We examine social preferences of Swedish and Austrian children and adolescents using the experimental design of Charness and Rabin (2002). We find that difference aversion decreases while social-welfare preferences increase with age.

We examine gender differences in trust in another party's cooperation (CC) or its ability (AC). While men and women do not differ concerning trust in cooperation, gender has a strong influence when trust in another subject's ability is required.

We show in a public goods experiment on three continents that conditional cooperation is a universal behavioral regularity. Yet, the number of conditional cooperators and the extent of conditional cooperation are much higher in the United States than anywhere else.

In an experiment, we study risk-taking of cohabitating student couples, finding that couples’ decisions are closer to risk-neutrality than single partners’ decisions. This finding is similar to earlier experiments with randomly assigned groups, corroborating external validity of earlier results.