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.

Prompting vegetable purchases in the supermarket by an affordance nudge: Examining effectiveness and appreciation in a set of field experiments.

The supermarket is a promising location for stimulating healthier food choices by nudging interventions. However, nudging healthy food choices in the supermarket has shown weak effects to date. The present research introduces a new nudge based on the concept of affordances - i.e., an animated character - that invites interaction with healthy food products and examines its effectiveness and appreciation in a supermarket context. We present findings of a series of three studies. In Study 1, evaluations of the new nudge were collected, revealing that the nudge was appreciated. In Studies 2 and 3, field experiments were conducted to test the nudge's effect on vegetable purchases in a real-life supermarket. Study 3 demonstrated that vegetable purchases increased significantly (up to 17%) when the affordance nudge was placed on the vegetable shelves. Furthermore, customers appreciated the nudge and its potential for implementation. Taken together, this set of studies presents compelling findings illustrating the potential of the affordance nudge for increasing healthy choices in the supermarket.

Under pressure: Nudging increases healthy food choice in a virtual reality supermarket, irrespective of system 1 reasoning.

Previous research has shown that nudging can effectively support people's healthy food choices. Yet, to date knowledge about the psychological premises of nudging is limited, highlighting the need for closer scrutiny to determine how and when nudging is most effective. In the current study, we assessed whether the presumed effect of nudging on healthy food choice is enhanced under time pressure, a condition probing alleged system 1 reasoning. Food choice was studied in a realistic virtual reality supermarket where healthier alternatives were nudged by making them more salient. We additionally explored possible differences in decision-making experiences related to nudging or time pressure. The study took place at a science festival where visitors could decide to participate in a study. Participants (n = 99) had to purchase four products, each from a different product category that was provided on a shopping list. In the nudging condition, one healthier option within each product category was nudged by making it more salient. While a main effect of nudging was found, showing in increased healthy food choices, this effect was not further qualified by time pressure, suggesting that the effectiveness of nudging is not enhanced under system 1 conditions. Relatedly, people who were and who were not aware of the nudges showed similar effects of nudging on healthy food choice. Furthermore, no differences in decision-making experiences showed, suggesting that people have similar experiences regarding impulsive and reflective decision-making irrespective of whether they are being nudged or put under time pressure. All in all, our findings are in line with recent viewpoints on the premises of nudges, suggesting that alleged system 1 conditions are not a prerequisite for nudging to be effective.

The effects of nudges on purchases, food choice, and energy intake or content of purchases in real-life food purchasing environments: a systematic review and evidence synthesis.

BACKGROUND: Adults with a low socioeconomic position (SEP) are more likely to engage in unhealthy diets as compared to adults with high SEP. However, individual-level educational interventions aiming to improve food choices have shown limited effectiveness in adults with low SEP. Environmental-level interventions such as nudging strategies however, may be more likely to benefit low SEP groups. We aimed to review the evidence for the effectiveness of nudges as classified according to interventions in proximal physical micro-environments typology (TIPPME) to promote healthy purchases, food choice, or affecting energy intake or content of purchases, within real-life food purchasing environments. Second, we aimed to investigate the potentially moderating role of SEP. METHODS: We systematically searched PubMed, EMBASE, and PsycINFO until 31 January 2018. Studies were considered eligible for inclusion when they i) complied with TIPPME intervention definitions; ii) studied actual purchases, food choice, or energy intake or content of purchases, iii) and were situated in real-life food purchasing environments. Risk of bias was assessed using a quality assessment tool and evidence was synthesized using harvest plots. RESULTS: From the 9210 references identified, 75 studies were included. Studies were generally of weak to moderate quality. The most frequently studied nudges were information (56%), mixed (24%), and position nudges (13%). Harvest plots showed modest tendencies towards beneficial effects on outcomes for information and position nudges. Less evidence was available for other TIPPME nudging interventions for which the harvest plots did not show compelling patterns. Only six studies evaluated the effects of nudges across levels of SEP (e.g., educational level, food security status, job type). Although there were some indications that nudges were more effective in low SEP groups, the limited amount of evidence and different proxies of SEP used warrant caution in the interpretation of findings. CONCLUSIONS: Information and position nudges may contribute to improving population dietary behaviours. Evidence investigating the moderating role of SEP was limited, although some studies reported greater effects in low SEP subgroups. We conclude that more high-quality studies obtaining detailed data on participant's SEP are needed. REGISTRATION: This systematic review is registered in the PROSPERO database ( CRD42018086983 ).

Reducing cardiometabolic risk in adults with a low socioeconomic position: protocol of the Supreme Nudge parallel cluster-randomised controlled supermarket trial.

BACKGROUND: Unhealthy lifestyle behaviours such as unhealthy dietary intake and insufficient physical activity (PA) tend to cluster in adults with a low socioeconomic position (SEP), putting them at high cardiometabolic disease risk. Educational approaches aiming to improve lifestyle behaviours show limited effect in this population. Using environmental and context-specific interventions may create opportunities for sustainable behaviour change. In this study protocol, we describe the design of a real-life supermarket trial combining nudging, pricing and a mobile PA app with the aim to improve lifestyle behaviours and lower cardiometabolic disease risk in adults with a low SEP. METHODS: The Supreme Nudge trial includes nudging and pricing strategies cluster-randomised on the supermarket level, with: i) control group receiving no intervention; ii) group 1 receiving healthy food nudges (e.g., product placement or promotion); iii) group 2 receiving nudges and pricing strategies (taxing of unhealthy foods and subsidizing healthy foods). In collaboration with a Dutch supermarket chain we will select nine stores located in low SEP neighbourhoods, with the nearest competitor store at > 1 km distance and managed by a committed store manager. Across the clusters, a personalized mobile coaching app targeting walking behaviour will be randomised at the individual level, with: i) control group; ii) a group receiving the mobile PA app. All participants (target n = 1485) should be Dutch-speaking, aged 45-75 years with a low SEP and purchase more than half of their household grocery shopping at the selected supermarkets. Participants will be recruited via advertisements and mail-invitations followed by community-outreach methods. Primary outcomes are changes in systolic blood pressure, LDL-cholesterol, HbA1c and dietary intake after 12 months follow-up. Secondary outcomes are changes in diastolic blood pressure, blood lipid markers, waist circumference, steps per day, and behavioural factors including healthy food purchasing, food decision style, social cognitive factors related to nudges and to walking behaviours and customer satisfaction after 12 months follow-up. The trial will be reflexively monitored to support current and future implementation. DISCUSSION: The findings can guide future research and public health policies on reducing lifestyle-related health inequalities, and contribute to a supermarket-based health promotion intervention implementation roadmap. TRIAL REGISTRATION: Dutch Trial Register ID NL7064, 30th of May, 2018.

Improving cardiometabolic health through nudging dietary behaviours and physical activity in low SES adults: design of the Supreme Nudge project.

BACKGROUND: Initiating and maintaining a healthy lifestyle -including healthy eating and sufficient physical activity- is key for cardiometabolic health. A health-promoting environment can facilitate a healthy lifestyle, and may be especially helpful to reach individuals with a lower socio-economic status (SES). In the Supreme Nudge project, we will study the effects of pricing and nudging strategies in the supermarket - one of the most important point-of-choice settings for food choices - and of a context-specific mobile physical activity promotion app. This paper describes the stepwise and theory-based design of Supreme Nudge, which aims to develop, implement and evaluate environmental changes for a sustained impact on lifestyle behaviours and cardiometabolic health in low SES adults. METHODS: Supreme Nudge uses a multi-disciplinary and mixed methods approach, integrating participatory action research, qualitative interviews, experimental pilot studies, and a randomized controlled trial in a real-life (supermarket) setting. First, we will identify the needs, characteristics and preferences of the target group as well as of the participating supermarket chain. Second, we will conduct a series of pilot studies to test novel, promising and feasible intervention components. Third, a final selection of intervention components will be implemented in a full-scale randomised controlled supermarket trial. Approximately 1000 low SES adults will be recruited across 8-12 supermarkets and randomised at supermarket level to receive 1) no intervention (control); 2) environmental nudges such as food product placement or promotion; 3) nudges and a tailored physical activity app that provides time- and context specific feedback; 4) pricing interventions, nudges, and the physical activity app. The effects on dietary behaviours and physical activity will be evaluated at 3, 6 and 12 months, and on cardiometabolic health at 6 and 12 months. Finally, we will evaluate the Reach, Effectiveness, Adoption, Implementation and Maintenance (RE-AIM) of the intervention, and we will use insights from System Innovation and Transition Management theories to define the best strategies for implementation and upscaling beyond the study period. DISCUSSION: The Supreme Nudge project is likely to generate thorough evidence relevant for policy and practice on the effects of a mixed method and multi-disciplinary intervention targeting dietary behaviours and physical activity. TRIAL REGISTRATION: The real-life trial has been registered on 30 May 2018, NTR7302 .

Spontaneous eye blink rate and dopamine synthesis capacity: preliminary evidence for an absence of positive correlation.

Dopamine is central to a number of cognitive functions and brain disorders. Given the cost of neurochemical imaging in humans, behavioural proxy measures of dopamine have gained in popularity in the past decade, such as spontaneous eye blink rate (sEBR). Increased sEBR is commonly associated with increased dopamine function based on pharmacological evidence and patient studies. Yet, this hypothesis has not been validated using in vivo measures of dopamine function in humans. To fill this gap, we measured sEBR and striatal dopamine synthesis capacity using [18 F]DOPA PET in 20 participants (nine healthy individuals and 11 pathological gamblers). Our results, based on frequentist and Bayesian statistics, as well as region-of-interest and voxel-wise analyses, argue against a positive relationship between sEBR and striatal dopamine synthesis capacity. They show that, if anything, the evidence is in favour of a negative relationship. These results, which complement findings from a recent study that failed to observe a relationship between sEBR and dopamine D2 receptor availability, suggest that caution and nuance are warranted when interpreting sEBR in terms of a proxy measure of striatal dopamine.

Feeding Releases Endogenous Opioids in Humans.

The endogenous opioid system supports a multitude of functions related to appetitive behavior in humans and animals, and it has been proposed to govern hedonic aspects of feeding thus contributing to the development of obesity. Here we used positron emission tomography to investigate whether feeding results in hedonia-dependent endogenous opioid release in humans. Ten healthy males were recruited for the study. They were scanned with the µ-opioid-specific ligand [11C]carfentanil three times, as follows: after a palatable meal, a nonpalatable meal, and after an overnight fast. Subjective mood, satiety, and circulating hormone levels were measured. Feeding induced significant endogenous opioid release throughout the brain. This response was more pronounced following a nonpalatable meal versus a palatable meal, and independent of the subjective hedonic responses to feeding. We conclude that feeding consistently triggers cerebral opioid release even in the absence of subjective pleasure associated with feeding, suggesting that metabolic and homeostatic rather than exclusively hedonic responses play a role in the feeding-triggered cerebral opioid release.SIGNIFICANCE STATEMENT The endogenous opioid system supports both hedonic and homeostatic functions. It has been proposed that overeating and concomitant opioid release could downregulate opioid receptors and promote the development of obesity. However, it remains unresolved whether feeding leads to endogenous opioid release in humans. We used in vivo positron emission tomography to test whether feeding triggers cerebral opioid release and whether this response is associated with pleasurable sensations. We scanned volunteers using the µ-opioid receptor-specific radioligand [11C]carfentanil three times, as follows: after an overnight fast, after consuming a palatable meal, and after consuming a nonpalatable meal. Feeding led to significant endogenous opioid release, and this occurred also in the absence of feeding-triggered hedonia. Feeding-triggered opioid release thus also reflects metabolic and homeostatic responses rather than hedonic responses exclusively.