Interventions at a student canteen restaurant for sustainable consumption
This intervention was created and tested by Dijksterhuis & van Baaren by request and funding by The Environment, Nature and Energy Department (LNE) of the Flemish Government. The project leads are; Timon Hoitink, Johnny Buivenga, Lotte Spijkerman.
In the student restaurant of Ghent University (GU) we aimed to stimulate the sales of the environmentally sound food. We wanted to create interventions where we did not communicate directly in terms of the environment, sustainability or health. The customer can choose between three different components: vegetables, protein (meat, vegetarian alternative) and carbohydrates (potatoes, pasta …). The interventions here were focused on promoting the sales of the most environmentally sound main component depending on the menu. We aimed to test an intervention package in which we applied (a) framing, (b) visual attractiveness, and (c) scarcity and social norm. This intervention package was pre-tested in order to fine-tune the setup.
We applied framing on the printed menu of the canteen by adding an attractive adjective in the (environmentally sound) dish description. The framing was visible on the tv screens in the student restaurant, information placards (containing information on allergic ingredients) and a miniature chalkboard next to the sample menu. Next to that, we increased the visual attractiveness of the environmentally best scoring dish. The dish was set on a wooden plate and put in a highly visible position in the corridor leading to the service counter. Finally, we added a sign (miniature chalkboard) denoting that the dish has a limited availability. We added a small element by replacing the chalkboard with another which says ‘popular choice, still limited available’.
In the course of one month, the intervention was implemented at a student restaurant in Ghent (n=2627). The student restaurant at a different location in Ghent (n=2187) was used as a control location. This means that 20 working days were measured of which 12 were used for the analysis (8 were discarded because the meals on offer were different between the two locations). We have found a positive result in all of the 12 days, of which 6 were a significant positive result. The average result was an increase of 5,5 percentage points (13,5% à 19%) of the share of the environmentally best scoring dish.
This intervention package was a success in terms of the overall goal, increasing the sales of the environmentally best scoring dish. By implementing these interventions as a package, the effect of the individual intervention components (a through c) cannot be measured. The measured effects also were highly volatile ranging from +1,3 percentage points to +19,4 percentage points. These large ranges cannot be explained with the available data.
Primary Institutions – Environment Department of the Flemish Government & Dijksterhuis & van Baaren.
Secondary Institutions – Ghent University
There has been given access to a report about this nudge. Here you can find more relevant information about the nudge.