Policy decisions have vast consequences, but there is little empirical research on how best to communicate underlying evidence to decision-makers. Groups in diverse fields (e.g., education, medicine, crime) use brief, graphical displays to list policy options, expected outcomes and evidence quality in order to make such evidence easy to assess. However, the understanding of these representations is rarely studied. We surveyed experts and non-experts on what information they wanted and tested their objective comprehension of commonly used graphics. A total of 252 UK residents from Prolific and 452 UK What Works Centre users interpreted the meaning of graphics shown without labels. Comprehension was low (often below 50%). The best-performing graphics combined unambiguous metaphorical shapes with color cues and indications of quantity. The participants also reported what types of evidence they wanted and in what detail (e.g., subgroups, different outcomes). Users particularly wanted to see intervention effectiveness and quality, and policymakers also wanted to know the financial costs and negative consequences. Comprehension and preferences were remarkably consistent between the two samples. Groups communicating evidence about policy options can use these results to design summaries, toolkits and reports for expert and non-expert audiences.

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.

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.

When policymakers focus on costs and benefits, they often find that hard questions become easy – as, for example, when the benefits clearly exceed the costs, or when the costs clearly exceed the benefits. In some cases, however, benefits or costs are difficult to quantify, perhaps because of limitations in scientific knowledge. In extreme cases, policymakers are proceeding in circumstances of uncertainty rather than risk, in the sense that they cannot assign probabilities to various outcomes. We suggest that in difficult cases in which important information is absent, it is useful for policymakers to consider a concept from poker: ‘freerolls.’ A freeroll exists when choosers can lose nothing from selecting an option but stand to gain something (whose magnitude may itself be unknown). In some cases, people display ‘freeroll neglect.’ In terms of social justice, John Rawls’ defense of the difference principle is grounded in the idea that, behind the veil of ignorance, choosers have a freeroll. In terms of regulatory policy, one of the most promising defenses of the Precautionary Principle sees it as a kind of freeroll. Some responses to climate change, pandemics and financial crises can be seen as near-freerolls. Freerolls and near-freerolls must be distinguished from cases involving cumulatively high costs and also from faux freerolls, which can be found when the costs of an option are real and significant, but not visible. ‘Binds’ are the mirror-image of freerolls; they involve options from which people are guaranteed to lose something (of uncertain magnitude). Some regulatory options are binds, and there are faux binds as well.

Meat-based food production has a detrimental impact on the environment and health. In response, Veganuary (an international non-profit organisation) encourages people to go vegan each January. We investigated the effects of a Veganuary campaign in workplace cafeterias which increased the availability and salience of plant-based products. We conducted an interrupted time series analysis on a large dataset from a UK catering company, which comprised 2,255,404 meals sold between 2016 and 2022, with Veganuary activity starting from 2019. Analysis indicated that Veganuary activity had a positive effect on sales of vegan products in 2020, 2021 and 2022, estimated at an initial increase of 86–113% in the proportion of weekly sales (relative to the baseline, depending on year). The effects of the 2020 and 2021 campaigns were still present – at approximately one third of their initial magnitude – one year following the campaigns. There was a positive effect on vegetarian products in 2019, 2021 and 2022; initial effects were smaller – 23–79% – due to higher levels of pre-campaign consumption. The effects of the 2019 and 2021 campaigns endured, with a small impact present after one year for 2019 and six months for 2021.

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.

Daniel Kahneman's legacy is best understood in light of developments in economic theory in the early-mid-20th century, when economists were eager to put utility functions on a firm mathematical foundation. The axiomatic system that provided this foundation was not originally intended to be normative in a prescriptive sense but later came to be seen that way. Kahneman took the axioms seriously, tested them for descriptive accuracy, and found them wanting. He did not view the axioms as necessarily prescriptive. Nevertheless, in the research program he conceived, factual discoveries about real decision-making were stated as deviations from the axioms and thus deemed ‘errors’. This was an unfortunate turn that needs to be corrected for the psychological enrichment of economics to proceed in a productive direction.

Debtors were stimulated to contact their creditors to negotiate a repayment plan. Contacting creditors was important because debtors were unlikely to repay the debt immediately and upon contacting, debtors could agree on a repayment plan to repay the debt in the long run. Using insights from scarcity theory and nudging techniques, a standard debt repayment letter was adapted and both letters were compared. Experimental results (N = 3,330) provide support for the use of nudging techniques as more debtors agreed on a repayment plan and response rates increased. The results underline the importance of stimulating debtors to contact their creditors.