We conducted online field experiments in large real-world social networks in order to decompose prosocial giving into three components: (1) baseline altruism toward randomly selected strangers, (2) directed altruism that favors friends over random strangers, and (3) giving motivated by the prospect of future interaction. Directed altruism increases giving to friends by 52% relative to random strangers, whereas future interaction effects increase giving by an additional 24% when giving is socially efficient. This finding suggests that future interaction affects giving through a repeated game mechanism where agents can be rewarded for granting efficiency-enhancing favors. We also find that subjects with higher baseline altruism have friends with higher baseline altruism.

Using data from an anti-vote-buying field experiment we conducted in the Philippines, we report and validate a proxy measure for vote-selling. We demonstrate that our proxy measure, vote-switching, changes as expected with voter preferences and monetary offers from candidates. Voters are less likely to vote for someone different than their initial preference the larger the favorability rating difference between the preferred and alternative candidates. Similarly, vote-switching increases the more money the alternative candidate offers compared to the preferred candidates. We also describe the effects of the promise-based interventions on vote-switching, reported in full in a companion paper.