Abstract
<p>While many people recycle at home, they are less likely to do so in public, where high waste production meets a diffusion of individual responsibility. We examine whether social identity can close this gap. Across two preregistered season-long field experiments at a Norwegian Premier Division football stadium, we test the separate and combined effects of ingroup identity appeals and intergroup comparison on the recycling behavior of football supporters. In Study 1 (N = 5,712), an ingroup identity appeal did not increase recycling relative to an outgroup appeal, suggesting that standalone identity appeals are insufficient to shift behavior. When the ingroup appeal was combined with a ranking of clubs by their recycling rate, recycling rates were more than two times higher than in any other condition. Study 2 (N = 6,598) replicated this effect against a no-intervention control. Study 3 (N = 761), a post-game survey among Study 2’s participants, showed that supporters exposed to the combined intervention reported greater motivation to recycle and greater perceived importance of contributing to the ingroup’s success. These findings extend social identity theory by showing that identity appeals increase recycling when group performance is tied to a concrete metric of success, which an intergroup comparison can supply, making the behavior a way to pursue positive group distinctiveness.</p>