The likes that bind: Even novel opinion sharing can induce opinion‐based identification

Research has found that psychological groups based on opinion congruence are an important group type. Previous research constructed such groups around opinions potentially connected to pre-existing identities. We strip away the socio-structural context by using novel opinions to determine whether opinion congruence alone can be a category cue which can foster identification and whether such group identification mediates the relationship between opinion exposure and opinion polarization. We assess this across two pre-registered online interactive experiments. Study 1 (N = 1168) demonstrate that opinion congruence fostered stronger identity than minimal groups. Study 2 (N = 505) demonstrate that opinion congruence fostered stronger identification than non-opinion congruence. The relationship between opinion exposure and opinion polarization occurs through group identification in both. Results demonstrate that (novel) opinions can be self-categorization cues informing identification and influencing opinion polarization.