How ingroup norms of multiculturalism (and tolerance) affect intergroup solidarity: The role of ideology

Multiculturalism and tolerance, as two sets of normative beliefs about how to deal with intergroup diversity, have been recognized as effective at reducing outgroup negativity among majority group members. However, whether majority group members' normative beliefs regarding them might motivate their solidarity-based collective actions and how their political ideology might qualify this influence remained unclear. To answer these questions, we conducted two pre-registered experimental studies (N = 626), both zooming in on the multiculturalism issues in the context of the relationships between native Dutch citizens and citizens with a Moroccan background within Dutch university campuses (Study 1) and broader Dutch society (Study 2). In both studies, we found an ingroup norm of tolerance (vs. control) undermined majority group members' engagement in collective actions in support of ethnic minorities. Additionally, ideological leftists were more sensitive to norms than rightists: Study 1 showed a facilitative effect of the multiculturalism norm (vs. control) on solidarity-based collective action intentions particularly among leftists, whilst Study 2 revealed a dampening effect of the tolerance norm (vs. control) on these intentions particularly among leftists.