The Role of Social Familiarity in the Transmission of Aggression

“Violence begets violence” is a long-standing notion, reflecting the premise that aggression can propagate after witnessing others' hostile behavior. From an evolutionary perspective, aggression can be useful in certain contexts, such as defending territory or resources, but harmful when expressed indiscriminately. Because aggressive acts carry significant social and physical costs, it is important to understand the conditions under which aggression is learned and spreads. Observational learning provides a fast and efficient, yet potentially dangerous, mechanism through which aggressive behavior can be transmitted. Classic work by Bandura et al. (1961) provided early empirical support for the idea that aggression can be learned through observation. In the famous Bobo doll experiment, children who observed adults behaving aggressively toward an inflatable doll were more likely to imitate those actions. Research shows that animals also can learn aggression through observation. For instance, Suzuki and Lucas (2010) demonstrated that rats chronically exposed to conspecific aggression became more aggressive themselves, despite never directly engaging in fights. However, the social circumstances under which observational learning of aggression occurs remain poorly understood. In Bandura's study, learning was influenced by social characteristics of the model: girls displayed more physical aggression after observing a male model, but more verbal aggression after observing a female model, suggesting that features of the model's identity matter. Social familiarity is another factor that might influence observational learning of aggression, yet its role has received little attention. Suzuki and Lucas did not examine whether the observer rat's relationship to the aggressor influenced learning, but other evidence suggests that familiarity may be important. For example, rodents acquire fear responses more readily when observing cagemates than strangers (Jones et al. , 2018). Despite this, whether familiarity similarly constrains the observational learning of aggression remains largely unexplored. If familiarity of the aggressor does influence the observer's learning, identifying the … Correspondence should be addressed to Jessie Y. S. Choy at jessie. choy. 25atucl. ac. uk.