In 1961, at the Stanford University Nursery School, psychologist Albert Bandura tested whether children learn aggression simply by watching. Seventy two children aged roughly three to five and a half were split into groups that saw an adult attack an inflatable Bobo doll, saw an adult play quietly with Tinker toys, or saw no model at all. The aggressive adults punched the doll, sat on it, hit it with a wooden mallet, and shouted scripted lines like sock him and pow. Each child was then frustrated by being shown fine toys and told they were reserved for other children, and observed for 20 minutes through a one way mirror.

The children copied the exact blows and phrases, and those who saw the calm model were less aggressive than the control group. Boys recorded 270 aggressive acts to the girls’ 128. In 1963 Bandura showed 96 children a live model, a filmed model, or an adult in a cartoon cat costume, and all three raised aggression, undercutting the idea that violent media was cathartic. In 1965, 66 children saw the model rewarded, punished, or neither, and the punished group held back until offered treats to show what they had seen, revealing the line between learning and performing that became social learning theory.

• Why girls imitated verbal aggression more from a female model and physical aggression more from a male model
• The reward in the 1965 film: candy, soda, and praise as a strong champion
• A 1990 replication finding children familiar with Bobo dolls up to five times less likely to imitate
• Critiques about ecological validity, biology, and brain development in children under eight
• The ethics of frustrating young children without consent or debriefing