Aggression can be defined in many different ways. Bandura suggests that it is the intent to cause harm to another human being who is motivated to avoid such treatment.
One of the main social psychological explanations of aggression comes from Bandura and Walters in 1963. He suggests that aggression is learned either indirectly; through observational learning and only replicated if vicarious reinforcement occurs, or directly- where aggressive behaviour is directly reinforced. While both are a form of operant conditioning, the direct approach parallels the ideas much closer. Bandura outlined the following three steps in the modelling process of SLT: Observation- by watching the behaviour of role models and then imitating that behaviour, mental representation- the child will only display the learned behaviour as long as the expectation of reward is greater than the expectation of punishment, and production of behaviour- if the child is rewarded (maintenance through direct experience) or by building the confidence from expectancies of like likely outcomes of their aggressive behaviour (self-efficacy).
In support of this theory, Bandura et al. proved that if children watch someone else behave aggressively towards a Bobo Doll, they were more likely to be aggressive themselves later on, specifically imitating individual actions they had previously seen. When the model was rewarded, the child was more likely to reproduce through vicarious reinforcement compared to those models punished, thus showing that observational learning only results in imitation when it is vicariously reinforced.
This study however, does not take into account of the nature vs. nurture debate. Although it seems that Bandura's research proves that behaviour is learnt (nurture), it must however be noted that there were many gender differences where the boys produced more physical aggression than girls, which consequently support the argument