Study finds social norm messaging in supermarkets ineffective at boosting plant-based food sales

A new study from Wageningen University has found that communicating dynamic social norms in supermarkets – such as highlighting trends in plant-based food purchases – did not significantly increase sales of meat alternatives or reduce meat consumption. The research, led by Sofia M. M. Wolfswinkel, Sanne Raghoebar, Josine M. Stuber, Emely de Vet, and Maartje P. Poelman, was published in BMC Medicine and is one of the first large-scale real-world studies to evaluate the effectiveness of social norm messaging in influencing purchasing decisions in supermarkets.

The study, conducted over a 12-week period in six Dutch supermarkets, sought to test whether consumers would be more likely to buy plant-based proteins if they were exposed to messaging that emphasized a shift in social norms. Researchers placed banners, stickers, and in-store signage communicating a dynamic norm – such as 'Our customers are increasingly buying vegetarian' – while also increasing the visibility of plant-based meat alternatives by positioning them closer to conventional meat products. The supermarkets selected for the study were matched based on factors such as sales trends and location, allowing for a comparative analysis between intervention and control stores.

Despite the intervention, the researchers found no significant change in the sales of meat alternatives, such as plant-based meat substitutes and legumes. "The intervention did not change meat alternative sales in intervention supermarkets compared to pre-implementation sales trends and to control supermarkets," the study reports. Meat sales also remained unchanged, suggesting that the messaging and strategic placement of plant-based alternatives did not meaningfully disrupt established shopping habits.

The findings challenge the effectiveness of social norm interventions in shifting purchasing behavior at the supermarket level. While similar techniques have been successful in other food environments – such as restaurants and workplace cafeterias – the study suggests that entrenched consumer preferences for meat in supermarkets may require more substantial efforts to change.

"Meat has a dominant presence in supermarkets, and this larger assortment of meat products may have served as a cue implying a norm favoring meat consumption," the researchers noted. They also pointed out that consumer shopping habits in supermarkets are often automatic and habitual, reducing the likelihood of behavioral shifts based on subtle nudges alone.

The study concludes that while social norm messaging may play a role in influencing long-term dietary trends, more structural interventions – such as pricing strategies, taxation on high-emission foods, or stronger product placement initiatives – may be necessary to significantly impact meat alternative sales in supermarkets. Given that over 75% of food purchases in the Netherlands take place in supermarkets, the researchers emphasize the importance of finding more effective strategies to encourage plant-based choices in retail settings.

This research adds to the growing body of literature examining consumer behavior in food retail and the challenges of promoting sustainable dietary transitions. Future studies, the authors suggest, could explore a combination of incentives, pricing adjustments, and targeted marketing efforts to better understand what drives plant-based food purchases at scale.