear after the experimentalconditions. (Trials are grouped in blocks of 4.)

used to force S out of the compartment if it failedto run in 30 sec. in Trials 1-5, and in 120 sec. inTrials 6-10. If 2 consecutive trials of over 120sec. occurred after Trial 5, S was considered to beextinguished. The minimum intertrial interval was5 min.

Results

The median percentage of time spenteating in the confinement with food trials ofthe combined Food and Food + Confine-ment groups was 78.8%, the range being0-96%. Only 10% of the Food group and15% of the Food + Confinement grouprefused to eat entirely; they were includedin the analysis on the grounds that theywere exposed to food.

The mean speeds of the running responsefrom the fear compartment during testtrials are shown in Figure 1. These resultswere analyzed in terms of the mean speedper S over the first 30 and over all 60 trials.An analysis of variance of these scores inthe four basic groups of Food, Confine-ment, Food + Confinement, and Confine-ment + Confinement yielded a significanttreatments effect (F = 5.76, df - 3/40,p < .01, and F = 3.95, df = 3/40, p < .05for the first 30 and all 60 trials, respec-tively) .

The differences between groups wereevaluated by t tests. In all of the follow-ing comparisons, the values for the first30 trials are presented first. The compari-

sons between the No-Confinement groupvs. the others show that confinement,with or without food, was more fearreducing than no confinement (p < .01 forall comparisons, except vs. Food group,p = .04, p = .08). A comparison of theFood group and the Confinement groupreveals that the Food group was more fear-ful (t = 2.48, df = 20, p = .02; t = 1.85,df — 20, p — .08), showing that thecounterconditioning procedure interferedwith the extinction of fear. Consistent withthis finding, and contrary to the possi-bility that the Food + Confinementcondition would extinguish the countercon-ditioning effect and reinstate fear, the com-parison between the Food + Confine-ment group and the Food group showedthat when confinement trials with foodwere followed by confinement trials with-out food, less rather than more fear re-sulted (t = 2.76, df = 20, p - .01; t =2.54, df = 20, p = .02). The performanceof the No-Confinement group was so dis-tinctly different from all others that it wasnot considered necessary to continue it forthe entire experiment; it was replaced afterthe fifth replication with an AlternatingFood and Confinement group, in order toassess the possibility, suggested by Lane's(1954) results, that the fear-reducing effectof food was related to its being presentedintermittently. The Alternating Food andConfinement group differed from the Food+ Confinement group in that its confine-ment trials without food alternated withthose with food. However, this conditiondid not produce more fear extinction thanthe Food + Confinement condition. Whenthe Food + Confinement and the Alternat-ing Food and Confinement conditions werecombined and compared with the Confine-ment + Confinement condition, the differ-ence was not significant, but its directionsupports the finding that confinement with-out food results in more extinction of fear(t = 1.43; t = .94).

EXPEKIMENT 2

The findings of Experiment 1 on theeffects of counterconditioning are in directcontrast to Lane's (1954) results. SinceExperiment 1 minimized the possibility of

EXTINCTION OF FEAR 211

conditioning motor responses to food in-compatible with the measure of fear, onemight conclude that the present resultsare more valid. A reinterpretation of theeffects of the experimental procedures sug-gests, however, that a more critical vari-able is the effect of feeding on exposure tothe fear-producing stimuli. In Lane's ex-periment, recordings of movement indi-cated that animals that were fed movedaround more during confinement than thosethat were not fed. By contrast, the presentexperimental procedures, which had beendesigned to minimize conditioning in-compatible motor responses, resulted in lessexposure for those confined with food:since no instrumental escape responses wereconditioned prior to confinement, nocrouching at the door resulted; in addition,presenting food by placing Ss over a dishof food, instead of intermittently feedingthem, had the effect of keeping themeither eating or in the area of the food dish,rather than alternating between the doorand the food dish.

Experiment 2 was designed to evaluatefurther the interpretation that exposure,and not counterconditioning, is the majorfactor in the relationship between food andfear; it employed the procedure of usingfood as an incentive for increased exposure.As in Experiment 1, the experimental pro-cedures were run in the following sequence:(a) fear conditioning, (b) introduction ofexperimental conditions during a period ofno shock, (c) measurement of residual fear.The interpolated experimental conditionswere: (a) Incentive: freedom to move fromone compartment to another, with food al-ways present in the shock compartment;(b) No Incentive: similarly, freedom tomove, with no food present; (c) IncentiveControl: being forced to spend an amountof time in the two compartments equal tothe time spent in each compartment by amatched S in the Incentive condition, withno food present; (d) No-Incentive Con-trol: a similarly matched group for theNo-Incentive condition, with no food pres-ent.

A comparison of the Incentive and No-Incentive groups provides a means forevaluating the use of food as an incentive

for increased exposure. Comparing the In-centive Control group with the Incentivegroup determines whether there is aneffect of food, like counterconditioning, inaddition to its effect as an incentive forexposure. Since the Incentive group is freeto expose itself to the cues for fear, whilethe Incentive Control group is not, the In-centive group may therefore be favored byan aspect of extinction similar to Guthrie's(1935) "toleration" method, i.e., voluntaryexposure implies that an S will expose it-self only to as much fear as it can tolerateat one time. A comparison of the No-In-centive and No-Incentive Control groupswill, however, permit assessing the effect ofthis possible factor.

The following experiment measured thelevel of fear in the same fashion as Experi-ment 1; however, it differed in that anescape response was conditioned duringfear conditioning. This procedure wasadopted in order to insure conflict in theIncentive group and thus increase thelikelihood that they would pay attentionto the cues of the fear compartment.

Method

Subjects and apparatus. Seventy-two male al-bino rats of the Sprague-Dawley strain, 90-120days old, were kept in individual cages with wateralways available.

The apparatus was similar to the one used pre-viously. It had two compartments, one white witha grid floor, the other black with a Masonite floor.The fear compartment measured 15 X 8 X 11 in.,had a plastic glass top, and a 2 X 4 in. glass windowon one side; its grid was made of stainless steelbars placed Vz in. apart. The safe compartment was

"14 X 9 X 11 in. and had a plastic glass top. Thecompartments were separated by a manually op-erated Masonite door. The floors of the two com-partments were hinged and each operated a sep-arate microswitch; these could be connected tosweep-second Teleehron wall clocks which wereused to record the amount of time spent in eachcompartment during the experimental conditions.These microswitches could also be connected to aStandard Electric Timer and used to record thespeed of running during the measurement of re-sidual fear.

Procedure. The experiment was run in six repli-cations of 12 /Ss each; each replication took 6 days.Twelve days prior to the first experimental day ofeach replication, a daily regime of 10 gm. of dryground Purina and one 5-gm. Purina checker wasinstituted. On the day prior to the first exposuretrials, food was omitted completely. The daily ra-

212 FRANKLIN NELSON

A—A Incentiveo o No-incentive*---i Incentive control•—• No-incentive control

FIG. 2. Mean speeds of the running responsereflecting the level of fear after the experimentalconditions. (Trials are grouped in blocks of 2.)

tion was always presented in a dish identical withthe one used in the experimental conditions.

On Day 1, each S was given 2 3-min. trials ofexploration in the apparatus. On Days 1 and 2, 20shock trials per day were run. Two types of escapeconditioning were jointly used on each S: an im-mediate-escape condition, in which S was placedon a charged grid with the door between compart-ments opened; and a delayed-escape condition, inwhich S was placed on an uncharged grid for 30sec. with the door between compartments closed,following which shock was turned on, and, 3 sec.later, the door opened. Delayed-escape trials wererun on Trials 26-35 and were used in order to maxi-mize the amount of fear conditioned. After /Ss hadrun into the safe compartment on each trial, theywere detained for 30 sec. The grid was electrifiedby 200 v. ac through a resistance of 180 K ohmsin series with S. The intertrial interval of imme-diate-escape trials was 12 min. and that of delayed-escape trials was 20 min.

The experimental conditions were introduced onDays 3 and 4. With shock turned off, each S re-ceived 5 2-min. trials and 1 10-min. trial on Day3, and 2 10-min. trials on Day 4. Each 2-min. trialwas begun by placing S in the fear compartment;in each 10-min. trial, however, S was placed in thesafe compartment. The procedure in the 2-min.trials was run in order to insure that Ss in the In-centive group saw that food was present in the fearcompartment.

The door between compartments was kept openthroughout all the experimental trials' of the In-centive and No-Incentive groups, but was closedthroughout for both the Control groups. A fooddish was fixed to the grid at a point first 6 in. andthen 10 in. from the door for each group; but onlyin the Incentive condition did it contain 15 gm. ofdry ground Purina. During the trials of the Incen-tive and No-Incentive groups, the number of en-trances into the fear compartment was recorded, aswas the total time spent in each compartment. Anentrance was recorded any time S completely left

the safe compartment. Each control S had a ran-domly assigned partner in its respective condition;these control Ss were first placed in the compart-ment in which their partner had been placed andconfined there for a period of time equal to thetotal amount of time spent there by their partner,and then immediately placed into the other com-partment and confined there for the remainder ofthe trial.

On Days 5 and 6, Ss were given 30 trials per dayof running from the fear to the safe compartment,with shock, food, and dish absent. The S wasplaced in the fear compartment with the dooropen; when the safe compartment was entered, thedoor was closed to prevent retracing. If S failed torun in 30 sec. in Trials 1-5, and in 120 sec. in Trials6-15, it was placed through the doorway into thesafe compartment. If, after this period, 2 120-sec.trials occurred in a row, S was considered to beextinguished and not run again. The minimumintertrial interval was 5 min.

Results

The mean amount of time voluntarilyspent in the fear compartment was 22.6min. for the Incentive group and 8.2 min.for the No-Incentive group (t = 4.80,df = 24, p < .01); the mean numberof entries was 20.4 and 11.6, respectively(t = 2.09, df = 24, p = .02). Thus,food was successful in getting Ss to exposethemselves to the cues for fear.

The mean speeds of the running responsefrom the fear compartment during testtrials are shown in Figure 2. The results ofthe running trials were analyzed in termsof the mean speed per S over the first 30and all 60 trials. An analysis of variance ofthese scores yielded a significant treatmentseffect for the first 30 trials (F = 2.84,df = 3/48, p = .05).

Except where indicated, the differencesbetween the groups were evaluated by ttests; the values for the first 30 trials arepresented first. The comparison of the In-centive and No-Incentive conditionsshowed that the presence of food will has-ten the process of fear extinction if itserves as an incentive for exposure (t =1.72, df = 24, p = .04; t = 1.41,df = 24, p - .08). The difference ismore impressive when the effect of twoextremely frightened Ss in the Incentivecondition is minimized by using a medianstest (xc2 = 9.00, p < .01, both compari-sons) .

EXTINCTION OF FEAR 213

A comparison of the means of the In-centive and Incentive Control groups sug-gests that there was no difference betweenthe two conditions (t — .34; t — .37).However, an examination of the two sets ofscores revealed that there was a greaterproportion of slow runners in the Incentivecondition, and a medians test showed that,in the first 30 trials, the Incentive groupwas less fearful (xc2 = 5.44, p = .02). Rele-vant to this finding is the comparison of theNo-Incentive and No-Incentive Controlgroups which failed to show any differ-ence (t = .34; t = .80), indicating that,at least for these groups, the variable offree, as opposed to forced, exposure wasnot a significant factor.

DISCUSSION

The findings that food can either slowdown or hasten the extinction of fear sup-port the interpretation that the primaryeffect of food on the level of fear is theeffect of the feeding procedure on theamount of exposure to the stimuli for fear.This effect of food in hastening fear ex-tinction by providing an incentive for ex-posure to fear-producing stimuli is not acounterconditioning effect.

The importance of exposure in extin-guishing fear suggests a reevaluation ofstudies (Farber, 1948; Jones, 1924; Wolpe,1952) which have been interpreted assupporting a counterconditioning effect.These studies found that Ss fed in a fear-producing situation were consequently less

fearful than Ss receiving no comparableexposure. The present results suggest thatthese experiments primarily reflect theeffects of exposure.

The difference between the Incentiveand Incentive Control conditions in Ex-periment 2 is an ambiguous one, and needsfurther study. This difference may reflect acounterconditioning effect, one which issecondary to the effect of food on exposure.

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(Received December 23, 1965)