Dynamic norms for dynamic times? An experiment on the effects of dynamic and static norms messages on COVID-19 vaccination intention

Social norms messages may motivate COVID-19 preventive behaviors, such as getting vaccinated. To date, however, the research has mainly focused on the established concept of static norms and widely ignored the potential of dynamic norms. Dynamic norms convey information about how norms are developing over time and have been shown to promote change when the behavior is not yet the majority norm. The present study investigated the potential of dynamic norms in the context of the COVID-19 vaccination campaign. It examined (a) the effects of static and dynamic norms messages on vaccination intention, (b) the mechanisms through which dynamic norms may influence vaccination intention, and (c) the potential of dynamic norms to increase vaccination intention of vaccine-hesitant people. We conducted a preregistered online experiment with three conditions (static norm, dynamic norm, control message) among people who were not yet vaccinated (N = 2,289, 16-60 years) in May 2021, during the early vaccine roll-out period for the general population in Switzerland. We found no effects of exposure to the static or dynamic norms messages on vaccination intention and no specific influence mechanisms of dynamic norms (e.g., via perceived future norm) - neither for participants who were willing to get vaccinated nor for the vaccine-hesitant group. However, further analyses showed that, among vaccine-hesitant participants, the normative perception that formerly vaccine-critical people were changing their minds was correlated with a stronger vaccination intention. We discuss potential reasons why social norms messages did not show an effect in our study and derive theoretical and practical implications