The experiment involved exposing the children to two different adult role models; an aggressive model and a non-aggressive one. After witnessing the adult's behavior, the children would be placed in a room without the model and observed to see if they would mimic the behaviors they had previously witnessed.
Bandura made several key predictions about what would happen during the Bobo doll experiment.
Boys would behave more aggressively than girls.
Children who observed an adult acting aggressively would likely act aggressively even when the adult model was not present.
Children are more likely to imitate models of the same sex than models of the opposite sex.
The children who observed the non-aggressive adult model would be less aggressive than the children who observed the aggressive model; the non-aggressive exposure group would also be less aggressive than the control group.
The participants in the experiment were 36 boys and 36 girls enrolled in the Stanford University Nursery School. The children ranged from 3 to almost 6 years old, and the average age of the participants was 4 years and 4 months.
There were a total of eight experimental groups. Of these participants, 24 were assigned to a control group that would not be exposed to adult models. The rest of the children were then divided into two groups of 24 participants each. One of the experimental groups would be exposed to aggressive models, while the other
24 children would be exposed to non-aggressive models.
These groups were again divided into groups of boys and girls. Each of these subgroups was then divided so that half of the participants were exposed to an adult role model of the same sex and the other half were exposed to an adult role model of the opposite sex.
Before conducting the experiment, Bandura also assessed the children's existing levels of aggression. The groups were then equally matched so that they had average levels of aggression.
Each child was assessed individually to ensure behavior was not influenced by other children. The boy was first taken to a playroom where there were a number of different activities to explore. The experimenter then invited an adult model into the playroom and encouraged the model to sit at a table across the room that had similar activities.
Over a period of ten minutes, the adult models began to play with sets of small toys. In the non-aggressive condition, the adult model simply played with the toys and ignored the Bobo doll throughout the period. However, in the aggressive model condition, the adult models would violently attack the Bobo doll.
"The model turned Bobo on his side, sat on him and hit him repeatedly on the nose. The model then picked up the Bobo doll, took the mallet and hit the doll on the head. After the assault with the mallet, The model aggressively threw the doll into the air and kicked it across the room. This sequence of physically aggressive acts was repeated three times, interspersed with verbally aggressive responses."
In addition to physical aggression, the adult models also used verbally aggressive phrases such as "Kick it" and "Pow." The models also added two non-aggressive phrases: "He sure is a tough guy" and "Keep coming back for more."