Effects of nudges categorized through Construal Level Theory on vegetarian meal choices: A large field experiment

This research examines the effectiveness of nudges to promote vegetarian meal choices in university cafeterias, using data from nearly 100,000 meal selections across seven waves (December 2023-June 2024). Four nudge mechanisms, distinguished on the basis of Construal Level Theory (visibility and accessibility for low-level construal; social desirability and emotional activation for high-level construal) were tested in isolation and in combination. In Studies 1 and 2, isolated nudges showed that visibility significantly increased vegetarian choices, whereas accessibility and social desirability had no significant impact. Emotional activation had a negative effect, reducing the choice of vegetarian meals. The combinations exhibited that adding accessibility to visibility reduced effectiveness (Study 3), visibility combined with social desirability produced the strongest effect (Study 4), social desirability mitigated emotional activation's negative effect (Study 5), and pairing emotional activation with visibility or accessibility improved outcomes, although less effectively than proximal/concrete nudges (Study 6). This research makes three key contributions. First, it provides large-scale field evidence on the nudges' effectiveness in real consumption settings and actual behaviour, addressing a gap in research dominated by hypothetical choices, preferences, attitudes, or intentions. Second, it extends Construal Level Theory to nudging research, providing a unique lens to understand the variable effectiveness of nudges depending on their level of construal. Third, this research emphasizes that not all nudges are equally effective, and some may even backfire. While visibility remains the most reliable isolated intervention, inter-lever combinations can enhance effectiveness. Finally, this research provides useful managerial and societal recommendations for policy-makers.