Listen to others or yourself? The role of personal norms on the effectiveness of social norm interventions to change pro-environmental behavior

Social norm interventions are a cheap and convenient strategy to promote proenvironmental behavior change. However, the effectiveness of using them has been debated. The present study argues that the effectiveness depends on one's own internal moral compass, as presented by personal norms. We examined this main assumption across 3 studies focusing on pro-environmental behavior in a food and diets context. Study 1 shows in a cross-sectional design that people with stronger personal norms are more likely to reduce their meat consumption regardless of their perceptions of the static or dynamic social norms towards meat consumption. Furthermore, quasi-experimental findings show that dynamic (Study 2) and static (Study 3) social normative messages are more effective the weaker one's personal norms towards the pro-environmental behavior. Therefore, when evaluating the effectiveness of social norm interventions people's personal norms should be taken into consideration.