When Being in the Minority Feels Threatening: Social Identity and the Reinforcement of Anti-Vaccination Attitudes.

The present research aims to contribute to the understanding of anti-vaccination attitudes. We do this by analyzing the role of social identity and intergroup threat. Drawing on intergroup threat theory, we hypothesize that being informed that the general population is positive toward vaccines may be perceived as threatening to individuals identifying as vaccine-hesitant, which may lead to stronger anti-vaccination attitudes. We evaluate this hypothesis in two survey experiments performed among Swedish citizens (Study 1, N = 376; Study 2, N = 698), where we present participants in the treatment group with information that the position toward vaccines in the general population is positive. We find that when vaccine-hesitant individuals are informed that the general population is positive toward vaccines, they express stronger anti-vaccination attitudes. We further find that this relationship is mediated by negative emotions, implying perceptions of intergroup threat. We conclude that individuals with a vaccine-hesitant identity feel threatened when learning that most others are positive toward vaccines, which is associated with stronger anti-vaccination attitudes. These results have important implications for the understanding of anti-vaccination attitudes, suggesting that such attitudes may increase when individuals feel that their identity is threatened.