Vending machine displays (Study 2)

For the second study, we aimed to test whether an increased healthy range could promote healthier beverage choices. To design the increased healthy beverage layout for the vending machine, we turned to guidelines that have been developed for this specific purpose, of which there were several available (e.g. USA⁽²⁴⁾, Canada⁽²⁵⁾, UK⁽²⁶⁾ and Australia⁽²³⁾). We focused on the Australian vending machine layout guidelines⁽²³⁾, as they were the most comprehensive and from the same source used in Study 1 to classify the beverages based on nutritional criteria. These guidelines suggest having at least 50 % green choices and no more than 20 % red choices. Therefore, the newly designed increased healthy range display featured twenty spaces (50 %) filled with green beverages, eight spaces (20 %) with amber beverages and twelve spaces (30 %) with red beverages. Compared to the range featured on the other displays, this offered a 20 % increase in the number of green choices, a 10 % decrease in the number of amber choices and a 10 % decrease in the number of red choices. To achieve these recommended percentages, the increased healthy range featured four additional green beverage choices (one additional water flavour and three additional sparkling water options) and two fewer red beverage choices (soft drinks), removed based on their very low popularity in Study 1. We also created an additional display that featured this increased healthy range in combination with the same traffic light system used in Study 1 (see Fig. ​Fig.2).2). These additional vending machine displays enabled us to independently test the main effects of the traffic light system and an increased healthy range, as well as the combination of the two, on beverage choices.

The four vending machine conditions featured in Study 2.