Social norms and climate-friendly behavior of adolescents

younger students. At the same time, we observed that (younger) students did not increase donations after learning that others donated large amounts. This selective effect of social norms in one direction only might be related to the fact that climate-friendly behavior (i.e., donations to the CO2 offsetting scheme) was already relatively widespread at baseline; thus, the ability of social norms to induce socially desirable behavior may have been limited. Future research might aim to assess the effect of social norm interventions among adolescents for climate- friendly behaviors that are less common in the target group, such as consciously reducing meat consumption or data consumption on the internet. Findings from research on adults’ pro-envi- ronmental behavior [29, 45, 46] suggest that making the behavior of others salient under these circumstances can induce behavioral change toward the socially desirable behavior. Further research is also warranted to better understand the change across age groups that we observed in our experimental data. We believe that the use of controlled experiments can help in this quest of gaining a deeper understanding of how social norms affect behavior over the course of adolescence and thus for the design of effective educational interventions [66]. In particular, we highly encourage future research to study a) whether reference groups for social norms change with age and b) whether the formation of personal normative beliefs dampens the influence of social norms on adolescent behavior with increasing age.

Though, we deem further research essential to provide a robust scientific foundation to develop recommendations for practitioners (in education, communication or public policy), we can outline some preliminary implications of our findings for practice. First, the overall effectiveness of social norm interventions seems limited among adolescents for (climate- friendly) behaviors that are already widespread. As suggested above, social norm intervention may bear greater potential for less common behaviors. Second, education programs and com- munication campaigns aimed at influencing youth behavior often target adolescents as a generic group. Our findings, however, underscore the importance of taking into account the fine-grained developmental stages during adolescence. Thus, inter- and transdisciplinary col- laborations between behavioral and educational sciences and public policy are called for to understand adolescents’ perceptions and behavior, and to subsequently co-develop appropri- ate and effective interventions. Supporting information S1 File. (PDF) Acknowledgments We would like to thank Jacqueline Dupont for excellent assistance in the practical implemen- tation and organization of the survey, Maria Angelica Lopez Ardila for her valuable research support. A special thanks goes to a great team of research assistants, the participating students, their teachers and the two school principals without we could have not realized this study. The publication of this article was funded by the Open Access Fund of Leibniz Universita¨t. Author Contributions

Conceptualization: Ann-Kathrin Koessler, Tobias Vorlaufer, Florian Fiebelkorn. Data curation: Tobias Vorlaufer. Formal analysis: Tobias Vorlaufer. Investigation: Ann-Kathrin Koessler, Tobias Vorlaufer, Florian Fiebelkorn. PLOS ONE Social norms and climate-friendly behavior of adolescents PLOS ONE | https://doi.org/10.1371/journal.pone.0266847 April 27, 2022 13 / 16