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

The paper, in plain language

Auditing a fast-growing theory

Identity-fusion theory claims that people whose personal self merges with a group become capable of extreme sacrifice on its behalf. The claim had accumulated hundreds of tests of varying quality across very different contexts — from combat units to football fans to political movements. With colleagues including Ángel Gómez, whose lab has driven much of fusion research, we meta-analysed the field to establish what actually holds.

What we found

The core claim holds, robustly. Fusion predicts extreme pro-group orientations — willingness to fight, sacrifice, and endorse radical action — with effect sizes that survive scrutiny across measures, populations and designs. The analysis also maps where the evidence thins: which moderators matter, and where causal designs remain scarce.

Why it matters

For a construct increasingly used in radicalization research and prevention practice, the difference between 'promising theory' and 'meta-analytically established predictor' is the difference between a hunch and a tool. This review gives researchers and practitioners the calibrated estimate — and connects directly to our earlier finding that fusion can attach to political leaders, with consequences for what followers will do.