Bandura recorded the behaviour of young children who watched an adult behave in an aggressive way towards a Bobo Doll.
The adult hit the doll with a hammer and shouted abuse at it.
Sample: American Children, 36 boys, 36 girls aged 3-6.
Group 1:
12 girls and 12 boys shown a model hitting a doll with a hammer and shouting
Group 2:
12 girls and 12 boys showed non-aggressive actions towards the doll.
Group 3:
12 girls and 12 boys were not shown a model, just the doll (control)
Then the children were taken to a room with some attractive toys but told not to play (aggression arousal).
Then children are taken individually into a room containing a Bobo doll, non-aggressive toys like pencils, and aggressive toys like a hammer and pistol.