The serial rapist model claims that a small number of intentional, repeat offenders are responsible for the majority of sexual assaults on college campuses. The model has formed the dominant argument for some of the most popular forms of campus intervention programs and is cited by high profile advocates and policymakers. Despite enthusiasm for the serial rapist model, it is not empirically well-supported and is contradicted by recent robust data. In this article, we ask: why does the serial rapist model have such broad and enduring appeal? In two US-based samples, one convenience and one representative, we find that people's endorsement of the serial rapist model correlates with worldviews that cohere around ideas of a just and good status quo, and a preference for simple stories. Specifically, we find a positive relationship between endorsement of the serial rapist model and belief in a just world, system justification, social dominance orientation, need for closure and essentialism.

This randomised online experiment aimed to investigate how eco-labelling and social nudging influenced sustainable food choice, as well as consider the effect of motivation to act sustainably. Participants were UK adults ≥18 years (n = 1399). Participants were asked to choose a hypothetical meal (beef, chicken or vegetarian burrito) and were randomly allocated to one of three conditions varying in labelling: eco-labelling; social nudge or control (no label). Co-primary outcomes were the frequency that the vegetarian and chicken burritos were chosen (i.e., the more sustainable food choices). There was evidence that more vegetarian (OR = 3.3 [95% CI 2.0, 5.3]) and chicken (OR = 2.5 [95% CI 1.8, 3.4]) burrito choices were made in the eco-label condition, over the beef burrito, compared to the control condition. In the social nudge condition, there was evidence that participants chose a vegetarian burrito over a beef burrito (OR = 1.7 [95% CI 1.1, 2.7]), but not a vegetarian burrito over a chicken burrito (OR = 1.4 [95% CI 0.9, 2.2]). Although both labels were effective at promoting participants to make more sustainable food choices, the eco-label was the most effective. Choice of burrito was modified by motivation to act sustainably across all conditions. This study suggests that future policy could include eco-labelling and/or a social nudge to reduce meat consumption and meet global climate change targets.

Recently, defaults have become celebrated as a low-cost and easy-to-implement nudge for promoting positive outcomes, both at an individual and societal level. In the present research, we conducted a large-scale field experiment (N = 32,508) in an educational context to test the effectiveness of a default intervention in promoting participation in a potentially beneficial achievement test. We found that a default manipulation increased the rate at which high school students registered to take the test but failed to produce a significant change in students’ actual rate of test-taking. These results join past literature documenting robust effects of default framings on initial choice but marked variability in the extent to which those choices ultimately translate to real-world outcomes. We suggest that this variability is attributable to differences in choice-to-outcome pathways – the extent to which the initial choice is causally determinative of the outcome.

Existing research demonstrates that parents are poorly informed consumers of early childhood education and care (ECEC) services. Choosing such services is a complex process shaped by a combination of logistical limitations (e.g., cost/location), informational barriers and ideas about what the goal of care should be (e.g., education of young children or provision of an environment that feels like home). Experimental studies have also demonstrated that when study participants are informed of the importance of a specific decision, they engage in more complex decision-making. In this article, we test whether providing parents with information about the regulatory stringency of ECEC options available influences their choices regarding ECEC. A conjoint survey designed to capture quasi-behavioural choices for ECEC services was completed by 682 parents. Before engaging with the survey, participants were randomly assigned into either a control group or a treatment group that informed them about the stringency of oversight regarding ECEC options available in the province of Ontario, Canada. Receiving information did not meaningfully change the choices of the entire sample. However, a subgroup analysis revealed an important information effect on parent decisions for lower income/lower-education parents.

Local public managers increasingly use behavioral policy instruments to influence the behavior of citizens. However, despite their increased reliance on these instruments, there is little evidence on why local public manager would prefer behavioral instruments over classic stick, carrot or sermon-type instruments. We conduct a mixed-methods study, combining a stated-preference survey and two focus groups, to examine whether senior local public managers (directors and deputy directors) in Flanders prefer behavioral policy instruments over classic stick, carrot and sermon-type instruments, and explore whether their trust in citizens (perceptions of citizen's ability, benevolence and integrity) affects these preferences for policy instruments. The results indicate that in some policy areas, such as health, public nuisance and road safety, public managers appear more willing to use behavioral policy instruments than classic sticks and carrots, but not sermons. Furthermore, we find that public managers’ trust in citizens does not appear to significantly affect their preferences for policy instruments, but that political and economic motives do play a role in their preferences for behavioral policy instruments. Finally, the results also indicate that the simultaneous use of behavioral and classic policy instruments (packaging) can help mediate the perceived risks of citizens’ non-compliance with behavioral policy instruments.

Once vaccines against COVID-19 became available in many countries, a new challenge has emerged – how to increase the number of people who vaccinate? Different policies are being considered and implemented, including behaviourally informed interventions (i.e., nudges). In this study, we have experimentally examined two types of nudges on representative samples of two countries – descriptive social norms (Israel) and saliency of either the death experience from COVID-19 or its symptoms (UK). To increase the legitimacy of nudges, we have also examined the effectiveness of transparent nudges, where the goal of the nudge and the reasons of its implementation (expected effectiveness) were disclosed. We did not find evidence that informing people that the vast majority of their country-people intend to vaccinate enhanced vaccination intentions in Israel. We also did not find evidence that making the death experience from COVID-19, or its hard symptoms, salient enhanced vaccination intentions in the UK. Finally, transparent nudges as well did not change the results. We further provide evidence for the reasons why people choose not to vaccinate, and whether different factors such as gender, belief in conspiracy theories, political ideology, and risk perception, play a role in people's intentions to vaccinate or susceptibility to nudges.

Field experiments which test the application of behavioural insights to policy design have become popular to inform policy decisions. This study is the first to empirically examine who and what drives these experiments with public partners. Through a mixed-methods approach, based on a novel dataset of insights from academic researchers, behavioural insight team members and public servants, I derive three main results: First, public bodies have a considerable influence on study set-up and sample design. Second, high scientific standards are regularly not met in cooperative field experiments, mainly due to risk aversion in the public body. Third, transparency and quality control in collaborative research are low with respect to pre-analysis plans, the publication of results and medium or long-term effects. To remedy the current weaknesses, the study sketches out several promising ways forward, such as setting up a matchmaking platform for researchers and public bodies to facilitate cooperation, and using time-embargoed pre-analysis plans.

Paternalistic nudging and framing aim to correct flaws in deliberation by relying on the same cognitive mechanisms that create those flaws. Regarding some choices as flawed and in need of correction requires some standard of correctness. In their well-known book, Nudge, Thaler and Sunstein take the individual's own “purified” preferences to be that standard, which is inconsistent with the finding of behavioral economics that individuals do not have a stable preference ranking of alternatives, but instead construct their preferences when faced with a choice. This essay defends an alternative, readily usable standard to judge whether individuals are choosing badly and whether nudges can help them to choose better.

With the increasing availability of life-saving vaccines against the SARS-CoV-2 virus, government agencies face the challenge of promoting vaccine uptake. Thus, encouraging vaccine uptake marks an urgent policy challenge in fighting the COVID-19 pandemic. This study builds on the theory of psychological ownership to design a behaviorally inspired local government vaccination campaign. We conducted a large-scale, cluster-randomized field experiment (N = 27,298 residents nested in 6,442 addresses) delivered to all registered residents of a German municipality via an official mailing campaign. The campaign included a psychological ownership intervention designed to boost residents’ intentions to get vaccinated – measured through unique link clicks on a municipal website where people can schedule a COVID-19 vaccination appointment. Findings suggest that adding possessive pronouns (i.e., ‘YOUR vaccination’) increases vaccination intentions by 39%, or 2.5 percentage points (p < 0.0001 [95% CI = 1.8%, 3.3%], control letter: 6.4%, treatment letter: 8.9%). The discussion outlines the value of using psychological ownership-based nudge interventions to increase vaccine uptake and other desirable behaviors.

Since the publication of the seminal book Nudge by Thaler and Sunstein, several critics have highlighted preference endogeneity as a serious obstacle to nudging. When individuals hold preferences that are dynamic and endogenous to the nudge frame, it is unclear what the normative benchmark for libertarian paternalistic policies should be. While acknowledging this issue, the pro-nudging camp has not yet sufficiently addressed it. This article aims to fill this void by presenting a conditional defence of nudging when preferences are endogenous. We explain the learning process through which individuals establish ‘agentic’ preferences: preferences that are sufficiently stable, reasonable, autonomous and associated with organismic well-being to ground the ‘welfare’ principle of libertarian paternalism. To describe this process, we draw on theories from psychological science, in particular self-discrepancy theory and self-determination theory. We argue that agentic preferences are not only welfare-relevant and thus appropriate to libertarian paternalism but can also be identified by choice architects.

The aim of this article is to better understand how judgements about nudge acceptability are formed and whether they can be manipulated. We conducted a randomized experiment with N = 171 participants to test whether acceptability judgements could be (1) more favourable when the decision to implement the nudges was made following a consultation with the targeted population and (2) influenced by the joint framing of the nudge's purpose and effectiveness (in terms of an increase in desirable behaviour versus decrease in undesirable behaviour). We tested these hypotheses on various nudge scenarios and obtained mixed results that do not clearly support our hypotheses for all nudge scenarios. A surprising result that calls for further work is that by mentioning that a nudge had been implemented through a consultation with the targeted population its acceptability could be lowered.

Dark patterns – design interfaces or features that subtly manipulate people in making suboptimal decisions – are ubiquitous especially in e-commerce websites. Yet, there is little research on the effectiveness of dark patterns, and even lesser studies on testing interventions that can help mitigate their influence on consumers. To that end, we conducted two experiments. The first experiment tests the effectiveness of different dark patterns within a hypothetical single product online shopping context. Results show that, indeed, dark patterns increase the purchase impulsivity across all dark patterns, relative to the control. The second experiment tests the effectiveness of three behaviorally informed interventions on four different dark patterns also in a hypothetical online shopping scenario, but this time offering multiple products instead of a single product. Between-subject analysis shows that not all interventions are equally effective, with uneven impact across dark patterns. However, within-subject results indicate that all interventions significantly reduce purchase impulsivity pre- versus post-intervention, indicating that any intervention is better than none when it comes to combating dark patterns. We then end by discussing the policy implications of our results.

Participatory work structure is a popular concept but its causal impacts in real-world work groups have heretofore been unquantified and research has been Western-centric. We test the hypothesis that participatory group structure increases productivity for blue-collar workers in a context where participation is not a normative default. We conducted a pre-registered longitudinal field experiment with 65 Chinese factory groups (1752 workers). Half of the groups were randomly assigned to a 20-minute participatory meeting once per week for 6 weeks, in which the group's supervisor stepped aside and workers contributed ideas and personal goals in an open discussion of their work. The other half continued with status-quo meetings in which supervisors spoke and set goals, workers listened, and a researcher observed. We found that a participatory versus a hierarchical structure led to a 10.6% average increase in individual treatment workers’ productivity, an increase that endured for 9 weeks after the experiment ended. The brief participatory meetings also increased treatment workers’ retention rate (an 85% vs. 77% retention rate in treatment vs. control groups) and feelings of empowerment such as job satisfaction and sense of control. We found no evidence of informational gains or new worker goals; instead, evidence suggests that the increase in frequency of workers’ voicing opinions may have driven higher productivity. These findings provide rare causal evidence in a setting where participation is not a normative default, indicating the benefits of direct group participation for changing and sustaining behavior and attitudes.

Many proponents of behavioural public policy work within a broadly consequentialist framework. From this perspective, the ultimate aim of public policy is to maximise utility, happiness, welfare, the satisfaction of preferences, or similar; and the behavioural aspect of public policy aims to harness a knowledge of human psychology to make this maximisation more effective. In particular, behavioural insights may be crucial to help policy-makers ‘save us from ourselves’ by helping citizens avoid falling into non-rational choices, for example, through framing effects, failures of will-power, and so on. But an alternative reading of the psychological literature is that human thoughts and actions are not biased from a rational standard, but are simply systematically inconsistent. If so, then utility and similar notions are not well defined either for individuals or as an objective of public policy. I argue that a different, contractarian viewpoint is required: that the determination of public policy is continuous with the formation of agreements we make with each other at all scales, from momentary social interactions, to linguistic and social conventions, to collective decisions by groups and organisations. Behavioural factors do not over-ride, but can (among many other factors) inform, our collective decision-making process. The point of behavioural insights in public policy is primarily to inform and enrich public debate when deciding the rules by which we should like to live.

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.

As US college costs continue to rise, governments and institutions have quadrupled financial aid. Yet, the administrative process of receiving financial aid remains complex, raising costs for families and deterring students from enrolling. In two large-scale field experiments (N = 265,570), we test the impact of nudging high-school seniors in California to register for state scholarships. We find that simplifying communication and affirming belonging each significantly increase registrations, by 9% and 11%, respectively. Yet, these nudges do not impact the final step of the financial aid process – receiving the scholarship. In contrast, a simplified letter that affirms belonging while also making comparable cost calculations more salient significantly impacts college choice, increasing enrollment in the lowest net cost option by 10.4%. Our findings suggest that different nudges are likely to address different types of administrative burdens, and their combination may be the most effective way to shift educational outcomes.

Evolutionary explanations for behavioral findings are often both fascinating and plausible. But even so, they do not establish that people are acting rationally, that they are not making mistakes, or that their decisions are promoting their welfare. For example, present bias, optimistic overconfidence, and use of the availability heuristic can produce terrible mistakes and serious welfare losses, and this is so even if they have evolutionary foundations. There might well be evolutionary explanations for certain kinds of in-group favoritism, and also for certain male attitudes and actions toward women, and also for human mistreatment of and cruelty toward nonhuman animals. But those explanations would not justify anything at all. It is not clear that in Darwinia (a nation in which departures from perfect rationality have an evolutionary explanation), policymakers should behave very differently from Durkheimian policymakers (a nation in which departures from perfect rationality have a cultural explanation).

Important challenges like climate change require transformative policy responses. According to a growing public policy literature, such transformative responses typically require complex policy packages that bundle various individual policy instruments to complement each other, compensate transition losers, and create positive synergies. Nevertheless, while adding new instruments to a package can increase policy effectiveness, it comes at a price: increased policy design complexity. Increased complexity potentially leads to fundamental public misperceptions that undermine policy legitimacy and feasibility. Here, I argue that complex policy packages affect public opinion through a compensation, policy perception, and design complexity mechanism. To test this argument, this study assesses if citizens evaluate proposals for isolated climate policies related to food and mobility behaviors differently to complex policy packages. Employing a novel two-stage conjoint-experimental approach with 9115 respondents from the USA and Germany, the study shows that policy packaging increases citizens’ perceived policy effectiveness to reduce climate pollutants, but also perceived restrictions on citizens’ lifestyles. Moreover, increased design complexity can lead citizens to pay special attention to salient costly parts of policy packages. However, increased design complexity does not fundamentally reverse preferences. Through packaging desired and undesired policy instruments, policymakers can increase public support for transformative climate policies.

Cass Sunstein's contention that evolutionary explanations for behavioural economic phenomena are of limited relevance to public policy – and his support for soft paternalism – rests on his view that policymakers ought to be pursuing increases in some overarching social planning conception of welfare. In this reply to Sunstein, I argue that people have differing and multifarious desires in life, with the social planner's conception of welfare being, at best, perhaps only a partial consideration for most people. The phenomena that behavioural economists and psychologists have empirically observed may well facilitate people in the pursuit of their own desires in life. Consequently, paternalistic manipulation or coercion to save people from themselves is questionable in the behavioural public policy space, but government intervention is warranted when one party implicitly or explicitly uses these phenomena to exploit others.