One group of children observed an adult being aggressive to the bobo doll, another group observed an adult playing non-aggressively with toys while the bobo doll was in the room.
The children were then placed in rooms with aggressive toys like hammers, mallets and a bobo doll and also some non-aggressive toys like a truck and some crayons.
Kids in the non-aggressive group were less aggressive than those in the aggressive group. Also kids who observed the aggressive behaviour acted aggressively towards the toys.