Contributions published at Microeconomics and Experimental Economic Research (Ernst Fehr)

In a laboratory experiment we show that minimum wages have significant and lasting effects on subjects’ reservation wages. The temporary introduction of a minimum wage leads to a rise in subjects’ reservation wages which persists even after the minimum wage has been removed. Firms are therefore forced to pay higher wages after the removal of the minimum wage than before its introduction. As a consequence, the employment effects of removing the minimum wage are significantly smaller than are the effects of its introduction. The impact of minimum wages on reservation wages may also explain the anomalously low utilization of subminimum wages if employers are given the opportunity of paying less than a minimum wage previously introduced. It may further explain why employers often increase workers' wages after an increase in the minimum wage by an amount exceeding that necessary for compliance with the higher minimum. At a more general level, our results suggest that economic policy may affect people’s behavior by shaping the perception of what is a fair transaction and by creating entitlement effects.

Engelmann and Strobel (AER 2004) question the relevance of inequity aversionnin simple dictator game experiments claiming that a combination of a preference fornefficiency and a Rawlsian motive for helping the least well-off is more important thanninequity aversion. We show that these results are partly based on a strong subject poolneffect. The participants of the E&S experiments were undergraduate students of economicsnand business administration who self-selected into their field of study (economics) andnlearned in the first semester that efficiency is desirable. We show that for non-economistsnthe preference for efficiency is much less pronounced. We also find a non-negligiblengender effect indicating that women are more egalitarian than men. However, perhapsnsurprisingly, the dominance of equality over efficiency is unrelated to political attitudes.

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Most previous studies on intertemporal labor supply found very small or insignificantnsubstitution effects. It is not clear, however, whether these results are due to institutionalnconstraints on workers’ labor supply choices or whether the behavioral assumptions of thenstandard life cycle model with time separable preferences are empirically invalid. We conducted a randomized field experiment in a setting in which workers were free to choose their working times and their efforts during working time. We document a large positive wage elasticity of overall labor supply and an even larger wage elasticity of labor hours, which implies that the wage elasticity of effort per hour is negative.nWhile the standard life cycle model cannot explain the negative effort elasticity, we show that a modified neoclassical model with preference spillovers across periods and a model withnreference dependent, loss averse preferences are consistent with the evidence. With the help of anfurther experiment we can show that only loss averse individuals exhibit a significantly negativeneffort response to the wage increase and that the degree of loss aversion predicts the size of the negative effort response.

There is abundant evidence that many individuals violate the rationality assumptionsnroutinely made in economics. However, powerful evidence also indicates that violations ofnindividual rationality do not necessarily refute the aggregate predictions of standard economicnmodels that assume full rationality of all agents. Thus, a key question is how the interactions between rational and irrational people shape the aggregate outcome in markets and other institutions. We discuss evidence indicating that strategic complementarity and strategic substitutability are decisive determinants of aggregate outcomes. Under strategic complementarity, a small amount of individual irrationality may lead to large deviations from the aggregate predictions of rational models, whereas a minority of rational agents may suffice to generate aggregate outcomes consistent with the predictions of rational models under strategic substitutability.

Trust pervades human societies. Trust is indispensable in friendship, love, families and organizations, and plays a key role in economic exchange and politics. In the absence of trust among trading partners, market transactions break down. In the absence of trust in a country's institutions and leaders, political legitimacy breaks down. Much recent evidence indicates that trust contributes to economic, political and social success. Little is known, however, about the biological basis of trust among humans. Here we show that intranasal administration of oxytocin, a neuropeptide that plays a key role in social attachment and affiliation in non-human mammals, causes a substantial increase in trust among humans, thereby greatly increasing the benefits from social interactions. We also show that the effect of oxytocin on trust is not due to a general increase in the readiness to bear risks. On the contrary, oxytocin specifically affects an individual's willingness to accept social risks arising through interpersonal interactions. These results concur with animal research suggesting an essential role for oxytocin as a biological basis of prosocial approach behaviour.

"The most fundamental solution concepts in Game Theory – Nash equilibrium, backward induction, and iterated elimination of dominated strategies – are based on the assumption that people are capable of predicting others' actions. These concepts require people to be able to view the game from the other players’ perspectives, i.e. to understand others’ motives and beliefs. Economists still know little about what enables people to put themselves into others’nshoes and how this ability interacts with their own preferences and beliefs. Social neuroscience provides insights into the neural mechanism underlying our capacity to represent others' intentions, beliefs, and desires, referred to as ""Theory of Mind"" or ""mentalizing"", and the capacitynto share the feelings of others, referred to as ""empathy"". We summarize the major findings about the neural basis of mentalizing and empathizing and discuss some implications for economics."

The prevailing labor market models assume that minimum wages do not affect the labor supply schedule. We challenge this view in this paper by showing experimentally that minimum wages have significant and lasting effects on subjects’ reservation wages. The temporary introduction of a minimum wage leads to a rise in subjects’ reservation wages which persists even after the minimum wage has been removed. Firms are therefore forced to pay higher wages after the removal of the minimum wage than before its introduction. As a consequence, the employment effects of removing the minimum wage are significantly smaller than are the effects of its introduction. The impact of minimum wages on reservation wages may also explain the anomalously low utilization of subminimum wages if employers are given the opportunity of paying less than a minimum wage previously introduced. It may furthernexplain why employers often increase workers' wages after an increase in the minimum wagenby an amount exceeding that necessary for compliance with the higher minimum. At a morengeneral level, our results suggest that economic policy may affect people’s behavior by shaping the perception of what is a fair transaction and by creating entitlement effects.

This paper discusses recent neuroeconomic evidence related to other-regarding behaviors and the decision to trust in other people’s other-regarding behavior. This evidencensupports the view that people derive nonpecuniary utility (i) from mutual cooperation in socialndilemma (SD) games and (ii) from punishing unfair behavior. Thus, mutual cooperation and the punishment of free riders in SD games is not irrational, but better understood as rationalnbehavior of people with corresponding social preferences. We also report the results of anrecent study that examines the impact of the neuropeptide Oxytocin (OT) on trusting andntrustworthy behavior in a sequential SD. Animal studies have identified Oxytocin as anhormone that induces prosocial approach behavior, suggesting that it may also affect prosocialnbehavior in humans. Indeed, the study shows that subjects given Oxytocin exhibit much morentrusting behavior, suggesting that OT has a direct impact on certain aspects of subjects’ social preferences. Interestingly, however, although Oxytocin affects trusting behavior, it has no effect on subjects’ trustworthiness.

We report on several experiments on the optimal allocation of ownership rights. The experiments confirm the property rights approach by showing that the ownership structure affects relationship-specific investments and that subjects attain the most efficient ownership allocation despite starting from different initial conditions. However, in contrast to the property rights approach, the most efficient ownership structure is joint ownership. These results are neither consistent with the self-interest model nor with models that assume that all people behave fairly, but they can be explained by the theory of inequity aversion that focuses on the interaction between selfish and fair players.

This paper reports on a two-task principal-agent experiment in which only one task is contractible. The principal can either offer a piece-rate contract or a (voluntary) bonus to the agent. Bonus contracts strongly outperform piece rate contracts. Many principals reward high efforts on both tasks with substantial bonuses. Agents anticipate this and provide high efforts on both tasks. In contrast, almost all agents with a piece rate contract focus on the first task and disregard the second.nPrincipals understand this and predominantly offer bonus contracts. This behavior contradicts the self-interest theory but is consistent with theories of fairness.

"We examine the characteristics and the relative strength of third party sanctions in a series of experiments. We hypothesize that egalitarian distribution norms and cooperation norms apply in our experiments, and that third parties, whose economic payoff is unaffected by the norm violation, may be willing to enforce these norms although the enforcement is costly for them. Almost two-thirds of the third parties indeed punish the violation of the distribution norm and their punishment increases the more the norm is violated. Likewise, up to roughly 60 percent of the third parties punish the violation of the cooperation norm. Thus, our results show that the notion of strong reciprocity also extends to the sanctioning behavior of "unaffected" third parties. In addition, these experiments suggest that third party punishment games are powerful tools for studying the characteristics and the content of social norms. Further experiments indicate that second parties, whose economic payoff is reduced by the norm violation, punish the violation much more strongly than do third parties. We also collect questionnaire evidence that is consistent with the view that fairness motives and negative emotions are a determinant of third party sanctions."

In a recent paper Engelmann and Strobl claim that a combination of a preference for efficiency and a Rawlsian motive for helping the least well-off is far more important than inequity aversion. Here we show that the relevance of the efficiency motive is largely restricted to students of economics and business administration. Students from other disciplines, adult academics from various disciplines and senior citizens value equality much higher than efficiency. Moreover, there is rather strong evidence that the relevance of the efficiency motive and the Rawlsian motive is largely restricted to non-strategic interactions.