Exploring the underpinning mechanisms of the proximity effect within a competitive food environment

One method of influencing an individual's food consumption involves placing unhealthy snacks further away from individuals, known as the "proximity effect". However, only one laboratory study has explored the effect while both an unhealthy and a healthy option are presented simultaneously. Further, little is known about the potential underpinning mechanisms of the effect. The current study aims to replicate the proximity effect in a competitive environment, and to explore the role of visual salience and effort in the proximity effect.

Fifty-six participants were asked to complete a two-part questionnaire under the cover story of a relaxation study. Two bowls were presented to participants, each containing either 250 g chocolate M&M's or 250 g mixed fruit pieces. Each bowl was positioned either 20 cm or 70 cm from the participant, creating four proximity conditions. Consumption of each snack was compared between proximity conditions.

No main effects were found. A significant interaction between snack type and chocolate position was found (p = .010, ȵ² = 0.159), with fruit consumption being significantly higher when chocolate was at located at 20 cm compared to 70 cm (53.35 g vs 22.35 g, p = .042). Higher visual salience of each snack type correlated to more of the snack being consumed, ps < .017. Results were similar when calories consumed were analysed.

We found an unconventional proximity effect where the consumption of a snack did not depend on its position, but rather the relative position of another snack. Implications of the study could inform café and supermarket layouts to exploit the interaction between moving healthy items closer in addition to moving unhealthy items further away, in order to maximise choice of healthy items.