The effect of deprivation level on extinctionfollowing acquisition under randomdeprivation conditions

ANDREW W. GREENE AND HOWARD R. POLLIO TH E UN1VERS1TY OF TENNESSE E

AbstraetSixteen albino rats learned to run a straight alley

after 10-1/2, 22-1/2, 34-1/2, and 46-1/2 hr. of fooddeprivation. The order of these deprivation periodsfor a given animal was randomized over successivetrials. After 12 acquisition trials, Ss were randomlyassigned to either a 10-1/2 or 46-1/2 extinction group.Results showed no significant effect of deprivationlevel on performance during acquisition but did showthat animals extinguished under 46-1/2 hr. tooksignificantly more trials to extinction and tended torun faster during this period. The results were inter­preted as supporting a non-specific drive effect fordeprivation level on extinction performance.Introduetlon

There are at least two ways in which to view theeffects of different levels of deprivation on performanceduring extinction: (1) in terms of the similarity ofdeprivation cues present in extinction to deprivationcues present during learning (Estes, 1958), and (2)in terms of a nonspecific energization effect broughtabout by different deprivation levels (Brown, 1961).Experiments dealing with this problem have madeextensive use of a factorial design in which two (ormore) groups of animals are trained under two (ormore) different levels of deprivation and are eithermaintained at the same level of deprivation or switchedto the other level of deprivation during extinction(see Kimble, 1961, pp. 411 ff). The use of this typeof design raises a number of methodological concerns,the most important of which are that in order to makevalid comparisons among animals during extinction,a ll animals must have been exposed to the samelength and conditions of training and that variationsin the level of deprivation during extinction mustrepresent no change in cue conditions from thosepresent during acquisition. The purpose of the presentstudy was to investigate the effects of different levelsof deprivation during acquisition and extinction onperformance during extinction through the use of aprocedure which was able to control both of thesemethodological problems .Method

Subjects . The Ss were 16 experimentally naive malealbino rats obtained from the Budd Mountain RodentFarm of New Jersey. The Ss were approximately3 months old at the beginning of the experiment.

Apparatus . The straight alley used in the presentexperiment was constructed of 1/8 in white Plexiglas.The alley was 55 in long, 4 in wide, and 5 in deep .

Psychon. sct . , 1965 , Vol. 3

The start box comprised the first 7 in of the alley,the runway the next 36 in, and the goal box the last11 in. A recessed food cup was located in the far endof the goal box. Both the start box and runway wereenclosed by clear plastic hinged tops while ventilationwas achieved by means of a removable wire meshtop over the goal box. A covering of black fabricminimized overhead cues. Running latency was measuredby two photoelectric relays (Lafayette, Model PC-45)opaced 2 ft apart in the exact center of the runwayitself. These relays were connected to a Hunter KlockKounter (Model 120 A, .001 sec.) ,

Procedure . The first stage of pretraining was de­signed to acquaint Ss with a random feeding scheduleand with eating in the goal box. Four Ss were randomlyassigned to each row of a 4 by 4 latin square con­taining 10-1/2, 22-1/2, 34-1/2, and 46-1/2 hr. de­privation periods. After each deprivation period Sswere brought to the experimental room and allowedto eat two 94 mg food pellets on each of five oppor­tunties approximately 2 min. apart. The Ss werethen returned to their individual home cages andallowed to eat for 1 additional hour. Purina Lab RatChow was fed in the home cage and water was alwaysavailable. Following the completion of four prelimi­nary deprivation periods Ss were randomly reassignedwithin a latin square for the second stage of pre­training. This second stage was conducted under thesame deprivation condition as the first with theexception that after each of the four periods Ss wereplaced in successively increasing blocked-off unitsof the runway. After the final deprivation period Sswere required to run 3/4 of the distance of the runwayproper. The result of this procedure was to eliminateany retracing behavior during acquisition. The entirepretraining schedule covered 10 days and also servedto stabilize Ss at approximately 80% initial body weight.

For the purpose of acquisition four Ss were randomlyassigned to each row of three, 4 by 4 latin squares.After each of the 12 deprivation periods, ss wereplaced in the start box and allowed to run five timesat 2 min. intervals. Running speed (l/latency) wasaveraged for each S over the five runs and this valuewas taken as the mean running speed for that trial.After each run the alley was cleaned with a 10%vinegar solution. The entire acquisition phase lasted14 days.

Immediately following acquisition two Ss from eachrow of the latin square were randomly assigned to

265

Fig. 1. Mean running speeds for acquisition and extinction.

Note: Valu es i n columns 2 and 3 denote number of tr ials toext i nc tion.

either a 10-1/2 or 46-1/2 hr. extinction group. Theprocedure used in this phase of the experiment wasthe same as that during acquisition except that nofood was placed in the goal box. The two extinctionmeasures recorded were the mean running speedfor the first five runs during extinction and the meannumber of runs prior to a criterion of three consecu­tive runs in which S failed to reach the food cup in30 sec. Latency was not recorded after the firstfive runs since the apparatus and training procedurewere not designed to prevent retracing' behavior.

Results and ConclusionsFigure 1 presents the acquisition and extinction

running speeds for the various groups of animalswith deprivation level serving as a parameter. Eachof the points on anyone of the acquisition functionsconfounds animals and deprivation levels . Each suc­cessive point represents one complete block of trialsfor four animals in each row of the latin square de­scribed earlier . In order to evaluate the effects ofLevel of Deprivation on running speed during acqutsi-

TABLE I

Number of Trials Required to Reach Extinction

Criteri on for Each Animal

tion, taking this confounding into effect, an analysisof variance was performed in which the unit ofanalysis employed was the value of all 16 animalsfor that deprivation level over that block of four trials.This analysis failed to reveal any significant effectof deprivation on acquisition (F(3,45) or any significantinteraction between level of deprivation and stage ofpractice (F(6,90) '"1.50) . As expected, stage of practiceLe., successive blocks of trials, did exert a significanteffect on running speed (F(2,30) = 203.00; P< .001).

For the extinction phase, each point represents themean running speed for all eight animals in each groupover the first five runs of extinction. An examinationof the data for each of the five runs failed to revealsystematic differences and consequently all five weretreated as a single trial. A t-test of the significanceof the difference between these means revealed atendency for animals extinguished under 46-1/2 hr.to run faster than animals extinguished under 10-1/2hr., although this difference was not unequivocal(t= 1.63; p = .13, two-tailed test).

A second measure of the difference between groupsextinguished under 10-1/2 and 46-1/2 hr. is presentedin Table 1 and concerns the number of trials taken tothe extinction criterion for animals under both ofthese conditions. As can be seen, there is no overlapin the distribution of scores between the two groupsindicating a significant effe ct of extinction deprivationlevel on the number of trials to extinction (Mann­Whitney, U'" 0; P < .001).

Although the running speed results fail to reachan acceptable level of statistical significance, thetrends reported are consistent with an energizationanalysis . The failure to attain a comfortable levelof significance is probably best attributable to thesmall number of animals entering into the statisticalevaluation of this effect.

In terms of the trials to criterion data, however,the present results strongly support a non-specificenergization explanation of the effects of deprivationlevel on performance during extinction. This occurredin the present experiment despite the fact that thelength, and conditions of acquisition were equivalentfor animals in both groups. These conditions precludean explanation of these data in terms of a cue changehypothesis , and strongly suggest that the level ofdeprivation present during extinction may be concep­tualized as providing a non-specific energization effecton behavior.

ReferencesBrown, J . S. Th e motivation of behavior . New Yor k : McGraW-Hill.

1961.Estes . W. K . Stimulus-r esponse theory of dri ve. In M. R. Jones

(Ed.) , Nebraska symposium on motivat ion . Lincoln : Univers ityof Nebr aska Pr ess, 1958.

Kimble , G.A. Hilgard and Morquis' condi t i oni ng and learni ng.New Yo rk: App le to n-Century Crofts, 1961.

11155

12318

14

AnimalNumber

ExtinctionI

• 10 1/2 hr.

.461.12 hr.

....3

• __...... 46 112 hr.

0 - --0 341/2 hr.

0 ········0 22 112 hr._10 V2hr.

2Blocks of 4 Trials

_----Acquisition--------'~

Le vel of Depr ivationAnimal During Extinct ionNumber

10);2 46);2

4 9 4310 15 4413 15 496 16 499 21 527 24 622 35 66

16 41 73

1.7

1.6

1.5

f 1.4

~ 1.:3

T 1.2

11.1engo 1.0

'2 .9~

.8

.7

.6

266 Psychon . Sci. , 1965, Vol. 3