Rewarding Volunteers: A Field Experiment

We conducted a field experiment with the American Red Cross to study the effects of economic incentives on volunteer activities. The experiment was designed to assess local and short-term effects, but also spatial and temporal substitution, heterogeneity and spillovers. Subjects offered $5, $10, and $15 gift cards to give blood were more likely to donate, and more so for the higher reward values. The incentives also led to spatial displacement and a short-term shift in the timing of donation activity, but no long-term effects. Many of the effects were also heterogeneous in the population. We also detected a spillover effect whereby informing some individuals of rewards through official ARC channels led others who were not officially informed to be more likely to donate. Thus the effect of incentives on pro-social behavior includes not only the immediate local effects, but also spatial displacement, social spillovers and dramatic heterogeneity. We discuss the implications of these findings for organizations whose activities rely on volunteers for the supply of key inputs or products, as well as for government agencies and public policy.