Explicit and implicit incentives and opportunities for mutually beneficial voluntary cooperation coexist in many economic relationships. In a series of eight laboratory gift-exchange experiments, we show that incentives can lead to crowding out of voluntary cooperation even after they have been abolished. This crowding-out also occurs in repeated relationships, which otherwise strongly increase effort compared to one-shot interactions. Using a unified econometric framework, we unpack these results as a function of positive and negative reciprocity, as well as the principals’ wage offer and the incentive compatibility of the contract. Crowding-out occurs mostly due to reduced wages and not a change in reciprocal wage–effort relationships. Our systematic analysis also replicates established results on gift exchange, incentives, and crowding out of voluntary cooperation while being exposed to incentives. Overall, our findings show that the behavioral consequences of explicit incentives strongly depend on the features of the situation in which they are embedded.

We study whether CEOs of private firms differ from other people with regard to their strategic decisions and beliefs about others’ strategy choices. Such differences are interesting since CEOs make decisions that are economically more relevant, because they affect not only their own utility or the well-being of household members, but the utility of many stakeholders inside and outside of the organization. They also play a central role in shaping values and norms in society. We expect differences between both groups, because CEOs are more experienced with strategic decision making than comparable people in other professional roles. Yet, due to the difficulties in recruiting this high-profile group for academic research, few studies have explored how CEOs make incentivized decisions in strategic games under strict controls and how their choices in such games differ from those made by others. Our study combines a stratified random sample of 200 CEOs of medium-sized firms with a carefully selected control group of 200 comparable people. All subjects participated in three incentivized games—Prisoner’s Dilemma, Chicken, Battle-of-the-Sexes. Beliefs were elicited for each game. We report substantial and robust differences in both behavior and beliefs between the CEOs and the control group. The most striking results are that CEOs do not best respond to beliefs; they cooperate more, play less hawkish and thereby earn much more than the control group.

ConG is software for conducting economic experiments in continuous and discrete time. It allows experimenters with limited programming experience to create a variety of strategic environments featuring rich visual feedback in continuous time and over continuous action spaces, as well as in discrete time or over discrete action spaces. Simple, easily edited input files give the experimenter considerable flexibility in specifying the strategic environment and visual feedback. Source code is modular and allows researchers with programming skills to create novel strategic environments and displays.

We explore if fairness and inequality motivations affect cooperation in indefinitely repeated games. Each round, we randomly divided experimental participants into donor–recipient pairs. Donors could make a gift to recipients, and ex-ante earnings are highest when all donors give. Roles were randomly reassigned every period, which induced inequality in ex-post earnings. Theoretically, income-maximizing players do not have to condition on this inequality because it is payoff-irrelevant. Empirically, payoff-irrelevant inequality affected participants’ ability to coordinate on efficient play: donors conditioned gifts on their own past roles and, with inequalities made visible, discriminated against those who were better off.

This paper reports three experiments with triadic or dyadic designs. The experiments include the moonlighting game in which first-mover actions can elicit positively or negatively reciprocal reactions from second movers. First movers can be motivated by trust in positive reciprocity or fear of negative reciprocity, in addition to unconditional other-regarding preferences. Second movers can be motivated by unconditional other-regarding preferences as well as positive or negative reciprocity. The experimental designs include control treatments that discriminate among actions with alternative motivations. Data from our three experiments and a fourth one are used to explore methodological questions, including the effects on behavioral hypothesis tests of within-subjects vs. across-subjects designs, single-blind vs. double-blind payoffs, random vs. dictator first-mover control treatments, and strategy responses vs. sequential play.

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.

The level-k literature classifies subjects into different Lk types by their observed levels of reasoning in games. However, it remains unclear whether the observed level-k behavior is determined by belief or reasoning ability. This study proposes a strategy to identify the ability-bounded Lk subjects, who could not reason more than k steps of iterated best responses and thus have reached the upper bounds of their reasoning capacity. The identification utilizes a combination of simultaneous and sequential ring games. In the sequential games, it requires an extra step to best respond as Lk, and thus the ability-bounded ones would fail the task. Results show that more than half of the L2 and L3 subjects are ability-bounded. Additionally, subjects’ CRT scores, a measure of their cognitive ability, support the separation of the ability-bounded types. The findings suggest that both belief and reasoning ability could determine the observed levels, and thus one must be cautious when trying to infer belief or ability from the existing level-k data.

Previous research has suggested that communication and especially promises increase cooperation in laboratory experiments. This has been taken as evidence for internal motivations such as guilt aversion or preference for promise keeping. The goal of this paper was to examine messages under a double-blind payoff procedure to test the alternative explanation that promise keeping is due to external influence and reputational concerns. Employing a 2 × 2 design, we find no evidence that communication increases the overall level of cooperation in our experiments with double-blind payoff procedures. However, we also find no evidence that communication impacts cooperation in our experiments with single-blind payoff procedures. Further, the payoff procedure does not appear to impact aggregate cooperation.

Two rationales have emerged for why individuals keep their promises: (a) an emotional commitment to keep actions and words consistent, a commitment rationale and (b) avoidance of guilt due to not meeting the expectations of the promisee, an expectations rationale. We propose a new dichotomy with clearer distinctions between rationales: (1) an internal consistency rationale, which is the desire to keep actions and words consistent regardless of others’ awareness of the promise and (2) a communication rationale, which captures all aspects of promise keeping that are associated with the promisee having learned of the promise, including but not limited to promisee expectations. Using an experiment that manipulates whether promises are delivered, we find no support for the internal consistency rationale; only delivered promises are relevant. In a second experiment designed to better understand what aspect of promise delivery influences promisor behavior, we manipulate whether the promise is delivered before or after the promisee is able to take a trusting action. We find late-arriving promises are relevant though not as relevant as promises delivered before the promisee chooses whether to take the trusting action. We conclude that implicit contracting does not fully explain promise keeping, because had it done so, late-arriving promises would also be irrelevant.

Within-group communication in competitive coordination games has been shown to increase competition between groups and lower efficiency. This study further explores potentially harmful effects of communication, by addressing the questions of (1) asymmetric communication and (2) the endogenous emergence of communication. Our theoretical analysis provides testable hypotheses regarding the effect of communication on competitive behavior and efficiency. We test these predictions using a laboratory experiment. The experiment shows that although asymmetric communication is not as harmful as symmetric communication, it leads to more aggressive competition and lower efficiency relative to the case when neither group can communicate. Moreover, groups vote to endogenously establish communication channels even though they would earn higher payoffs if jointly they chose to restrict within-group communication.

This article investigates the use of standard econometric models for quantal choice to study equilibria of extensive form games. Players make choices based on a quantal-choice model and assume other players do so as well. We define an agent quantal response equilibrium (AQRE), which applies QRE to the agent normal form of an extensive form game and imposes a statistical version of sequential rationality. We also define a parametric specification, called logit-AQRE, in which quantal-choice probabilities are given by logit response functions. AQRE makes predictions that contradict the invariance principle in systematic ways. We show that these predictions match up with some experimental findings by Schotter et al. (1994) about the play of games that differ only with respect to inessential transformations of the extensive form. The logit-AQRE also implies a unique selection from the set of sequential equilibria in generic extensive form games. We examine data from signaling game experiments by Banks et al. (1994) and Brandts and Holt(1993). We find that the logit-AQRE selection applied to these games succeeds in predicting patterns of behavior observed in these experiments, even when our prediction conflicts with more standard equilibrium refinements, such as the intuitive criterion. We also reexamine data from the McKelvey and Palfrey (1992) centipede experiment and find that the AQRE model can account for behavior that had previously been explained in terms of altruistic behavior.

Experimental dictator games have been used to explore unselfish behaviour. Evidence is presented here, however, that subjects’ generosity can be reversed by allowing them to take a partner's money. Dictator game giving therefore does not reveal concern for consequences to others existing independently of the environment, as posited in rational choice theory. It may instead be an artefact of experimentation. Alternatively, evaluations of options depend on the composition of the choice set. Implications of these possibilities are explored for experimental methodology and charitable donations respectively. The data favour the artefact interpretation, suggesting that demand characteristics of experimental protocols merit investigation, and that economic analysis should not exclude context-specific social norms.

International economic theory suggests that people should embrace economic integration because it promises large gains. But policy reversals such as Brexit indicate a desire for economic disintegration. Here we report results of an experiment of how size and cross-country distribution of gains from integration influence individuals’ inclination to cooperate to reap its intended benefits and to embrace or reject integration. The design considers an indefinitely repeated helping game with multiple equilibria and strategic uncertainty. The data reveal that inequality of potential gains neither affected behavior nor reduced support for economic integration. However, integration may lead to disappointing, unequally distributed welfare gains, undermining support for the policy. This suggests that to better assess integration policies, we should account for the spillover effects of integration on behavior. Miscalculating this behavioral aspect may undermine the intended development goals and motivate calls for dramatic policy-reversals.

Objective: To use meta-analysis techniques to assess the impact of various factors on the extent of cooperation in standard linear public goods experiments using the voluntary contributions mechanism.

Data Sources: Potentially relevant experiments were identified through searches of EconLit, the Internet Documents in Economics Access Service (IDEAS), and a survey article.

Review Methods: A total of 349 potentially relevant studies were identified. Of these, 27 (representing a total of 711 groups of participants) met the inclusion criteria. Data were abstracted from these studies using a standardized protocol. Results were analyzed using weighted ordinary least squares. Average group efficiency was the dependent variable.

Results: The marginal per capita return, communication, constant group composition over the session (“partners”), positive framing, and the use of children as subjects had a positive and significant effect (p < 0.05) on the average level of contribution to the public good. Heterogeneous endowments to subjects, experienced participants, and soliciting subjects’ beliefs regarding other participants’ behaviour prior to the start of the session/period had a negative and significant effect. A number of other factors were not identified as significant.

Conclusion: The meta-analysis results parallel several key findings from previous literature reviews. In addition, they offer parameter estimates and an analysis of significance based on the totality of the available research evidence. More consistent reporting of the results of experiments would greatly improve the ability to conduct this type of research.

This paper reports the results of the Ultimatum Game (UG), Dictator Game (DG) and Public Goods Game (PGG) played among the Tsimane, a group of forager-horticulturalists living in the Bolivian Amazon. Game results differ significantly from those commonly reported among modern, westernized populations. Without a long history of anonymous interactions, it is highly suspect whether the Tsimane or other traditional populations play economic games under assumptions of anonymity and one-shot exposure. Employing a behavioral ecology framework, I test predictions that differential market exposure, costs of giving, and experience with cooperation can help explain much of the variance in game outcomes. While these factors sometimes act as important predictors of game behavior, the most significant predictor is village membership. Implications for understanding the role of markets, frequent interaction with strangers, and payoffs to cooperation in daily life can help us better understand cross-cultural variation in pro-social behavior.

Legal disputes are often negotiated under the backdrop of an adjudicated award. While settlements are common, they are not universal. In this paper, we empirically explore how uncertainty in adjudicated awards impacts settlement negotiations. To do so, we develop an experimental design to test how increases in variance and positive skewness of the award distribution impact negotiations and settlement rates. We find increases in variance decrease settlement rates, while increases in skewness generally increases settlement rates. We also gather individual measures of risk aversion and prudence, and incorporate these measures into the analysis to test for heterogeneous treatment effects. Overall, our results suggest that highly variable adjudicated awards can contribute to the excess use of inefficient litigation, while more positively skewed awards can reduce the use of inefficient litigation.

We augment a standard bilateral gift exchange game so employees can send messages at the same time as choosing an effort level. Employee effort (controlling for wages) is unaffected by allowing messages, but wages dramatically increase. Messages affect wages because employees give managers advice to set higher wages, usually explaining that this will result in higher effort. This advice prompts managers to try higher wages, helping them learn that raising wages increases their payoffs. In a follow-up experiment, we directly provide managers with additional information about the relationship between wages and effort. This too causes wages to increase, but to a lesser extent than allowing messages. Our results highlight the critical role of learning in generating gains from positive gift exchange.

The three dissertation essays investigate different aspects of reputation in games where fairness is an important consideration. The first essay studies the effects of reputation on indirect reciprocity in different dictator games. The first experiment places dictators in two environments where they can either give money to the paired player or take money away from them: in one treatment the paired player is a stranger and in the other treatment the dictator has information on the paired player's reputation. Contrary to anecdotal evidence, the statistical tests show that the dictators’ behavior towards a stranger is not statistically significantly different from their behavior towards an individual with an established reputation. The findings arise because a high proportion of dictators acted purely in their own self interest in both treatments. The data also provides evidence that dictators are more generous when they know that their choices (but not their identities) will be revealed in the future. In the second experiment the dictators’ choices were restricted to only generous actions. In such environment the dictators sent more money on average to recipients with a reputation for being generous than to recipients without a reputation.

The second essay explores the ways in which information about others’ actions affects one's own behavior in a dictator game. The experimental design discriminates behaviorally between three possible effects of recipient's within-game reputation on the dictator's decision: reputation causing indirect reciprocity, social influence, and identification. The separation of motives helps to identify the mechanisms of social transmission of impulses towards selfish or generous behavior. The data analysis reveals that the reputation effects have a stronger impact on dictators’ actions than social influence and identification.

In the third essay we examine the reputation effects in a labor market setting by analyzing the influence of negative technological shocks on long run relationships between firms and workers. The positive correlation between wage and effort in static conditions has been demonstrated in many experimental studies and has been one of the prominent explanations for the existence of wage rigidity. We subject these findings to further tests in a non-stationary environment that better corresponds to outside-the-lab market conditions. We observe the positive correlation of wages and effort but do not find support for downward wage rigidity in our data. Once the shocks occur, firms lower the wages and relationships often break down. The workers who accept a lower wage respond with exerting a lower effort.

Many social dilemmas involve deciding among alternative public goods, and include cases where part of the population may dislike a particular option. In such cases, an agent may want to spend resources to oppose or reduce the provision of the option they don’t like. We propose the generalized voluntary contributions mechanism (GVCM), which allows allocating resources to increase or decrease the level of public good. Our main treatment variables include two versions of the GVCM (uncensored, or censored at positive provision). We study performance of GVCM for various compositions of the polarized preferences. We find that uncensoring the mechanism does not impose net efficiency costs and leads to more diversity in the provision of the public good. The nature of efficiency loss is more complex compared to standard VCM and is not driven by free riding.

The ability to strategically reason is important in many competitive environments. In this paper, we examine how relatively mild temporal variations in cognition affect reasoning in the Beauty Contest. The source of temporal cognition variation that we explore is the time-of-day that decisions are made. Our first result is that circadian mismatched subjects (i.e., those making decisions at off-peak time of day) display lower levels of strategic reasoning in the p < 1 Beauty Contest but not in the p > 1 game. This suggests that a cognitively more challenging environment is required for circadian mismatch to harm strategic reasoning. A second result is that choice adaptation or mimicry (i.e., a more automatic type of responding than what is typically considered to be “learning”) during repeated play is not significantly affected by circadian mismatch. This is consistent with the hypothesis that automatic thought is more resilient to cognitive resource depletion than controlled-thought decision making.