Recycling Rivalry: Combining Social Identity Appeals with Intergroup Comparison Increases Pro-Environmental Behavior

This research examines how social identity can increase pro-environmental behavior (PEB) in public settings. Across two preregistered season-long field experiments conducted at a Norwegian Premier Division football stadium, we test the independent and combined effects of ingroup identity appeal and intergroup comparison interventions on real recycling behavior. In Study 1 (N = 5,712), standalone ingroup identity appeals did not increase recycling relative to outgroup appeals, suggesting that identity salience alone is insufficient to shift behavior in public settings. However, when an ingroup identity appeal was combined with a ranking of visiting clubs by recycling rate, recycling rates significantly increased to 52.9% from 15.8% at baseline. Study 2 (N = 6,598) replicated this effect against a pure control, with recycling rates of 56.7% in the intervention condition significantly higher than 34.7% in the control condition. Study 3, a preregistered post-game survey among Study 2’s participants, found that the ingroup appeal combined with intergroup comparison was associated with increased motivation to contribute to the ingroup’s collective effort. These findings extend social identity theory by showing that combining ingroup identity salience and intergroup comparison provides an outlet for identity expression that can significantly increase PEB in public settings.