We perform a meta analysis of gender differences in the standard windfall gains dictator game (DG) by collecting raw data from 53 studies with 117 conditions, giving us 15,016 unique individual observations. We find that women on average give 4 percentage points more than men (Cohen’s $d=0.16$), and that this difference decreases to $3.1\%$ points (Cohen’s $d=0.13$) if we exclude studies where dictators can only give all or nothing. The gender difference is larger if the recipient in the DG is a charity, compared to the standard DG with an anonymous individual as the recipient (a 10.9 versus a $2.3\%$ points gender difference). These effect sizes imply that many individual studies on gender differences are underpowered; the median power in our sample of standard DG studies is only $9\%$ to detect the meta-analytic gender difference at the $5\%$ significance level. Moving forward on this topic, sample sizes should thus be substantially larger than what has been the norm in the past.

Do people discriminate between men and women when they have the option to punish defectors or reward cooperators? Here, we report on four pre-registered experiments that shed some light on this question. Study 1 (N = 544) shows that people do not discriminate between genders when they have the option to punish (reward) defectors (cooperators) in a one-shot prisoner’s dilemma with third-party punishment/reward. Study 2 (N = 253) extends Study 1 to a different method of punishing/rewarding: participants are asked to rate the behaviour of a defector/cooperator on a scale of 1–5 stars. In this case too, we find that people do not discriminate between genders. Study 3a (N = 331) and Study 3b (N = 310) conceptually replicate Study 2 with a slightly different gender manipulation. These latter studies show that, in situations where they do not have specific beliefs about the gender of the defector/cooperator’s partner, neither men nor women discriminate between genders.

The personal experience of events such as financial crises and natural disasters can alter economic preferences. We administered a repeated cross-sectional preference survey during the early stages of the COVID-19 outbreak, collecting three bi-weekly samples from participants recruited through Amazon Mechanical Turk. The survey elicits economic preferences, self-reported fear of the pandemic, and beliefs about economic and health consequences. Preferences varied over time and across regions, and self-reported fear of the pandemic explains this variation. These findings suggest caution about the generalizability of some types of experimental work during times of heightened fear.

We study the effects on performance of incentives framed as gains or losses, as well as the effort channels through which individuals increase performance. We also explore potential spill-over effects on a non-incentivised activity. Subjects participated in a medically framed real-effort task under one of the three contracts, varying the type of performance incentive received: (1) no incentive; (2) incentive framed as a gain; or (3) incentive framed as a loss. We find that performance improved similarly with incentives framed as losses or gains. However, individuals increase performance differently under the two frames: potential losses increase participants’ performance through a greater attention (fewer mistakes), while bonuses increase the time spent on the rewarded activity. There is no spill-over effect, either negative or positive, on the non-incentivised activity. We discuss the meaning and implications of our results for the design of performance contracts.

Access to information via social media is one of the biggest differentiators of public health crises today. During the early stages of the Covid-19 outbreak in January 2020, we conducted an experiment in Wuhan, China to assess the impact of viral social media content on pro-social and trust behaviours and preferences towards risk taking with known and unknown probabilities. Prior to the experiment, participants viewed one of two videos that had been widely and anonymously shared on Chinese social media: a central government leader visiting a local hospital and supermarket, or health care volunteers transiting to Wuhan. In a control condition, participants watched a Neutral video, unrelated to the crisis. Viewing one of the leadership or volunteer videos leads to higher levels of pro-sociality and lesser willingness to take risks in an ambiguous situation relative to the control condition. The leadership video, however, induces lower levels of trust. We provide evidence from two post-experiment surveys that the video’s impact on pro-sociality is modulated by influencing the viewer’s affective emotional state.

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.

Cooperation motives are traditionally elicited in experimental games where players have misaligned interests that yield noncooperation in equilibrium. Research finds a typology of behavioral types such as free riders and conditional cooperators. However, intrinsic motives in conflict settings such as appeasement, punishment, and greed are elusive in such games where noncooperation is the equilibrium prediction. To identify types in the dark side of human interaction, we apply hierarchical cluster analysis to data from the Vendetta Game, which has a payoff structure similar to public goods games but a dynamic move structure that yields cooperation in equilibrium. It allows us to observe diverse non-equilibrium conflict strategies, and to understand how feuds perpetuate. We relate our method and typology to other social dilemmas.

This study is a conceptual replication of Kelley & Schmeichel (PLOS ONE 10: e0144228, 2015), which found that thinking about death reduces delay discounting. Unlike the original study, the current study was conducted in an environment where there was a real and tangible mortality threat across the world, that is, COVID-19. Contrary to the findings of the original study, results of the current study revealed that thinking about death increases delay discounting, such that participants who were primed with death thoughts traded “₺200 now” for “₺342.35 three months later,” whereas those in the control condition traded “₺200 now” for “₺319.27 three months later”. The current study also explored the moderating roles of goal orientation and self-esteem in the effect of mortality salience on delay discounting; however, it failed to provide evidence for the moderating roles of these variables.

Internet services are often free of charge but ask for customers’ personal data in exchange for usage. We experimentally study whether the provision of information-based public goods is susceptible to restraint when contributions not only make contributors better off but also enable a non-contributing “big player” to acquire substantial profits. We show that the presence of the big player crowds out the willingness to provide neutral tokens, but no such effect is observed for the provision of private information. Hence, collecting anonymized personal data instead of monetary fees can be more profitable to service providers and create greater benefits for customers.

We report the results of a novel protocol for running online experiments using a combination of an online experimental platform in parallel with web-conferencing software in two formats—with and without subject webcams—to improve subjects’ attention and engagement. We compare the results between our online sessions with the offline (lab) sessions of the same experiment. We find that both online formats lead to comparable subject characteristics and performance as the offline (lab) experiment. However, the webcam-on protocol has less noisy data, and hence better statistical power, than the protocol without a webcam. The webcam-on protocol can detect reasonable effect sizes with a comparable sample size as in the offline (lab) protocol.

We establish whether the efficacy of mutual monitoring in fostering cooperation is dependent on the degree of approval motivation within teams. Approval motivation is defined as the desire to produce positive perceptions in others and the incentive to acquire the approval of others as well as the desire to avoid disapproval, (Martin in J Personality Assess 48(5):508–519, 1984). Contrary to the theoretical predictions, the results from the experiment suggest that mutual monitoring was not effective in fostering cooperation in teams. Furthermore, the efficacy of mutual monitoring in fostering cooperation was not correlated with the degree of approval motivation within teams.

The famous linguistic-savings hypothesis states that languages that grammatically separate the future from the present (like English) causally induce less future-oriented behavior than languages in which speakers can refer to the future using present tense (like German or Chinese). Chen et al., European Economic Review 120 (2019) experimentally investigate the effect of using future-oriented language on incentivized intertemporal choices and find no support for the hypothesis. We replicate Chen et al., European Economic Review 120 (2019)’s study in the German-speaking context. In our experiment with 332 subjects, we randomly refer to future payments using present or future tense and find no causal effect of language on intertemporal choice. Given the importance of replications for confidence in scientific findings, our results provide corroborating evidence that the linguistic-savings hypothesis is not empirically tenable. Eventually, the results provide a methodological contribution to the conduct of experiments.

Laboratory experiments have been often replaced by online experiments in the last decade. This trend has been reinforced when academic and research work based on physical interaction had to be suspended due to restrictions imposed to limit the spread of Covid-19. Therefore, data quality and results from web experiments have become an issue which is currently investigated. Are there significant differences between lab experiments and online findings? We contribute to this debate via an experiment aimed at comparing results from a novel online protocol with traditional laboratory settings, using the same pool of participants. We find that participants in our experiment behave in a similar way across settings and that there are at best weakly significant and quantitatively small differences in behavior observed using our online protocol and physical laboratory setting.

We convey our experiences developing and implementing an online experiment to elicit subjective beliefs and economic preferences. The COVID-19 pandemic and associated closures of our laboratories required us to conduct an online experiment in order to collect beliefs and preferences associated with the pandemic in a timely manner. Since we had not previously conducted a similar multi-wave online experiment, we faced design and implementation considerations that are not present when running a typical laboratory experiment. By discussing these details more fully, we hope to contribute to the online experiment methodology literature at a time when many other researchers may be considering conducting an online experiment for the first time. We focus primarily on methodology; in a complementary study we focus on initial research findings.

The replication crisis across several disciplines raises challenges for behavioural sciences in general. In this report, we review the lessons for experimental economists of these developments. We present the new research methods and practices which are being proposed to improve the replicability of scientific studies. We discuss how these methods and practices can have a positive impact in experimental economics and the extent to which they should be encouraged.

We consider a dictator game experiment in which dictators perform a sequence of giving tasks and taking tasks. The data are used to estimate the parameters of a Stone–Geary utility function over own-payoff and other’s payoff. The econometric model incorporates zero observations (e.g. zero-giving or zero-taking) by applying the Kuhn–Tucker theorem and treating zeros as corner solutions in the dictator’s constrained optimisation problem. The method of maximum simulated likelihood (MSL) is used for estimation. We find that selfishness is significantly lower in taking tasks than in giving tasks, and we attribute this difference to the “cold prickle of taking”.