Supplemental Material for On efficient mass-media messages during the COVID-19 pandemic: The role of expertise and expressed social identity.

Abstract

The Coronavirus disease (COVID-19) pandemic requires swift behavior change based on the most up-to-date recommendations. To reach many people, the use of mass media and technology is key. We therefore investigate how health advice in the media can most effectively change behavioral intentions. Specifically, we integrate the literature on science rejection and on intergroup criticism to argue that people are likely to follow expert advice, but only if these experts communicate a common group identity ("we"). Our preregistered and high-powered experiment showed weak support for these registered hypotheses. Exploratory moderation analyses including trust in science and political orientation produced inconsistent results. Exploratory mediation analyses showed a consistent positive impact of rated expertise on intention to comply and perceived inadequacy of public response, mediated by message motive ratings. Health experts or public figures who communicate health-advice in the media should thus clarify their expertise and intention. We discuss implications and future directions.