Albert Bandura (1961) conducted an experiment with children using Bobo dolls in which children observed adults model violent behavior at the dolls. Subsequently, those children who saw adults being reinforced for the violent behavior exhibited similar violent behavior, and children not exposed to the model of violence did not exhibit said behavior. His findings suggested that humans, in addition to learning through trial and error (classical and operant conditioning) also learn through observational learning. These findings led to Social Cognitive Theory. Within this theory, Bandura proposed that three determinants (personal, behavioral, and environmental) influence the likelihood for an observed behavior to be reproduced, and four components of observational learning: attention, retention, production, and motivational process.
Bandura, A., Social foundations of thought and action : a social cognitive theory. 1986, Englewood Cliffs, N.J.: Prentice-Hall.