Sorting and Social Preferences

Laboratory experiments on social preferences typically do not allow for sorting, while many field settings do. We demonstrate a strong effect of sorting when introduced in the laboratory. Across four experiments, most individuals who share with others do so reluctantly, preferring to avoid the opportunity to share. The attractiveness of the sorting option strongly affects the composition of self-selected participants. Subsidized entry into the sharing environment attracts those who share the least. Costly entry attracts few participants, but those share large amounts. Finally, we find that a similar proportion of sharers opt out even after inducing positive reciprocity.