The power of ‘feeling one’ with a group: identity fusion and extreme pro-group behaviours / El poder de ‘sentirse uno’ con un grupo: fusión de la identidad y conductas progrupales extremas

Abstract Why do some people make extreme sacrifices for their group? We propose that the identity fusion theory helps to understand extreme pro-group behaviour. Identity fusion entails a visceral feeling of oneness with the group. Since the borders between the personal and social self are highly permeable for fused persons, they care about the outcomes of the group as much as their own outcomes. In this article we start by introducing what identity fusion is and the four principles that conceptually capture its essence. After presenting the three alternative methods for measuring identity fusion, we review empirical evidence demonstrating what identity fusion predicts, and the underlying mechanisms that moderate and mediate its consequences. The next sections focus on the possible causes of identity fusion, and we introduce suggestions for diminishing undesirable extreme behaviours by decreasing fusion (i.e., ‘de-fusion’). In a final section, we briefly discuss alternative theories of the causes of extreme behaviours and their relation to identity fusion theory.