Obesity prevalence is increasing around the globe, with interventions manipulating the decision environment thought to have a large potential to change behaviour. One such simple yet effective intervention utilises the Proximity Effect, whereby snack consumption is decreased as the physical distance (proximity) between the individual and the snack is increased. Recent studies have suggested that visual salience and physical effort may underpin the effect. The current protocol outlines the first study to experimentally manipulate effort to determine its potential role in the proximity effect. A sample of 90 university students will be randomly allocated to one of four conditions in a 2 (proximity; 20cm vs 70cm) x 2 (effort; unwrapped vs wrapped) between subjects study. Twenty chocolate brownies will be presented at either 20cm or 70cm, with these brownies being either unwrapped or wrapped in a single layer of clear plastic film (high effort). Participants will also complete self-report measures for potential moderating factors including eating behaviour and perceived visual salience.Primary outcomes of the study are likelihood of consumption (whether an individual consumed any of the snack), and the actual amount consumed (kCal) according to experimental conditions. Implications of the results may be implemented in food service areas to decrease consumption of unhealthy foods by increasing the physical effort required to attain such foods.

Obesity and overweight levels are rising nationally, despite recent governmental advertising campaigns being implemented to tackle the prevalence rise at a population level. Therefore, alternative approaches should be investigated in an effort to reduce obesity prevalence rises. One such approach modifies the external cues and the environment where decisions about food are made, and it is commonly known as Choice Architecture (CA). The proximity effect is a strategy within CA that could reduce overall calorie consumption by placing healthier foods at relatively closer distances compared to unhealthy foods. Amongst studies examining the proximity effect, only one so far has explored the simultaneous presentation of healthy and unhealthy foods, referred to as a competitive food environment. As unhealthy foods are often preferred over healthy foods, the current study aims to investigate whether food choice can be overridden by varying degrees of proximity effect and whether key factors such as visual salience, perceived effort, BMI, age, food preference, and executive function moderate this effect. A sample of 48 undergraduate students will participate in a laboratory experiment, believing they are taking part in a relaxation study. Participants will be simultaneously presented with two bowls of food: A healthier fruit selection and an unhealthier chocolate option, each varying according to proximity (either 20cm or 70cm). The participants will be asked to complete a questionnaire measuring multiple factors that may influence food consumption, such as perceived effort and hunger level. The primary outcome of the study is the amount of each food consumed (in grams) depending on relative proximity, with the secondary outcome exploring whether the effect of the latter is influenced by the key moderators. The proposed study explores the proximity effect in a competitive food environment, an area rarely explored in research but high in real-world applicability. If a greater amount of the most proximal food is consumed in each condition, regardless of food healthiness, the intervention can be scaled up to a novel field experiment to further evaluate the effectiveness of the proximity effect in reducing calorie intake.

Research into why the proximity effect occurs and understanding of the underpinning mechanisms is relatively scarce. Attempts have been made to explore whether cognitive load and physical effort underpin the effect, but no previous study has experimentally manipulated visual salience to determine its role in the proximity effect. The present study aims to be the first to do so, starting with a pilot study to determine an effective operationalisation of visual salience in a laboratory setting. The selected manipulation will then be used in a laboratory study conducted with 68 individuals in a 2(Distance; 20cm vs 70cm) x 2(Visual Salience; Low vs High) between subjects design. Actual and Likelihood of consumption will be measured and statistically compared between conditions to determine the potential role of Visual Salience within the Proximity Effect.