The notorious Rossi’s ‘Iron Law of Evaluation’ – that the expected net impact of any large-scale social programme is zero – reminds us that expectations about policy interventions rarely survive real-world delivery. Behavioural Public Policy (BPP) faces many implementation challenges. Implementation Science (IS), which studies how evidence-based practices are adopted, delivered and sustained, offers BPP a toolkit for overcoming the knowledge–action gap. We show how IS frameworks like CFIR (Consolidated Framework for Implementation Research) and RE-AIM (Reach, Effectiveness, Adoption, Implementation, Maintenance) diagnose contextual barriers – leadership, workflow fit, resources – and supply metrics of fidelity, adoption, cost and sustainment. Next, we outline three hybrid trial types from IS that co-test policy impact and implementation: Type 1 emphasises behavioural effects while sampling implementation data; Type 2 balances both; Type 3 optimises implementation while tracking outcomes. Cluster-randomised and stepped-wedge roll-outs create feedback loops that enable mid-course adaptation and speed scale-up. Cases illustrate how spotting delivery slippage early averts costly failure; they reveal how early IS integration can turn isolated behavioural wins into scalable, system-wide transformations that genuinely endure long. We situate these recommendations within the literature on scalability and the ‘voltage effect’, clarifying how common drops from pilot to scale can be anticipated, diagnosed and mitigated using IS outcomes and process data.

Is narrative entertainment simply a form of recreation, or does it have meaningful effects on public opinion? Building on prior reviews, we present a meta-analysis of 377 findings from 77 experiments evaluating the persuasive effects of narrative radio, television and film, including a growing body of work from low- and middle-income countries. Our sample includes both entertainment-first narratives – popular media created primarily to entertain but which may incidentally shape audiences’ attitudes, beliefs and behaviors – and education-first narratives designed by policymakers to inform, persuade or motivate public action. Using a hierarchical-effects model, we assess narrative media’s influence across a wide range of settings and issue domains. The results suggest that narrative entertainment is quite influential, with sizable persuasive effects that remain apparent weeks after initial exposure. A smaller literature reports head-to-head tests of the relative effectiveness of narrative vs non-narrative messages; although inconclusive, the evidence suggests that narratives may be only slightly more persuasive than non-narrative messages. If true, this finding would imply that the main advantage of narratives may be their ability to attract and engage large and diverse audiences. We conclude by calling attention to gaps in the literature and proposing avenues for further research.

Perspective-taking has been theorized to be a central psychological process in how people make punishment decisions. However, previous research has only tested theory in low-stakes or hypothetical contexts. The current research describes how jurors perspective-take in real capital punishment trials (N = 1,198) and tests a series of hypotheses from previous research in a high-stakes, naturalistic context. In examining the predictors of perspective-taking, we found that jurors are more likely to perspective-take for white victims than black victims, but not more likely to perspective-take if the trial participant is demographically similar to themselves. We further uncovered new findings that older jurors perspective-take less (regardless of whether it is for perpetrators or victims), and women perspective-take for victims more than men do. In examining how perspective-taking relates to capital punishment decisions, we found that jurors who take victims’ perspectives are more likely to vote for the death penalty. We found mixed support for the theory that jurors who take defendants’ perspectives are more lenient. We conclude by discussing the implications of our findings for legal arguments on the arbitrary and biased nature of capital punishment decisions.

The aim is to examine how vaccine misinformation shapes perceived social norms and assess their mediating role in vaccination intentions during pandemics, an underexplored mechanism in misinformation’s influence on vaccine decisions. In a pre-registered online experiment, UK residents (n = 332) were randomly assigned to either a misinformation or control condition in a hypothetical pandemic scenario. I measured changes in vaccination intentions, first-order normative beliefs (perceptions of others’ vaccination intentions) and second-order normative beliefs (perceptions of others’ beliefs about vaccine safety) before and after exposure. Causal mediation analysis using inverse odds ratio weighting assessed the indirect effects of misinformation through changes in normative beliefs. The pre–post comparison revealed that vaccine intentions declined 2.5% more in the misinformation condition compared to the control group (p = 0.024, d = 0.24). In the misinformation group, average vaccine intentions dropped from 62.4% to 59.3%, while the control group showed minimal change from 60.8% to 60.2%. Changes in first-order normative beliefs mediated 39.52% of misinformation’s total effect on vaccination intentions. The findings reveal that vaccine misinformation operates through dual pathways: directly affecting individual beliefs while simultaneously distorting perceptions of social consensus about vaccination.

Over the past twenty years, behavioural insights and nudges have gained prominence in public policy design. Public opinion research on this subject has largely considered two questions: (1) who supports nudges? and (2) where is support for nudges strongest? Using data from two nationally representative surveys fielded in 2023 and 2024 (N = 2020 and N = 1991), we take up these questions in Canada—a ‘principled pro-nudge’ country. We measure opinion toward 30 nudge policies across three policy domains—15 that provide a benchmark to other country studies, coupled with 15 that reflect policies that were implemented by Canadian nudge units. We also analyze open-ended responses to a question that asks what individuals think of nudging (if they think of them at all). We find that approval for nudges is high, with 71% of respondents supporting nudges that have been implemented in Canada. Second, we identify similar gender, ideological and identity-based patterns for support as observed in countries with different social and market structures. Third, analyzing open-ended responses that gauge respondents’ thoughts on BI, our findings highlight the complicated nature of public opinion toward BI, which includes optimism alongside uncertainty and skepticism.

A lack of common terminology and shared understanding of behavioural interventions across academic disciplines and professional groups limits the multidisciplinary application of such interventions and our collective ability to share and compare their effects. The current study attempts to narrow this gap by developing a comprehensive classification system of nudges and similar behavioural interventions that can aid researchers and practitioners in understanding and describing such interventions to steer desired behaviour change. We develop an initial classification system drawing on our expert knowledge and subsequently validate it in an iterative procedure with 44 experts from various fields, disciplines and sectors during two feedback rounds (i.e. a Delphi approach). The result is META BI (Mapping of Environment, Target group and Agent for Behavioural Interventions), a classification system describing interventions across 20 dimensions and using 17 distinct psychological mechanisms. META BI is aligned with a system lens, shifting the focus from single true effects to contextualised assessments. It can help to understand, compare and evaluate nudges and selected interventions for the desired effects.

Low take-up of government services continues to challenge public investments in social services. Behaviorally informed interventions, so-called nudges, can overcome barriers that keep eligible individuals from accessing services. We report results from a pre-registered randomized controlled trial (RCT) to test email-based interventions to increase the take-up of publicly funded employment services in British Columbia, Canada. Our RCT design distinguishes between getting people ‘to-the-door’ (awareness and interest) and ‘through-the-door’ (enrollment). We find that emails with concise information that route individuals directly to online enrollment are most effective. The best-performing interventions more than doubled enrollment within 14 days, relative to a control group that received no communication. Using machine learning identify subgroups within the population who benefit most from our interventions. Yet despite these positive effects on take-up, we find that converting expressions of interest into enrollments remains a challenge. To increase take-up, policymakers must identify the nature of the challenge: getting people to-the-door or through-the-door. We also contribute to current debates about the quality of public service delivery.

The research of many decades by behavioral economists and psychologists has shown that the standard rationality axioms do not describe how individuals actually behave in many circumstances. Nevertheless, behavioral economists still argue for the normative character of the axioms: they describe how individuals should behave. Violations of the axioms are red flags for some type of pathology. This article argues that the history of the axiomatic approach in economics does not lend support to the normative case. Furthermore, it is argued analytically that the rationality axioms are vacuous. The attribution of irrationality to behavior can only be accomplished by reference of a more inclusive idea of rationality. The axioms are too thin and misleading. They do not have policy significance.

Behavioural status and demographic characteristics of target groups influence the implementation and effects of interventions to reduce and prevent harm. We examine the implementation of a statutory identification regime and associated monetary limit-setting in the context of electronic gambling machine gambling in Finland. Mandatory identification of players is a prerequisite for various policy measures aimed at preventing and reducing gambling harms. We use a large account-based dataset (N = 28,351) from the state gambling monopoly to examine behavioural differences between those who identified voluntarily before and those who did so only after identification became mandatory. The identification regime was implemented in steps. Consequently, we defined player groups based on different implementation phases. We compare these groups in terms of demographic variables and consumption patterns. Results show that those who identified for the first time only after identification became mandatory experienced the highest average losses. Mandatory loss limits were associated with a clear reduction in overall consumption across all three groups. We conclude that when implementing harm prevention policies, it is important to consider differences across gambler groups. Furthermore, preventive policies need to be rules-based. Voluntary measures, although favoured and actively lobbied by the gambling industry, are not as effective.

We provide the first large-scale statistical investigation of the role of the saliency of (dis)honesty on future behavior in a multi-wave experiment with 1,260 subjects. In the first wave, we vary the saliency of subjects’ past dishonesty and explore the impact on behavior in tasks that include the scope to lie. In the second wave, we vary the degree of competitiveness in one of our core tasks. In a real effort task with individual incentives, being asked to recall experiences that involve honesty, or dishonesty reduces dishonesty in the task. This effect persists, albeit with a smaller effect size, when we purposefully introduce competitive incentives to this task in wave 2. On the other hand, in a competitive environment in which subjects could earn more by lying to their counterparts, inducing them to think more about (dis)honesty pushes them toward becoming more dishonest.

Our daily lives are shaped by the digital platforms we engage with, presenting both challenges and opportunities in the pursuit of health and social well-being. Despite extensive public efforts to increase physical activity, sedentary lifestyles and car-dependence persist; often exacerbated by digital apps functioning at odds with these initiatives. With growing urbanization, walking for transportation becomes a feasible way for many Americans to achieve daily activity goals. This work explores the potential of leveraging nudges within digital apps, specifically Google Maps, to encourage walking. I found that displaying walking directions as the default in Google Maps, instead of driving, and complemented by graphics depicting social norms, significantly increased the hypothetical choice to walk — particularly among less active individuals. This underscores the power of digital environments in shaping our choices and outcomes; and highlights the need for us to critically assess digital app design. I advocate for collaboration between ‘big tech’, policymakers, and the public to create digital tools that balance our immediate convenience with long-term health and environmental sustainability goals. Re-envisioning technology’s role in daily life, we can potentially harness its vast influence to foster choices that contribute to both personal well-being and the collective good.

This study tests the causal link between corruption perception and corruption in the public sector by using stereotyping theories. Using three experiments, this study manipulates corruption perception in 1,356 Anglo-Saxon public servants through information consistent with corrupt bureaucrat stereotypes. While the treatment significantly influenced their belief in the stereotype, it did not alter dishonest behaviors. However, public servants selectively use the information in line with how acceptable they perceive the corrupt behavior to be to decide whether they will engage in corruption. The findings shed light on how public servants process corruption-related information and its implications on anti-corruption policies.

System change and individual behavior change are often conceptualized as contrasting, mutually exclusive strategies for climate change mitigation, with system change usually considered more powerful, direct or urgent. We argue that this alleged duality is misguided and that system change and behavior change are fundamentally co-dependent: system change is often effective to the extent that it promotes individual behavior change and, vice versa, individual behavior change contributes to the critical mass that is needed to spur system change. We map four pathways that link behavior change and system change, driven by consumer activism, consumer demands, policies that address people as part of a community and the provision of collective action arrangements. Together, these pathways illustrate that system and behavior change are often interconnected and suggest promising avenues for developing climate mitigation policies that jointly promote system and behavior change.

One relatively recent pivot in the discussion concerning the possibility of interpersonal utility comparisons (IUCs) centers on evolutionary biological considerations. In particular, it has been suggested that, since all human beings are part of the same species, we should expect our utility functions to be structured similarly and thus be comparable. However, a closer look at this argument shows that it is not compelling as it stands: since cultural learning plays a crucial role in our cognitive evolution, the conclusion that we evolved to be psychologically similar to each other needs to be revised. This, though, does not mean that evolutionary theory has nothing to say about the possibility of IUCs. In fact, as this paper makes clear, by expanding the evolutionary argument with work in gene–culture–technological coevolutionary theory, it becomes possible to support the contention that IUCs may well be sometimes possible. This has important implications for the analysis and design of social institutions.

For all their differences, the two rival theories of human behavior have many unfortunate similarities. Standard rational choice theory posits that individuals use rational techniques to pick ends that meet their set of private preferences. Modern theories of behavioral economics point to systematic deviations from those principles. Both approaches assume that all preferences are individually based. However, the evolutionary principle of inclusive fitness insists that in family situations, it is the welfare of the unit, not of any of single individual, that explains various forms of natural love and affection that arise because of the interdependence of − and the redistribution of − wealth it requires. Likewise, both standard theories ignore variations in tastes and in competence levels that allow for gains from trade across competence levels. This paper then reinterprets the common treatment of nudges and the various legal doctrines dealing with disabilities, product liability, and firm structure where the standard assumptions of uniform behavior miss the salient features of human behavior and social interactions.

It is perhaps uncontroversial to claim that behavioral science research is playing an increasingly important role in practice. However, practitioners largely rely on media reports rather than original research articles to learn about the science. Do these media reports contain all the information needed to understand the nuances of the research? To assess this question, we develop a set of rubrics to evaluate the fidelity of the media report to the original research article. As an illustration, we apply these rubrics to a sample of media reports based on several research articles published in one journal and identify common patterns, trends, and pitfalls in media presentations. We find preliminary evidence of low fidelity in presenting participant characteristics, contextual elements, and limitations of the original research. The media also appear to misreport correlational evidence as causal and sometimes miss acknowledging the hypothetical nature of evidence when hypothetical scenarios were used as the sole basis of conclusions. Furthermore, the media often present broad conclusions and personal opinions as directly backed by scientific evidence. To support more discerning consumption of behavioral insights from media sources, we propose a checklist to guide practitioners in evaluating and using information from media sources.

Especially in the context of climate adaptation policy, creating support for hard policy instruments and convincing people that their individual contributions do matter are two significant challenges. In this study, we test the effect of an individually versus collectively framed gain-appeal infographic on the acceptance of hard policy instruments and this in the context of strictly private climate change adaptation behaviour. We used a mixed methods approach focussing on reducing private paving in domestic gardens in Belgium. Evidence from an online survey experiment (n = 3,389) showed that policy makers implementing a collectively framed infographic can increase the acceptance of a more strict permit policy and a yearly financial contribution, while simultaneously enhancing personal and collective self-efficacy and outcome expectancy beliefs. Complementary insights from qualitative data learned that perceived (in)equity is a crucial point of attention when designing climate policies addressing private paving. A collectively framed infographic may convey the message ‘yes, we ánd I can’. With these “findings, we want to trigger new opportunities in climate policies beyond the current policy scopes.

The COVID-19 pandemic provided a stark reminder that societies will struggle to address global challenges unless they are able to change behaviour at scale. The widely adopted ‘nudge’ approach epitomizes an individualistic, deficit model of human cognition and motivation that leverages or overcomes people’s weaknesses and biases to get them to do things they would otherwise not. By contrast, we argue that tackling the challenges facing humanity requires a collective, capacity-building approach – one that boosts the competences, opportunities, and motivations of individuals to act together.