Cooperative and caring behaviors are key drivers of human social progress, especially during catastrophes or pandemic events. While COVID-19 pandemics was arriving to Colombia in absence of any approved therapeutic strategy or vaccine, and based on evidence from other viral diseases, we anticipated to hypothesize the protective role of some nutritional supplements such as Vitamin D and C against SARS-CoV2. Therefore, for health workers, we proposed a voluntarily nutritional supplementation plan to fortify their immune system aiming to prevent or mitigate eventual COVID-19 infection and disease. Using the behavioral EAST framework, all our health workers (n = 1,063) were invited via email to participate voluntarily in a supplementation strategy for a period of 3 months. 77.4% accepted participation, and among them, we identified a group with optimal adherence to the proposed supplementation plan (20%) and a predominant group with no adherence at all (57.29%). Adherence seemed to be associated to a risk perception bias that was predominant in female workers and those workers performing in working areas with higher risk of infection. Of importance, adherence to the supplementation strategy was associated to a lower percentage of COVID-19 diagnostics (12%) as compared with that observed in non-adherence participants (19%). Moreover, the sustained adherence during the time of intervention seemed to promote adoption of this target behavior, as up to 35% of the adherent participants remained attached (on their own) to the supplementation habit, 3 months after the end of the intervention. All these data show the potential relevance of EAST frameworks as tools to trigger health care and altruistic behaviors to avoid the spread of pandemic diseases. In line with other authors, our observations suggest that nutritional vitamin D and C supplementation could mitigate the risk of COVID-19, highlighting the behavioral and biological relevance of this type of interventions during emerging or re-emerging infectious diseases.

Effective communication is essential for delivering public health messages and enabling behaviour change. Little is known about possible backfiring, or spillover effects, of COVID-19 vaccine messaging. In a study with n = 1,848 United Kingdom (UK) adults, we assess whether communication strategies that target vaccine hesitancy have any unintended, positive or negative, spillover effects on people's intention to engage in protective, compliance and prosocial behaviours. In June–July 2021, we conducted an online experiment to assess the potential spillover effects of three messages, emphasising (a) the medical benefits of COVID-19 vaccination, (b) the non-medical collective benefits of vaccination or (c) the non-medical individual benefits of holding a vaccination certificate. Exposure to different messages did not significantly affect people's intention to engage in protective, compliance, or prosocial behaviours. Instead, vaccination status (being vaccinated vs not) was positively associated with intentions to engage in protective, compliance and prosocial behaviours. Our results suggest that communication strategies that aim to increase vaccination uptake do not have any unintended effects on other health behaviours and vaccination campaigns can be tailored to specific populations to increase uptake and compliance.

Humankind's main defence against the virus that causes COVID-19 (SARS-CoV-2), besides vaccine development, was co-ordinated behaviour change. In many countries, co-ordination was assisted by tracking surveys designed to measure self-reported behaviour and attitudes. This paper describes an alternative, complementary approach, which was undertaken in close collaboration with officials in the Department of the Taoiseach (Irish Prime Minister). We adapted the Day Reconstruction Method (DRM) to develop the ‘Social Activity Measure’ (SAM). The study was conducted fortnightly for 18 months, with findings delivered directly to the Department. This paper describes the method and shows how SAM generated a detailed picture of where and why transmission risk occurred. By using the DRM, we built aggregate measures from narrative accounts of how individuals spent their previous day. SAM recorded the amount, location and type of social activity, including the incidence of close contact and mask-wearing, as well as compliance with public health restrictions by shops and businesses. The method also permitted a detailed analysis of how public perceptions and comprehension are related to behaviour. The results informed government communications and strategies for lifting public health restrictions. The method could be applied to other future situations that might require co-ordinated public behaviour over an extended period.

A reduction in the demand for meat and particularly red meat has the potential to significantly enhance the sustainability and health of many people's diets. In the current work, I examine situational predictors of meat consumption in nationally representative nutrition surveys from three Western European countries: Switzerland, France and the Netherlands. More specifically, I examine whether the situational factors – the meal type, the day of the week and the location of the food consumption occasion – are predictive of whether meat and red meat are consumed. The results indicate that all three factors are linked to meat and red meat consumption with the patterns varying substantially across the different case study countries and in some cases also the gender of the consumer. The results emphasise the value of mapping situational correlates to inform situated interventions aimed at influencing meat consumption, while also highlighting important differences across both cultures and people.

Behavioural science has sought to promote pro-environmental behaviours including climate-friendly dietary change, and to reduce travel emissions and excessive wastes. Nevertheless, there is a debate about how effective behavioural interventions are, and in turn, about the real barriers to enduring pro-environmental behaviour change. In this context, we conceptualise brown sludge as multi-level impediment to pro-environmental behaviour change, which results in higher environmental costs shared by the broader society, rather than solely by the individual actor. We propose that brown sludge comprises an array of additional transaction costs, encompassing, but not restricted to, psychological, temporal, and uncertainty costs. Brown sludge can occur at the individual, social, institutional, and societal levels. Examples include confusing eco-information, delay and disinformation campaigns, and complicated systems and infrastructure leading to carbon lock-in.

Whether nudges succeed in promoting pro-environmental behavior strongly depends on their public acceptance. Prior literature shows that the framing of nudges, i.e., whether they address the individual (personal framing) or the society (societal framing), is one critical factor in determining nudging acceptance. Since a personal framing highlights the costs individuals have to bear to comply, we hypothesize that people accept nudges more when addressing the general public rather than themselves personally. We expect the framing effect to be stronger for nudges that elicit high-effort behavior than low-effort behavior. Results of multilevel linear regression analyses in two online experiments (nStudy 1 = 294, nobs = 4,410; nStudy 2 = 565, nobs = 11,300) reveal an opposite pattern: People accept nudges more when personally (vs societally) framed. As predicted, nudges receive higher support when the promoted behavior is perceived as low effort. Exploratory path analysis in Study 2 shows that the perceived effectiveness of the nudge mediates the positive relation between personal framing and nudging acceptance. This project provides novel insights on facilitators and barriers in nudging acceptance and their implications for policy-making.

We conducted a large-scale online experiment to examine whether climate change messaging can induce emotions and motivate pro-environmental action. We study how exposure to explicit positive (‘warm glow’) and negative (‘cold prickle’) emotional appeals as well as a traditional social norm communication affects pro-environmental action. We find that a simple call to take action to mitigate climate change is at least as affective as social norm message framing and emotional appeals. Our results highlight the difficulty of designing messaging interventions that effectively harness emotional incentives to promote pro-environmental action. Messages that explicitly emphasise the personal emotional benefits of contributing to environmental causes or the adverse emotional effects of not doing so seem to fall short of motivating pro-environmental effort. Our findings underscore the need for caution when incorporating emotive appeals into policy interventions.

Financial policymakers increasingly rely on behavioural insights to protect the interests of consumers. However, little is known about how citizens feel about interventions designed to nudge their financial behaviour. Most literature on the acceptability of behavioural interventions focuses on the health domain. To address this gap, we present the results of an experiment on the acceptability of seven financial behavioural interventions (N = 684, members of a panel of the Dutch Authority for the Financial Markets). We investigate the role of the agent implementing the intervention (policymaker versus financial company) and perceived effectiveness in relation to the acceptability of these interventions. The acceptability of behavioural interventions in financial decision-making appears to be lower than the acceptability levels found in previous studies. We find no effect of the agent on acceptability. Perceived effectiveness is strongly correlated with acceptability, but only perceived effectiveness in influencing one's own decisions has a consistently positive relationship with acceptability. Perceived effectiveness in influencing others' decisions has either no, a positive, or a negative relationship with acceptability. These results highlight that acceptability appears to be at least partly domain-specific and show that we have only just begun understanding the acceptability of behavioural interventions and its drivers.

Recently, there has been a lively discussion of “Hayekian Behavioral Economics” in Behavioral Public Policy). We aim to contribute to this debate by identifying the main building blocks of a Hayekian psychology. We highlight that the starting point for Hayek was the quest to understand why humans are typically quite successful in navigating the world. In Hayek's framework, the individual mind is conceptualized as a “system within a system”, i.e., the mind is a complex adaptive system that is continuously interacting with the wider socio-cultural system. Three core ideas are central to a Hayekian psychology: subjectivity, learning and adaptation. We argue that these ideas are quite different from the still dominant heuristics-and-biases perspective and lead to different emphases in economic and social science explanations. One, economists should be cautious in their interpretation of experimental findings since subjective meaning is central to agents' behavior. Two, static and isolated models of individuals' biases might underestimate people's capacity to learn with and from others. And three, despite complex processes of adaptation of the mind and the market, a Hayekian framework is consistent with economists' “explanations of the principle” and “pattern predictions.”

Promoting agency – people's ability to form intentions and to act on them freely – must become a primary objective for Behavioural Public Policy (BPP). Contemporary BPPs do not directly pursue this objective, which is problematic for many reasons. From an ethical perspective, goals like personal autonomy and individual freedom cannot be realised without nurturing citizens’ agency. From an efficacy standpoint, BPPs that override agency – for example, by activating automatic psychological processes – leave citizens ‘in the dark’, incapable of internalising and owning the process of behaviour change. This may contribute to non-persistent treatment effects, compensatory negative spillovers or psychological reactance and backfiring effects. In this paper, we argue agency-enhancing BPPs can alleviate these ethical and efficacy limitations to longer-lasting and meaningful behaviour change. We set out philosophical arguments to help us understand and conceptualise agency. Then, we review three alternative agency-enhancing behavioural frameworks: (1) boosts to enhance people's competences to make better decisions; (2) debiasing to encourage people to reduce the tendency for automatic, impulsive responses; and (3) nudge+ to enable citizens to think alongside nudges and evaluate them transparently. Using a multi-dimensional framework, we highlight differences in their workings, which offer comparative insights and complementarities in their use. We discuss limitations of agency-enhancing BPPs and map out future research directions.

Transparency is intimately linked to debates about the ethics, political legitimacy and effectiveness of nudging. This paper provides an overview of empirical studies investigating how changes in the transparency of a nudge affect people's choices and evaluations of the nudge. I conclude that the present literature provides generally consistent evidence supporting that the effectiveness of a nudge does not decrease when choosers are given good opportunity to detect and understand the influence it might have on their choices. However, several conceptual and methodological issues are identified, significantly limiting the scope of the conclusions that can be drawn. The limitations are discussed and organized into six themes, with recommendations provided for how future research may address them.