Group favoritism is typically directed toward in-group members and against out-group members, but these cross-group effects often vary. Little is known about why group effects on economic choices vary. We use a survey method developed in social psychology to measure stereotyped attitudes of one group toward another. These attitudes are then associated with prosociality in five experimental games (also using an unusual amount of individual-level sociodemographic control). We present evidence from an artificial field experiment of a majority group with high status (Vietnamese) exhibiting no disfavoritism toward a lower-status out-group (Khmer) and typical disfavoritism to a second out-group (Chinese). Both Vietnamese and Chinese groups see the Khmer as warm but incompetent, attitudes which seem to activate empathy rather than contempt. The results suggest that measuring between-group stereotype attitudes can be used to predict the sign of cross-group favoritism in other natural settings.

We introduce the “ball-catching task”, a novel computerized task, which combines a tangible action (“catching balls”) with induced material cost of effort. The central feature of the ball-catching task is that it allows researchers to manipulate the cost of effort function as well as the production function, which permits quantitative predictions on effort provision. In an experiment with piece-rate incentives we find that the comparative static and the point predictions on effort provision are remarkably accurate. We also present experimental findings from three classic experiments, namely, team production, gift exchange and tournament, using the task. All of the results are closely in line with the stylized facts from experiments using purely induced values. We conclude that the ball-catching task combines the advantages of real effort tasks with the use of induced values, which is useful for theory-testing purposes as well as for applications.

Strictly proper scoring rules are designed to truthfully elicit subjective probabilistic beliefs from risk neutral agents. Previous experimental studies have identified two problems with this method: (i) risk aversion causes agents to bias their reports toward the probability of $1/2$, and (ii) for moderate beliefs agents simply report $1/2$. Applying a prospect theory model of risk preferences, we show that loss aversion can explain both of these behavioral phenomena. Using the insights of this model, we develop a simple off-the-shelf probability assessment mechanism that encourages loss-averse agents to report true beliefs. In an experiment, we demonstrate the effectiveness of this modification in both eliminating uninformative reports and eliciting true probabilistic beliefs.

We investigate whether piece-rate and competitive incentives affect creativity, and if so, how the incentive effect depends on the form of the incentives. We find that while both piece-rate and competitive incentives lead to greater effort relative to a base-line with no incentives, neither type of incentives improve creativity relative to the base-line. More interestingly, we find that competitive incentives are in fact counter-productive in that they reduce creativity relative to base-line condition. In line with previous literature, we find that competitive conditions affect men and women differently: whereas women perform worse under competition than the base-line condition, men do not.

We examine strategic awareness in experimental games, that is, the question of whether subjects realize they are playing a game and thus have to form beliefs about others’ actions. We conduct a beauty contest game and elicit measures of cognitive ability and beliefs about others’ cognitive ability. We show that the effect of cognitive ability is highly non-linear. Subjects below a certain threshold choose numbers in the whole interval and their behavior does not correlate with beliefs about others’ ability. In contrast, subjects who exceed the threshold avoid choices above 50 and react very sensitively to beliefs about the cognitive ability of others.

This paper tests how subjects behave in an intertemporal consumption/saving experiment when borrowing is allowed and whether subjects treat debt differently than savings. Two treatments create environments where either saving or borrowing is required for optimal consumption. Since both treatments share the same optimal consumption levels, observed consumption choices can be directly compared across treatments. The experimental findings imply that deviations from optimal behavior are higher when subjects have to borrow than when they have to save in order to consume optimally, suggesting debt aversion. Signifiant under-consumption is observed when subjects have to borrow in order to reach optimal consumption. In line with previous experiments, weak evidence is found suggesting that subjects over-consume when saving is necessary for optimal consumption.

We examine experimentally how complexity affects decision-making, when individuals choose among different products with varying benefits and costs. We find that complexity in costs leads to choosing a high-benefit product, with high costs and overall lower payoffs. In contrast, when complexity is in the benefits of the product, we cannot reject the hypothesis of random mistakes. We also examine the role of heterogeneous complexity. We find that individuals still (mistakenly) choose the high-benefit but costly product, even if cheaper and simple products are available. Our results suggest that salience is a main driver of choices under different forms of complexity.

We investigate how employee potential influences wage offers and effort exertion in a gift exchange experiment. In particular, we test if gift exchange based on a commonly accepted norm for wage differentiation can emerge in a setting where the wage demands of agents are heterogeneous. We also analyse how communication by principals responds to the unequal wage demands and how it influences agents’ decisions about working effort in the presence of varying degrees of bargaining power. We find that differences in productivity and the resulting entitlements lead to differentiation in wages. High productivity agents are offered substantially higher wages than low productivity agents. Results from a control experiment suggest that a large part of this wage markup is related to the future productivity potential of high performers. At the same time, unequal wage schemes do not substantially crowd out effort exertion: we observe no strong detrimental effects from disadvantageous relative wage positions. Certain communication patterns significantly influence effort exertion.

It has recently been argued that giving is spontaneous while greed is calculated (Rand et al., in Nature 489:427–430, 2012). If greed is calculated we would expect that cognitive load, which is assumed to reduce the influence of cognitive processes, should affect greed. In this paper we study both charitable giving and the behavior of dictators under high and low cognitive load to test if greed is affected by the load. This is tested in three different dictator game experiments. In the dictator games we use both a give frame, where the dictators are given an amount that they may share with a partner, and a take frame, where dictators may take from an amount initially allocated to the partner. The results from all three experiments show that the behavioral effect in terms of allocated money of the induced load is small if at all existent. At the same time, follow-up questions indicate that the subjects’ decisions are more impulsive and less driven by their thoughts under cognitive load.

In this paper we provide new evidence showing that fair behavior is intuitive to most people. We find a strong association between a short response time and fair behavior in the dictator game. This association is robust to controls that take account of the fact that response time might be affected by the decision-maker’s cognitive ability and swiftness. The experiment was conducted with a large and heterogeneous sample recruited from the general population in Denmark. We find a striking similarity in the association between response time and fair behavior across groups in the society, which suggests that the predisposition to act fairly is a general human trait.

Directed search models labor markets where workers observe wages before deciding where they will apply. This paper tests this model for the case of heterogeneous firms in a laboratory experiment. The theory predicts that more productive firms offer higher wages and workers apply more often to these higher wages. In consequence, more productive firms are more likely to match and the market is more efficient than the prediction of an alternative model where search is random. The main results of the experiment are that average firms offer wages that are close to or a little lower than the theoretical predictions but highly variable and workers apply more often to high offers but not to the extent predicted. The markets are no more efficient than random search predicts, because of the variation in wage offers.

This paper examines the effects of competition in experimental posted-offer markets where sellers can confuse buyers. I report two studies. In one, the sellers offering heterogeneous goods can obfuscate buyers by means of spurious product differentiation. In the other study, sellers offer identical goods and make their prices unnecessarily complex by having multi-part tariffs. I vary the level of competition by having treatments with two and three- sellers in both studies, and having an additional treatment with five-sellers in one study. The results show that average complexity created by a seller is not different for the treatments with two, three and five sellers. In addition, market prices are highest and buyer surplus is lowest when there are two sellers in a market.

How to hire voluntary helpers? We shed new light on this question by reporting a field experiment in which we invited 2859 students to help at the ‘ESA Europe 2012’ conference. Invitation emails varied non-monetary and monetary incentives to convince subjects to offer help. Students could apply to help at the conference and, if so, also specify the working time they wanted to provide. Just asking subjects to volunteer or offering them a certificate turned out to be significantly more motivating than mentioning that the regular conference fee would be waived for helpers. By means of an online-survey experiment, we find that intrinsic motivation to help is likely to have been crowded out by mentioning the waived fee. Increasing monetary incentives by varying hourly wages of 1, 5, and 10 Euros shows positive effects on the number of applications and on the working time offered. However, when comparing these results with treatments without any monetary compensation, the number of applications could not be increased by offering money and may even be reduced.

We explore the effect of fixed versus dynamic group membership on public good provision. In a novel experimental design, we modify the traditional voluntary contribution mechanism (VCM) by periodically replacing old members of a group with new members over time. Under this dynamic, overlapping generations matching protocol we find that average contributions experience significantly less decay over time relative to a traditional VCM environment with fixed group membership and a common termination date. These findings suggest that the traditional pattern of contribution and decay seen in many public goods experiments may not accurately reflect behavior in groups with changing membership, as is the case in many real-world environments.

Using a laboratory experiment, we investigate whether a variety of behaviors in repeated games are related to an array of individual characteristics that are popular in economics: risk attitude, time preference, trust, trustworthiness, altruism, strategic skills in one-shot matrix games, compliance with first-order stochastic dominance, ability to plan ahead, and gender. We do find some systematic relationships. A subject’s compliance with first-order stochastic dominance as well as, possibly, patience, gender, and altruism have some systematic effects on her behavior in repeated games. At the level of a pair of subjects who are playing a repeated game, each subject’s gender as well as, possibly, patience and ability to choose an available dominant strategy in a one-shot matrix game systematically affect the frequency of the cooperate–cooperate outcome. However, overall, the number of systematic relationships is surprisingly small.

Numerous experiments have shown that people often engage in third-party punishment (3PP) of selfish behavior. This evidence has been used to argue that people respond to selfishness with anger, and get utility from punishing those who mistreat others. Elements of the standard 3PP experimental design, however, allow alternative explanations: it has been argued that 3PP could be motivated by envy (as selfish dictators earn high payoffs), or could be influenced by the use of the strategy method (which is known to influence second-party punishment). Here we test these alternatives by varying the third party’s endowment and the use of the strategy method, and measuring punishment. We find that while third parties do report more envy when they have lower endowments, neither manipulation significantly affects punishment. We also show that punishment is associated with ratings of anger but not of envy. Thus, our results suggest that 3PP is not an artifact of self-focused envy or use of the strategy method. Instead, our findings are consistent with the hypothesis that 3PP is motivated by anger.

Our paper reconsiders the triadic design proposed by Cox (Games and Economic Behavior 46:260–281, 2004) to identify trust and reciprocity in investment games. Specifically, we extend the design in two directions. First, we collect information on investors’ choices by using both the direct-response (as does Cox) and strategy methods. Using the latter, we are able to condition reciprocity on initial inequality, which is endogenous when investigating reciprocity. We demonstrate that the triadic design provides evidence for reciprocity once that initial inequality is considered. Second, we elicit expectations and test their coherence with the triadic outcomes. By examining the relationship between trust actions and expected gains, we analyze whether investors’ expectations are consistent with their behavior. Finally, we test for the existence of an emotional bias, i.e., whether expectation mismatches induce trustees to change actual choices from the planned ones.

Inspired by Clower’s conjecture that the necessity of trading through money in monetised economies might hinder convergence to competitive equilibrium, and hence, for example, cause unemployment, we experimentally investigate behaviour in markets where trading has to be done through money. In order to evaluate the properties of these markets, we compare their behaviour to behaviour in markets without money, where money cannot intervene. As the trading mechanism might be a compounding factor, we investigate two kinds of market mechanism: the double auction, where bids, asks and trades take place in continuous time throughout a trading period; and the clearing house, where bids and asks are placed once in a trading period, and which are then cleared by an aggregating device. We thus have four treatments, the pairwise combinations of non-monetised/monetised trading with double auction/clearing house. We find that: convergence is faster under non-monetised trading, implying that the necessity of using money to facilitate trade hinders convergence; that monetised trading is noisier than non-monetised trading; and that the volume of trade and realised surpluses are higher with the double auction than the clearing house. As far as efficiency is concerned, monetised trading lowers both informational and allocational efficiency, and while the double auction outperforms the clearing house in terms of allocational efficiency, the clearing house is marginally better than the double auction in terms of informational efficiency when trade is through money. Crucially we confirm the conjecture that inspired these experiments: that the necessity to use money in trading hinders convergence to competitive equilibrium, lowers realised trades and surpluses, and hence may cause unemployment.

It is still an open question when groups perform better than individuals in intellective tasks. We report that in an Acquiring a Company game, what prevailed when there was disagreement among group members was the median proposal and not the best proposal. This aggregation rule explains why groups underperformed with respect to a “truth wins” benchmark and why they performed better than individuals deciding in isolation in a simple version of the task but worse in the more difficult version. Implications are drawn on when to employ groups rather than individuals in decision making.

We theoretically and experimentally investigate a game in which exactly one person should make a costly effort to achieve a socially efficient outcome. This setting is commonly known as the volunteer’s dilemma. We implement one-way communication by allowing one player to send a message indicating whether she intends to volunteer and investigate the message’s effects on behavior and efficiency in the subsequent game. We theoretically demonstrate that there are asymmetric mixed-strategy equilibria in the volunteer’s dilemma and argue that one of these is likely to emerge through one-way communication. The experimental data support this notion. We find that the actions of both the sender and receiver of the message are crucially affected by the cheap talk stage and that efficiency in the volunteer’s dilemma increases with one-way communication.