In recent decades, the immigration of workers and refugees to Europe has increased substantially, and the composition of the population in many countries has consequently become much more heterogeneous in terms of ethnic background. If people exhibit in-group bias in the sense of being more...

We explore network effects on generosity for different network dimensions. To this end we elicit multiple network dimensions (friendship, social support, economic exchange, etc.) in a rural village in the Southern hemisphere and measure generosity with a sequence of dictator games conducted in...

This paper considers a dynamic model of the evolution of open source software projects, focusing on the evolution of quality, contributing programmers, and users who contribute customer support to other users. Programmers who have used open source software are motivated by reciprocal altruism to...

This paper studies how a preference for consistency can affect economic decision-making. We propose a two-period model where people have a preference for consistency because consistent behavior allows them to signal personal and intellectual strength. We then present three experiments that study...

Decisions to donate time or money for charitable purposes are typically seen as make-or-buy decisions, implying that there should be a clear distinction between individuals engaging in one of these two forms of giving and that this distinction should be somehow linked to opportunity costs. But...

A body of literature suggests that ethnic heterogeneity limits economic growth. This paper provides microeconometric evidence on the direct effect of ethnic divisions on productivity. In team production at a plant in Kenya, an upstream worker supplies and distributes flowers to two downstream...

The neoclassical model in economics envisages humans as amoral and self-regarding (Econs). This model, also known as the homo-economicus model, is not consistent with the empirical evidence. In light of the evidence, the continued use of the homo-economicus model is baffling. It also stymies...

Cooperativeness among genetically unrelated humans remains a major puzzle in the social sciences. We explore the causal impact of physical distance on willingness to help. In a field setting, participants decide about supporting local refugees at the dispense of money to themselves. We vary...

We conduct experimental games with police applicants in Germany to investigate whether intrinsically motivated agents self-select into public service. Our focus is on trustworthiness and the willingness to enforce norms as key dimensions of intrinsic motivation in the police context. We find...

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...