The development of aggressive modes of response by children of aggressively punitive adults, however, may simply reflect object displacement without involving any such mechanism of defensive identification. In studies of child training antecedents of aggressively antisocial adolescents (Bandura & Walters, 1959) and of young hyperaggressive boys (Bandura, 1960), the parents were found to be nonpermissive and punitive of aggression directed toward themselves. On the other hand, they actively encouraged and reinforced their sons aggression toward persons outside the home. This pattern of differential reinforcement of aggressive behavior served to inhibit the boys' aggression toward the original instigators and fostered the displacement of aggression toward objects and situations eliciting much weaker inhibitory responses.

generally restricts the range of behavior emitted by the subjects.

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 procedure employed by Miller and Dollard (1941)

Thus subjects given an opportunity to observe aggressive models later reproduced a good deal of physical and verbal aggression (as well as nonaggressive responses) substantially identical with that of the model. In contrast, subjects who were exposed to nonaggressive models and those who had no previous exposure to any models only rarely performed such responses.

Much current research on social learning is focused on the shaping of new behavior through rewarding and punishing consequences

Analyses of variance of the remaining aggression measures (Table 2) show that treatment conditions did not influence the extent to which subjects engaged in aggressive gun play or punched the Bobo doll.

Imitation of physical aggression: This category included 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."

The subject spent 20 minutes in this experiments room during which time his behavior was rated in terms of predetermined response categories by judges who observed the session though a one-way mirror in an adjoining observation room. The 20 minute session was divided into 5-second intervals by means of at electric interval timer, thus yielding a total number of 240 response units for each subject.

The experimental room contained a variety of toys including some that could be used in imitative or nonimitative aggression, and others that tended to elicit predominantly nonaggressive forms of behavior. The aggressive toys included a 3-foot Bobo doll, a mallet and peg board, two dart guns, and a tether ball with a face painted on it which hung from the ceiling. The nonaggressive toys, on the other hand, included a tea set, crayons and coloring paper, a ball, two dolls, three bears, cars and trucks, and plastic farm animals.

It was necessary for the experimenter to remain in the room during the experimental session; otherwise a number of the children would either refuse to remain alone or would leave before the termination of the session

the experimenter remarked that these were her very 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. However, the subject could play with any of the toys that were in the next room.

At the end of 10 minutes,

Fifty-one subjects were rated independently by both judges so as to permit an assessment of interrater agreement.

the subject could design pictures with potato prints and picture stickers provided

The subjects were rated on four five-point rating scales by the experimenter and a nursery school teacher, both of whom were well acquainted with the children

Subjects were divided into eight experimental groups of six subjects each and a control group consisting of 24 subjects

The implications of the findings

Moreover, the findings from an earlier study

The subjects were 36 boys and 36 girls enrolled in the Stanford University Nursery' School. They ranged in age from 37 to 69 months, with a mean age of 52 months.

According the prediction, subjects exposed to aggressive models would reproduce aggressive acts resembling those of their models and would differ in this respect both from subjects who served nonaggressive models and from those ho had no prior exposure to any models

The prediction that exposure of subjects to aggressive models increases the probability [p. 578] of aggressive behavior is clearly confirmed

Subjects in the aggression condition reproduced a good deal of physical and verbal aggressive behavior resembling that of the models, and their mean scores differed markedly from those of subjects in the nonaggressive and control groups who exhibited virtually no imitative aggression

Two adults, a male and a female, served in the role of model, and one female experimenter conducted the study for all 72 children.

Imitative learning can be clearly demonstrated if a model performs sufficiently novel patterns of responses which are unlikely to occur independently of the observation of the behavior of a model and if a subject reproduces these behaviors in substantially identical form. For this reason, in addition to punching the Bobo doll, a response that is likely to be performed be children independently of a demonstration, the model exhibited distinctive aggressive acts which were to be scored as imitative responses. The model laid the Bobo doll on its side, sat on it and punched it repeatedly in the nose. The model then raised the Bobo doll, pick 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."

subjects in the experimental and control groups were matched individually on the basis of ratings of their aggressive behavior in social interactions in the nursery school.

Since aggression, however, is a highly masculine-typed behavior, boys should be more predisposed than girls toward imitating aggression, the difference being most marked for subjects exposed to the male aggressive model.

a more crucial test of imitative learning involves the generalization of imitative response patterns new settings in which the model is absent.

the influence of the sex of model and sex of subjects on imitation.

It was further predicted that observation of subdued nonaggressive models would have generalized inhibiting effect on the subjects' subsequent behavior,

This hypothesis assumed that subjects had learned imitative habits as a result of prior reinforcement, and these tendencies would generalize to some extent to adult experimenters

Albert Bandura

children readily imitated behavior exhibited by an adult model in the presence of the model