How identity fusion predicts extreme pro-group orientations: A meta-analysis

Researchers have productively tested identity fusion theory, aiming to explain extreme pro-group orientations. However, the strength of effects, types of measurements, and study contexts have varied substantially. This first meta-analysis (90 studies from 55 reports, 106 effects, N = 36,880) supported four main conclusions based on the available literature: (1) identity fusion has a strong and positive but very heterogeneous relationship with extreme pro-group orientations; (2) its effect is significantly stronger than that of social identification; however, some evidence suggests that this difference is primarily observed in published rather than unpublished studies; (3) the verbal identity fusion scale has the best explanatory power; (4) identity fusion is most strongly associated with extreme collective action, followed by a willingness to sacrifice oneself, fight or die for the group, and outgroup hostility. We discuss the findings’ implication for identity fusion theory. Based on the literature’s limitations, we highlight avenues for future research.