Global food consumption threatens climate stability and ecosystem resilience. Because hard regulation of food choice through taxes and bans is politically difficult, behavioral approaches provide a promising alternative, given that they influence food choice to a meaningful extent. We test the effect of framing of a menu on the choice of ordering climate-friendly dishes in a randomized controlled experiment. Rearranging the menu in favor of vegetarian food has a large and significant effect on the willingness to order a vegetarian dish instead of meat. Our results demonstrate that small, inexpensive interventions can be used toward decreasing carbon emissions from food consumption.

Insights from the behavioural sciences are increasingly used by governments and other organizations worldwide to ‘nudge’ people to make better decisions. Furthermore, a large philosophical literature has emerged on the ethical considerations on nudging human behaviour that has presented key challenges for the area, but is regularly omitted from discussion of policy design and administration. We present and discuss FORGOOD, an ethics framework that synthesizes the debate on the ethics of nudging in a memorable mnemonic. It suggests that nudgers should consider seven core ethical dimensions: Fairness, Openness, Respect, Goals, Opinions, Options and Delegation. The framework is designed to capture the key considerations in the philosophical debate about nudging human behaviour, while also being accessible for use in a range of public policy settings, as well as training.

Social norms are strongly associated with pro-environmental behaviors, but the evolution and dynamic effects of norms are less well understood. This article builds on the distinction of norms being descriptive, characterizing what people actually do, or injunctive, characterizing what people should do. It identifies four categories of norms with the further distinction of whether the norms arise from the personal beliefs and actions or from the behaviors and judgments of others. The analysis uses five years of longitudinal US data that track household recycling and controls for household characteristics as well as differences in state recycling laws. The results extend previous research by showing that personal norms exhibit cascading dynamics in which norms encourage later changes in recycling, while recycling encourages later changes in personal norms. This mutual reinforcement implies that societal actions encouraging change in either personal norms or recycling will support growth in the other. Recognizing this interdependence can assist in the effective utilization of social norms as a behavioral policy instrument.

The success of choice architecture, including its adoption in government policy and practice, has prompted questions of whether choice architecture design decisions are sufficiently transparent and publicly acceptable. We examined whether disclosing to decision-makers that a particular choice architecture is in place reduces its effectiveness and whether an understanding of the effectiveness of choice architecture design decisions increases their acceptability. We find that disclosure of the design decision does not reduce its effectiveness and that individuals perceive the effectiveness of specific designs to be higher for others than for themselves. Perceived effectiveness for self increases when individuals have actually experienced the effect of a design decision rather than having it simply described to them. Perceived effectiveness for oneself and others increases the acceptability of the designs. We also find that the intentions of the source matter more than who the source actually is. Important for policy-makers, then, is that disclosure of design decisions does not reduce their effectiveness, and their acceptability depends on their perceived effectiveness and the inferred motivations of the design architect.

A recent development within nudge theory is the concept of sludge, which imposes frictions on decision-making. Nascent literature adopts a normative interpretation of sludge: nudge good, sludge bad. However, this normative interpretation leaves much to be desired. A clear definition and treatment of sludge remains absent from this literature, as is a complete understanding of ‘frictions’. Furthermore, the relationship between nudges and sludges is unclear. This paper proposes the concept of nudge/sludge symmetry in an attempt to advance the conceptual understanding of sludge. Building from the definition of a nudge, three types of friction permissible under nudge theory are identified: hedonic, social and obscurant. Sludge is then positioned, in terms of frictions, relative to nudge: nudges decrease relative frictions, sludges increase relative frictions. A consequence of this proposition is nudge/sludge symmetry – where a nudge decreases the frictions associated with a specific option, sludge is simultaneously imposed on all other options available to a decision-maker. Nudge/sludge symmetry subsequently challenges the normative interpretation of sludge, and so a new framework drawing on the literature on nudges in the private sector is offered, with the choice architect placed at the centre. This new approach to sludge and emphasis on the role of the choice architect, in turn, reaffirms the importance of transparency in public policy interventions.

From an ethical standpoint, transparency is an essential requirement in public policy-making. Ideally, policy-makers are transparent and actively disclose the presence, purpose and means of a decision aid. From a practical point of view, however, transparency has been discussed as reducing the effectiveness of decision aids. In the present paper, we elaborate on how transparency affects the effectiveness of defaults. In three experiments, we manipulated whether the endorser was transparent about the default or not and assessed participants’ decisions to opt out or comply. Throughout the experiments, we found that proactive transparency reduced opt-out rates as compared to a non-transparent default condition. Moreover, proactive disclosure of a default reduced opt-out rates as compared to informed control groups, where participants imagined they had retrieved the default-related information by themselves (Studies 1 and 2). The results further indicate that a lack of proactive disclosure may lead targets to perceive the endorser as less sincere and to feel deceived, which in turn hinders the effectiveness of the default. In general, our findings lend support to the proactive transparency paradigm in governance and show that a default-based policy can be transparent and effective at the same time.

A growing body of evidence shows that politicians use motivated reasoning to fit evidence with prior beliefs. In this, they are not unlike other people. We use survey experiments to reaffirm prior work showing that politicians, like the public they represent, engage in motivated reasoning. However, we also show that politicians are more resistant to debiasing interventions than others. When required to justify their evaluations, politicians rely more on prior political attitudes and less on policy information, increasing the probability of erroneous decisions. The results raise the troubling implication that the specialized role of elected officials makes them more immune to the correction of biases, and in this way less representative of the voters they serve when they process policy information.

It is commonly assumed in affluent, Western, democratic societies that by enhancing opportunities for choice, we enhance freedom and well-being, both by enabling people to get exactly what they want and by enabling people to express their identities. In this paper, we review evidence that the relationships between choice, freedom, and well-being are complex. The value of choice in itself may depend on culture, and even in cultural contexts that value choice, too much choice can lead to paralysis, bad decisions, and dissatisfaction with even good decisions. Policy-makers are often in a position to enhance well-being by limiting choice. We suggest five questions that policy-makers should be asking themselves when they consider promulgating policies that will limit choice in the service of enhanced well-being. The relationships between choice, freedom, and well-being are not simple, and an appreciation of their complexity may help policy-makers target their interventions more effectively.

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.

The most effective behavioral policies are often also the most contentious. Psychologically informed interventions that promote non-deliberative behaviors (‘nudges’) are often more effective than ‘traditional’ policies (like informational and educational campaigns) that target more deliberative processes. Yet, precisely because of their deliberative nature, people are often said to prefer the latter over the former. In contrast, we provide evidence that people's preferences regarding nudges are malleable and influenced by the method of evaluation – whether the policy alternatives are evaluated separately or jointly. We show that while people exhibit a strong preference for more traditional public policies in joint evaluation, this preference is significantly attenuated in separate evaluation. We find that people perceive nudges as less paternalistic when judged on their own merits, that they are more likely to endorse nudges in separate than in joint evaluation, and that, provided with relative effectiveness information, people are willing to endorse nudges even in joint evaluation. We discuss the implications of these findings for researchers, policy-makers, and the general public.

Corruption in the form of bribery continues to be a major societal challenge around the world. The current lab-in-the-field study tested whether dynamic descriptive norms messages on posters can help to reduce bribery. Before, during and after placing posters throughout a medium-sized South African town, incentivized measures of social norms and bribery were assessed in a mobile lab. A total of 311 participants stemming from the general population took part. In line with the pre-registered predictions, the results reveal that people: (1) perceive bribery to be less common; and (b) engage in bribery in a corruption game less frequently when the posters were displayed. The discussion outlines how social norms nudging campaigns can be leveraged to spur collective action against corruption.

Persuading people to choose strong passwords is challenging. One way to influence password strength, as and when people are making the choice, is to tweak the choice architecture to encourage stronger choice. A variety of choice architecture manipulations (i.e. ‘nudges’) have been trialled by researchers with a view to strengthening the overall password profile. None has made much of a difference so far. Here, we report on our design of an influential behavioural intervention tailored to the password choice context: a hybrid nudge that significantly prompted stronger passwords. We carried out three longitudinal studies to analyse the efficacy of a range of ‘nudges’ by manipulating the password choice architecture of an actual university web application. The first and second studies tested the efficacy of several simple visual framing ‘nudges’. Password strength did not budge. The third study tested expiration dates directly linked to password strength. This manipulation delivered a positive result: significantly longer and stronger passwords. Our main conclusion was that the final successful nudge provided participants with absolute certainty as to the benefit of a stronger password and that it was this certainty that made the difference.

Policymakers are increasingly turning to insights gained from the experimental method as a means to inform large-scale public policies. Critics view this increased usage as premature, pointing to the fact that many experimentally tested programs fail to deliver their promise at scale. Under this view, the experimental approach drives too much public policy. Yet, if policymakers could be more confident that the original research findings would be delivered at scale, even the staunchest critics would carve out a larger role for experiments to inform policy. Leveraging the economic framework of Al-Ubaydli et al. (2019), we put forward 12 simple proposals, spanning researchers, policymakers, funders and stakeholders, which together tackle the most vexing scalability threats. The framework highlights that only after we deepen our understanding of the scale-up problem will we be on solid ground to argue that scientific experiments should hold a more prominent place in the policymaker's quiver.

We join the call for governments to routinely collect survey-based measures of self-reported wellbeing and for researchers to study them. We list a number of challenges that have to be overcome in order for these measures to eventually achieve a status that is competitive with traditional economic indicators. We discuss in more detail one of the challenges, comprehensiveness: single-question wellbeing measures do not seem to fully capture what people care about. We briefly review the existing evidence, suggesting that survey respondents, when asked to make real or hypothetical trade-offs, would not always choose to maximize their predicted response to single-question wellbeing measures. The deviations appear systematic, and they persist under conditions where alternative explanations are less plausible. We also review an approach for combining single-question measures into a more comprehensive wellbeing index – an approach that itself is not free of ongoing theoretical and implementational challenges, but that we view as a promising direction.

Do differences in worldview ideology hinder people from objectively interpreting the effect of immigration? In an experiment with Swedish adults (n = 1015), we investigate whether people display motivated reasoning when interpreting numerical information about the effects of refugee intake on crime rate. Our results show clear evidence of motivated reasoning along the lines of worldview ideology (i.e., whether people identify themselves primarily as nationally oriented or globally oriented). In scenarios where refugee intake was associated with higher crime rate, nationally oriented people were 18 percentage points more likely to make the correct assessment compared to globally oriented people. Likewise, in scenarios where refugee intake was associated with lower crime rate, nationally oriented people were 20 percentage points less likely to make the correct assessment compared to globally oriented people. Individuals with higher numeric ability were less likely to engage in motivated reasoning, suggesting that motivated reasoning more commonly is driven by feelings and emotional cues rather than deliberate analytical processes.

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.

In a large study that involved 2637 participants recruited from a representative UK and US sample, we tested the influence of four behavioural interventions (versus control) on a range of behaviours important for reducing the spread of COVID-19 a day after the interventions were administered. Even if people largely complied with social distancing measures, our analyses showed that for certain subgroups of the population the interventions made a positive difference. More specifically, for those who started practising social distancing relatively recently, an information-based intervention increased general compliance with social distancing and reduced both the number of times people went out and the number of hours they spent outside. However, for people who started practising social distancing relatively early, the interventions tended to backfire and, in some cases, reduced compliance with social distancing. Overall, this research has various policy implications and shows that, although behavioural interventions can positively impact compliance with social distancing, their effect may depend on personal circumstances.

In this study, we investigated how people evaluate behavioral interventions (BIs) that are targeted at themselves, aiming to promote their own health and wellbeing. We compared the impact on people's assessments of the acceptability of using BIs to change their own behavior of: the transparency of the BI (transparent or opaque); the designer of the BI (researchers, government policy-makers, advertisers); and three types of arguments regarding their efficacy (positive, positive + negative, negative). Our target BIs were actual interventions that have been used in a range of policy domains (diet, exercise, alcohol consumption, smoking, personal finances). We found that transparent BIs were considered more acceptable than opaque BIs. On average, all BIs were considered acceptable for changing participants’ own behavior, except for the opaque BI in the finance context; there was differential acceptability of BIs across contexts, with finance clearly least acceptable. However, the perceived effectiveness of the BIs was at least as influential a predictor of acceptability ratings as the ease of identification of the behavior change mechanism across the five contexts. Furthermore, effectiveness was partially mediated by desire to change, suggesting that people do think BIs make them better off, ‘as judged by themselves’.

This paper compares the effects of two types of behaviorally informed policy – nudges and boosts – that are designed to increase consumer demand for insurance against low-probability, high-consequence events. Using previous findings in the behavioral sciences literature, this paper constructs and implements two nudges (an ‘informational’ and an ‘affective’ nudge) and a statistical numeracy boost and then elicits individual risk beliefs and demand for flood insurance using a contingent valuation survey of 331 participants recruited from an online labor pool. Using a two-limit Tobit model to estimate willingness to pay (WTP) for flood insurance, this paper finds that the affective and informational nudges result in increases in WTP for flood insurance of roughly $21/month and $11/month relative to the boost, respectively. Taken together, the findings of this paper suggest that nudges are the more effective behaviorally informed policy in this setting, particularly when the nudge design targets the affect and availability heuristics; however, additional research is necessary to establish sufficient conditions for this conclusion.

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.