We report the results of a field experiment designed to increase honest disclosure of claims at a U.S. state unemployment agency. Individuals filing claims were randomized to a message (‘nudge’) intervention, while an off-the-shelf machine learning algorithm calculated claimants’ risk for committing fraud (underreporting earnings). We study the causal effects of algorithmic targeting on the effectiveness of nudge messages: Without algorithmic targeting, the average treatment effect of the messages was insignificant; in contrast, the use of algorithmic targeting revealed significant heterogeneous treatment effects across claimants. Claimants predicted to behave unethically by the algorithm were more likely to disclose earnings when receiving a message relative to a control condition, with claimants predicted to most likely behave unethically being almost twice as likely to disclose earnings when shown a message. In addition to providing a potential blueprint for targeting more costly interventions, our study offers a novel perspective for the use and efficiency of data science in the public sector without violating citizens’ agency. However, we caution that, while algorithms can enable tailored policy, their ethical use must be ensured at all times.

In this project, we manipulate the public observability of forecasts and outcomes of a physical task. We explore how these manipulations affect overconfidence (OC). Participants in the experiment are asked to hold a weight after predicting how long they think they could do it for. Comparing the prediction and outcome times (in seconds) yields a measure of OC. We independently vary two dimensions of public observability (of the outcome and of the prediction). Additionally, we manipulate incentives to come up with an accurate prediction. This design allows us to shed light on the mechanism behind male and female OC. Following the existing literature, we formulate several hypotheses regarding the differences in predictions and outcomes for males and females in the presence of the public observability of predictions and outcomes. Our experimental data do not provide support to most of the hypotheses: in particular, there is no evidence of a gender gap in overconfidence. The most robust finding that emerges from our results is that incentives on making correct predictions increase participants’ forecasts on their own performance (by about 24%) and their actual performance as well, but to a lower extent (by about 8%); in addition, incentives to predict correctly in fact increase error for females (by about 33%).

If being asked to give to charity stimulates an emotional response, like empathy, that makes giving difficult to resist, a natural self-control mechanism might be to avoid being asked in the first place. We replicate a result from a field experiment that points to the role of empathy in giving. We conduct an experiment in a large superstore in which we solicit donations to charity and randomly allow shoppers the opportunity to avoid solicitation by using the other door. We find the rate of avoidance by store entrants to be 8.9 %. However, we also find that the avoidance effect disappears in very cold weather, suggesting that avoidance behavior is sensitive to its cost.

Governments across the world have implemented restrictive policies to slow the spread of COVID-19. Recommended face mask use has been a controversially discussed policy, among others, due to potential adverse effects on physical distancing. Using a randomized field experiment (N = 300), we show that individuals kept a significantly larger distance from someone wearing a face mask than from an unmasked person during the early days of the pandemic. According to an additional survey experiment (N = 456) conducted at the time, masked individuals were not perceived as being more infectious than unmasked ones, but they were believed to prefer more distancing. This result suggests that wearing a mask served as a social signal that led others to increase the distance they kept. Our findings provide evidence against the claim that mask use creates a false sense of security that would negatively affect physical distancing. Furthermore, our results suggest that behavior has informational content that may be affected by policies.

In this paper, we propose a network model to explain the implications of the pressure to share resources. Individuals use the network to establish social interactions that allow them to increase their income. They also use the network as a safety and to ask for assistance in case of need. The network is therefore a system characterized by social pressure to share and redistribute surplus of resources among members. The main result is that the potential redistributive pressure from other network members causes individuals to behave inefficiently. The number of social interactions used to employ workers displays a non-monotonic pattern with respect to the number of neighbors (degree): it increases for intermediate degree and decreases for high degree. Respect to a benchmark case without social pressure, individuals with few (many) network members interact more (less). Finally, we show that these predictions are consistent with the results obtained in a set of field experiments run in rural Tanzania.

The widespread Internet “piracy” continues to fuel the debate about business models impervious to copyright infringement. We studied the displacement effects of “piracy” on sales in the book industry. We conducted a year-long large-scale field experiment: in the treatment group, we removed unauthorised copies appearing on the Internet and observed the sales data, whereas in the control group, we simply observed sales. We were able to substantially curb the unauthorised distribution, which resulted in a small, positive effect on sales. While using classical analysis we found it not to be significantly different from zero, a Bayesian approach using previous “piracy” studies to generate a prior led to the conclusion that protecting from piracy resulted in a significant sales boost of about 9 per cent.

Small and medium-sized enterprises constitute the largest share of companies in most economies. As major resource users and significant contributors to environmental pollution, they are relevant targets for public policy programs aimed at increasing sustainability. We study how ‘sludge’ – small frictions in the choice architecture – can impact the uptake and effectiveness of such public policy programs targeted at SMEs. To this end, we conducted a field experiment within an existing policy program designed to support SMEs in implementing cost-effective environmental management practices. We manipulated the process of receiving free green items intended to support the implementation of those environmentally friendly practices within firms. We find that sludge, in the form of minor additional effort required to order the items, substantially undermined the program’s effectiveness. These results have important implications for policymakers: even minor sludge in the choice architecture can seriously impair the effectiveness of public policy programs targeted at companies.

Opposition in autocracies often uses negativism against the regime to frame its principal message. This study is the first to experimentally evaluate the effectiveness of a negative campaign on a regime candidate’s vote share. For the field experiment conducted during the 2013 Moscow mayoral election, we published a newspaper criticizing the incumbent mayor. We distributed approximately 130,000 copies near the entrances of 20 stations on four randomly selected metro lines one month prior to the election. We found that the incumbent’s vote share was 1.7 percentage points lower at the voting stations where the newspaper was distributed. These votes go to other candidates who address issues raised by the negative campaign. Anti-regime campaigning does not suppress turnout or increase disapproval voting.

Iron toxicity is one of the constraints limiting rice production in Africa. This study used a randomized controlled trial to assess the impact of an iron toxicity-tolerant variety, named ARICA 6, on different outcomes and investment in modern inputs by smallholder farmers. Two rounds of data were collected from 520 rice-farming households in Guinea. Results showed that the use of ARICA 6 increased rice yield by 330 kg ha−1 and net income by US$ 120 ha−1. However, adoption of improved variety may not be enough to crowd in investment in modern inputs because farmers face other constraints.

Much research on the antecedents of proactive behavior has appeared in the literature, but this research introduces a new ritual perspective to rethink this question. Drawing on the process model of interaction rituals, we propose that work rituals urge employees to share emotional energy, and then, employees are likely to experience a higher level of work meaningfulness. In turn, employees tend to engage in more proactive behavior. Using data from a random assignment field experiment involving 204 employees from a communication corporation in China, we found support for our hypotheses. The implications of our research for theory and practice are discussed.

Communication is well-known to increase cooperation rates in social dilemma situations, but the exact mechanisms behind this remain largely unclear. This study examines the impact of communication on public good provisioning in an artefactual field experiment conducted with 216 villagers from small, rural communities in northern Namibia. In line with previous experimental findings, we observe a strong increase in cooperation when face-to-face communication is allowed before decision-making. We additionally introduce a condition in which participants cannot discuss the dilemma but talk to their group members about an unrelated topic prior to learning about the public good game. It turns out that this condition already leads to higher cooperation rates, albeit not as high as in the condition in which discussions about the social dilemma are possible. The setting in small communities also allows investigating the effects of pre-existing social relationships between group members and their interaction with communication. We find that both types of communication are primarily effective among socially more distant group members, which suggests that communication and social ties work as substitutes in increasing cooperation. Further analyses rule out better comprehension of the game and increased mutual expectations of one’s group members’ contributions as drivers for the communication effect. Finally, we discuss the role of personal and injunctive norms to keep commitments made during discussions.

The effect of exposure to repository-like conditions on compacted Wyoming bentonite was determined by comparing the hydraulic, mechanical, and mineralogical properties of samples from the bentonite buffer of the Canister Retrieval Test (CRT) with those of reference material. The CRT, located at the Swedish Äspö Hard Rock Laboratory (HRL), was a full-scale field experiment simulating conditions relevant for the Swedish, so called KBS-3, concept for disposal of high-level radioactive waste in crystalline host rock. The compacted bentonite, surrounding a copper canister equipped with heaters, had been subjected to heating at temperatures up to 95°C and hydration by natural Na-Ca-Cl type groundwater for almost 5 y at the time of retrieval.

Under the thermal and hydration gradients that prevailed during the test, sulfate in the bentonite was redistributed and accumulated as anhydrite close to the canister. The major change in the exchangeable cation pool was a loss in Mg in the outer parts of the blocks, suggesting replacement of Mg mainly by Ca along with the hydration with groundwater. Close to the Cu canister, small amounts of Cu were incorporated into the bentonite. A reduction of strain at failure was observed in the innermost part of the bentonite buffer, but no influence was noted on the shear strength. No change in swelling pressure was observed, while a modest decrease in hydraulic conductivity was found for the samples with the highest densities. No coupling was found between these changes in the hydro-mechanical properties and the montmorillonite — the X-ray diffraction characteristics, the cation exchange properties, and the average crystal chemistry of the Na-converted <1 μm fractions provided no evidence of any chemical/structural changes in the montmorillonite after the 5 y hydrothermal test.

Compliance with hygiene and other safety measures in the workplace was an important component of society's strategy for reducing infections at the onset of the COVID-19 pandemic, in particular before vaccinations were widely available. We report the results of a field trial of well-established behavioural interventions (social norms, pledging and messenger effects) we implemented to improve compliance with such measures in an occupational setting. We use daily reports of own and other's behaviour to assess the effects of these interventions and supplement these subjective (self-reported) measures with objective data on hand sanitiser usage. The behavioural interventions tested have statistically significant but quantitatively moderate effects on subjective compliance measures and minimal effects on hand sanitiser usage. All effects of our interventions are short-term in nature and dissipate shortly after implementation. Our findings thus provide at most weak support for the notion that typical behavioural interventions can help support compliance with infection prevention measures in the workplace.

Using an app for smartphones, we run an experiment among high-school students to study the pattern of aggregation of sparsely distributed information. Agents are randomly arranged in small networks and can share only non-verifiable pieces of information. Results show that while information exchange is high, the level and the distribution of centralities among network members are important to shape the overall level of information aggregation. A reduction in the asymmetry among agents’ network centralities is associated with an improvement in the performance of the group in terms of aggregation of information.

Government programs promoting locally produced foods have risen dramatically. But are these programs actually convincing consumers to pay more for locally produced food? Studies to date, which have mostly relied on hypothetical stated preference surveys, suggest that consumers will pay premiums for various local foods and that the premiums vary with the product and presence of any geographic identity. This study reports results from a large field experiment involving 1,050 adult consumers to reveal consumers’ willingness to pay (WTP) premiums for “locally produced” foods – mushrooms and oysters. Despite strong statistical power, this study reveals no positive effect of the locally produced label on consumer WTP. These null results are contrary to most of the existing literature on this topic. The finding that consumers are not willing to pay more for local foods has important implications for state and federal agencies that promote labeling campaigns that seek to increase demand and generate premiums for locally produced foods.

Misinformation is widely seen as a threat to democracy that should be promptly addressed by scholars, journalists, and policymakers. However, some of the debated solutions are either controversial (internet platform regulation) or may be difficult and costly to implement in many settings (fact-checking corrections). This study investigates the effectiveness of preemptive interventions, a type of solution that has received considerably less attention in this debate. Studies show that interventions through awareness and media literacy campaigns can inoculate citizens against misinformation, but these interventions are restricted to a few contexts and settings. Our paper uses two field experiments, one of which was conducted in partnership with Brazil’s main newspaper, to investigate the effectiveness of multidimensional interventions against misinformation in São Paulo. The findings show that preemptive interventions can indeed reduce rumor acceptance and provide insights into the strategies to combat misinformation in democracies.

It is widely thought that lobbyists exert influence over legislators’ policy positions and, as a result, over policy outcomes. One mechanism of influence is the provision of policy expertise. Yet, there is little credible empirical evidence that lobbyists’ expertise influences legislative outcomes. Across four experiments fielded with three lobbyists in two state legislatures that examine two public measures of legislators’ positions, we find no evidence that lobbyists’ expertise influences legislators’ policy positions. We do find, in contrast, that the same policy expertise treatment is influential when provided by a legislative staffer. We conclude that policy information can influence legislators’ positions, but that legislators are cautious when that information is provided by lobbyists.

Providers’ tendency to cream skim clients according to certain sociodemographic traits is widely believed to increase under marketization, and therefore also discrimination. However, due to a lack of experimental research, little is known about the presence of discrimination in marketized welfare services and of the potential drivers of such biased treatment. The lack of research is particularly evident in regard to socioeconomic status (SES) discrimination and publicly financed for-profit providers. Moreover, competition, an important aspect of marketization, has not been investigated. Focusing on the interesting case of the Swedish school sector, we aim to improve knowledge on these matters. In a field experiment, 3,430 elementary school principals were randomly contacted though e-mail by parents with Arabic- or Swedish-sounding names and in low- or high-socioeconomic professions. The fictional parents were interested in placing their children at the school. The Swedish school sector resembles marketized public services in several Western countries. The results show clear signs of ethnic as well as SES discrimination, particularly in regard to more qualitative aspects of the replies. However, we find no significant differences in discrimination between public and private/for-profit schools and depending on the degree of competition in the school market.

The 2020 presidential election brought expanded vote-by-mail opportunities, a rise in attacks on this process’s integrity, and the implementation of novel programs such as California’s Where’s My Ballot? system to ensure confidence in mail balloting. Can heightening awareness of this ballot-tracking system and other election protections alleviate fraud concerns and raise turnout? We assess whether messages reinforcing election integrity increased participation in the 2020 election through a large-scale voter mobilization field experiment. California registrants were mailed a letter that described either existing safeguards to prevent vote-by-mail fraud or the ability to track one’s ballot and ensure that it was counted. Analysis of state voter records reveals that neither message increased turnout over a simple election reminder or even no contact, even among subgroups where larger effects might be expected. In the context of a high-profile, high-turnout presidential election, assurances about ballot and electoral integrity did not increase turnout.