Both theory on motivational crowding and recent empirical evidence suggest that nudging may sometimes backfire and actually crowd out prosocial behavior, due to decreased intrinsic motivation and warm glow. In this study, we tested this claim by investigating the effects of three types of nudges (default nudge, social norm nudge, and moral nudge) on donations to charity in a preregistered online experiment (N = 1098). Furthermore, we manipulated the transparency of the nudges across conditions by explicitly informing subjects of the nudges that were used. Our results show no indication that nudges crowd out prosocial behavior; instead, all three nudges increased donations. The positive effects of the nudges were driven by the subjects who did not perceive the nudges as attempts to manipulate their behavior, while donations among subjects who felt that the nudges were manipulative remained unaffected. Subjects’ self-reported happiness with their choice also remained unaffected. Thus, we find no indication that nudges crowded out warm glow when acting altruistically. Generally, our results are good news for the proponents of nudges in public policy, since they suggest that concerns about unintended motivational crowding effects on prosocial behavior have been overstated.

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.

Behavioural science has been effectively used by policy makers in various domains, from health to savings. However, interventions that behavioural scientists typically employ to change behaviour have been at the centre of an ethical debate, given that they include elements of paternalism that have implications for people's freedom of choice. In the present article, we argue that this ethical debate could be resolved in the future through implementation and advancement of new technologies. We propose that several technologies which are currently available and are rapidly evolving (i.e., virtual and augmented reality, social robotics, gamification, self-quantification, and behavioural informatics) have a potential to be integrated with various behavioural interventions in a non-paternalistic way. More specifically, people would decide themselves which behaviours they want to change and select the technologies they want to use for this purpose, and the role of policy makers would be to develop transparent behavioural interventions for these technologies. In that sense, behavioural science would move from libertarian paternalism to liberalism, given that people would freely choose how they want to change, and policy makers would create technological interventions that make this change possible.

The Internet is gaining relevance as a platform where extremist organizations seek to recruit new members. For this preregistered study, we developed and tested a novel online game, Radicalise, which aims to combat the effectiveness of online recruitment strategies used by extremist organizations, based on the principles of active psychological inoculation. The game “inoculates” players by exposing them to severely weakened doses of the key techniques and methods used to recruit and radicalize individuals via social media platforms: identifying vulnerable individuals, gaining their trust, isolating them from their community and pressuring them into committing a criminal act in the name of the extremist organization. To test the game's effectiveness, we conducted a preregistered 2 × 2 mixed (pre–post) randomized controlled experiment (n = 291) with two outcome measures. The first measured participants’ ability and confidence in assessing the manipulativeness of fictitious WhatsApp messages making use of an extremist manipulation technique before and after playing. The second measured participants’ ability to identify what factors make an individual vulnerable to extremist recruitment using 10 profile vignettes, also before and after playing. We find that playing Radicalise significantly improves participants’ ability and confidence in spotting manipulative messages and the characteristics associated with vulnerability.

Whether nudges succeed in promoting pro-environmental behavior strongly depends on their public acceptance. Prior literature shows that the framing of nudges, i.e., whether they address the individual (personal framing) or the society (societal framing), is one critical factor in determining nudging acceptance. Since a personal framing highlights the costs individuals have to bear to comply, we hypothesize that people accept nudges more when addressing the general public rather than themselves personally. We expect the framing effect to be stronger for nudges that elicit high-effort behavior than low-effort behavior. Results of multilevel linear regression analyses in two online experiments (nStudy 1 = 294, nobs = 4,410; nStudy 2 = 565, nobs = 11,300) reveal an opposite pattern: People accept nudges more when personally (vs societally) framed. As predicted, nudges receive higher support when the promoted behavior is perceived as low effort. Exploratory path analysis in Study 2 shows that the perceived effectiveness of the nudge mediates the positive relation between personal framing and nudging acceptance. This project provides novel insights on facilitators and barriers in nudging acceptance and their implications for policy-making.

Behavioral scientists have begun to research ‘sludge,’ excessive frictions that make it harder for people to do what they want to do. Friction is also an important concept in transaction-cost economics. Nevertheless, sludge has been discussed without explicit referral to transaction costs. Several questions arise from this observation. Is the analogy to friction used differently in both literatures? If so, what are the key differences? If not, should we develop the concept of sludge when the well-established literature on transaction costs already exists? This conceptual article shows that sludge and transaction costs are related, but distinct, concepts, and that the literature on sludge can benefit from incorporating elements from transaction-cost research. For example, we suggest defining sludge as aspects of the choice architecture that lead to the experience of costs, organize sludges using a typology inspired by the transaction-cost literature, highlight specificity, uncertainty, and frequency as important determinants of the ‘sludginess’ of choice architecture, and show that sludge audits can be conducted using methods developed in the transaction-cost literature.

Although there has been a proliferation of research and policy work into how nudges shape people's behaviour, most studies stop far short of consumer welfare analysis. In the current work, we critically reflect on recent efforts to provide insights into the consumer welfare impact of nudges using willingness to pay and subjective well-being reports and explore an unobtrusive approach that can speak to the immediate emotional impacts of a nudge: automatic facial expression coding. In an exploratory lab study, we use facial expression coding to assess the short-run emotional impact of being presented with calorie information about a popcorn snack in the context of a stylised ‘Cinema experience’. The results of the study indicate that calorie information has heterogeneous impacts on people's likelihood of choosing the snack and on the emotions they experience during the moment of choice which varies based on their level of health-consciousness. The information does not, however, affect the emotions people go on to experience while viewing movie clips, suggesting that the emotional effects of the information are short-lived. We conclude by emphasising the potential of automatic facial expression coding to provide new insights into the immediate emotional impacts of nudges and calling for further research into this promising technique.

Nudges based on social norms (norm-nudges) can be compelling behavioral interventions compared with traditional interventions such as taxes and regulations, but they do not work in all circumstances. We tested two empirical norm-nudge frames in an online experiment on taking measures for flood preparedness with large samples of homeowners (N = 1805) in two European countries, to evaluate the possible interactions between norm-nudge effectiveness, individual characteristics, and intercultural differences. We contrasted these norm-nudge treatments with a control and norm-focusing treatment by asking respondents to express their beliefs about what other respondents would do before making a decision relevant to their own payoff. We find no evidence of a treatment effect, suggesting that our social norm-nudges do not affect flood preparedness in the context of a flood risk investment game.

Loot boxes provide randomized rewards in video games; their purchase is linked to disordered gambling and they are present in approximately half of UK video games. The relative novelty of loot boxes means that regulators and policymakers in various jurisdictions are still deciding how to regulate them. The People's Republic of China (PRC) is the first, and presently only, jurisdiction to legally require companies to disclose the probabilities of obtaining randomized loot box rewards – an approach that is also favored by the industry as self-regulation. This study is the first to assess paid loot box prevalence in the PRC and companies’ discretionary interpretations of probability disclosure regulations. Loot boxes were found in 91 of the 100 highest-grossing PRC iPhone games. Of games deemed suitable for children aged 12+, 90.5% contained loot boxes. Probability disclosures could not be found for 4.4% of games containing loot boxes. Disclosures were implemented through various methods both in-game and on the games’ official websites; however, consistent with the concept of ‘sludge,’ only 5.5% used the most prominent format of automatically displaying the probabilities on the in-game loot box purchase page. Loot box probability disclosures should be uniform and visually prominent to best help inform consumers.

On the one hand, default nudges are proven to strongly influence behavior. On the other hand, a number of consumer autonomy and welfare concerns have been raised that hinder public policy applications. Both nudge success and ethical concerns depend heavily on the design of defaults. We identify six taxonomic characteristics that matter to the ethical and the nudge success dimension. We review the default nudge literature (N = 61) and review ethical studies to assess both dimensions concerning the taxonomy. When designing a default, a choice architect inevitably makes a decision concerning the characteristics. Among others, the results show three main findings. (1) The initial choice architecture regularly imposes welfare losses and impedes consumer autonomy. Forced active choosing can mitigate both issues. (2) Empirical evidence suggests that transparent defaults are similarly effective as the non-transparent counterparts. (3) The framing of the choice in combination with a choice structuring default leads to greater nudge success and tends to involve the reflective decision-making patterns. Choice architects can trade-off nudge success for legitimacy but a design change may also benefit one without harming the other. We discuss further options of choice architects to legitimize a default.

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.

In this paper, we critically review three assumptions that govern the debate on the legitimacy of nudging interventions as a policy instrument: (1) nudges may violate autonomous decision-making; (2) nudges lend themselves to easy implementation in public policy; and (3) nudges are a simple and effective mean for steering individual choice in the right direction. Our analysis reveals that none of these assumptions are supported by recent studies entailing unique insights into nudging from three disciplinary outlooks: ethics, public administration and psychology. We find that nudges are less of a threat to autonomous choice than critics sometimes claim, making them ethically more legitimate than often assumed. Nonetheless, because their effectiveness is critically dependent on boundary conditions, their implementation is far from easy. The findings of this analysis thus suggest new opportunities for identifying when and for whom nudge interventions are preferable to more conventional public policy arrangements.

Recent surveys in China, South Korea, Brazil, South Africa, Russia, Australia, Italy, the UK, Canada, France, Germany, the USA, Japan, Hungary, and Denmark indicate that citizens generally are positive toward state nudging. However, less is known about differences in the support for nudging across socio-demographics and political party preferences, a research gap recently identified in the literature. This article investigates the relationship between the support for nudging and trust in public institutions through a population-representative survey in Sweden. It also analyzes differences in the support for nudging across political party preferences in two ideological dimensions: the economic left-right and cultural GAL-TAN spectra. Data were collected in December 2017 through a custom web survey, using Reisch and Sunstein's (2016) questionnaire. The respondents (N = 1032) were representative of the adult population with regard to gender, age, education, job sector, household income, living region, and political party preference. Sweden was found to belong to the cautiously pronudge nations (along with Japan, Hungary, and Denmark), contrary to hypotheses in previous research. Differences in the support for nudging were found along the economic left-right and GAL-TAN spectra. Individual nudges’ variation in support, polarization, and politicization are analyzed and discussed.

Are people more likely to (mis)interpret information so that it aligns with their ideological identity when relying on feelings compared to when engaging in analytical thinking? Or is it the other way around: Does deliberation increase the propensity to (mis)interpret information to confirm existing political views? In a behavioral experiment, participants (n = 1207, Swedish sample) assessed numerical information concerning the effects of gender quotas and immigration either under time pressure or under no time pressure. To measure trait differences in cognitive sophistication, we also collected data on numeric ability. We found clear evidence of motivated reasoning when assessing both the effects of gender quotas on companies’ financial results and the effect of refugee intake on crime rates. Subjects who prioritized equality over liberty on the labor market were 13 percentage points less likely to correctly assess numerical information depicting that companies that used gender quotas when hiring made less profit. Subjects who classified themselves as ‘Swedes’ rather than ‘World citizens’ were 14 percentage points less likely to correctly assess numerical information depicting that crime rates decreased following immigration. Time pressure did not affect the likelihood to engage in motivated reasoning, while subjects with higher numeric ability were less likely to engage in motivated reasoning when analyzing information concerning refugee intake, but more likely to engage in motivated reasoning when analyzing information regarding the effect of gender quotas. Together these results indicate that motivated reasoning is primarily driven by individual differences in analytical thinking at the trait level and not by situational factors such as time pressure, and that whether motivated reasoning is primarily driven by analysis or feelings depends on the topic at hand.

In a previously published article, I reported some tests of prospect theory's reflection effect over outcomes defined by money and life years gained from treatment. Those results suggested qualified support for the reflection effect over money outcomes and strong support over longevity outcomes. This article reruns those tests while accounting for the intensity of individual risk attitudes, and, overall, show consistency with the reflection effect. However, I argue that these results do not necessarily offer support for the explanatory power of prospect theory. Rather, the results may be driven by evolved responses to circumstances that provoke perceptions of scarcity and abundance. Therefore, from an ecological perspective, behavioral patterns such as those that are consistent with the reflection effect, which, by extension, tend to be considered as erroneous or biased by most behavioral economists because they conflict with the postulates of rational choice theory, may not be unreasonable. Recognizing as such is important when considering how behavioral insights ought to inform public policy design and implementation.

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.

The ultimatum and dictator games were developed to help identify the fundamental motivators of human behavior, typically by asking participants to share windfall endowments with other persons. In the ultimatum game, a common observation is that proposers offer, and responders refuse to accept, a much larger share of the endowment than is predicted by rational choice theory. However, in the real world, windfalls are rare: money is usually earned. I report here a small study aimed at testing how participants react to an ultimatum game after they have earned their endowments by either building a Lego model or spending some time sorting out screws by their length. I find that the shares that proposers offer and responders accept are significantly lower than that typically observed with windfall money, an observation that is intensified when the task undertaken to earn the endowment is generally less enjoyable and thus perhaps more effortful (i.e., screw sorting compared to Lego building). I suggest, therefore, that considerations of effort-based desert are often important drivers behind individual decision-making, and that laboratory experiments, if intended to inform public policy design and implementation, ought to mirror the broad characteristics of the realities that people face.

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).

Recently, there has been a lively discussion of “Hayekian Behavioral Economics” in Behavioral Public Policy). We aim to contribute to this debate by identifying the main building blocks of a Hayekian psychology. We highlight that the starting point for Hayek was the quest to understand why humans are typically quite successful in navigating the world. In Hayek's framework, the individual mind is conceptualized as a “system within a system”, i.e., the mind is a complex adaptive system that is continuously interacting with the wider socio-cultural system. Three core ideas are central to a Hayekian psychology: subjectivity, learning and adaptation. We argue that these ideas are quite different from the still dominant heuristics-and-biases perspective and lead to different emphases in economic and social science explanations. One, economists should be cautious in their interpretation of experimental findings since subjective meaning is central to agents' behavior. Two, static and isolated models of individuals' biases might underestimate people's capacity to learn with and from others. And three, despite complex processes of adaptation of the mind and the market, a Hayekian framework is consistent with economists' “explanations of the principle” and “pattern predictions.”

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.