In this study, Bandura set out to demonstrate that if children are passive witnesses to an aggressive display by an adult, they will imitate this aggressive behavior when given the opportunity. More specifically, the study made the following predictions:
Thirty-six boys and 36 girls aged between 37 and 69 months were tested. The mean age was 52 months. They used one male adult and one female adult to act as role models.
The study had three major conditions: a control group, a group exposed to an aggressive model, and a group exposed to a passive model. The children who were exposed to the adult models were further subdivided by their gender and by the gender of the model that they were exposed to. In other words, there were three independent variables. A summary of the groups is shown in the table below.
| 6 boys with same-sex model - aggressive condition | 6 boys with opposite-sex model - aggressive condition | 6 girls with same-sex model - aggressive condition | 6 girls with opposite-sex model - aggressive condition |
|---|---|---|---|
| 6 boys with same-sex model - non-aggressive condition | 6 boys with opposite sex model - non-aggressive condition | 6 girls with same-sex model - non-aggressive condition | 6 girls with opposite-sex model - non-aggressive condition |
This is quite a complicated design that appears to cover a lot of different possibilities. However, the number of children in each group is quite small, and the results could be distorted if one group contained a few children who are normally quite aggressive. the researchers tried to reduce this problem by pre-testing the children and assessing their aggressiveness. They observed the children in the nursery and judged their aggressive behavior on a 5-point rating scale. The rating scales assessed the child's level of physical aggression, verbal aggression, and aggression toward inanimate objects
A composite score for each child was obtained by adding the results of the ratings. It was then possible to match the children in each group so that they had similar levels of aggression in their everyday behavior. The observers were the experimenter (female), a nursery school teacher (female), and the model for male aggression. The study reports that the first two observers were “well acquainted with the children”.
A disadvantage of using rating scales in this way is that different observers see different things when they view the same event. This might mean that the ratings will vary from one observer to another. To check the inter-rater reliability of the observations, 51 of the children were rated by two observers working independently and their ratings were compared. The high correlation that was achieved (r = 0.89) showed these observations to be highly reliable, suggesting that the observers were in close agreement about the behavior of the children.
The children were tested individually. In stage one they were taken to the experimental room which was set out for play. One corner was arranged as the child’s play area, where there was a table and chair, potato prints, and stickers, which were all selected as having high interest for the children. The adult model was escorted to the opposite corner where there was a small table, chair, blocks, mallet, and Bobo (an inflatable doll). The experimenter then left the room.
In the non-aggressive condition, the model quietly played with the blocks, ignoring Bobo. In the aggressive condition, the model started to play with the blocks, but after one minute turned to Bobo and was aggressive to the doll in a scripted way. The aggression was both physical (for example, “raised the Bobo doll, picked up the mallet and struck the doll on the head”) and verbal (for example, “Pow!” and “Sock him in the nose!”) After 10 minutes the experimenter returned and took the child to another games room.
In stage two, the child was subjected to “mild aggression arousal.” The child was taken to a room with attractive toys, but after starting to play with them, the child was told that these were the experimenter’s very best toys and she had decided to reserve them for the other children.
Then the child was taken to the next room for stage three of the study. The experimenter stayed in the room “otherwise many children would either refuse to remain alone or would leave before termination of the session.” In this room, there was a variety of toys, both non-aggressive (three bears, crayons, and so forth) and aggressive toys (for example, a mallet, dart guns, and a three-foot Bobo). The child was kept in this room for 20 minutes and their behavior was observed by judges through a one-way mirror. Observations were made at five-second intervals giving 240 response units for each child.
The observers recorded three measures of imitation in which they looked for responses from the child that were similar to the display by the adult model:
In addition, they recorded three types of aggressive behavior that were not imitations of the adult model: punching Bobo, non-imitative physical and verbal aggression, and aggressive gunplay.
By looking at the results we can consider which children imitated the models, which models they imitated, and whether they showed a general increase in aggressive behavior rather than a specific imitation of the adult behaviors.