Hints from the crowd: how descriptive norms influence food choices in the Udine hospital canteen

Abstract Background Descriptive norm messages provide information about how most people typically behave. It has been reported that people adjust their food choices according to their perceptions of others’ eating habits. However, evidence of their effectiveness varies by context and population. The aim of the study was to examine the impact of descriptive norms in a hospital canteen to promote healthy and sustainable food choices among employees. Materials and methods For 2 months, norms based on previously detected habits were displayed in the canteen of Udine Hospital (Italy) and removed just before data collection. These norms concerned the choice of vegetables (at least one portion), water (versus soft drinks) and fruit (versus other desserts). Users’ trays were photographed on first access over 5 days in September 2023, and a questionnaire was distributed to assess correct message recall. A multiple logistic regression (alpha < 0.05) was performed to examine the association between each message and the corresponding choice, adjusted for sex, age class, vision of the proposed meal, type of work (shift/non-shift). Results 500 questionnaires and food choices were analysed (54% female - 46% male, with median age of 41). 76% of 108 recalling the message and 68% of 392 who did not, chose vegetables. 89% of 213 recalling the message and 82% of 287 who did not, chose water. Of the 359 participants who took at least one dessert: 80% of 86 recalling the message and 73% of 273 who did not, chose fruit as dessert. Only for choice of water over soft drinks there was a significant recall/action association (OR 1.96 [1.12-3.43]). Conclusions A low percentage of users read and recalled the norms, which were only effective on water choice. The norm structure, not adapted to the target population, may explain the limited effectiveness. Defining additional criteria that influence the impact of descriptive norms is necessary to create tailored interventions for each target group. Key messages • Norms about water increased its choice over soft drinks, while those about fruits and vegetables were ineffective. • Limited norm efficacy may stem from their poor adaptation to target population.