Convenient tools and social norms: Measuring the effectiveness of an intervention to reduce household food waste

Halving food loss and waste is the target of the UN's Sustainability Development Goal 12.3, and household food waste constitutes a substantial part of global food waste. Effective interventions that decrease household food waste are urgently needed, and these could target various underlying behaviours such as planning, storing, preparing and consuming. There is a lack of studies that develop interventions based on theory and that compare different intervention options. Moreover, in testing the effectiveness of such interventions, possible influences caused by the measurement method need to be assessed. The current study explores two interventions, based on the Motivation-Opportunity-Ability framework, to test if combining a tool package (containing various waste reducing tools such as a measuring cup, stickers, leaflets, recipes) with a motivational message based on social norms is more effective than the tool package alone. Additionally, it examines the effects of using a self reported survey measurement for household food waste, to ensure that results are not caused by increased consumer awareness of food waste due to measurement alone. Findings show that the tool package significantly improves waste-preventing behaviours, and decreases self-reported food waste by 39.2% (experiment 1) and 23.0% (experiment 2). Effects on waste-preventing behaviours are stronger when social norm elements are added in the intervention. Results of the second experiment indicate that effects of self-reported measurement are minimal, which provides initial support for the use of self-reported food waste measurement in intervention testing albeit that underreporting remains an issue and more research is needed.