Table 1 Overview of implemented supermarket interventions in the Supreme Nudge trial
Intervention strategies | Components | Explanation of intervention | Targeted product groups | Static or dynamic |
|---|---|---|---|---|
Placement nudges | Healthy shelf layout | Healthy products placed at eye level | Shelves including pasta and rice products, bread substitutes, and breakfast cereals | Static |
Healthy checkout | One check-out till presenting only healthy products | Sugar-free beverages, nuts, snack vegetables, dried fruits, whole-grain crackers, instead of confectionery products | Static | |
Healthy end of aisle | Promoting only healthy products on a prominent end of aisle; monthly product switch | Whole-grain products, oils, canned fish/legumes/ tomatoes, nuts, natural peanut butter, sugar-free beverages | Dynamic | |
Healthy aisle baskets | Three to four aisle baskets filled with healthy products; monthly product switch | Nuts, canned fish/legumes/tomatoes, whole-grain products | Dynamic | |
Property nudges | Shelf-labels | Symbols which highlighted the product’s tastiness (smiley symbol), convenience (stopwatch symbol indicating ease of preparation) or popularity (thumbs-up symbol) | All healthy products across a range of food groups (i.e. vegetables, fruits, all whole-grain products, fish, milk and yogurt, cheese, legumes, butters and oils, nuts, sugar-free bottled beverages, and tea) | Static |
Shelf feedback strips | Positive feedback strip with popularity symbol | Underneath whole-grain bread, fresh fish and snack vegetables | Static | |
Shelf-stoppers | Shelf cards highlight one healthy product per product group; monthly product switch | At each shelf including the shelf-labels | Dynamic | |
Healthy suggestions shelf-banners | Seasonal shelf-banners suggesting different healthy product combinations using the convenience symbol | Whole-grains, legumes and bread substitutes | Static | |
Explanation of nudging symbols | The symbols are introduced on the shopping cart handles, and also shown on shopping cart/baskets boards and the checkout divider bars | N/A | Static | |
Pricing strategies | Price reductions | Price reductions were − 25% or − 10% when combined with price increases in the same food group; three-weekly product switch | Healthy product groups: vegetables, fruit, whole-grain products, fresh fish, low and medium-fat dairy, low-salt legumes, butters and oils with unsaturated fats, unsalted nuts, sugar-free beverages | Dynamic |
Price increases | Price increases were + 15%; three-weekly product switch | Unhealthy product groups: non-whole-grain products, processed/salted fish, high fat and sugary dairy, high-salt legumes, butters and oils with saturated fats, salted nuts, sugary beverages | Dynamic |