When charities compete: A laboratory experiment with simultaneous public goods

What happens when charities compete? We begin to answer this question through a laboratory experiment in which subjects play two public goods games simultaneously. We systematically vary the incentives for contributing in one of the games - investigating the effects of recognition, a bonus conditional on contributing, and non-monetary sanctions - and measure the effect on contributions in both games. Monetary incentives in the form of conditional bonuses increase contributions, even when two games are played simultaneously. However, non-monetary incentives such as recognition and sanctions are less effective than in related literature on games played in isolation. Moreover, we find mixed evidence of a treatment spillover on the un-treated games - bonuses increase contributions initially, recognition decreases contributions, and sanctions have no effect.