The Emergence of Revenge Social Norms

Social norms of revenge can be found across the world and these impose serious costs on the people following them and others in those societies. Here we study: how do norms of revenge emerge and stabilise given the severe costs that they impose? The cultures of honour literature proposes that revenge is rational, in order to create a fearsome reputation and deter potential attacks, when state protection is weak, communities are stable to allow reputation transmission, and personal resources are valuable. While this explains the emergence of revenge, it does not explain how revenge becomes a social norm. We argue that a key missing component is intra-group interdependence. Individuals under the sway of revenge norms are embedded with groups (e.g. family, tribe) that outsiders perceive as sharing a reputation, and, that members of which care about. By creating this interdependence, individually failing to take revenge impose negative externalities on other group members promoting the change from individual behaviour to social norms. From these propositions, we derive a series of hypotheses and systematically test them with six treatments in a large-scale behavioural experiment (n=1090). Consistent with the cultures of honour literature, we find that reputation and high resource value promote the emergence of revenge behaviours. Yet, these factors lead to small increases in normativity. Instead, group reputations generate stronger social norms of revenge if groups are able to cooperate and create intimidating shared reputations. This demonstrates the key role of socio-economic factors in the emergence of revenge behaviours and the importance of group interdependence in turning them into social norms.