Bandura's Bobo Doll Experiment Notes

Transmission of Aggression Through Imitation of Aggressive Models

Introduction

Previous research has shown that children imitate behavior exhibited by adult models, even in the model's presence (Bandura & Huston, 1961).
Studies by Blake (1958) and others have demonstrated that observing a model's responses influences subjects' reactions in social settings.
The study aims to investigate whether imitative response patterns generalize to new settings where the model is absent.
Children were exposed to aggressive and non-aggressive adult models and then tested for imitative learning in a new situation without the model.
It was hypothesized that subjects exposed to aggressive models would reproduce aggressive acts resembling those of their models, differing from those who observed nonaggressive models or had no prior exposure.
The hypothesis also assumed that subjects had learned imitative habits from prior reinforcement, which would generalize to adult experimenters (Miller & Bollard, 1941).
Observation of subdued nonaggressive models was predicted to have a generalized inhibiting effect on subjects' subsequent behavior.
Hypotheses were also advanced concerning the influence of the sex of the model and the sex of the subjects on imitation.
Pauls and Smith (1956) found that preschool children perceive their parents as having distinct preferences regarding sex-appropriate behavior.
Parents reward imitation of sex-appropriate behavior and discourage or punish sex-inappropriate imitative responses.
Tendencies to imitate male and female models acquire differential habit strength due to differing reinforcement histories.
Subjects are expected to imitate the behavior of a same-sex model to a greater degree than a model of the opposite sex.
Boys should be more predisposed than girls toward imitating aggression, as it is a highly masculine-typed behavior, especially when exposed to a male aggressive model.

Method

Subjects: 36 boys and 36 girls enrolled in the Stanford University Nursery School, ranging in age from 37 to 69 months (mean age of 52 months).
Models: A male and a female adult served as models.
Experimenter: One female experimenter conducted the study for all 72 children.
Experimental Design:
- Subjects were divided into eight experimental groups of six subjects each and a control group of 24 subjects.
- Half the experimental subjects were exposed to aggressive models, and half were exposed to nonaggressive models.
- These groups were further subdivided into male and female subjects.
- Half the subjects in the aggressive and nonaggressive conditions observed same-sex models, while the remaining subjects viewed models of the opposite sex.
- The control group had no prior exposure to the adult models and was tested only in the generalization situation.
Subject Matching:
- Subjects were matched individually based on ratings of their aggressive behavior in social interactions in the nursery school to increase the precision of treatment comparisons.
- The experimenter and a nursery school teacher rated the subjects on four five-point rating scales: physical aggression, verbal aggression, aggression toward inanimate objects, and aggressive inhibition.
- The aggression inhibition scale measured the subjects' tendency to inhibit aggressive reactions.
- Interrater agreement was assessed on 51 subjects, and the reliability of the composite aggression score was estimated using the Pearson product-moment correlation, which was $\r = .89$ .
- The composite score was obtained by summing the ratings on the four aggression scales; subjects were arranged in triplets based on these scores and assigned randomly to one of two treatment conditions or to the control group.

Experimental Conditions

Procedure:
- Subjects were brought individually to the experimental room by the experimenter.
- The model was invited to join in the game.
- The experimenter escorted the subject to their play area and demonstrated how to design pictures with potato prints and picture stickers.
- After settling the subject, the experimenter escorted the model to the opposite corner of the room, which contained a small table and chair, a tinker toy set, a mallet, and a 5-foot inflated Bobo doll.
- The experimenter explained that these materials were for the model to play with and then left the room.
Nonaggressive Condition:
- The model assembled the tinker toys quietly, ignoring the Bobo doll.
Aggressive Condition:
- The model began by assembling the tinker toys but, after approximately a minute, turned to the Bobo doll and aggressed toward it.
- The model laid Bobo on its side, sat on it, and punched it repeatedly in the nose.
- The model then raised the Bobo doll, picked up the mallet, and struck the doll on the head.
- Following the mallet aggression, the model tossed the doll up in the air aggressively and kicked it about the room.
- This sequence of physically aggressive acts was repeated approximately three times, interspersed with verbally aggressive responses such as, "Sock him in the nose…," "Hit him down…," "Throw him in the air…," "Kick him…," "Pow…," and two non-aggressive comments, "He keeps coming back for more" and "He sure is a tough fella."

Aggression Arousal

Subjects were tested for the amount of imitative learning in a different experimental room set off from the main nursery school building.
All subjects, experimental and control, were subjected to mild aggression arousal to ensure they were under some degree of instigation to aggression.
Arousal Experience:
- The experimenter brought the subject to an anteroom that contained attractive toys: a fire engine, a locomotive, a jet fighter plane, a cable car, a colorful spinning top, and a doll set complete with wardrobe, doll carriage, and baby crib.
- The experimenter explained that the toys were for the subject to play with but, after the subject became sufficiently involved (usually in about 2 minutes), the experimenter remarked that these were her best toys, that she did not let just anyone play with them, and that she had decided to reserve these toys for the other children.
- The subject could play with any of the toys that were in the next room.

Test for Delayed Imitation

The experimental room contained a variety of toys, including some that could be used in imitative or non-imitative aggression and others that elicited nonaggressive behavior.
Aggressive toys: a 3-foot Bobo doll, a mallet and peg board, two dart guns, and a tether ball with a face painted on it.
Nonaggressive toys: a tea set, crayons and coloring paper, a ball, two dolls, three bears, cars and trucks, and plastic farm animals.
The play material was arranged in a fixed order for each session to eliminate variation due to toy placement.
The subject spent 20 minutes in this experimental room, during which time their behavior was rated in terms of predetermined response categories by judges who observed the session through a one-way mirror.
The 20-minute session was divided into 5-second intervals, yielding 240 response units per subject.
The male model scored the experimental sessions for all 72 children, without knowledge of the subjects' group assignments (except when he served as the model).
The performances of half the subjects were also scored independently by a second observer to estimate interscorer agreement.
Responses scored involved highly specific concrete classes of behavior, yielding high interscorer reliabilities (product-moment coefficients in the .90s).

Response Measures

Three measures of imitation were obtained:
- Imitation of physical aggression: Acts of striking the Bobo doll with the mallet, sitting on the doll and punching it in the nose, kicking the doll, and tossing it in the air.
- Imitative verbal aggression: Subject repeats the phrases, "Sock him," "Hit him down," "Kick him," "Throw him in the air," or "Pow."
- Imitative nonaggressive verbal responses: Subject repeats, "He keeps coming back for more," or "He sure is a tough fella."
Partial Imitation:
- Mallet aggression: Subject strikes objects other than the Bobo doll aggressively with the mallet.
- Sits on Bobo doll: Subject lays the Bobo doll on its side and sits on it but does not aggress toward it.
Nonimitative Aggression:
- Punches Bobo doll: Subject strikes, slaps, or pushes the doll aggressively.
- Nonimitative physical and verbal aggression: Physically aggressive acts directed toward objects other than the Bobo doll and any hostile remarks except for those in the verbal imitation category.
- Aggressive gun play: Subject shoots darts or aims the guns and fires imaginary shots at objects in the room.
Ratings were also made of the number of behavior units in which subjects played nonaggressively or sat quietly and did not play with any of the material.

Results

Complete Imitation of Models' Behavior

Subjects in the aggression condition reproduced physical and verbal aggressive behavior resembling that of the models, with mean scores differing markedly from those of subjects in the nonaggressive and control groups.
The Friedman two-way analysis of variance by ranks was used to test the significance of the obtained differences due to the non-normality of data in the control and non-aggressive groups.
Exposure to aggressive models increases the probability of aggressive behavior.
The main effect of treatment conditions is highly significant for both physical and verbal imitative aggression.
Comparison of pairs of scores by the sign test shows that the obtained over-all differences were due almost entirely to the aggression displayed by subjects exposed to the aggressive models.
Subjects exposed to aggressive models also repeated the model's nonaggressive verbal responses, while none of the subjects in either the nonaggressive or control groups made such remarks.

Partial Imitation of Models' Behavior

Treatment conditions are a statistically significant source of variation in the subjects' use of the mallet aggressively toward objects other than the Bobo doll.
Both the aggressive and the control groups, relative to subjects in the nonaggressive condition, produced significantly more mallet aggression.
Subjects in the aggressive group reproduced the models' behavior of sitting on the Bobo doll to a greater extent than did the nonaggressive or the control subjects.

Nonimitative Aggression

Treatment conditions did not influence the extent to which subjects engaged in aggressive gun play or punched the Bobo doll.
The effect of conditions is highly significant in the subjects' expression of nonimitative physical and verbal aggression, with subjects exposed to the aggressive models displaying a greater amount of aggression.

Influence of Sex of Model and Sex of Subjects on Imitation

Boys reproduced more imitative physical aggression than girls.
Male subjects exhibited more physical and verbal imitative aggression, more non-imitative aggression, and engaged in significantly more aggressive gun play following exposure to the aggressive male model than the female subjects.
Girls exposed to the female model performed considerably more imitative verbal aggression and more non-imitative aggression than did the boys.
Subjects exposed to the nonaggressive male model performed significantly less imitative physical aggression, less imitative verbal aggression, less mallet aggression, less non-imitative physical and verbal aggression, and they were less inclined to punch the Bobo doll, compared to the control group.

Nonaggressive Behavior

Female subjects spent more time than boys playing with dolls, with the tea set, and coloring.
The boys devoted significantly more time than the girls to exploratory play with the guns.
Subjects in the nonaggressive condition engaged in significantly more nonaggressive play with dolls than subjects in the aggressive or control groups.
Subjects who observed nonaggressive models spent more than twice as much time as subjects in the aggressive condition in simply sitting quietly without handling any of the play material.

Discussion

Observation of others' behavior is an effective means of eliciting certain forms of responses for which the original probability is very low or zero.
Social imitation may hasten or short-cut the acquisition of new behaviors without reinforcing successive approximations.
Observation of adult models displaying aggression communicates permissiveness for aggressive behavior, which may weaken inhibitory responses and increase the probability of aggressive reactions to subsequent frustrations.
Subjects expressed their aggression in ways that resembled the novel patterns exhibited by the models, providing evidence for learning by imitation.
Subjects learned to combine fractional responses into relatively complex novel patterns solely by observing the performance of social models without any opportunity to perform the models' behavior in the exposure setting and without any reinforcers delivered either to the models or to the observers.
Rewards and punishments are self-administered in conjunction with the covert responses.
The male model influenced the subjects' behavior outside the exposure setting to a greater extent than the female model.
In the case of a highly masculine-typed behavior such as physical aggression, there is a tendency for both male and female subjects to imitate the male model to a greater degree than the female model.
In the case of verbal aggression, which is less clearly sex-linked, the greatest amount of imitation occurs in relation to the same-sex model.
Mere observation of aggression, regardless of the quality of the model-subject relationship, is a sufficient condition for producing imitative aggression in children.
Subjects exposed to the quiet models were more inhibited and unresponsive than subjects in the aggressive condition, suggesting that exposure to inhibited models decreases the probability of occurrence of aggressive behavior and generally restricts the range of behavior emitted by the subjects.

Summary

Subjects exposed to aggressive models reproduced aggression resembling that of the models and differed markedly from subjects in the nonaggressive and control groups.
Subjects in the aggressive condition also exhibited more partially imitative and nonimitative aggressive behavior and were generally less inhibited.
Imitation was differentially influenced by the sex of the model, with boys showing more aggression than girls following exposure to the male model.
Subjects who observed the nonaggressive models, especially the subdued male model, were generally less aggressive than their controls.