Résumé
We run a series of experiments in which subjects have to choose their level of contribution to a pure public good. Our design differs from the standard public good game with respect to the decision procedure. Instead of deciding simultaneously in each round, subjects are randomly ordered in a sequence which differs from round to round. We compare sessions in which subjects can observe the exact contributions from earlier decisions ("Sequential treatment with Information") to sessions in which subjects decide sequentially but cannot observe earlier contributions ("Sequential treatment without information"). Furthermore, we investigate the effect of group size on aggregate contributions. Our result indicate that contributing sequentially increases the level of contribution to the public good when subjects are informed about the contribution levels of lower ranked subjects. Moreover, we observe that earlier players in the sequence try to influence positively the contributions of subsequent decision makers in the sequence, by making a large contribution. Such behaviour is motivated by the belief that subsequent players will reciprocate by also making a large contribution.