Using social norm nudges in supermarket shopping trolleys to increase fruit and vegetable purchases

Abstract

Fruit and vegetable (F&V) consumption is associated with a reduced risk of developing obesity and chronic diseases: however, only one in twenty Australian adults consume F&Vs at the recommended two servings of fruit and five servings of vegetables per day. What and how much people eat is influenced by their social and physical environments. Supermarkets are a key setting influencing food purchases, and as such, they can shape consumption patterns of F&Vs. Implementing effective strategies to increase F&V intake is crucial. The objective of this research was to test if shopper purchasing behaviour can be modified to purchase more F&Vs using social norm nudge messages (prompts) placed in shopping trolleys. Placards giving the message that the majority of shoppers purchased F&Vs at each shop were placed in shopping trolleys. Applying an intervention research design, 30 out of ~100 trolleys were fitted with the placards and shopper purchases were measured by collecting receipts to measure the quantity (kg), total and F&V spending (Australian dollars) for intervention versus control trolleys. We also conducted a short intercept survey that was administered independently from the research study day. Shoppers who selected trolleys with the social norm nudge placards (n = 109) purchased 1.25 kg more F&Vs (Intervention: mean = 5.45 kg, SD = 4.23 kg, 95% CI 4.65 kg, 6.26 kg vs. Control: mean 4.19 kg, SD = 3.75 kg, 95% CI 3.48 kg, 4.90 kg, p = 0.020, Cohen's d = 0.32) and spent an extra $9.10 more on F&Vs compared to shoppers in the control group (n = 109; Intervention: mean = $36.20, SD = $26.30, 95% CI = $31.24, $41.26 vs. Control: mean $27.10, SD = $24.00, 95% CI = $22.50, $31.67, p = 0.008, Cohen's d = 0.36). The social norm nudge placard shows promise in modifying shoppers' purchases to buy more F&Vs. Larger studies are required to elucidate and confirm these findings over the longer term.

Using a divider nudge in supermarket shopping trolleys to increase fruit and vegetable purchases: A feasibility study using an intervention design

“…The results from the current study found a 4% increase in spending on F&Vs, resulting in a 3.6% increase in the weight of F&Vs purchased, although this was not statistically significant. A previous study (McGrath, 2023) using the same intervention research design as the current study also showed a similar trend using a social norm nudge and found a 33.6% increase in spending on F&Vs, resulting in a 30% increase in the weight of F&Vs purchased. This suggests that total spending on F&Vs does not translate to the same increase in weight of F&Vs, with the increase in weight of F&Vs lower by 10.7% and 10% respectively, suggesting that shoppers are purchasing more expensive produce per gram with the increased spending.…”

“…It could be that the divider nudge needed to be more “explicit” or used alongside a second social norm nudge. For example, a study by McGrath (2023) investigated placing a social norm nudge in supermarket trolleys giving the message that most shoppers purchased F&Vs at each shop resulting in a significant 33.5% more F&Vs purchased.…”

“…A study by McGrath (2023) investigated placing a social norm nudge in supermarket trolleys giving the message that most shoppers purchased F&Vs at each shop. Shoppers who selected trolleys with the social norm nudge placards purchased a significant 30% more F&Vs than the control group while keeping shopper total spending stable.…”

“…The current study aimed to address the limitations in the former studies while building on the study by McGrath (2023), which used the same intervention research design as the current study and investigated the impact of one 50% visual divider nudge (implied social norm) placed in supermarket trolleys on shopper F&V purchases. It was hypothesised that shoppers who were covertly exposed to the divider nudge placard would purchase more F&Vs (measured in kilograms) and spend more on F&Vs (measured in Australian dollars) compared to shoppers who were not exposed to the divider nudge.…”

Changing the retail food environment

“…This Virtual Issue on Changing the Retail Food Environment brings together 10 studies to investigate and consider how consumer behaviour can be influenced towards healthier and more sustainable choices across retail settings and product categories (Bunten et al., 2022; Fildes et al., 2022; Jenneson et al., 2020; Jenneson & Morris, 2021; Lonnie et al., 2023; McGrath, 2023a, 2023b; Thomas et al., 2023; Trafford & de la Hunty, 2021; White & Lockyer, 2020).…”