A Bobo doll is a toy used famously in an aggression experiment by Albert Bandura. Bandura developed social learning theory which proposes that behaviors are learned socially by observing and imitating others. In the bobo doll study Bandura wanted to see if observation of aggressive behaviors would lead to imitation of the aggressive behaviors by children.
Children were placed in one of three groups - an observing aggression role model, an observing non-aggression role model, and a control group with no role model.
In the aggression group children would observe adults acting aggressively towards the bobo doll (an inflatable clown) by punching it, hitting it with a hammer, throwing it, and shouting at it.
The non-aggression role models ignored the bobo doll and played with other toys in the room. Afterwards the children were placed in a room with a bobo doll and other toys and observed for 20 minutes.
The results showed that children in the aggression group were much more likely to engage in aggressive behaviors towards the bobo doll in comparison to the non-aggression and control groups. This supports social learning theory in that the children observed the behaviors of the role models and imitated them.