Public policy encourages healthier diets using interventions like financial incentives, calorie labelling or social-norm nudges. While evidence shows these interventions can influence behaviour, effects vary across individuals, indicating a need for tailored approaches. This study explores the effects of tailoring through choice, i.e., whether allowing individuals to choose interventions improves effectiveness. In a field experiment, 839 university students chose between healthier and less healthy snacks under three interventions: (i) small financial incentives, (ii) calorie information or (iii) a social-norm nudge (i.e., 60% chose healthily). Half the respondents were randomly assigned an intervention (or no-intervention control), while the rest selected and received their chosen intervention. Among respondents given a choice, 51%, 41% and 8% selected financial incentives, calorie labelling or social norms, respectively. Self-selected interventions (marginally) significantly increased healthy snack choices compared to the no-intervention control, while randomly assigned interventions did not. When accounting for individual characteristics, chosen calorie labelling and social norm nudges significantly increased healthy choices, while financial incentives did not. Allowing respondents to choose their intervention appears effective, while random assignment is not. This positive effect of choice may be driven by selection into calorie labelling and social norms, although respondent characteristics partially explain this effect.

The gambling industry tends to frame gambling harms as a matter of personal responsibility, which is implicit in their messages like ‘gamble responsibly’ or ‘take time to think’. Jurisdictions such as Australia and the UK are replacing industry messages with a range of independently designed ones, like in tobacco warning labels. Counter-industry messages have been proposed to challenge industry narratives, e.g., ‘gambling products are designed to be addictive’. Here we tested 10 potential counter-industry messages among UK gamblers (N = 4,094) using a mixed-methods approach. Results showed that the three best-performing messages came from existing counter-industry campaigns. Participants believed the messages and agreed that they were relevant to people experiencing gambling harm. Participants experiencing higher levels of harm tended to see the messages as more personally relevant to them. Free-text analysis showed that ‘gambling products are designed to be addictive’ received the most positive responses, and also that personal responsibility views were widespread among participants. Messages randomly shown later in the experiment were appraised more positively, suggesting that counter-industry messaging may become more effective when its core message is repeated in multiple ways. Continual design and testing will contribute to the development of best approaches and inform future implementation.

Honest behavior of public sector workers is an important quality of governance, impacting the functioning of government institutions, the level of corruption, economic development and public trust. Scholars often assume that honesty is inherent to public sector culture, however empirical evidence on the causal effect of public sector culture on honest behavior is lacking. This research addresses this question by estimating the causal effect of priming public sector identity on the honest behavior of public employees. We validated an instrument for priming public sector identity and employed it in five preregistered incentivized experiments among civil servants in Germany, Israel, Italy, Sweden, and the UK (N = 2,827). We find no evidence for the effect of public sector culture on honest behavior in both individual (four studies) and collaborative (one study) tasks. The theoretical implications of these results for the study of moral behavior in the public sector are discussed.

Drawing on the example of a novel flat-fare public transport ticket, this study explores the potential of behavioral insights to contribute to the success of traditional policy instruments. The ticket is evaluated using the EAST framework to identify attributes that are aligned with recommendations from behavioral science. The impact of these attributes on the decision to use the ticket is analyzed with a representative survey of German citizens. The results highlight the importance of nonmonetary attributes for using the ticket, especially those that are associated with simplicity and flexibility. These behaviorally aligned attributes are found to be particularly important for new subscribers and to differ in relevance for respondents of different income groups. Notably, a ‘flat-rate bias’ is indicated by a discrepancy between the stated importance of relevant attributes and stated usage. The study underscores the necessity for policymakers to integrate behavioral insights into the design of public transport policies.

The UK has recently introduced regulations to prevent design features of online gambling products that may ‘encourage problem gambling behaviour’. One change has been to prohibit win-associated and celebratory audiovisual effects following monetary losses in online slots, intended to disable a misleading design feature known as ‘losses disguised as wins’ (LDWs). We assessed 26 popular online slots available to UK consumers. Contrary to regulatory guidance, 17 used win-associated sounds following LDWs, and 18 used sound effects following LDWs that we judged as ‘celebratory’. To independently validate our appraisal of these sound effects, we asked 400 UK-based gamblers to assess whether a selection of sound effects recorded from commercially available online slots communicated a positive outcome. In every case, the average consumer classifications of the recorded sounds were consistent with our own, validating our initial assessments. These results suggest that the misuse of celebratory sound effects in online slots still occurs in the UK market, despite this regulation. We argue that this is in part due to ambiguities in regulatory guidance that have enabled operators to technically comply with the regulation while circumventing its intended effect. We conclude by offering suggestions to amend and improve this regulation.

Personal autonomy is increasingly challenged by institutional rules and societal demands. This research examines how institutional restrictions on what people do, when they do it, and how they do it influence their experience of agency. Across two experimental studies, participants indicated their experienced agency in everyday scenarios where institutions determined one or more of these three components. The results indicate that experienced agency is most strongly undermined when institutions decide what goal a person must pursue. The more components were restricted, the lower the experienced agency, revealing a cumulative effect. The second study further tested whether framing the achievement of a goal as an opportunity to experience freedom could buffer against these effects. This manipulation did not attenuate the impact of restrictions, suggesting that immediate control over decision-making plays a more critical role in shaping experience of agency than anticipated future freedoms. These findings offer insight into how institutional rules shape people’s experience of agency and may help guide the design of policies that better respect and preserve personal autonomy.

This study examines whether behaviourally informed training can improve the effectiveness of phone-based tax debt collection in a public-sector setting. In collaboration with the Bulgarian National Revenue Agency, we implemented a two-day training programme for call centre agents focused on persuasion, negotiation and behavioural influence techniques derived from behavioural science and nudge theory. The impact of the intervention is assessed using descriptive comparisons of monthly aggregated debt-collection performance indicators before and after the training. We find that, following the intervention, trained agents achieved markedly better outcomes relative to pre-intervention periods, including an increase of approximately 20% in the total amount of debt collected over the subsequent three months and a higher rate of secured payment agreements. Notably, these improvements contrast with historical seasonal patterns that typically show a decline in collections during the same period. While the analysis is descriptive and does not permit definitive causal inference, the results provide strong indicative evidence that targeted behavioural training can enhance compliance outcomes in live, interpersonal interactions. The study contributes to the behavioural public policy and persuasion literatures by extending behavioural insights beyond written or digital nudges to real-time, conversational settings. From a practical perspective, the findings highlight the potential value of soft-skills and behavioural training for frontline public servants as a scalable and cost-effective tool for improving tax administration performance.

Public support is crucial for the success of policy interventions that aim to change behaviour. While communicating evidence of policy effectiveness can increase support, it remains unclear which type of evidence is most effective. Statistical evidence is often seen as objective and persuasive, yet personal anecdotes can strongly influence beliefs. We examined how statistical and anecdotal evidence affect policy perceptions. In three online experiments with representative UK samples (N = 908), we showed participants different types of evidence (statistical, anecdotal, or both) that argued for or against six policies, such as meat taxes (climate change), banning e-cigarettes (public health), and 20 mph speed limits (community safety). We measured policy support and perceived effectiveness before and after exposure and explored participants’ reasoning through open-text responses. Results showed that positive statistical and anecdotal evidence did not significantly increase perceived policy effectiveness or support, even when combined. However, negative anecdotes significantly reduced both, though this effect was sometimes mitigated when paired with statistical evidence. Qualitative results found that participants have broader concerns beyond policy effectiveness, such as fairness. Our findings suggest that communicating evidence on policy effectiveness alone may not increase support, as it does not address broader public concerns.

This article explores the ‘rationality wars’, contemporary debates about the nature and scope of rationality across economics, psychology, behavioral public policy and philosophy. It traces the evolution of the concept from classical thinkers and shows how modern disagreements – such as Daniel Kahneman’s logical model versus Gerd Gigerenzer’s ecological approach – restate long-standing philosophical tensions. These divergences arise from the distinct epistemological demands of each discipline. Using Gustavo Bueno’s distinction between concepts (discipline-specific) and ideas (transdisciplinary), the article critiques reductionist attempts to impose one framework as definitive. Instead, it argues for a pluralistic, scientifically grounded understanding of rationality that respects diverse aims, methods and standards.

Behavioral instruments have unique advantages in certain governance contexts for the reasonable use of public products. Drawing on bounded rationality, we compare two major behavioral instruments – nudging and boosting – and experimentally test their effectiveness in promoting reasonable use of public products. We select the default option (nudging) and future orientation (boosting) as specific instruments. In Study 1, we conduct a laboratory experiment and find that (1) both the default option and future orientation reduce free electricity usage; (2) the immediate effect of the default option is greater than that of future orientation, but its delayed effect is smaller; and (3) the combination strategy is more effective than any single intervention. In Study 2, we conduct a field experiment targeting reasonable use of public toilet paper and basically replicate the results of the laboratory experiment. These findings reinforce our confidence in the effectiveness of nudging and boosting and suggest the possibility of bridging behavioral science with governance theory.

What should mostly matter is how successful environmental policies are at satisfying citizens’ policy preferences (e.g., reducing carbon emissions), relative to the policies’ cost. Yet, across 6 studies (N = 2759, 2 pre-registered), we found that French citizens tended to be rather insensitive to policy efficiency. In Experiments 1a–d (N = 854), citizens regarded an environmental policy driven by an altruistic intention that turned out to be inefficient as being more commendable than a policy motivated by selfishness that dramatically reduced carbon emissions. In Experiment 2 (N = 1105), altruistic but low efficiency policies were supported only slightly less than selfish but highly efficient policies. Independent manipulation of intent and efficiency indicated low sensitivity to large differences in efficiency expressed numerically, and substantial sensitivity to actors’ intentions. Moreover, moral commitment predicted stronger support for any environmental policy addressing the issue, regardless of its efficiency. Finally, Experiment 3 (N = 800) found that introducing reference points and qualitative appraisals of a policy’s impact and financial cost can nudge participants towards greater attention to its efficiency. Our paper highlights the importance of using contextual and qualitative (vs. numeric) descriptions of policies to make citizens more focused on their efficiency.

Qualitative data and analysis can enrich our understanding of key questions in behavioural public policy. In this perspective, I make the case for incorporating qualitative approaches better and more often into our research. I offer practical ideas on how to do this, and a call for action from researchers, reviewers, editors, policy makers and our Higher Education and funding institutions.

Sludge is one of the most important yet underappreciated problems in modern society. Examples of sludge include unnecessarily complex paperwork requirements, hard-to-navigate documents and websites, long waiting time, and unfriendly or confusing staff interactions. However, little is known about whether some people are more vulnerable to and less accepting of some types of sludge than others. Drawing on data from a nationally representative survey with 1,591 participants from Ireland, we show that people report being particularly vulnerable to outdated websites with broken links, unfriendly staff interactions, complex documents laden with jargon, and hard-to-navigate websites. These are also the types of sludge that are least acceptable. Less vulnerability is reported to long waiting times and requirements about having to provide private information. We find only minor differences in sludge perceptions depending on whether the sludge emerges in the public or the private sector. Moreover, people with poor mental health report being more vulnerable to and less accepting of sludge. Self-reported administrative literacy is related to less reported vulnerability, and the tendency to procrastinate and a lack of time and mental energy predict more reported vulnerability to sludge. Administrative literacy and a lack of mental energy also predict acceptability of sludge.

Carbon labelling has been proposed as a strategy to encourage cafeteria diners to reduce meat consumption, choose lower carbon-emitting meals and contribute towards global climate change targets. However, field-experimental evidence for label effectiveness is largely limited to trials in universities with student samples. This study evaluated whether the beneficial effects of carbon labelling observed in universities could be replicated in the wider workplace population through a natural field experiment in four call-centre cafeterias in Northern England. Baseline vegetarian uptake in the call-centre cafeterias was significantly lower than in previous university trials (7% vs 15–66%), potentially reflecting a more meat-attached population. The introduction of labels resulted in a 1.5 percentage-point shift from meat to vegetarian meals compared to 1.7–4.6 percentage-point shifts observed in university trials. The increase was almost entirely driven by higher vegetarian sales during the first week of the intervention, with little to no effect observed in subsequent weeks. No statistically significant changes were found in average cafeteria emissions. The findings suggest that carbon labels are not a panacea, and where worksite cafeterias have ambitious emissions targets, labels will need to be implemented alongside other measures.

In three between-subject experiments, involving a total of 3180 participants, the majority of respondents indicated that during a weather emergency they would continue to use high bandwidth functions after receiving a text message requesting only emergency use. Projected excess demand for bandwidth could bring down the cellular communication network in the affected area. Messages incorporating an appeal to altruism, the incentive of a reduced phone bill, and the disincentive of an imminent collapse of the network for 24 hours all had no effect on intentions to use high bandwidth functions. Younger respondents and male respondents were less compliant than older respondents and female respondents. Their responses imply that an increasing number of individuals view even a brief separation from their cell phone as an existential threat that overrides other concerns including empathy for people in life-threatening circumstances.

Emerging scholarship suggests that willingness to engage in violent or risky behavior relates to Need for Chaos – a trait-state combination reflecting disaffection with society and politics, independent of political identity and beliefs. While previous research links Need for Chaos to a stronger gain-seeking mentality, it remains unclear whether those higher in Need for Chaos respond differently to gain and loss frames. We use a framing experiment based on prospect theory to test whether Need for Chaos moderates decision making about two salient policy issues in the United States: the debt ceiling and government shutdown negotiations in US Congress in 2023. Results from both studies (n = 2,704; 3,002) suggest that individuals low in Need for Chaos are risk-averse toward gains but risk-seeking toward losses, whereas those high in Need for Chaos exhibit the opposite pattern, seeking risk when anticipating gains and avoiding risk when anticipating losses. Our findings add important nuance to existing research by demonstrating that individuals higher in Need for Chaos are not merely indifferent to framing; rather, they also systematically respond to gain and loss frames. This work underscores how individual differences may help to shape judgment and decision making, particularly in times of societal and political uncertainty.

Individual-level solutions, such as lifestyle changes, are often regarded as cost-effective complements to systemic policies like government regulations in addressing climate change. However, some argue that exposure to these solutions may shift focus away from systemic interventions, potentially crowding-out support for large-scale policies. Across two experiments in Iran (N = 303) and Australia (N = 308 and 625), we tested whether exposure to different numbers of individual and systemic policies would affect individuals’ perception of systemic climate solutions. Results showed that, regardless of country or exposure type, whether through daily life or experimental manipulation, participants consistently supported systemic policies and changes, attributed greater responsibility to the government, perceived minimal conflict between systemic and individual approaches, rated systemic policies as more effective than individual ones, and viewed individual actions as only moderately substitutable for systemic solutions. These findings challenge the crowding-out hypothesis, suggesting that exposure to individual solutions does not diminish support for systemic policies or structural reforms.

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.