Transplants of donated stem cells save the lives of many patients with blood diseases. Donation is somewhat painful, but rarely has lasting adverse effects. Patients can accept transplants only from donors with compatible immune systems. Those lacking a sibling match must seek donations from the...

We conduct a large-scale survey experiment in nine European countries to study how priming a major crisis (COVID-19), common economic interests, and a shared identity influences altruism, reciprocity and trust of EU citizens. We find that priming the COVID-19 pandemic increases altruism and...

Economic and social interaction takes place between individuals with heterogeneous characteristics. We investigate experimentally the emergence and informal enforcement of different contribution norms to a public good in homogeneous and different heterogeneous groups. When punishment is not...

Policies and explicit private incentives designed for self-regarding individuals sometimes are less effective or even counterproductive when they diminish altruism, ethical norms and other social preferences. Evidence from 51 experimental studies indicates that this crowding out effect is...

We report an experiment comparing sequential and simultaneous contributions to a public good in a quasi-linear two-person setting (Varian, Journal of Public Economics, 1994). Our findings support the theoretical argument that sequential contributions result in lower overall provision than...

Does the cultural background influence the success with which genetically unrelated individuals cooperate in social dilemma situations? In this paper we provide an answer by analyzing the data of Herrmann et al. (Science 2008, pp. 1362-1367), who study cooperation and punishment in sixteen...

Concern about potential free riding in the provision of public goods has a long history. More recently, experimental economists have turned their attention to the conditions under which free riding would be expected to occur. A model of free riding is provided here which demonstrates that...

Matching mechanisms are regarded as an important instrument to bring about Pareto optimal allocations in a public good economy and to cure the underprovision problem associated with private provision of public goods. The desired Pareto optimal interior matching equilibrium, however, emerges only...

We consider a voluntary contributions game, in which players may punish others after contributions are made and observed. The productivity of contributions, as captured in the marginal-per-capita return, differs among individuals, so that there are two types: high and low productivity. Every two...

In public good games, voluntary contributions tend to start off high and decline as the game is repeated. If high contributors are matched, however, contributions tend to stay high. We propose a formalization predicting that high contributors will self-select into groups committed to charitable...