We introduce the “Fork Game,” a graphical interface designed to elicit higher-order risk preferences. In this game, participants connect forked pipes to create a final structure. A ball is then dropped into the top opening of this structure and follows a downward path, randomly turning left or right at each forked joint. This construction is effectively isomorphic to the apportionment of binary-outcome lotteries, allowing participants to construct complex gambles. Furthermore, the game is easily comprehensible, highly modular, and provides a flexible means of assessing risk aversion, prudence, temperance, and even higher-order risk preferences.

Physical inactivity is a leading cause globally of noncommunicable diseases such as diabetes, heart attacks, and strokes. Here, we present the results from a 4-week-long experimental test of a nudge designed to promote physical activity among 206 seniors in Abu Dhabi, United Arab Emirates—a population with one of the highest rates of physical inactivity in the world. We find that the “Forever Fit” nudge—a booklet containing a simple exercise program and information about the health benefits of physical activity—has a large positive effect on 93 previously inactive seniors. The nudge increases the time previously inactive participants spend being physically active from about 5 to about 15 minutes per day.

Volunteering is a widespread allocation mechanism in the workplace. It emerges naturally in software development or the generation of online knowledge platforms. Using a field experiment with more than 2,000 workers, we study the effect of team size on volunteering in an online labor market. In contrast to our theoretical predictions and previous research, we find no effect of team size on volunteering, although workers react to free-riding incentives, and volunteering is perceived as costly. Eliciting workers’ beliefs about their co-workers’ volunteering reveals conditional volunteering as the primary driver of our results: Workers tend to volunteer more when they believe that others are volunteering, even when doing so is highly inefficient. Using additional experiments, we identify the importance of the task itself as an essential mitigating factor for those results.

We performed a field experiment in Uruguay in which a 20-year-old chooses between a socially visible and a non-socially visible good after a friend randomly received one of these goods or an unknown one. We find no differences in choices when the friend received the nonvisible good instead of the unknown one. However, decision-makers significantly changed their allocation when their friend received the visible good. Consistent with status concerns driving the results, those in a disadvantaged position consumed more and those in an advantaged position consumed less of the visible good. These findings constitute the first experimental evidence of Duesenberry’s demonstration effects and show that status consumption is a relevant phenomenon among the youth in a developing country setting.

In a field experiment where revelation of co-worker earnings and the shape of the earnings distribution are exogenously controlled, I test whether relative earnings information itself influences effective labor supply and labor supply elasticity. Piece-rate workers shown their peer earnings standing provide significantly more labor effort. However, the productivity boost from earnings disclosure disappears when inequalities in the underlying piece rate exist. By cross-randomizing net of tax piece rates, labor supply elasticity with respect to the net of tax wage is also estimated. Unlike labor level, I find this labor elasticity is unchanged by the relative standing information. Taken together, these findings have direct implications for how to best model relative status concerns in utility functions, supporting some and precluding other common ways. More speculatively, they also suggest social comparisons could be strategically used to grow firm output or the tax base, and, that underlying inequalities in compensation schemes inhibit the ability of social comparisons to incentivize work.

Information about the consequences of our consumption choices can be unwelcome, and people sometimes avoid it. Thus, when people possess information that is inconvenient for another person, they may face a dilemma about whether to inform them. We introduce a simple and portable experimental game to analyze the transmission of inconvenient information. In this game, a Sender can, at a small cost, inform a Receiver about a negative externality associated with a tempting and profitable action for the Receiver. The results from our online experiment (N = 1,512) show that Senders transmit more information when negative externalities are larger and that Senders’ decisions are largely driven by their own preferences towards the charity and their own use of information. We do not find evidence that Senders take the Receiver’s preferences into account, as they largely ignore explicit requests for information, or ignorance, even if Receivers have the option to punish the Sender.

Pledges are ubiquitous in charitable giving, but they are often reneged upon. To investigate whether adding the phrase “I swear” to pledge language can reduce pledge reneging, we conduct a series of experiments in the context of online fundraising. We find that including “I swear” at the beginning of the pledge language significantly increases immediate giving and pledge fulfillment, with more individuals switching from pledging to giving immediately. We also observe individual heterogeneity in moral identity: Our findings are present among individuals with low moral identity, but not among those with high moral identity. Our paper presents a simple and no-cost strategy for increasing the effectiveness of pledges in online fundraising.

Norm-based accounts of social behavior in economics typically reflect tradeoffs between maximization of own consumption utility and conformity to social norms. Theories of norm-following tend to assume that there exists a single, stable, commonly known injunctive social norm for a given choice setting and that each person has a stable propensity to follow social norms. We collect panel data on 1468 participants aged 11–15 years in Belfast, Northern Ireland and Bogotá, Colombia in which we measure norms for the dictator game and norm-following propensity twice at 10 weeks apart. We test these basic assumptions and find that norm-following propensity is stable, on average, but reported norms show evidence of change. We find that individual-level variation in reported norms between people and within people across time has interpretable structure using a series of latent transition analyses (LTA) which extend latent class models to a panel setting. The best fitting model includes five latent classes corresponding to five sets of normative beliefs that can be interpreted in terms of what respondents view as “appropriate” (e.g. equality vs. generosity) and how they view deviations (e.g. deontological vs. consequentialist). We also show that a major predictor of changing latent classes over time comes from dissimilarity to others in one’s network. Our application of LTA demonstrates how researchers can engage with heterogeneity in normative perceptions by identifying latent classes of beliefs and deepening understanding of the extent to which norms are shared, stable, and can be predicted to change. Finally, we contribute to the nascent experimental literature on the economic behavior of children and adolescents.

We conducted an experiment in a high-immersive virtual reality environment to study the effect of the presence of a virtual observer on cheating behavior. Participants were placed in a virtual room and played 30 rounds of a cheating game without a chance of their cheating being detected. We varied whether or not a virtual observer (an avatar) was present in the room, and, if so, whether the avatar was actively staring at the decision maker or passively seated in a corner watching his smartphone. Results display significantly less cheating with an active than with a passive avatar, but not less cheating than in a control condition without an avatar. This suggests that an active (virtual) observer can intensify reputational concerns, but that the presence of someone passive and uninterested may actually alleviate such concerns.

In this study, we report experimental results on the dictator decision collected in two neighboring ethnic minority groups, the matrilineal Mosuo and the patriarchal Yi, in southwestern China. We follow the double-blind protocol as in Eckel and Grossman (in Handbook of experimental economics results, 1998), who find that women in the U.S. donate more than men. We find this pattern reversed in the Mosuo society and find no gender difference in the Yi society. This is highly suggestive that societal factors play an important role in shaping the gender differences in pro-social behavior such as dictator giving.

We report on sealed-bid second-price auctions that we conducted on the Internet using subjects with substantial prior experience: they were highly experienced participants in eBay auctions. Unlike the novice bidders in previous (laboratory) experiments, the experienced bidders exhibited no greater tendency to overbid than to underbid. However, even subjects with substantial prior experience tended not to bid their values, suggesting that the non-optimal bidding of novice subjects is robust to substantial experience in non-experimental auctions. We found that auction revenue was not significantly different from the expected revenue the auction would generate if bidders bid their values. Auction efficiency, as measured by the percentage of surplus captured, was substantially lower in our SPAs than in previous laboratory experiments.

Are there positive or negative externalities in knowledge production? We analyze whether current contributions to knowledge production increase or decrease the future growth of knowledge. To assess this, we use a randomized field experiment that added content to some pages in Wikipedia while leaving similar pages unchanged. We compare subsequent content growth over the next 4 years between the treatment and control groups. Our estimates allow us to rule out effects on 4-year growth of content length larger than twelve percent. We can also rule out effects on 4-year growth of content quality larger than four points, which is less than one-fifth of the size of the treatment itself. The treatment increased editing activity in the first 2 years, but most of these edits only modified the text added by the treatment. Our results have implications for information seeding and incentivizing contributions. They imply that additional content may inspire future contributions in the short- and medium-term but do not generate large externalities in the long term.

Online labor markets have great potential as platforms for conducting experiments. They provide immediate access to a large and diverse subject pool, and allow researchers to control the experimental context. Online experiments, we show, can be just as valid—both internally and externally—as laboratory and field experiments, while often requiring far less money and time to design and conduct. To demonstrate their value, we use an online labor market to replicate three classic experiments. The first finds quantitative agreement between levels of cooperation in a prisoner's dilemma played online and in the physical laboratory. The second shows— consistent with behavior in the traditional laboratory—that online subjects respond to priming by altering their choices. The third demonstrates that when an identical decision is framed differently, individuals reverse their choice, thus replicating a famed Tversky-Kahneman result. Then we conduct a field experiment showing that workers have upward-sloping labor supply curves. Finally, we analyze the challenges to online experiments, proposing methods to cope with the unique threats to validity in an online setting, and examining the conceptual issues surrounding the external validity of online results. We conclude by presenting our views on the potential role that online experiments can play within the social sciences, and then recommend software development priorities and best practices.

We examine how taxes impact charitable giving and how this relationship is affected by the degree of wasteful government spending. In our model, individuals make donations to charities knowing that the government collects a flat-rate tax on income (net of charitable donations) and redistributes part of the tax revenue. The rest of the tax revenue is wasted. The model predicts that a higher tax rate increases charitable donations. Surprisingly, the model shows that a higher degree of waste decreases donations (when the elasticity of marginal utility with respect to consumption is high enough). We test the model’s predictions using a laboratory experiment with actual donations to charities and find that the tax rate has an insignificant effect on giving. The degree of waste, however, has a large, negative and highly significant effect on giving.

The use of real decision-making incentives remains under debate after decades of economic experiments. In time preferences experiments involving future payments, real incentives are particularly problematic due to between-options differences in transaction costs, among other issues. What if hypothetical payments provide accurate data which, moreover, avoid transaction cost problems? In this paper, we test whether the use of hypothetical or one-out-of-ten-participants probabilistic—versus real—payments affects the elicitation of short-term and long-term discounting in a standard multiple price list task. We analyze data from a lab experiment in Spain and well-powered field and online experiments in Nigeria and the UK, respectively (N = 2,038). Our results indicate that the preferences elicited using the three payment methods are mostly the same: we can reject that either hypothetical or one-out-of-ten payments change any of the four preference measures considered by more than 0.18 SD with respect to real payments.

Nothing is known about the effectiveness of defaults when moving the target outcomes requires substantial effort. We conduct two field experiments to investigate how defaults fare in such situations: we change the university exam sign-up procedure in two study programs to “opt-out” (a) for a single exam, and (b) for many exams. Both interventions increase task uptake (exam sign-up). Concerning the outcomes which require effort, we find no effects for many exams. For a single exam, the opt-out increases task completion (exam participation) in the study program where the default arguably entails stronger endorsement. Within this program, the effects on successful task completion (exam passing) are heterogeneous: treated students who in the past were willing to communicate with the university (responsive individuals) invest more effort into exam preparation and are more likely to pass the exam than their control counterparts.For non-responsive individuals, we find increased sign-ups but no effects on the target outcomes. Defaults can thus be effective and may be an attractive policy option even when the target outcome requires substantial effort provision. It is, however crucial that the interventions target the appropriate individuals.

We investigate the external validity of giving in the dictator game by using the misdirected letter technique in a within-subject design. First, subjects participated in standard dictator games (double blind) conducted in labs in two different studies. Second, after four to five weeks (study 1) or two years (study 2), we delivered prepared letters to the same subjects. The envelopes and the contents of the letters were designed to create the impression that they were misdirected by the mail delivery service. The letters contained 10 Euros (20 Swiss Francs in study 2) corresponding to the endowment of the in-lab experiments. We observe in both studies that subjects who showed other-regarding behavior in the lab returned the misdirected letters more often than subjects giving nothing, suggesting that in-lab behavior is related to behavior in the field.

This paper combines laboratory with field data from professional sellers to study whether social preferences are related to performance in open-air markets. The data show that sellers who are more pro-social in a laboratory experiment are also more successful in natural markets: They achieve higher prices for similar quality, have superior trade relations and better abilities to signal trustworthiness to buyers. These findings suggest that social preferences play a significant role for outcomes in natural markets.

With the evolution of the Web and development of web-based search engines, online searching has become a common method for obtaining information. Given this popularity, the question arises as to how much time people save by using search engines for their information needs compared to offline sources, as well as how online searching affects both search experiences and search outcomes. Using a random sample of queries from a major search engine and a sample of reference questions from the Internet Public Library (IPL), we conduct a real-effort experiment to compare online and offline search experiences and outcomes. We find that participants are significantly more likely to find an answer on the Web (100 %), compared to offline searching (between 87 % and 90 %). Restricting our analysis to the set of questions in which participants find answers in both treatments, a Web search takes on average 7 (9) minutes, whereas the corresponding offline search takes 22 (19) minutes for a search-engine (IPL) question. Furthermore, while raters judge library sources to be significantly more trustworthy and authoritative than the corresponding Web sources, they judge Web sources as significantly more relevant. Balancing all factors, we find that the overall source quality is not significantly different between the two treatments for the set of search-engine questions. However, for IPL questions, we find that non-Web sources are judged to have significantly higher overall quality than the corresponding Web sources. In comparison, for factual questions, Web search results are significantly more likely to be correct (66 % vs. 43 %). Lastly, post-search questionnaires reveal that participants find online searching more enjoyable than offline searching.

Buying lottery tickets is not a rational investment from a financial point of view. Yet, the majority of people participate at least once a year in a lottery. We conducted a field experiment to increase understanding of lottery participation. Using representative data for the Netherlands, we find that lottery participation increased the happiness of participants before the draw. Winning a small prize had no effect on happiness. Our results indicate that people may not only care about the outcomes of the lottery, but also enjoy the game. Accordingly, we conclude that lottery participation has a utility value in itself and part of the utility of a lottery ticket is consumed before the draw.