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.

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.

Many foodborne illness outbreaks originate in food service establishments. We tested two behavioural interventions designed to improve the duration and quality of handwashing. We ran a three-armed parallel trial in a laboratory kitchen, from 7 March to 27 May 2022. Participants were n = 195 workers who handle food. We randomly allocated participants to three groups: Timer – tap-mounted timer that counted seconds while participants washed their hands; Precommitment – agreed to five statements on good hand hygiene before attending the kitchen; and Control. Participants completed a food preparation task under time pressure. Cameras focused on the sink captured handwashing. Outcome measures were number of times participants washed their hands; number of times they washed their hands using soap; number of times they washed using soap and washed the backs of their hands; and mean duration of handwashing attempts using soap. Participants in Timer washed their hands for 1.9 s longer on average than Control (β = 2.20, 95% CI = 0.34-4.06, p = 0.021). Participants in Precommitment washed their hands for 2.5 s longer on average than Control (β = 2.30, 95% CI = 0.33-4.27, p = 0.022). We found no statistically significant differences on any other outcome measure.

This study examines how beliefs interact with heterogeneous donation preferences in determining people's donation decisions and choices of revision and observability. We conducted an online experiment eliciting participants’ first-order beliefs, that is, beliefs about an average donor's contribution, with the opportunity of being recognized. We also provided the opportunity for donation revision to a group of randomly selected participants. Our study results show that people's first-order beliefs are positively correlated with their willingness to donate and their actual donations. Moreover, first-order beliefs also interact with people's heterogeneous donation preferences in jointly determining their decisions of donation revision and observability – their tendency to opt in for public recognition. Donors with low first-order beliefs and high donation preferences are most likely to opt in for recognition, but they are unlikely to revise their donations. Donors with high first-order beliefs and low donation preferences are most likely to revise their donations, but they are less likely to choose to be recognized. Donors with low first-order beliefs and low donation preferences display the lowest tendency toward revision and observability.

Consequentialist theories of the behavioral state are largely grounded in satisfying self-interested preferences through policies that employ choice architecture and related strategies to encourage rational decision-making. Even when allowing for free choice, however, this stance tends to be characterized by a paternalistic ‘view from nowhere’ that may not fully accommodate a plurality of values. Alternative approaches such as contractarianism position policy in the context of marketplace exchange, bolstered by shared beliefs in the legitimacy of social institutions. Yet this view may not sufficiently consider issues of asymmetric access, or ideological frames that do not see these institutions as legitimate. To address these deficits, we propose the value of a dialogical approach to behavioral public policy that facilitates collaborative engagement and behavioral justice to redress asymmetries and inequities through a more discursive approach, which builds on practices employed by design for public policy. In so doing, this political theory suggests an actionable counterpoint to paternalistic and competition-based conceptions of the State to address frame plurality and increase the potential for system equity.

This paper explores the complexities and unintended consequences of conflict of interest (COI) disclosures in various professional settings. It highlights key psychological processes encountered by recipients of such disclosures. Notably, it describes the burden of disclosure effect, which paradoxically reduces trust while increasing compliance due to social pressures, and disclosure's expertise cue, where disclosures inadvertently increase trust and persuasiveness by signalling expertise. The paper also outlines best practices for improving COI disclosures, emphasising the need for external third-party involvement and encouraging deliberation. It concludes that effective disclosure depends not only on how recipients process information but also critically on how the disclosure influences the behaviour of advisors, underscoring the need for a holistic approach to managing COIs that goes beyond mere transparency. A version of this paper was presented as a keynote at the Second Annual International Behavioural Public Policy Conference at the University of North Carolina in September 2023.

Similarly to other domains of the social sciences, behavioural science has grappled with a crisis concerning the effect sizes of research findings. Different solutions have been provided to answer this challenge. This paper will discuss analytical strategies developed in the context of computational social science, namely causal tree and forest, that will benefit behavioural scientists in harnessing heterogeneity of treatment effects in RCTs. As a mixture of theoretical and data-driven approaches, these techniques are well suited to exploit the rich information provided by large studies conducted using RCTs. We discuss the characteristics of these methods and their methodological rationale and provide simulations to illustrate their use. We simulate two scenarios of RCTs-generated data and explore the heterogeneity of treatment effects using causal tree and causal forest methods. Furthermore, we outlined a potential theoretical use of these techniques to enrich behavioural science ecological validity by introducing the notion of behavioural niche.

Companies face increasing pressure to adopt social responsibility initiatives while simultaneously providing shareholder value. However, consumers may respond negatively to ‘win-win’ initiatives that benefit society while bringing financial gain to the corporation, producing a backlash effect. Previous researchers have attributed this backlash effect to the violation of a communal relationship norm that companies trigger in consumers when communicating their win-win initiatives. We propose the alternative hypothesis that the backlash derives from people's deception aversion. We find evidence supporting deception aversion in three preregistered studies showing that companies are evaluated negatively when their actions differ from those implied by their stated prosocial policy and not, as predicted by the communal norm violation hypothesis, when they merely earn a profit. Our results suggest that companies should not fear that earning a profit from prosocial activities will carry reputational risk, so long as they are transparent.

Compliance with hygiene and other safety measures in the workplace was an important component of society's strategy for reducing infections at the onset of the COVID-19 pandemic, in particular before vaccinations were widely available. We report the results of a field trial of well-established behavioural interventions (social norms, pledging and messenger effects) we implemented to improve compliance with such measures in an occupational setting. We use daily reports of own and other's behaviour to assess the effects of these interventions and supplement these subjective (self-reported) measures with objective data on hand sanitiser usage. The behavioural interventions tested have statistically significant but quantitatively moderate effects on subjective compliance measures and minimal effects on hand sanitiser usage. All effects of our interventions are short-term in nature and dissipate shortly after implementation. Our findings thus provide at most weak support for the notion that typical behavioural interventions can help support compliance with infection prevention measures in the workplace.

Boosts and nudges are two separate types of behavioral public policies, distinguished by the mechanisms through which they operate. We investigated whether this theoretical distinction translates into different effects when instances of these policy types are implemented in the context of energy consumption. In a long-term field randomized controlled trial, we competitively tested boosts against nudges. We found that boosts outperform nudges throughout a seven-month period in a student dormitory setting – both in terms of accumulated energy savings, as well as in keeping consumption consistently low during the experimental period. Furthermore, we explored the processes behind the boosts and nudges through a number of mechanistic markers and showed that the tested interventions indeed are instances of the respective types.

Political scientists have proposed that party cues can be used to compensate for the public's well-documented lack of substantive political knowledge, but some critics have argued that applying party cues is more difficult than assumed. We argue that this debate has proven intractable in part because scholars have used ambiguous normative criteria to evaluate judgments. We use a unique task and clear normative criteria to evaluate the use of party cues in making political judgments among two samples: a sample of state legislators and an online sample of the public. We find that the public sample performs poorly when using cues to make judgments. State legislators make much more accurate judgments on average than even the most attentive segment of the public and are more likely to place less weight on irrelevant cues when making judgments, although there is evidence that both samples performed worse with the inclusion of non-diagnostic cues. We conclude with a discussion of the relevance of the results, which we interpret as showing that party cue use is more difficult than theorized, and discuss some practical implications of the findings.

Why are take up rates incomplete or low when the relevant opportunities are unambiguously advantageous to people who are eligible for them? How can public officials promote higher take up of opportunities? All over the world, these are challenges of the first order. There are three primary barriers to take up: learning costs, compliance costs, and psychological costs. These costs lower the net expected benefit of opportunities, and reduce participation in otherwise advantageous programs. Fully rational agents would consider these costs in their take up decisions, and in light of behavioral biases, such costs loom especially large and may seem prohibitive. Experimental and other evidence suggest methods for reducing the barriers to take up and the effects of behavioral biases. Use of such methods has the potential to significantly increase access to a wide range of opportunities that would increase individual well-being and social welfare.

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.

Dark patterns are user interface design elements which harm users but benefit vendors. These harms have led to growing interest from several stakeholders, including policymakers. We develop a high-level analytical framework – the dark patterns auditing framework (DPAF) – to support policymaker efforts concerning dark patterns. There are growing links between dark patterns and the behavioural science concept of sludge. We examine both literatures, noting several worthwhile similarities and important conceptual differences. Using two ‘sludge audits,’ and the DPAF, we examine 14 large online services to provide a high-level review of the user experience of these services. Our approach allows policymakers to identify areas of the user ‘journey’ (dark paths) where sludge/dark patterns persist. For regulators with constrained resources, such an approach more be advantageous when planning more granular analyses. Our approach also reveals several important limitations, notably, within some of the tools for sludge auditing which we develop, such as the ‘equal clicks principle.’ We discuss these limitations and directions for future research.

The effectiveness and uptake of financial incentives can differ substantially between reward- and deposit-based incentives. Therefore, it is unclear to whom and how different incentives should be assigned. In this study, the effect of different modes of assigning reward- and deposit-based financial incentives on effort is explored in a two-session experiment. First, students’ (n = 228, recruited online) discounting, loss aversion and willingness to pay a deposit were elicited. Second, an incentivized real-effort task was completed (n = 171, 25% drop-out). Two modes of assigning reward- or deposit-based financial incentives were compared: random assignment and ‘nudged’ assignment – assignment based on respondent characteristics allowing opting out. Our results show that respondents receiving nudged assignment earned more and persisted longer on the real-effort task than respondents randomly assigned to incentives. We find no differences in effectiveness between reward-based or deposit-based incentives. Overall, 39% of respondents in the nudged assignment mode followed-up the advice to take deposit-based incentives. The effect of deposit-based incentives was larger for the respondents who followed-up the advice than for respondents that randomly received deposit-based incentives. Overall, these findings suggest that nudged assignment may increase incentives’ effect on effort. Future work should extend this approach to other contexts (e.g., behaviour change).

Existing regulation in the UK states that the term ‘milk’ can only be used in labelling to describe products that originate from animals. We conducted an observational study, which surveyed the availability and labelling of milk substitutes in UK supermarkets, and an online experimental study, which assessed the impact of using the term ‘milk’ on milk substitute labelling. In the experimental study, 352 UK adults were randomised to one of the two conditions where they saw milk substitutes that were either labelled with UK regulations (e.g., soya drink) or using the term ‘milk’ (e.g., soya milk). Our primary aims were to assess whether adding the term ‘milk’ to labels would (1) more accurately communicate the uses of milk substitutes or (2) confuse consumers about which products come from an animal source. In our observational study, milk substitutes were readily available and labelling varied significantly. In our experimental study, labelling products with the term ‘milk’ increased understanding of the product's use. However, participants who saw the term ‘milk’ on milk substitute labelling misidentified more milk substitutes as coming from an animal source. Future policy should consider the clarification of such labelling.

There is growing public concern about the ‘unfairness’ of many pricing practices that have become common in consumer, particularly digital, markets. Industrial and behavioural economists have developed theories that explain the conditions under which these practices are profitable for firms, and their implications for consumer welfare. We identify a mismatch between the welfare economic principles used in this theoretical work and the normative perspective in which these practices are viewed as unfair. We develop a concept of ‘transactional fairness’, grounded in the normative approach of Sugden's Community of Advantage, that is reflective of public concerns. Transactional fairness is complementary to established criteria of economic efficiency and distributional equity but is based entirely on the relationship between individual buyers and sellers. It establishes clear principles with realistic information requirements that are appropriate for compliance by firms. Regulation based on this approach can help to restore public faith in markets.

The purpose of this paper is to first review William James's explicit positions on paternalism in the context of medical licensure and the annexation of the Philippines. Then I wish to show that these positions, as well as a more generalized antipaternalist stance, are the implications of James's philosophy and psychology and not simply his ‘personal’ sentiments. The elements of James's thought are arranged in such a way as to facilitate a comparison with contemporary behavioral (heuristics and biases) paternalism. The conclusion is that James has arguments against behavioral paternalism avant la lettre that are still useful and deserve discussion.