Field Experiments on Reducing Food Waste: Separating the Effects of Imperative and Descriptive Norm Messaging

Food waste is a global issue with significant economic, social, and environmental implications. In three field studies (N = 1705) conducted in restaurants across Northern Italy, we investigated the effectiveness of table-tent interventions on reducing food waste. A pilot study replicated a slightly modified table-tent intervention by Giaccherini et al. (2021), featuring a social norm (“A recent Coldiretti survey shows that a significantly increasing percentage of Italians are using doggy bags to take home uneaten food”) paired with an imperative (“Ask your waiter for a doggy bag.”). Study 1 separated these components, testing social norm-only and imperative-only messages, while Study 2 compared the combined message with the imperative-only message. All interventions significantly reduced food waste compared to baseline, with no clear winner. A follow-up study showed that the imperative was most frequently interpreted as either an injunctive norm or a neutral prompt or reminder, and almost never as a descriptive norm. This suggests that imperative messages influence behavior through multiple psychological pathways distinct from those activated by descriptive norm messages. In practical terms, our findings demonstrate that simpler, less data-dependent imperative interventions can effectively reduce food waste and offer actionable guidance for scalable behavioral nudges.