Posters of Watching Eyes and Nature Promote and posters of Injunctive Norms Undermine Clean Environments

Abstract Fostering pro-environmental behavior is central to mitigate climate change. In the present paper four distinct interventions are tested which, based on different processes, should reduce littering: monetary information, depiction of the injunctive norm, watching eyes and a nature picture. To test these interventions, a randomized controlled trial (RCT) involving 440 community building’s waste disposal areas (N = 71,155) was conducted in Vienna. Littering was assessed before the intervention, 24 to 48 hours after and again seven weeks after the intervention. Results show that the financial intervention (monetary information) hardly had any effect on littering whereas the norm-based intervention (depicted injunctive norm) led to more littering compared to the control condition. In contrast, the reputation-based intervention (watching eyes) and ecological-based intervention (nature picture) reduced littering over time. Thus, modern interventions based on soft appeals to reputational and ecological motivations are more effective in fostering clean environments than classical interventions applying information on finances and norms.