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Reinforcing “DisplacedAggression” and DominanceHierarchy in White RatsLoh Seng Tsai a b & George Ellis Dexter a ba Department of Psychology , California StateCollege , Fullerton, USAb U.S. War College and 8th Special Forces Group(Airborne), United States Army , USAPublished online: 06 Jul 2010.

To cite this article: Loh Seng Tsai & George Ellis Dexter (1970) Reinforcing “DisplacedAggression” and Dominance Hierarchy in White Rats, The Journal of GeneralPsychology, 83:1, 97-105, DOI: 10.1080/00221309.1970.9710790

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The Journal of General Psychology, 1970, 83, 97-105.

R E I N F O R C I N G “DISPLACED AGGRESSION” A N D D O M I N A N C E H I E R A R C H Y I N WHITE RATS*

De)artmeni of Psychology, California State College, Fullerton; and U.S. W a r College and 8th Special Forces Group (Airborne), United States Army

LOH SENC TSAI AND GEORGE ELLIS DEXTER

A. INTRODUCTION The frustration-aggression hypothesis postulated by Dollard, Doob, Miller,

Mower, and Sears (1) has stimulated much experimental work with both human and animal Ss concerning the nature and causes of aggression. In fur- therance of such an hypothesis, Miller (2) demonstrated the use. of reinforce- ment training as a technique for experimentally producing displaced aggres- sion. By placing two rats in a shocking device and turning on the current he induced fighting between the animals, which was reinforced by the termina- tion of the shock. Later the animals were placed singly in the shocking device with a doll. When shocked the animals attacked the doll. Miller related such stimulus-response generalization to the psychoanalytical concept of displaced aggression.

B. PROBLEM T h e general purpose of this investigation was to find out whether aggres-

sion can be developed or trained through reinforcement. Specifically, our ex- periments were designed to determine the effect, if any, of reinforcing “dis- placed aggression” upon dominance hierarchy in white rats.

If i t is postulated ( a ) that two rats placed together in a shocking device and subjected to mild electric shock will commence fighting, (b) that if the shock is terminated when the aggression begins, the aggression will be rein- forced, and (c) that an animal subjected to this reinforcement training will develop a higher overall aggression level than before; then the dominance hierarchy status of the animal so trained should be raised above the level ex- isting prior to the reinforcement training.

C. EXPERIMENT I The present investigation applied Miller’s “displaced aggression” technique

to an already established dominance hierarchy to determine what hierarchical

Received in the Editorial Office, Provincetown, Maaaachuaetta, on June 16, 1969. Copyright, 1970, by The Journal Press.

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changes would occur as a result of experimentally reinforced aggression. T h e Tsai Dominance-Submission Apparatus ( 4 ) was used to obtain an objective and quantitative measure of dominance and submission in terms of the num- ber of wins or losses in an equal number of bouts by both experimental and control animals.

1. Method

a. Subjects. Thirty-two experimentally naive, male albino rats, 120 days old a t the start of the experiment, were obtained from Albino Farms, Red- bank, New Jersey. Twenty-four of these rats, divided into six groups of four subjects each, were used for the determination of the hierarchy. T h e remain- ing eight rats were utilized as shocking dummies o r scapegoats in the aggres- sion training.

Ss were housed in individual nontransportable cages a t all times except during daily sessions in the experimental room. Here they remained in their transporting cages unless they were being trained or tested in the apparatus.

b. Experimental apparatus. T h e Dominance-Submission Apparatus con- sisted of two open-topped end-boxes, either of which could be used as a start- ing point or the goal. They were each 12 inches long by 7 inches wide by 8 inches deep, connected by an enclosed alley or tunnel 35% inches long with cross-section dimensions of two by two inches. A horizontal sliding gate at the center of the alley blocked passage when closed. One wall of the alley was constructed of Plexiglas for convenience of observation ; the remainder of the apparatus, of wood painted a uniform grey. A small dish for holding water was placed in each end-box.

T w o shocking devices were constructed, each with internal dimensions 11 % inches long by 11 inches wide by 10 inches deep. T w o sides of each box were of Plexiglas, the ends of wood, and the top of masonite. T h e floors con- sisted of a grid made of s-inch-diameter brass rods. A vertical sliding mason- ite partition divided the interior of each box in half. Removable interior lids were later provided which permitted reducing the height of the interior space to 4% inches. One box was connected to two 1%-v dry-cell batteries, a vari- able induction coil, and a switch. T h e second box, a dummy, was not con- nected to any electrical source.

T h e experimental room was separated from where the animals were housed. I n the room there was a window directly opposite the Plexiglas side of the alley. A ceiling fluorescent-light fixture was located directly over the perpen- dicular bisection of the alley. These light sources provided uniform illurnina- tion for each of the two end-boxes.

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LOH SENG TSAI AND GEORGE ELLIS DEXTER 99

c. Deprivation schedule. Hierarchy animals were placed on a 23-hour water deprivation schedule and permitted to drink for one hour after daily runs. Each animal was permitted to take Purina Laboratory Chow ad lib in his cage.

d . Conduct of experiment. Experiment I was conducted in four phases as follows: Phase I, Preliminary training; Phase 11, Establishment of hierar- chies; Phase 111, Reinforcement training of selected animals; and Phase IV, Testing of hierarchy changes.

T h e purpose of Phase I, which lasted 12 days, was to train the rats in the use of the Dominance-Submission Apparatus. Training was continued until each animal had learned that, regardless of which starting box he was placed in, he must proceed into the alley, wait five seconds at the gate, and when the gate was opened, proceed to the goal box at the other end in order to receive a drink. If he should back up and return to his starting box, he would receive no drink. After the first eight days of preliminary training, each animal was able to make six successful runs a day, with the starting box alternated in a random fashion.

T h e purpose of Phase I1 was to establish a dominance hierarchy within each group of rats. E took two rats at a time from a single group, one in each hand, and introduced them simultaneously into the opposite end-boxes. When both animals had reached the middle of the alley, the gate was opened. T h e alley was too narrow for the passage of more than one rat, and it was neces- sary for one rat to push the other all the way back to his starting box in or- der to gain entrance to the goal. When one animal had been pushed out of the alley, E lifted that animal out of the way and with an eye-dropper placed water in the dish in that box for the winning animal. T h e losing animal was then permitted a free run through the alley to the opposite goal box and given water in like amount.

Each animal competed against each of the other animals in his group twice daily. One run from the right box and the other from the left box. T h e se- quence of bouts within groups was changed daily according to a random schedule. In order to ensure that each animal received a rest between bouts, trials were alternated between two groups of rats which were present in the room concurrently.

Phase I1 lasted for a period of 10 days, the first five of which served as an orientation period. Relative dominance within groups was determined on the basis of total victories won by each animal during the last five days only.

T h e purpose of Phase I11 was to train aggression through reinforcement of the rats which stood at the number two and number four positions in the

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dominance hierarchies of Groups A and D. Each of these rats was placed i n one compartment of the live shocking device together with one of the scape- goat rats. A shock was administered and terminated when the hierarchy rat attacked the scapegoat. Four such shocks were administered each morning for 10 days, concurrently with the conduct of Phase IV in the afternoons of thr same days. For the first five days of this training the two animals had use of the entire space within their compartment of the shocking device. For the last five days the inner lid of the compartment was closed, restricting the animals to a space only 4 5 inches high, more closely resembling the restricted area of the dominance-submission apparatus.

There was a possibility that an overly aggressive scapegoat might producc anxiety rather than aggression in the hierarchy rat. T h e work of Tedeschi et ol. ( 3 ) with tranquilized mice suggested a means of avoiding this danger, and pilot studies were conducted concurrently with Phase I1 to determine for each of the scapegoats the correct tranquilizing dosage to ensure that thr scapegoat would jump, but not attack, when shocked. T w o difficulties were encountered in these studies. First, the aggressive behavior of each animal, even under the influence of the tranquilizer, appeared to depend in some de- gree upon the aggression displayed by his partner in the shocking device. Sec- ondly, the intraperitoneal dosage of three mg/kg of chlorpromazine initially established had to be raised in most cases to four or five mg/kg during thr conduct of Phase 111, because the tranquilized animal displayed too high a level of aggression when shocked. T o avoid possible cumulative effect of thc drug, two scapegoats were designed for each of the hierarchy animals receiving training, and the two were alternated daily in the shocking schedule.

For the sake of control, two extra groups were instituted and were tested alongside the experimental group. One of these, the solitary shock-control group, consisted of the number two and number four rats in the hierarchirs of Groups B and E. These rats received the same shocking schedule as thr rats of Groups A and D, but under solitary conditions. While a rat of Groups A or D and a scapegoat rat occupied one compartment of the live shocking device, a rat of the solitary shock-control group occupied the other compart- ment of the same device. These solitary rats thus received the same shocks as the rats receiving reinforcement training, but without the presence of any scapegoat on which to vent aggression. T h e other control group, the nonshock- control group, consisted of number two and number four rats in the hierar- chies of Groups C and F.

T h e purpose of Phase IV was to determine what changes of the original hierarchies occurred as a result of the reinforcing training conducted in Phase

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LOH SENG TSAI AND GEORGE ELLIS DEXTER 101

111. T h e procedure was identical with the establishment of initial hierarchies in Phase 11. Testing was conducted during the afternoons for a period of 10 consecutive days, concurrently with the conduct of Phase I11 in the forenoons.

2. Results and Discussion

T h e results of Experiment 1 are presented in Table 1. O u r data apparently did not support the hypothesis. Of the rats receiving the reinforcement train- ing, two changed to a lower hierarchy status, one to a higher status, and one remained at his previous level. Of the solitary shock-control group, one went up, one went down, and two remained at their previous level. Of the non- shockcontrol group, two went up, one went down, and one remained at his previous level. None of the changes, however, was statistically significant. Neither were they in the predicted direction. T h e data do, however, indicate some trend, even though not of a significant degree, of a relatively down- ward hierarchical shift among rats receiving reinforcement training, which is directly contrary to the hypothesis. Prior to rejecting the hypothesis the question might be asked: were there any technical difficulties in Phase I11 which possibly might have served to inhibit rather than to train aggres- sion in the experimental animals? First, i t was observed that the aggressive behavior of the experimental animal during shock appeared to be largely dependent on the behavior of the scapegoat. Since the scapegoat, in his tran- quilized state, merely jumped and squealed, the experimental animal f re- quently followed suit. Secondly, some of the scapegoats were larger than the experimental animals because they were not on a water deprivation schedule. In two cases, even under the influence of chlorpromazine, they were still able to counterattack their opponents. It appeared that the use of the tran- quilizer had backfired? Where i t had been effective in reducing the aggression of the scapegoat, the experimental animal frequently was not induced to fight. Where i t had been ineffective, the experimental animal was exposed to coun- terattack. Therefore, the question remains open as to whether what the hier- archy animals received was actually training in aggression.

Age of the animals may be another factor involved. Young rats might be growing at differential rates and thus the constancy of their hierarchies might be affected between Phase I1 and Phase IV. It has been demonstrated by Tsai (4), as well as by Tsai and Napier ( 5 ) , that fully grown adult rats main- tained a very high degree of stability in their relative status within the dom- inance hierarchy.

All the benefits of hindsight from Experiment I were fully utilized to en- sure better control in Experiment 11.

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TABLE 1 RESULTS OF EXPERIMENT I

Phase I1 Phase IV Days 6-10 Days 1-10

Hier- Hier- Proportion archy Proportion archy Hierarchy

'Treatment Rat'sname of wins status of wins status change

Reinforcement Allen .53 A 2 .13 -4 4 Down 2

Danny .70 D 2 .47 D3 Down 1 Dick .03 DQ .oo D4 None

Solitary Bill .67 B2 .38 D3 Down 1 shock Bob .03 B4 .18 B4 None

Elvis .73 E2 .68 E2 None

training Andy .17 A 4 .72 A2 UP 2

Emmit .13 E4 .33 E3 UP 1

Cory .23 C4 .85 c1 UP 3 Frank .63 F2 .93 F1 UP 1

Nonshock Clem .43 c2 .05 C4 Down 2

Filbert .17 F4 .10 F4 None

D. EXPERIMENT I1 1. Method

SS were 12 male albino rats received from the same source a t the same timc as the animals used in Experiment I. However, these animals were 17 days older, and were 137 days old when they started the preliminary training. They were divided into three groups, G, H, and I , of four animals each. Apparatus and deprivation schedule were identical with those of Experiment I.

Phases I, 11, and IV were identical with those of Experiment I except for the following minor variation: During Phases I1 and IV, all 12 transporting cages were brought into the experimental room, and their locations were ro- tated daily. Individual trials were rotated among the 'three groups to allow each animal adequate rest between trials.

T w o major changes were introduced in the conduct of Phase 111. T h e first concerned the scapegoats and was aimed a t avoiding the difficulties previously experienced with the tranquilized animals. W e decided to use as scapegoats animals which were ( u ) not tranquilized, ( b ) smaller than the hierarchy rats with which they were paired, and ( c ) sufficiently aggressive to induce fighting behavior in the experimental animals. Immediately following the completion of Experiment I, pilot studies were made utilizing animals from Experiment I in order to select two scapegoats which met the criteria. These rats werc also placed on the same water deprivation schedule as the other animals to preclude their gaining too much weight and exceeding the size of their oppo- nents.

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LOH SENG TSAI A N D GEORGE ELLIS DEXTER 1 03

The second change concerned the animals in the nonshock-control group and was aimed at preventing number 2 and number 4 rats from receiving ad- ditional handling over number 1 and number 3 animals in their groups. In this experiment all the animals of the nonshock group were placed two at a time in one of the two compartments of the dummy box, concurrently with the shocking of animals of the other two groups in the live shocking device.

2. Results and Discussion

T h e results of Experiment I1 are presented in Table 2. Here again the ex- perimental data failed to support the hypothesis. Only one hierarchy c h a n p occurred during Phase IV, and this change involved an exchange of position between two rats of the nonshock-control group whose scores differed by only one victory during Days 6 through 10 of Phase 11.

TABLE 2 RESULTS OF EXPERIMENT I

Phase I1 Phase IV Days 6-10 Days 1-10

Hier- Hier- Proportion archy Proportion archy Hierarchy

Treatment Rat’sname of wins status of wins status change ~~

Reinforcement Glen training Gary

Solitary Hubert shock Henry

Nonshock Greg George Horace Hal Issac Ian Ira Ivan

.60

.07

.so .oo .83 S O .83 ~. ~

.37

.93

.53 S O .03

~ ~~

G2 G4 H2 H4 G1 G3 H1 H3 I1 I2 I3 I4

.73

.02

.65 .oo .93 .32

1.00 .3 5

1.00 .4 0 .60 .oo

G2 G4 H2 H4 G1 G3 H1 H3 I1 I3 I2 14

None None None None None None None None None Down 1 UP 1 None

By substituting a small untranquilized animal in Experiment 2 for the tranquilized scapegoat of Experiment I, we accomplished the desired purpose of instigating more fighting behavior on the part of the animal receiving rein- forcement training. Fighting occurred almost instantaneously in the majority of cases as soon as shock was administered, and the fights appeared to be more aggressive than in Experiment I. On most occasions, though not always, the experimental animal appeared to be worsting the scapegoat. Yet in spite of 10 days of such training in aggression invariably followed by reinforcement, there was no change in the hierarchy status of the experimental animals. T h e results

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of Experiment 11, obtained under carefully controlled conditions, showed that 40 spaced trials of training in reinforced aggression by attacking scapegoats in a shocking device did not raise the aggression level of rats so trained, as de- termined objectively by their relative status in the dominance hierarchy.

These results raise some basic questions concerning Miller’s concept and technique of “reinforcing displaced aggression” (2). Miller believed he dem- onstrated a relationship between psychoanalytical displacement and stimulus- response generalization. H e spoke of generalization in Pavlovian paradigm wherein a CR is established to a CS, and then a generalization gradient is obtained by varying the stimulus dimension. In his experiment the CS was the other rat, and in its absence generalization was made to a somewhat different stimulus, the doll. Now if the other rat in the shocking device is considered to be the CS, then after conditioning the CR of fighting should have occurred eventually without the US of shock. Merely placing the two animals together in the defunct shocking device should have induced a fight. This, however, never occurred in the present investigation. Instead, after the first one or two experiences in the shocking device the animals tried desperately to escape. Then when they found escape impossible, they merely cringed and stared through the Plexiglas, paying no attention whatsoever to each other. Between shocks they frequently remained squared off in a sparring stance, ready to re- sume fighting as soon as the shock reoccurred ; but never once did the animals fight before the first daily shock. Thus it appears that the US, shock, was the only effective stimulus to produce a fight and that fighting became an instru- mental response to terminate the shock.

T h e failure of our present investigation to raise dominance hierarchy status by repeatedly reinforcing “displaced aggression” in experimental animals can now be understood. When our animals learned to put up a gesture against the scapegoat, they did not necessarily receive any positive training in aggression ; and when they were placed in the dominance-submission apparatus, they were not subjected to the unconditioned stimulus of shock. Hence the reinforcement training did not raise the aggression level as we expected from the hypothesis. I n the same manner, the so-called displaced aggression toward the doll by Miller’s rats may be just a gesture in order to terminate the shock. It can be interpreted as an instrumental CR of the escape-training type.

E. SUMMARY After dominance hierarchies were established in seven groups of four male

rats each, number 2- and number 4-ranking rats were each placed in a shock- ing device with either a tranquilized or a smaller rat. As soon as S attacked

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LOH SENG TSAI A N D GEORGE ELLIS DEXTER 105

the scapegoat, shock was turned off. Forty spaced trials of such reinforcement training failed to raise the aggressive level or hierarchy status as objectively determined in the Tsai dominance-submission apparatus. Rats in both solitary shock- and nonshock-control groups did not show any significant hierarchical changes either. Displaced aggression in Miller's rats and those in the present investigation was interpreted as an instrumental conditioned response of the escape-training type to terminate the shock.

REFERENCES 1. DOLLARD, J . , DOOB, L. W., MILLER, N. E., MOWER, 0. H., & SEARS, R. R. Frustra-

tion and Aggression. New Haven, Conn.: Yale Univ. Press, 1939. 2. MILLER, N. E. Theory and experiment relating psychoanalytical displacement to

stimulus-response generalization. J . A h . eb SOC. Psyrhol., 1948, 43, 155-178. 3. TIWEBCHI, R. E., et al. Science N e w s Letter, 1958, April 26, 73, 263. 4. TSAI, L. S. Dominance hierarchy and time gradients in white rate with a new

5. TSAI, L. S., & NAPIER, H. S. Social conditioning in the modification of dominance

Department of P s y c h o l o g y California State College, Fullerton 800 N o r t h State College Boulevard Fullerton, California 92631

technique. Amer. Psyrhol., 1953, 8, 498.

hierarchy in white rats. 1. SOC. Psychol., 1968, 76, 83-88.

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