$\mu$Cap is a software package (citeware) for economic experiments enabling experimenters to analyze emotional states of subjects using z-Tree and FaceReader™. $\mu$Cap is able to create videos of subjects on client computers based on stimuli shown on screen and restrict recording material to relevant time frames. Another feature of $\mu$Cap is the creation of time stamps in csv format at prespecified screens (or at prespecified points in time) during the experiment, measured on the client computer. The software makes it possible to import these markers into FaceReader™ easily. $\mu$Cap is the first program that significantly simplifies the process of connecting z-Tree and FaceReader™ with the additional benefit of extremely high precision. This paper describes the usage, underlying principles as well as advantages and limitations of $\mu$Cap. Furthermore, we give a brief outlook of how $\mu$Cap can be beneficial in other contexts.

Most large real-world organizations contain multiple smaller groups, such as working groups within firms. However, can this sort of nested groups be used to alleviate coordination failures in the larger group? We report on a multi-player Stag Hunt experiment wherein we hierarchically structure a large group into mutually exclusive small groups. We offer varying incentive payments if efficient coordination is achieved at a large or small group level. The novelty of our design is that we hold the total payment size constant between treatments. In our nested incentive treatment, we reduce the reward for achieving large-group coordination by a small amount and reallocate the same amount to successful small-group coordination. The results reveal that incentive reallocations privileging small groups facilitate efficient large-group coordination in the nested group structure.

An intriguing study concluded that political conservatives exhibited enhanced self-control using the Stroop task [Clarkson et al.: The self-control consequences of political ideology. Proc. Natl. Acad. Sci. U.S.A, 112(27): 8250–8253 (2015)]. We preregistered our plans to re-examine this finding using a larger, representative, incentivized, and ideologically balanced sample (n = 476). Across a variety of specifications, we report a consistent null effect of ideology on Stroop response latencies and the Stroop interference effect. These findings suggest that the previously reported result may not generalize. We conclude that there is no causal relationship between political ideology and self-control, as measured by the Stroop task.

This study investigates whether individuals engage in prosocial behavior when it requires an investment of their time, but not money. In a laboratory experiment with rigorous anonymity arrangements, senders receive their payoff at the beginning. They may then engage in a tedious task to increase the earnings of exogenously disadvantaged recipients who otherwise receive no earnings. We find that senders are willing to sacrifice time to benefit recipients. Whether or not the recipient is present in the laboratory during the working time does not alter this decision. However, in a treatment variation some senders also display antisocial behavior.

Households are frequently subject to income and asset shocks. We performed a lab experiment, inducing losses on a real effort task, after which we measured cognitive performance, loss aversion and cheating behavior. We found that asset losses, but not income losses, act as a cognitive load, by decreasing accuracy and increasing response times. We did not detect any change in dishonesty or loss aversion.

By means of a laboratory experiment, Rubin and Sheremeta (Manag Sci 62(4):985–999, 2016), study a bonus-version of the gift-exchange game, including two treatment variations. First they vary whether the effort provided by the agent directly translates into output for the principal, or whether it is distorted by a shock. Second, for the condition with a shock they vary whether the shock is observed by the principal, or not. The authors’ main findings are that (1) the introduction of an unobservable shock significantly reduces welfare; and (2) informing the principal about the size of the shock does not restore gift-exchange. In a replication study we largely reproduce finding (1), but we fail to confirm finding (2). Our data suggests that small behavioral differences in the initial rounds lead to a hysteresis effect that is responsible for the differences in results across studies.

The literature on rent-seeking primarily focuses on contests for achieving gains, although contests for avoiding losses are also omnipresent. Examples for such ‘reverse’ contests are activities to prevent the close-down of a local school or the construction of a waste disposal close-by. While under standard preferences, investments in ‘reverse’ and ‘conventional’ contests should not be different, loss aversion predicts contests for avoiding losses to be fiercer than conventional ones. In our experimental data, the difference in investments between conventional and reverse Tullock contests is small and statistically insignificant. We discuss several explanations for this remarkable finding.

People behave much more cooperatively than predicted by the self-interest hypothesis in social dilemmas such as public goods games. Some studies have suggested that many decision makers cooperate not because of genuine cooperative preferences but because they are confused about the incentive structure of the game—and therefore might not be aware of the dominant strategy. In this research, we experimentally manipulate whether decision makers receive explicit information about which strategies maximize individual income and group income or not. Our data reveal no statistically significant effects of the treatment variation, neither on elicited contribution preferences nor on unconditional contributions and beliefs in a repeated linear public goods game. We conclude that it is unlikely that confusion about optimal strategies explains the widely observed cooperation patterns in social dilemmas such as public goods games.

We conduct a laboratory experiment to investigate the impact of deliberation time on behavior under risk and uncertainty. Towards this end we ask our participant to make quick, intuitive evaluations of a number of lotteries and report resulting certainty equivalents. Yet, we invite them to modify these initial decisions, whenever they find, after (additional) deliberation, that they do not precisely represent their preference. Both certainty equivalents are incentivized (a double-response method). The choice of evaluated lotteries allows us to semi-parametrically estimate the value function and the probability weighting function within the paradigm of the cumulative prospect theory. The main finding is that deliberation raises the probability weighting function (reduces pessimism), especially in the case of lotteries involving unknown probabilities.

For the trust game, recent models of belief-dependent motivations make opposite predictions regarding the correlation between back transfers and second-order beliefs of the trustor: while reciprocity models predict a negative correlation, guilt-aversion models predict a positive one. This paper tests the hypothesis that the inconclusive results in the previous studies investigating the reaction of trustees to their beliefs are due to the fact that reciprocity and guilt aversion are behaviorally relevant for different subgroups and that their impact cancels out in the aggregate. We find little evidence in support of this hypothesis and conclude that type heterogeneity is unlikely to explain previous results.

We experimentally study intention-based social influence in standard and modified Ultimatum and Impunity games. Standard games with bi-dimensional strategy vectors let individuals decide independently in the role of proposer and responder and allow fairness intentions to be role dependent. Uni-dimensional strategy vectors in modified games constrain individuals to consistent offers and acceptance thresholds. To induce social influence, we randomly match participants in groups of four, which are minimally identified by colors. Social influence is assessed by how one reacts to information about median group intention(s). The $2\times 2$ factorial experimental design varies the order of the two game types and the strategy vector dimensionality. Social influence, depending on the game type and strategy dimensionality, significantly impacts participants’ behavior compared to their own intention. At the aggregate level, however, these differences cancel each other out. As there are more constraints on the action space, uni-dimensionality increases strategic concerns.

This paper studies the impact of human subjects in the role of a seller on bidding in experimental second-price auctions. Overbidding is a robust finding in second-price auctions, and spite among bidders has been advanced as an explanation. If spite extends to the seller, then the absence of human sellers who receive the auction revenue may bias upwards the bidding behavior in existing experimental auctions. We derive the equilibrium bidding function in a model where bidders have preferences regarding both the payoffs of other bidders and the seller’s revenue. Overbidding is optimal when buyers are spiteful only towards other buyers. However, optimal bids are lower and potentially even truthful when spite extends to the seller. We experimentally test the model predictions by exogenously varying the presence of human subjects in the roles of the seller and competing bidders. We do not detect a systematic effect of the presence of a human seller on overbidding. We conclude that overbidding is not an artefact of the standard experimental implementation of second-price auctions in which human sellers are absent.

Consumers typically overstate their intentions to purchase products, compared to actual rates of purchases, a pattern called “hypothetical bias”. In laboratory choice experiments, we measure participants’ visual attention using mousetracking or eye-tracking, while they make hypothetical as well as real purchase decisions. We find that participants spent more time looking both at price and product image prior to making a real “buy” decision than making a real “don’t buy” decision. We demonstrate that including such information about visual attention improves prediction of real buy decisions. This improvement is evident, although small in magnitude, using mousetracking data, but is not evident using eye-tracking data.

A survey of instruction delivery and reinforcement methods in recent laboratory experiments reveals a wide and inconsistently reported variety of practices and limited research evaluating their effectiveness. Thus, we experimentally compare how methods of delivering and reinforcing experiment instructions impact subjects’ comprehension and retention of payoff-relevant information. We report a one-shot individual decision task in which non-money-maximizing behavior can be unambiguously identified and find that such behavior is prevalent in our baseline treatment which uses plain, but relatively standard experimental instructions. We find combinations of reinforcement methods that can eliminate half of non-money-maximizing behavior, and we find that we can induce a similar reduction via enhancements to the content of instructions. Residual non-money-maximizing behavior suggests that this may be an important source of noise in experimental studies.

In this study we investigate the effect of framing on bribery behaviour. To do this, we replicate Barr and Serra (Exp Econ, 12(4):488–503, (2009) and carry out a simple one-shot bribery game that mimics corruption. In one treatment, we presented the experiment in a framed version, in which wording was embedded with social context; in the other, we removed the social context and presented the game in a neutral manner. The contribution of this paper is that it offers a comparison of framing effects in two highly corrupt countries: China and Uganda. Our results provide evidence of strong and significant framing effects for Uganda, but not for China.

Janssen et al. (Exp Econ 14:547–566, 2014) studied an asymmetric, finitely repeated common-pool resource dilemma with free-form communication in which subjects made decisions about investments in an infrastructure, and about extraction from a resource made available by this infrastructure. They found that infrastructure provision and joint payoffs converged to high levels because structurally advantaged head-enders tend to behave fairly by restricting themselves voluntarily at the extraction stage, and structurally disadvantaged “tail-enders” reciprocate by investing. This paper reports a fully independent, pre-registered, double-blind replication attempt conducted in a different lab, that also supplies elevated statistical power and adheres to the highest principles of scientific transparency and openness. We find that the key results of Janssen et al. not only re-appear qualitatively but are quantitatively and statistically strengthened. The conclusions drawn from the results are therefore robust, and the basic design can be confidently used for follow-up research.

This article studies whether people want to control what information on their own past pro-social behavior is revealed to others. Participants are assigned a color that depends on their past pro-social behavior. They can spend money to manipulate the probability with which their color is revealed to another participant. The data show that participants are more likely to reveal colors with more favorable informational content. This pattern is not found in a control treatment in which colors are randomly assigned, thus revealing nothing about past pro-social behavior. Regression analysis confirms these findings, also when controlling for past pro-social behavior. These results complement the existing empirical evidence, confirming that people strategically and, therefore, consciously manipulate their social image.

In oligopoly, imitating the most successful competitor yields very competitive outcomes. This theoretical prediction has been confirmed experimentally by a number of studies. A recent paper by Friedman et al. (J Econ Theory 155:185–205, 2015) qualifies those results in an interesting way: While they replicate the very competitive results for the first 25–50 periods, they show that when using a much longer time horizon of 1200 periods, results slowly turn to more and more collusive outcomes. We replicate their result for duopolies. However, with 4 firms, none of our oligopolies becomes permanently collusive. Instead, the average quantity always stays above the Cournot–Nash equilibrium quantity. Thus, it seems that “four remain many” even with 1200 periods.

Studying the likelihood that individuals cheat requires a valid statistical measure of dishonesty. We develop an easy empirical method to measure and compare lying behavior within and across studies to correct for sampling errors. This method estimates the full distribution of lying when agents privately observe the outcome of a random process (e.g., die roll) and can misreport what they observed. It provides a precise estimate of the mean and confidence interval (offering lower and upper bounds on the proportion of people lying) over the full distribution, allowing for a vast range of statistical inferences not generally available with the existing methods.

Since Holt and Laury (Am Econ Rev 92(5):1644–1655, 2002), the multiple price list (MPL) procedure has widely been used to elicit individual risk preferences. We assess the impact of varying list order and spacing, and of presentation via text or graphs. Relative to the original MPL baseline, some non-linear transformations of lottery prices systematically increase elicited risk aversion, while some graphical displays tend to reduce it.