Social norm nudges in shopping trolleys to promote vegetable purchases: A quasi-experimental study in a supermarket in a deprived urban area in the Netherlands

Ethnic differences in meat consumption attitudes, norms and behaviors: A survey of White, South Asian and Black ethnic groups in the UK

A reduction in meat consumption is necessary to mitigate negative impacts of climate change and adverse health outcomes. The UK has an increasingly multi-ethnic population, yet there is little research on meat consumption habits and attitudes among ethnic groups in the UK. We ran a survey (N = 1014) with quota samples for ethnic groups and analyzed attitudes, behaviors and norm perceptions of White, South Asian and Black British respondents. Most respondents believe overconsumption of red and processed meat has negative impacts on health (73.3%) and the environment (64.3%).South Asian respondents were statistically significantly less likely to be meat eaters than White respondents (OR = 0.44, 95% CIs: 0.30-0.65, t = -4.15, p = 0.000), while there was no significant difference between White and Black respondents (OR = 1.06, 95% CIs: 0.63-1.76, t = 0.21, p = 0.834). Both South Asian (OR = 2.76, 95% CIs: 1.89-4.03 t = 5.25, p = 0.000) and Black respondents (OR = 2.09, 95% CIs: 0.1.30-3.35, t = 3.06, p = 0.002) were significantly more likely to express being influenced by friends and family in their food choices than White respondents. South Asian (OR = 3.24,95% CIs: 2.17-4.84, t = 5.74, p = 0.000) and Black (OR = 2.02,95% CIs: 1.21-3.39, t = 2.69, p = 0.007) respondents were also both significantly more likely to report they would want to eat similarly to their friends and family than White respondents. Statistical analyses suggested some gender and socioeconomic differences across and among ethnic groups, which are reported and discussed. The differences in meat consumption behaviors and norm conformity between ethnic groups raises the prospect that interventions that leverage social norms may be more effective in South Asian groups than Black and White groups in the UK.

Using the Australian Dietary Guidelines 2&5 education message in supermarket shopping trolleys to nudge shoppers to purchase more fruit and vegetables: A feasibility study using an intervention design

Fruit and vegetable (F&V) consumption is associated with a reduced risk of developing chronic diseases; however, only one in 16 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 the feasibility of modifying shopper purchasing behaviour to purchase more F&Vs using the Australian Dietary Guidelines 2&5 education message covering one-half of the base of shopping trolleys. Placards giving the message that eating 2 fruits and 5 vegetables every day for good health were placed at the base of shopping trolleys as an educational nudge. Applying an intervention research design, 30 out of ~100 trolleys were fitted with the placards and shopper purchases were measured by collecting paper sales receipts to measure the weight (kg), total spending and F&V-specific spending (Australian dollars) for intervention versus control trolleys for one Saturday. We also conducted a short intercept survey that was administered independently from the research study day on non-trial shoppers. Shoppers who selected trolleys with the 2&5 education nudge placards (n = 101) purchased 1.66 kg less weight of F&Vs (Intervention: mean = 3.89 kg, SD = 3.40 kg, 95% CI = 3.21 kg, 4.56 kg, vs. Control: mean 5.55 kg, SD = 4.16 kg, 95% CI = 4.73 kg, 6.37 kg, p = 0.002) and spent less on F&Vs compared to shoppers in the control group (n = 102; Intervention: mean = $26.00, SD = $21.60, 95% CI = $21.78, $30.32 vs. Control: mean $36.00, SD = $27.00, 95% CI = $30.72, $42.36, p = 0.004). Intervention group shoppers also spent less in total spending between groups (Intervention: mean = $115.40, SD = $68.30, 95% CI = $101.95, $128.95 vs. Control: mean $151.30, SD = $79.40, 95% CI = $135.73, $166.93, p = 0.001). The 2&5 education nudge placard had the opposite effect as intended on shoppers' purchases to buy more F&Vs, although there may have been other differences between the intervention and the control groups since they were not randomised. Larger studies are required to elucidate and confirm these findings over the longer term.

To move or not to move while on campus: Examining the influence of others

OBJECTIVE

To examine the influence of dynamic and trending descriptive norms on increasing physical activity and decreasing the sedentary behaviors of university students while on campus.

PARTICIPANTS

One-hundred fifty-six university students from a Canadian university completed this study.

METHODS

Participants were randomly assigned to receive one of four online messages containing normative information about the on-campus behavior of university students. On-campus physical activity and sedentary behavior were measured pre- and post-message.

RESULTS

The results revealed that students exposed to the trending norm reported a greater decrease in sedentary behavior than students in the control condition, p = .007.

CONCLUSION

Results provide preliminary experimental evidence that trending norm messages may serve to decrease the sedentary behavior of students while on campus.

Nudging healthy food choices through e-messages in a supermarket

This paper analyses the impact of a healthy food nudge intervention on purchases of 1590 customers of a supermarket chain's loyalty program in Uruguay through a randomized controlled trial. Nudges were presented in the form of messages sent through WhatsApp to customers three times a week for 8 weeks (between July and September 2020). Messages highlighted the benefits of cooking at home and eating mindfully and healthy (vegetables, fruits, healthy snacks, legumes, and fish), and included easy to implement tips. Results show that, on average, customers assigned to the treatment group increased their purchases of healthy food by 8% and substituted sugar-sweetened for sugar-free beverages. We find an unintended increase in purchases of unhealthy food of 7%, with no correlative increase in calories, suggesting that customers substituted higher calorie products for lower calorie ones. We find that households with lower educational attainment, lower income, and with children under the age of 12 are more likely to increase purchases of fruits and vegetables, while other households are more likely to improve the diet quality without increasing expenditure. Effects do not persist after the intervention is over, suggesting that salience, rather than information is the main channel triggering the effects.

Real-world nudging, pricing, and mobile physical activity coaching was insufficient to improve lifestyle behaviours and cardiometabolic health: the Supreme Nudge parallel cluster-randomised controlled supermarket trial

BACKGROUND

Context-specific interventions may contribute to sustained behaviour change and improved health outcomes. We evaluated the real-world effects of supermarket nudging and pricing strategies and mobile physical activity coaching on diet quality, food-purchasing behaviour, walking behaviour, and cardiometabolic risk markers.

METHODS

This parallel cluster-randomised controlled trial included supermarkets in socially disadvantaged neighbourhoods across the Netherlands with regular shoppers aged 30-80 years. Supermarkets were randomised to receive co-created nudging and pricing strategies promoting healthier purchasing (N = 6) or not (N = 6). Nudges targeted 9% of supermarket products and pricing strategies 3%. Subsequently, participants were individually randomised to a control (step counter app) or intervention arm (step counter and mobile coaching app) to promote walking. The primary outcome was the average change in diet quality (low (0) to high (150)) over all follow-up time points measured with a validated 40-item food frequency questionnaire at baseline and 3, 6, and 12 months. Secondary outcomes included healthier food purchasing (loyalty card-derived), daily step count (step counter app), cardiometabolic risk markers (lipid profile and HbA1c via finger prick, and waist circumference via measuring tape), and supermarket customer satisfaction (questionnaire-based: very unsatisfied (1) to very satisfied (7)), evaluated using linear mixed-models. Healthy supermarket sales (an exploratory outcome) were analysed via controlled interrupted time series analyses.

RESULTS

Of 361 participants (162 intervention, 199 control), 73% were female, the average age was 58 (SD 11) years, and 42% were highly educated. Compared to the control arm, the intervention arm showed no statistically significant average changes over time in diet quality (β - 1.1 (95% CI - 3.8 to 1.7)), percentage healthy purchasing (β 0.7 ( - 2.7 to 4.0)), step count (β - 124.0 (- 723.1 to 475.1), or any of the cardiometabolic risk markers. Participants in the intervention arm scored 0.3 points (0.1 to 0.5) higher on customer satisfaction on average over time. Supermarket-level sales were unaffected (β - 0.0 (- 0.0 to 0.0)).

CONCLUSIONS

Co-created nudging and pricing strategies that predominantly targeted healthy products via nudges were unable to increase healthier food purchases and intake nor improve cardiometabolic health. The mobile coaching intervention did not affect step count. Governmental policy measures are needed to ensure more impactful supermarket modifications that promote healthier purchases.

TRIAL REGISTRATION

Dutch Trial Register ID NL7064, 30 May 2018, https://www.onderzoekmetmensen.nl/en/trial/20990.

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

Fruit and vegetable (F&V) consumption is associated with a reduced risk of developing obesity and chronic diseases: however, only one in 16 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 the feasibility of covertly modifying shopper purchasing behaviour to purchase more F&Vs using a visual divider nudge message (prompts) covering the entire base of shopping trolleys. Placards provided a visual representation of the recommended proportion of the trolley base that should be allocated to fruits and vegetables (implied social norm). 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 weight (kg), total spending and F&V specific spending (Australian dollars) for intervention versus control trolleys for one weekend day only. We also conducted a short intercept survey that was administered independently from the research study day on non-trial shoppers. Shoppers who selected trolleys with the divider nudge placards (n = 102) purchased equal weight of F&Vs (Intervention: mean = 6.25 kg, SD = 5.60 kg, 95% CI = 5.14 kg, 7.35 kg, vs. Control: mean 6.03 kg, SD = 5.17 kg, 95% CI = 5.01 kg, 7.04 kg, p = 0.768) and spent equal amounts on F&Vs compared to shoppers in the control group (n = 102) (Intervention: mean = $41.46, SD = $36.68, 95% CI = $34.25, $48.66, vs. Control: mean $39.85, SD = $33.30, 95% CI = $33.34, $46.39, p = 0.744). There was no difference in the total spending between groups (Intervention: mean = $135.99, SD = $90.10, 95% CI = $118.29, $153.68, vs. Control: mean $155.68, SD = $96.46, 95% CI = $136.73, $174.63, p = 0.133). The divider nudge placard did not lead to any difference in shoppers' purchases of F&Vs. However, this study demonstrates the feasibility of testing a cheap, simple and easy supermarket nutrition intervention. Larger studies are required to elucidate and confirm these findings over the longer term.

The role of attention and health goals in nudging healthy food choice

Introduction

Nudging is a promising intervention technique that supports people in pursuing their healthy eating goals. Recent research suggests that, despite previous assumptions, disclosure of the presence of a nudge does not compromise nudge effectiveness. However, it is unknown whether attention to a nudge affects nudge effects. We assessed the role of attention systematically, by examining explicit and implicit attention to nudges, while also exploring healthy eating goals as a potential moderator.

Methods

Participants were assigned to a nudge (i.e., a shopping basket inlay with pictures of healthy items) or control condition (i.e., a shopping basket inlay with neutral pictures) and chose a snack in an experimental supermarket field study. Explicit and implicit attention (with a mobile eye-tracker) to nudges, healthiness of snack choice, and healthy eating goals were assessed.

Results

Results showed that attention to the nudge did not hamper the nudge's effect. Furthermore, individuals with strong healthy eating goals made healthier food choices in the nudge condition. Individuals with weak to non-existent healthy eating goals were not influenced by the nudge.

Discussion

Findings are in line with the viewpoint that nudging does not by definition work 'in the dark', and suggests that nudges support people in adhering to their healthy eating goal.

Real-life experiments in supermarkets to encourage healthy dietary-related behaviours: opportunities, challenges and lessons learned

BACKGROUND

Supermarkets are the primary source of food for many people yet their full potential as a setting to encourage healthy dietary-related behaviours remains underutilised. Sharing the experiences from research groups who have worked with supermarket chains to evaluate strategies that promote healthy eating could improve the efficiency of building such relationships and enhance the design quality of future research studies.

METHODS

A collective case study approach was used to synthesise experiences of engaging and sustaining research collaborations with national supermarket chains to test the effectiveness of health-focused in-store interventions. The collective narrative covers studies conducted in three high-income countries: Australia, the Netherlands and the United Kingdom.

RESULTS

We have distilled our experiences and lessons learned into six recommendations for conducting high quality public health research with commercial supermarket chains. These include: (i) using personal contacts, knowledge of supermarket activities and engaging executive management to establish a partnership and allowing time to build trust; (ii) using scientifically robust study designs with appropriate sample size calculations; (iii) formalising data exchange arrangements and allocating adequate resource for data extraction and re-categorisation; (iv) assessing effects at individual/households level where possible; (v) designing a mixed-methods process evaluation to measure intervention fidelity, dose and unintended consequences; and (vi) ensuring scientific independence through formal contract agreements.

CONCLUSIONS

Our collective experiences of working in non-financial partnerships with national supermarket chains could be useful for other research groups looking to develop and implement supermarket studies in an efficient manner. Further evidence from real-life supermarket interventions is necessary to identify sustainable strategies that can improve population diet and maintain necessary commercial outcomes.

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

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.

Modeling Behavioral Economics Strategies in Social Marketing Messages to Promote Vegetable Consumption to Low-Resource Louisiana Residents: A Conjoint Analysis

BACKGROUND

Behavioral economics strategies implemented within social marketing campaigns improve eating behavior.

OBJECTIVE

To identify which behavioral economics strategies in social marketing messages particularly messengers, norms, and commitments will promote low-income Louisiana residents to add more vegetables to meals.

DESIGN

Full profile traditional conjoint analysis survey with single concept ratings.

PARTICIPANTS

Purposive sample of low-resource Louisiana residents (N = 213) SETTING: Online survey.

INTERVENTION

Participants rated randomized concepts that featured a messenger and a message.

MAIN OUTCOME MEASURE

Ratings (one to nine) of likelihood to add vegetables to meals.

STATISTICAL ANALYSIS

A model of ratings was generated using mixed-effects multiple regression, which accounted for repeated measurement of participants. Interactions of variables and covariates were modeled.

RESULTS

There was a significant main effect of the messenger variable (P = 0.02) and main effect of the message variable (P = 0.008). Pairwise comparisons demonstrated differences between friend (μ (predicted mean) = 6.80) and mother (μ = 7.06; P = 0.03) as well as friend and normal-weight doctor (μ = 7.03; P = 0.04). Pairwise comparisons demonstrated differences between descriptive norm (μ = 6.79) and grocery list precommitment (μ = 7.02; P = 0.05) along with descriptive norm and injunctive norm (μ = 6.98; P = 0.04). Covariate models demonstrated main effects of race (P = 0.006) and sex (P = 0.0001). There was significant variation in the message variable and frequency of vegetable intake interaction (P = 0.01).

CONCLUSIONS

Both message and messenger variables predicted the likelihood to add vegetables to meals. Race and sex influenced ratings to add vegetables. As reported vegetable consumption increased, behavioral economics messages improved the likelihood to add vegetables to meals. Behavioral economic approaches are well suited to social marketing messages that aim to promote healthy eating behavior in low-income LA residents.

Evaluation of two social norms nudge interventions to promote healthier food choices in a Canadian grocery store

The objective of this study was to determine the impact of two nudge interventions on customers’ produce purchases at a rural Canadian grocery store. A pre- and post-intervention observational study design was used. Sales data were gathered before and after the staggered implementation of two nudge-based interventions to encourage produce purchases: grocery cart dividers to encourage shoppers to fill one-third of their cart with produce and grocery cart plaques with information about how many fruits and vegetables were typically purchased in the store. The proportion of total sales accounted for by produce was compared between baseline and implementation of the first intervention (Phase 1), between implementation of the first intervention and the addition of the second intervention (Phase 2), and between baseline and post-implementation of both interventions together. There was a 5% relative increase (0.5% absolute increase) in produce spending between baseline and post-implementation of both interventions (10.3% to 10.8%, p < 0.001, 95% CI 0.2%, 0.7%). Intervention phase-specific produce spending showed no significant change in the percentage of produce spending from baseline to Phase 1 of the intervention, and an 8% relative increase (0.8% absolute increase) in the percentage of produce spending from Phase 1 to Phase 2 of the intervention (10.3% to 11.1%, p < 0.001, 95% CI 0.5, 1.1%). Simple, low-cost nudge interventions were effective at increasing the proportion of total grocery spend on produce. This study also demonstrated that partnerships with local businesses can promote healthier food choices in rural communities in Canada.

A dynamic social norm messaging intervention to reduce meat consumption: A randomized cross-over trial in retail store restaurants

Perceptions of social norms around eating behavior can influence food choices. Communicating information about how others are changing their eating behavior over time (dynamic descriptive social norms) may motivate individuals to change their own food selection and consumption. Following a four-week baseline period, 22 in-store restaurants of a major retail chain across the UK were randomized to display a dynamic descriptive social norm message intended to motivate a shift from meat-to plant-based meals either during the first two, or last two weeks of the four-week study period. A linear regression model showed there was no evidence of an effect of the intervention (β = -0.022, p = .978, 95% CIs: -1.63, 1.58) on the percentage sales of meat- vs plant-based dishes. Fidelity checks indicated that adherence to the intervention procedure was often low, with inconsistencies in the placement and display of the intervention message. In four stores with high fidelity the estimated impact of the intervention was not materially different. The lack of apparent effectiveness of the intervention may reflect poor efficacy of the intervention or limitations in its implementation in a complex food purchasing environment. The challenges highlighted by this study should be considered in future design and evaluation of field trials in real-world settings.

Point-of-sale nutrition information interventions in food retail stores to promote healthier food purchase and intake: A systematic review

Providing simple information that identifies healthier/less healthy products at the point-of-sale has been increasingly recognized as a potential strategy for improving population diet. This review evaluated the effect on healthiness of food purchasing/intake of interventions that identify specific products as healthier/less healthy at the point-of-sale in food retail settings. Five databases were searched for peer-reviewed randomized controlled or quasi-experimental trials published 2000-2020. Effects on primary outcomes of the 26 eligible studies (322 stores and 19,002 participants) were positive (n = 14), promising (effective under certain conditions; n = 3), mixed (different effect across treatment arms/outcomes; n = 4), null (n = 3), negative (n = 1), or unclear (n = 1). Shelf-label studies (three studies of two rating systems across all products) were positive. Technology-delivered (mobile applications/podcast/kiosk) interventions were positive (n = 3/5) or promising/mixed (n = 2/5). In-store displays (n = 16) had mixed effectiveness. Interventions provided information on targeted healthier products only (n = 17), unhealthy products only (n = 1), both healthy and unhealthy (n = 2), and across all products (n = 5). No patterns were found between behavior change technique used and effectiveness. Study quality was mixed. These findings indicate that point-of-sale interventions identifying healthy/unhealthy options can lead to healthier customer purchasing behavior, particularly those delivered using shelf-labels or technology. Further research on discouraging unhealthy foods is needed.

Increasing vegetables purchase with a descriptive-norm message: A cluster randomized controlled intervention in two university canteens

Exposure to social norms is a popular way to foster healthy food behavior. Testing the robustness of this effect, we report a field study assessing the impact of a vegetable-related descriptive norm message on vegetables purchase. The first contribution was to rely on a cluster randomized crossover design: Two canteens were randomly selected to display either a vegetable-related or a neutral-behavior norm message. After a first period of data collection, the displays were reversed for a second period: The number of vegetable portions on the main plate were recorded before, during and after the message display (N = 12.994). The second contribution was to test the impact of a message describing vegetables as the normative choice beyond the mere selection of vegetables, on the quantity of vegetables purchased in lunches containing some. Results indicated that the vegetable-related norm message led to a sustained probability of choosing vegetables, contrary to a decrease observed in the control condition. Moreover, students who ordered vegetables ordered a higher quantity when exposed to a vegetable-related message than before whereas quantity declined in the control condition. By treating both canteens as experimental and control and by analyzing both the presence and the amount of vegetables, these results extend and strengthen those previously observed, bringing support for the effectiveness of a descriptive norm message in eliciting healthier food behavior.

Invitations and incentives: a qualitative study of behavioral nudges for primary care screenings in Armenia

BACKGROUND

Non-communicable diseases account for a growing proportion of deaths in Armenia, which require early detection to achieve disease control and prevent complications. To increase rates of screening, demand-side interventions of personalized invitations, descriptive social norms, labeled cash transfers, and conditional cash transfers were tested in a field experiment. Our complementary qualitative study explores factors leading to the decision to attend screening and following through with that decision, and experiences with different intervention components.

METHODS

Informed by the Health Belief Model as our conceptual framework, we collected eighty in-depth interviews with service users and twenty service providers and analyzed them using open coding and thematic analysis.

RESULTS

An individual's decision to screen depends on 1) the perceived need for screening based on how they value their own health and perceive hypertension and diabetes as a harmful but manageable condition, and 2) the perceived utility of a facility-based screening, and whether screening will provide useful information on disease status or care management and is socially acceptable. Following through with the decision to screen depends on their knowledge of and ability to attend screenings, as well as any external motivators such as an invitation or financial incentive.

CONCLUSIONS

Personalized invitations from physicians can prompt individuals to reconsider their need for screening and can, along with financial incentives, motivate individuals to follow through with the decision to screen. The effect of descriptive social norms in invitations should be further studied. Efforts to increase preventive screenings as an entry point into primary care in Armenia may benefit from implementation of tailored messages and financial incentives.

TRIAL REGISTRATION

The protocol was approved on January 11, 2019 by the Institutional Review Board of the Center of Medical Genetics and Primary Health Care in Armenia (02570094). https://www.socialscienceregistry.org/trials/3776 .