Journal of Experimental Psychology:Animal Behavior Processes1976, Vol. 2, No. 2, 130-141

Learned Irrelevance and Learned Helplessness: Rats Learn thatStimuli, Reinforcers, and Responses are Uncorrelated

A. G. BakerUniversity of Sussex, Brighton, England

In a series of four experiments, preexposure to uncorrelated presentations ofnoises and shocks retarded the acquisition of conditioned emotional response(CER) and signaled punishment suppression when this preexposure wascarried out while the rats were not permitted to respond. When preexpo-sure was carried out while the rats were responding, preexposure to uncor-related noises and shocks interfered with signaled punishment suppressionon the first test day, and both preexposure to uncorrelated noises and shocksand preexposure to the shocks caused similar interference on the remainingdays of the test. Signaled punishment suppression was interfered with morewhen preexposure to uncorrelated noises and shocks was carried out whilethe rats were responding, but CER suppression was similarly affectedwhether the rats were permitted to continue responding or not. These re-sults suggest that rats may learn that both noises and shocks and responsesand shocks are uncorrelated, and these two types of learning may interferewith learning CER suppression and the punishment contingency, respectively.

Rescorla (1967) and Prokasy (1965) havesuggested that the uncorrelated or "trulyrandom" procedure, in which a conditionedstimulus (CS) and unconditioned stimulus(US) are presented with no temporal rela-tion to one another, is a useful control pro-cedure for classical conditioning experiments.Rescorla (1966) described an experiment inwhich dogs, after being trained to carry outSidman avoidance in a shuttlebox, weregiven one of three types of conditioning pro-cedures while restrained in one side of theshuttlebox. The animals in the uncorrelatedgroup received a number of temporally un-related tone and shock presentations. Theanimals in the positive correlation groupreceived the same treatment as the uncor-related group except that all shocks that did

These experiments were carried out as part of adoctoral dissertation presented to Dalhousie Uni-versity in June 1974. The research was supportedby National Research Council of Canada GrantAPA 259 to N. J. Mackintosh. I would like tothank N. J. Mackintosh, V. L. M. LoLordo, W. K.Honig, and R. A. Rescorla for their helpful com-ments.

Requests for reprints should be sent to A. G.Baker, Laboratory of Experimental Psychology,University of Sussex, Falmer, Brighton, England,BN1 9QG.

not occur in the 30 sec following each tonewere omitted. For the negative correlationgroup only those shocks that occurred in the30 sec following the tone were omitted.Later, when the dogs were again avoidingshocks and the tone was presented, responserate increased for those animals that hadreceived the positive correlation and de-creased for those animals that had receivedthe negative correlation. The result of presentinterest, however, is that the response rateof those animals that had received the uncor-related procedure was little affected by thetone. Rescorla (1967) interpreted data suchas these to imply that this uncorrelated pro-cedure produced little or no associative learn-ing and yielded a good neutral baseline fromwhich the occurrence of Pavlovian condi-tioning could be measured. This notion ofthe associative neutrality of the random pro-cedure was later more clearly specified inRescorla's (1969) contingency theory ofPavlovian conditioning. Under certain re-stricted conditions it is also an implicationof Rescorla and Wagner's (Rescorla & Wag-ner, 1972; Wagner & Rescorla, 1972) modelof associative learning.

Some experiments by Mackintosh (1973)lead to an alternative view of the effects ofthe uncorrelated procedure. In a typical

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LEARNED IRRELEVANCE AND LEARNED HELPLESSNESS 131

experiment thirsty rats were placed in anapparatus that contained a drinking tube.First, they were trained to lick the tube toreceive water delivered on a variable intervalschedule. During the next phase (preexpos-ure) of the experiment, one group receiveduncorrelated presentations of tones andshocks, a second group was exposed to thetones only, a third, to the shocks only, andthe final group received no presentations ofeither stimulus. Following this phase theanimals were trained on a standard condi-tioned emotional response (CER) procedure.This is a classical conditioning paradigm inwhich a CS (in this case, the tone) signalinginescapable shocks is presented to a subjectresponding on an appetitive instrumentalschedule. The typical conditioned responseto such a procedure is a suppression of theinstrumental response during the CS. Themajor finding of this experiment was thatthe uncorrelated group acquired CER sup-pression more slowly than the other groups.Mackintosh (1973) suggested, in a view thatwas hinted at by Rescorla (1967, p. 77), thatthe uncorrelated procedure was not associa-tively neutral but that the animals could learnthe specific lack of correlation that it entailed.Such "learned irrelevance" could interferewith future conditioning to that CS and US.

The experiments and theories of Mack-intosh and Rescorla deal mainly with classicalconditioning. However, a number of looselyanalogous experiments dealing with escape-avoidance learning in dogs have been re-ported by Maier, Seligman, and Solomon(1969; Seligman, Maier, & Solomon, 1971).Typically in these experiments restraineddogs were given a series of severe inescap-able shocks before being given the opportun-ity to escape or avoid shock in a two-wayshuttlebox. The main finding was that thedogs that were preexposed to unavoidableshock took longer to acquire escape-avoid-ance behavior than nonpreexposed controls.Maier et al. (1969) suggested that this inter-ference was the result of "learned helpless-ness." The dogs preexposed to inescapableshock learned that their behavior did notaffect the presentation of the shocks andhence were unlikely to learn that the latershocks, in the shuttlebox, were avoidable.

Demonstration of learned helplessnesswith rats has been quite difficult. In fact,Weiss, Krieckhaus, and Conte (1968) wereled to suggest that learned helplessness mightbe specific to dogs and that the small effectsfound in rats were a result of conditionedfreezing learned during the preexposureperiod. Maier, Albin, and Testa (1973) havereported that a strong learned helplessnesseffect in rats depends on the use of responses,such as double crossing of the shuttlebox orturning a wheel, which are learned moreslowly than single crossing in the shuttlebox.Although this demonstration does not ruleout the possibility that "learned helplessness"in rats may be the result of conditioned freez-ing, its results make this explanation lessplausible. It is difficult to see why doublecrossing of the shuttlebox should be inter-fered with by conditioned freezing and singlecrossing should not.

Preexposure to shocks and CSs has thusbeen shown to interfere with the later learn-ing of both Pavlovian conditioned responsesand instrumental escape-avoidance re-sponses. It seems plausible to suppose thatthe two effects are related. The present ex-periments were designed both to evaluate thereliability of both effects and also, by study-ing each under comparable conditions, toelucidate the relationship between them.

The procedures used in the present experi-ments were the CER and signaled punish-ment. The signaled punishment procedureclosely resembles the CER procedure, withthe sole exception that shocks are deliveredin the presence of the CS or signal only ifthe subject responds. In CER, therefore,there is a classical contingency between CSand shock; in signaled punishment there isa further instrumental contingency in thatthe delivery of shock is contingent on theoccurrence of a response in the presence ofthe CS. The particular CER schedule usedhere was similar to that employed by Church,Wooten, and Mathews (1970), in whichshocks were programmed on a variable timeschedule throughout each CS rather thanoccurring only at the termination of the CS.This procedure was chosen to increase thesimilarity between CER and the signaledpunishment procedure in which shocks were

132 A. G. BAKER

programmed on a variable interval (re-sponse-contingent) schedule throughout eachCS.

Although the main reason for usingsignaled punishment as the instrumentalparadigm in the present experiments wasthat it is formally similar to a particularclassical paradigm, there were other reasonsfor its use. First, learned helplessness hasso far been studied only in instrumentalescape or avoidance paradigms. If the effectis of any generality, it should be possible toobtain in other situations. Second, if uncor-related presentations of CS and US could beshown to interfere with the suppression ofresponding on a signaled punishment sched-ule, this would be difficult to reconcile withthe conditioned freezing hypothesis advancedby Weiss et al. (1968). Subjects that havelearned to freeze in the presence of a CS mayfail to learn an active avoidance response butshould show more rather than less suppres-sion of responding in a signaled punishmentsituation.

EXPERIMENT 1This experiment was an attempt to demon-

strate, in similar preparations, that the un-correlated procedure could interfere with theacquisition of both CER and signaled punish-ment suppression. After being trained topress a lever for food delivered on a variableinterval schedule, two groups of rats werepreexposed to uncorrelated presentations ofshocks and noises, whereas two other groupsreceived no such preexposure. In the latertest phase of the experiment, one preexposedgroup (Group Noise-Shock/CER) and onenonpreexposed group (Group CER) re-ceived a CER procedure, whereas the othertwo groups (Group Noise-Shock/Punish-ment and Group Punishment) received asignaled punishment procedure.

MethodSubjects. The subjects were 32 male hooded Long-

Evans rats which were shipped to the laboratory,from the Quebec Breeding Farms, at weightsvarying from 250 g to 300 g. The rats wereallowed to adapt to the laboratory conditions withfree access to Purina Rat Chow and water for 5days. They were then weighed and reduced to

of their free-feeding weights for the remainder ofthe experiment.

Apparatus. The four conditioning chambers were23-cm high, 20-cm deep, and 25-cm wide. One sidewall of each was transparent Perspex, the ceilingswere translucent Perspex, and the three remain-ing walls were sheet metal. In each chamber oneend wall contained a lever, a food cup, and anacoustic speaker. The lever was a Lehigh Valleyretractable lever which was centered 4 cm fromthe metal side wall and 4 cm above the gridfloor. The food cup was located behind a 4-cm2hole, which was centered 6 cm from the Perspexwall and 4 cm above the grid floor. A Ralph Ger-brands pellet dispenser could deliver 45-mg Noyesfood pellets into the cup. The speaker was centeredin the wall 16 cm above the grid floor and couldpresent the auditory CS, which was a 75-db.white noise re 20 /iN/m2 (background 65 db.)from a Grason Stadler Model 901 B noise gen-erator. Scrambled shock could be delivered throughthe grid floor, lever, and metal walls from a Gra-son Stadler Model 900 shock generator. Shockswere .25 mA in intensity and .5 sec long. A verydim houselight (40 W 110 vac bulb in series witha 1,000-fi resistor) glowed above the translucentceiling of the chamber. The chambers were locatedin separate sound and light attenuating chestswhich were located in a separate room from theautomatic programming and recording equipment.

Procedure. The rats were trained to press thelever for pellets over 3 days. On the first day thelevers were removed and each rat received 30pellets individually delivered at random timesthroughout the 30-min. session. During the next2 days the levers were present and each leverpress was reinforced. On these 2 days each ratwas removed after it had responded 50 times orafter 30 min. had elapsed. All further daily sessionslasted for 30 min. During the next six sessions therats were allowed to respond for pellets, whichwere delivered according to a variable interval1-min. schedule (i.e., a lever press was reinforcedon the average of one time per minute).

The next 5 days constituted the preexposurephase of the experiment. This phase was conductedwith the lever retracted. For this phase and theremainder of the experiment the rats were dividedinto four groups of eight rats. Groups Noise-Shock/CER and Noise-Shock/Punishment werepreexposed to uncorrelated -presentations of thenoise and shocks, whereas Groups CER andPunishment were placed in the boxes each sessionbut received no noise or shock presentations. Theuncorrelated procedure consisted of six shocksoccurring at irregular intervals each session andtwo 3-min. noise presentations commencing on the9th and 21st minute of each session. The presenta-tion of shocks was governed by two constraints.Two shocks never occurred within less than 10 secof one another and one shock occurred during anoise trial each day.

Following the preexposure phase was a lever-press recovery day during which the lever was

LEARNED IRRELEVANCE AND LEARNED HELPLESSNESS 133

present and the animals were permitted to respondon the variable interval food schedule. The final Sdays of the experiment comprised the test phase.During this phase, Groups Noise-Shock/CER andCER received the CER test procedure and GroupsNoise-Shock/Punishment and Punishment receivedthe punishment test. For the punishment and CERtests, two 3-min. noise trials beginning on the 9thand 21st minute of each session were given. Dur-ing each of these trials for both tests, three shockswere programmed. In the CER test the shocksoccurred immediately when programmed. However,for the punishment test, the shocks did not occuruntil after the next response during a noise trial.During this phase the response rate during eachtrial (CS score) and during the 3 min. immedi-ately preceding each trial (pre-CS score) wasrecorded. During the recovery day, two "mock Pre-CS scores" were recorded during the periods inwhich they would have occurred if the CS had beenpresented. Suppression was measured using Kamin'ssuppression ratio (cf. Annau & Kamin, 1961),which is simply the proportion of the total responsesoccurring in both pre-CS and CS periods that occurin the CS period]

Rodger's (1967) method was chosen as themethod of analysis. By this method analyses ofvariance and orthogonal a posteriori comparisonsare calculated in a manner identical to that pro-posed by Scheffe (1959). These variance ratios,however, are compared against Rodger's statistic(Rodger, 1975) rather than Fisher's (cf. Winer,1971). Choice of this statistic implies choice of adecisionwise error rate rather than an experiment-wise one and thereby keeps the power to detectdifferences constant in experiments containingvarious numbers of groups.

ResultsDuring the shaping and variable interval

training sessions all of the animals developedadequate rates of responding. On the last dayof variable interval training the groups'response rates varied from 30 to 35 responsesper minute and did not differ reliably, -F(3,28) = .84, p > .10. However, after the pre-exposure phase, during the mock pre-CStrial on the lever press recovery day, thegroups' mean response rates did differreliably, F(3, 28) = 23.8, p < .05. Aposteriori tests indicated that this differencewas due to Group CER responding at afaster rate (48 responses/min.) than theother groups (range: 24-27 responses/min.), F(3, 28) = 2.28, p > .05.

The daily mean suppression ratios areplotted in Fig. 1. Analyses of variance werecomputed for each day of the test. These

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Figure 2 depicts the mean daily suppres-sion ratios for each day of the test. One-wayanalyses of variance were calculated for eachday and they were all significant, Day 1 F= 4.58, p < .01; Day 2 F = 3.52, p < .01;Day 3 F = 2.75, p < .05; Day 4 F = 2.91,p < .05; Day 5 F = 2.91, p < .05 (all df =3, 28). A posteriori analyses indicated thaton Day 1 the noise/shock group was lesssuppressed than the other groups, F(3, 28)= 4.36, p < .01, while on the remainingdays the noise/shock and shock groups were

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136 A. G. BAKER

less suppressed than the noise and no-stimuligroups, Day 2 F(3, 28) = 3.23, p < .05;Day 3 F = 2.60, p < .05, Day 4 F = 2.67,p < .05, Day 5 F = 2.62, p < .05.

A split-plot analysis of variance was car-ried out on the mean daily pre-CS scores forthe test phase. The overall mean responserates were 48 responses/min. for the noise/shock group, 32 responses/min. for theshock group, 43 responses/min. for the noisegroup, and 31 responses/min. for the no-stimuli group. These rates did not differreliably, F(3, 28) = 1.16, p > .10. Theoverall mean daily rates increased from 33to 38 responses/min., F(4, 112) = 4.03, p< .01. On the first test day, the no-stimuligroup, with a rate of 20 responses/min., wasless suppressed than the other groups, whoserates varied from 33 to 38 responses/min.On the final 2 days of the test, the noise/shock and noise groups, whose mean rateswere 54 and 53 responses/min., respondedmore often than the shock and no-stimuligroups, both of which responded at 31 re-sponses/min. These differences account forthe reliable Treatments X Days interaction,F(12, 112) = 3.04, p < .01. The formerdifference may well account for the fact thatpreexposure to the noise caused no apparentinterference with the acquisition of suppres-sion. In fact, the response rate of the noisegroup was 27 responses/min. during the firstCS period of the test, while that of the no-stimuli group was 15 responses/min. Theserates differ reliably, *(14) - 2.18, p < .05.The difference between the noise/shock andnoise groups and the shock and no-stimuligroups on the final 2 days of testing appearsto have had no effect on the groups' relativesuppression, as measured by suppressionratios. This is because, as inspection of Fig-ure 1 indicates, suppression of all groupsremained stable on the final 4 days of thetest.

DiscussionThe results of this experiment are that the

noise/shock group was less suppressed thanthe remaining groups on the first day of thetest and that on all subsequent clays thenoise/shock and shock groups, though not

differing from each other, were less sup-pressed than the noise and no-stimuli groups.These results replicate those of Experiment1, in which it was found that preexposureto uncorrelated noises and shocks interferedwith the acquisition of punishment suppres-sion. They also demonstrate that preexposureto shock alone, at least while responding, issufficient to cause interference with the ac-quisition of punishment suppression. Finally,there was no evidence that preexposure tonoise alone had any effect on test perform-ance, but it is possible that this failure toobserve latent inhibition (Lubow & Moore,1959) was due to the fact that the appro-priate comparison group, no-stimuli, re-sponded slowly on the first test day.

The difference between the noise/shockand shock groups on the first test day sug-gests either an effect of latent inhibition pro-duced by exposure to the noise alone or aneffect of learned irrelevance produced byexposure to uncorrelated presentations ofnoise and shock. In either case, it is reason-able to suggest that the difference reflects afailure of the classical contingency betweennoise and shock to affect subjects in thenoise/shock group on early test trials. Thus,the initial suppression in the shock groupmay have been largely due to the effects ofthis classical contingencya conclusion con-sistent with the argument advanced in thediscussion of Experiment 1.

The most important feature of the presentresults, however, is that after the first day,exposure to shock alone interfered as muchwith the acquisition of suppression as didexposure to uncorrelated noise and shock.The discussion of Experiment 1 suggestedthat after one or two days of a signaled pun-ishment procedure, the instrumental con-tingency between responding and shock be-came the most important determinant of sup-pression. If this is true, the implication isthat exposure to shock alone was sufficientto interfere with the effects of this instru-mental contingency. This is consistent withthe fact that Mackintosh (1973) found littleor no effect of exposure to shock alone onthe acquisition of conditioned suppression ina CER paradigm. Exposure to shock may

LEARNED IRRELEVANCE AND LEARNED HELPLESSNESS 137

affect suppression produced by an instrumen-tal contingency without affecting suppressionproduced by a classical contingency.

In the present context this seems a rea-sonable suggestion since in Experiment 2animals were exposed to shock while contin-uing to lever press on a variable intervalschedule. Therefore, both the noise/shockand shock groups had the opportunity tolearn that lever pressing was uncorrelatedwith the delivery of shock. If learned irrele-vance is a consequence of learning that aparticular CS and US are uncorrelated, thenit is possible that at least one component oflearned helplessness (there may, of course,be more general components) is a conse-quence of learning that a particular responseand reinforcer are uncorrelated. Experiment3, therefore, was designed to discoverwhether the effect of preexposure to uncor-related noise and shock on the acquisitionof punishment suppression depended onwhether or not preexposure was conductedwhile animals continued to lever press.

EXPERIMENT 3This experiment was carried out to at-

tempt to demonstrate that rats preexposedto the uncorrelated procedure while respond-ing (Group On) and hence able to learn thatresponding and shocks are uncorrelatedwould suppress less in a signaled punishmenttest than rats also preexposed to the uncor-related procedure but without the oppor-tunity to respond (Group Off).Method

Subjects and apparatus. Twenty-four hooded maleLong-Evans rats, obtained and maintained in asimilar manner to Experiment I, were used. Theconditioning chambers and stimuli described forExperiment 1 were used. Shocks were .25 mA inintensity and lasted for .5 sec.

Procedure. The rats were shaped to lever pressand given 7 days of variable interval lever-presstraining in a similar manner to Experiment 1. Allsessions except the shaping sessions were 30 min.in duration.

The rats were divided into two equal groups forthe preexposure phase, which lasted 5 days. Duringthis phase, both groups of animals received theuncorrelated procedure described in Experiment 1.Group On was allowed to continue responding forfood, but for Group Off the lever was removed and

hence they could not respond. After the preexposurephase came a lever-press recovery day, duringwhich two nonreinforced noise trials occurred. Thefinal 5 days comprised the test phase, during whichboth groups received the punishment test describedfor Experiment 1 (i.e., three response-contingentshocks programmed to occur in each of two 3-min.noise trials per day).Results

Groups On and Off behaved similarly dur-ing shaping and variable interval training.On the last day of training both groups hadmean response rates of 28 responses/min.,t(22) = .024, p ^ .10. On the lever-pressrecovery day, Group On responded at 23responses/min., while Group Off respondedat 29 responses/min. These rates did notdiffer reliably, *(22) = 1.35, p ^ .10. Dur-ing the first pre-CS period of the test,Groups On and Off responded at 34 and 30responses/min. These rates did not differreliably, *(22) = .29, p ^ .10. Groups Onand Off had suppression ratios of .53 and .51to the noise on the lever-press recovery day.These ratios did not differ reliably, t(22) =.57, p >. .10.

The results of the test phase are shownin Figure 3. A split-plot analysis of variancewas carried out on the test suppression

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