Improvements and Future Challenges for the Research Infrastructure in the Field “Experimental Economics”

Experimental economics is an established method of generating controlled and replicable empirical knowledge. It is complementary to other empirical methods in the social sciences. The research infrastructure for laboratory experiments is very good in Europe and also in Germany. One useful instrument would be to develop a short socio-economic questionnaire with questions already used in surveys that experimental economists could use to administer to their participants. The analyses of the selectivity of subject pools would then be an easy task. However, among experimental economists no standard exists yet, which limits the comparability of respective data sets. An effort shall be undertaken to “create” such a common questionnaire. The status quo with regard to data reporting is that no standard has emerged yet. There exists one data repository (in the United States) where data of experiments are collected and are freely available. Building up a data archive that integrates (merges) existing data is very laborious and requires substantial scientific inputs of interested researchers.Experimental economics, data archives, selectivity of subject pools

(Dis)advantages of student subjects: what is your research question?

In this comment on Henrich et al. (2010) I argue that the right choice of subject pool is intimately linked to the research question. At least within economics, students are often the perfect subject pool for answering some fundamental research questions. Student subject pools can provide an invaluable benchmark for investigating generalizability across different social groups or cultures.

Social learning and voluntary cooperation among like-minded people

Many people contribute to public goods but stop doing so once they experience free riding. We test the hypothesis that groups whose members know that they are composed only of ‘like-minded’ cooperators are able to maintain a higher cooperation level than the most cooperative, randomly-composed groups. Our experiments confirm this hypothesis. We also predict that groups of ‘like-minded’ free riders do not cooperate. Yet, we find a high level of strategic cooperation that eventually collapses. Our results underscore the importance of group composition and social learning by heterogeneously motivated agents to understand the dynamics of cooperation and free riding.Public goods, social learning, conditional cooperation, free riding, experiments

Peer Effects and Social Preferences in Voluntary Cooperation

Substantial evidence suggests the behavioral relevance of social preferences and also the importance of social influence effects ("peer effects"). Yet, little is known about how peer effects and social preferences are related. In a three-person gift-exchange experiment we find causal evidence for peer effects in voluntary cooperation: agents' efforts are positively related despite the absence of material payoff interdependencies. We confront this result with major theories of social preferences which predict that efforts are unrelated, or negatively related. Some theories allow for positively-related efforts but cannot explain most observations. Conformism, norm following and considerations of social esteem are candidate explanations.social preferences, voluntary cooperation, peer effects, reflection problem, gift exchange, conformism, social norms, social esteem

The full list of CeDEx Discussion Papers is available at

The focus for the Centre is research into individual and strategic decision-making using a combination of theoretical and experimental methods. On the theory side, members of the Centre investigate individual choice under uncertainty, cooperative and non-cooperative game theory, as well as theories of psychology, bounded rationality and evolutionary game theory. Members of the Centre have applied experimental methods in the fields of public economics, individual choice under risk and uncertainty, strategic interaction, and the performance of auctions, markets and other economic institutions. Much of the Centre's research involves collaborative projects with researchers from other departments in the UK and overseas. Please visi

Design a contract! : A simple principal-agent problem as a classroom experiment

We present a simple classroom principal-agent experiment that can effectively be used as a teaching device to introduce important concepts of organizational economics and contracting. In a first part, students take the role of a principal and design a contract that consists of a fixed payment and an incentive component. In the second part, students take the role of agents and decide on an effort level. The experiment can be used to introduce students to the concepts of efficiency, incentive compatibility, outside options and participation constraints, the Coase theorem, and fairness and reciprocity in contracting. --Classroom experiments,post-contractual opportunism,incentive contracts,efficiency,reciprocity,Coase theorem

Social Comparison and Performance: Experimental Evidence on the Fair Wage-Effort Hypothesis

We investigate the impact of wage comparisons for worker productivity. We present three studies which all use three-person gift-exchange experiments. Consistent with Akerlof and Yellen's (1990) fair wage-effort hypothesis we find that disadvantageous wage discrimination leads to lower efforts while advantageous wage discrimination does not increase efforts on average. Two studies allow us to measure wage comparison effects at the individual level. We observe strongly heterogeneous wage comparison effects. We also find that reactions to wage discrimination can be attributed to the underlying intentions of discrimination rather than to payoff consequences.fair wage-effort hypothesis, wage comparison, gift exchange, horizontal fairness, discrimination

(Dis)advantages of student subjects: what is your research question?

In this comment on Henrich et al. (2010) I argue that the right choice of subject pool is intimately linked to the research question. At least within economics, students are often the perfect subject pool for answering some fundamental research questions. Student subject pools can provide an invaluable benchmark for investigating generalizability across different social groups or cultures

Peer Effects in Pro-Social Behavior: Social Norms or Social Preferences?

We compare social preference and social norm based explanations for peer effects in a three-person gift-exchange game experiment. In the experiment a principal pays a wage to each of two agents, who then make effort choices sequentially. In our baseline treatment we observe that the second agent's effort is influenced by the effort choice of the first agent, even though there are no material spillovers between agents. This peer effect is predicted by a model of distributional social preferences (Fehr-Schmidt, 1999). As we show from a norms-elicitation experiment, it is also consistent with social norms compliance. A conditional logit investigation of the explanatory power of payoff inequality and elicited norms finds that the second agent's effort can be best explained by the social preferences model. In further treatments with modified games we find that the presence/strength of peer effects changes as predicted by the social preferences model. As with the baseline treatment, a conditional logit analysis favors an explanation based on social preferences, rather than social norms following for these treatments. Our results suggest that, in our context, the social preferences model provides a parsimonious explanation for the observed peer effect.peer effects, social influence, gift-exchange, experiment, social preferences, inequity aversion, measuring social norms

The Impact of Social Comparisons on Reciprocity

We investigate the effects of pay comparison information (i.e. information about what co-workers earn) and effort comparison information (information about how co-workers perform) in experimental firms composed of one employer and two employees. Exposure to pay comparison information in isolation from effort comparison information does not appear to affect reciprocity toward employers: in this case own wage is a powerful determinant of own effort, but co-worker wages have no effect. By contrast, we find that exposure to both pieces of social information systematically influences employees’ reciprocity. A generous wage offer is virtually ineffective if an employee is matched with a lazy co-worker who is also paid generously: in such circumstances the employee tends to expend low effort irrespective of her own wage. Reciprocity is more pronounced when the co-worker is hard-working, as effort is strongly and positively related to own wage in this case. Reciprocity is also pronounced when the employer pays unequal wages to the employees: in this case the co-worker’s effort decision is disregarded and effort decisions are again strongly and positively related to own wage. On average exposure to social information weakens reciprocity, though we find substantial heterogeneity in responses across individuals, and find that sometimes social information has beneficial effects. We suggest that group composition may be an important tool for harnessing the positive effects of social comparison processes.reciprocity, gift-exchange, social information, social comparisons, pay comparisons, peer effects