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Testing the effects of food product placement on customers’ visual attention and intended product purchases: a randomised trial in a virtual supermarket setting (Phase II)

Principal Investigator:  Janis Baird and Christina Vogel, Professor of Public Health and Epidemiology and Principal Research Fellow in Public Health Nutrition respectively, MRC Lifecourse Epidemiology Centre, University of Southampton

Team: Dr Sarah Crozier, Senior Statistician, MRC Lifecourse Epidemiology Centre, University of Southampton

Dr Hayward Godwin, Associate Professor of Psychology, University of Southampton

Professor Marcus Munafo and Dr Olivia Maynard, Bristol University

Ravita Taheem, Southampton City Council, Sure Start Children’s Centres

Start date: 1 March 2022

End date: 1 October 2023

Background

Poor diet has been recognised as a major contributor to the burden of non- communicable diseases in the UK and costs the NHS approximately £6 Billion annually.

Most adults in England consume too much salt, saturated fat and free sugar, and do not eat the recommended five daily portions of fruit and vegetables. Among low-income groups these trends are more extreme. Almost 90% of UK grocery sales occur within supermarkets4 and their subtle use of marketing techniques influences the food choices of an almost captive market. Women of childbearing age are an important target group to study because they remain primarily responsible for domestic food tasks such as shopping and cooking and their nutrition status influences the short and long-term health of their children.

Our prior work in Hampshire showed that the diets of women with low educational attainment were more affected by less healthy supermarket environments than women with higher attainment. Shopping at less healthy discount and small supermarkets, with poorer availability, pricing and placement of healthy foods, was associated with poor dietary quality among women who left school aged 16 years but not among those with degree qualifications. UK government policy recognises that more effort is needed to develop interventions to improve health equitably and is introducing legislation on product placement initiatives to support families to make healthier food choices in supermarkets.

Research using adequately powered clustered randomised controlled trials in supermarkets is limited, largely due to the complexity and large number of stores required. Evaluating changes in supermarket layout is notoriously challenging due to differing health and business agendas and randomisation at the store level requires commitment that is problematic in this highly competitive, commercial setting. Virtual supermarkets offer a viable alternative to investigate the likely impact of supermarket-based, healthy eating policy options using robust trial designs. Additionally, neuroscience techniques, such as eye-tracking, offer objective evidence that complements self-report behaviours, and facilitate a deeper understanding of the cognitive mechanisms underlying health-related behaviours. Such techniques have been used to examine how product placement facilitates customers’ visual attention, however there is a gap in understanding of how visual attention differs according to the healthfulness of products, particularly while placed in prominent in-store locations and whether visual attention differs according to customer’s socioeconomic position.

This study aims to use experimental randomised trials and a virtual supermarket setting to determine differences in visual attention and intended purchase of healthy, unhealthy and non-food products placed in prominent in-store locations such as checkouts. It will also assess effect modification by educational attainment on these relationships to explore potential effects on inequalities.

This is the second of two phases if research assessing visual responses to product placement. In phase I, heat mapping technology using Qualtrics software determined whether interest in and intended purchase of products in prominent in-store locations differed if the products were healthy, unhealthy or non-food items. We assessed effect modification by educational attainment to explore potential effects on inequalities. Women with young children (n=230), recruited through Sure Start Children’s Centres, early years setting and other community groups in Hampshire, undertook shopping trips in a virtual supermarket to assess whether their purchasing intentions differ if unhealthy foods, healthy foods or non-food items are placed in prominent positions (store entrances, checkouts and end of aisle). Preliminary findings indicated differences in women’s intention to buy certain types of products according to their educational attainment. Women with no educational qualifications beyond aged 16 years were intent on purchasing fewer healthy products when they were placed in prominent locations whereas those with higher educational attainment were intent on buying significantly more healthy products. A total of 230 women participated in phase I, exceeding our target sample size of 52.