An enjoyment-focused social identity intervention to reduce buffet plate waste

Buffets produce substantial plate waste, which is environmentally harmful and unnecessary. Dominant approaches of environmental beliefs messaging have limited effectiveness in reducing plate waste. We test a novel intervention in the form of a world map game which leverages enjoyment and social identity salience. In a 2 (map intervention vs no map intervention) × 2 (beliefs messaging vs no beliefs messaging) between-subjects design ( N = 400) we used a virtual buffet scenario to measure plate waste intentions implicitly. The world map game significantly reduced the number of calories added to a virtual plate (implicit measure) and increased intentions to leave zero plate waste (explicit measure) for both participants and their children (as reported by parents). In contrast, beliefs messaging did not significantly affect these measures. In a second experiment ( N = 400) we (1) replicated the effectiveness of the novel intervention; (2) confirmed underlying theoretical mechanisms (identity salience and beliefs) by assessing the effect of the interventions on theoretical constructs. Beliefs messaging showed a significant effect on plate waste intentions for participants but not for their children. The map intervention increased positive affect (feeling more entertained, enthusiastic, and inspired), whereas the beliefs messaging decreased positive affect and increased negative affect (feeling more upset, irritable, distressed, and ashamed). Our results suggest that identity salience can be a strong leverage point to reduce plate waste. Practically, we introduce a promising new plate waste intervention which has potential to be more effective than common messaging approaches and does not negatively affect emotions. • Plate waste at buffets is environmentally harmful and unnecessary • We test an intervention leveraging enjoyment and social identity salience • The novel intervention outperformed environmental beliefs messaging • It increased intentions to leave no plate waste whilst increasing positive affect • It decreased calories added to the plate at a virtual buffet task