A Social Norms Intervention Going Wrong: Boomerang Effects from Descriptive Norms Information

A large body of research supports the idea of social norms communication promoting pro-social and pro-environmental behaviour. This paper investigates social norms communication in the field. Signs prompting consumers about sustainable seafood labels and informing them about other consumers’ sustainable choices were displayed in supermarkets in Norway and Germany. Seafood sales (sustainably labelled versus unlabelled products) were observed before, during, and after the implementation of the signs. The expected change towards more sustainable choices was generally not found. In Norway, the choice of sustainable seafood increased in the prompt-only condition, but the effect was neutralised when social norms information was added. In Germany, social norm messages lead to a decline in sustainable choices compared to baseline, a boomerang effect. Overall, an increase in the purchase of seafood (both sustainably labelled and unlabelled) was noted during the intervention. A second study was carried out to further explore the finding that consumers were mainly primed with “seafood” as a food group. In a laboratory setting, participants were confronted with stereotypical food pictures, combined with short sentences encouraging different consumption patterns. Subsequently, they were asked to choose food products in a virtual shop. Confirming the findings of Study 1, participants chose more of the groceries belonging to the food group they were primed with. These studies suggest that social norms interventions—recently often perceived as “the Holy Grail” for behaviour change—are not as universally applicable as suggested in the literature. According to this study, even descriptive norm messages can produce boomerang effects.