Imitation and the Incentive to Contribute Early in a Sequential Public Good Game


  • Edward Cartwright, Department of Economics, Keynes College, University of Kent, Canterbury, Kent, CT2 7NP. UK. ( and Amrish Patel, Department of Economics, University of Gothenburg, Box 640, SE 405 30, Gothenburg, Sweden (

  • The authors are indebted to two anonymous referees and the associate editor, Ted Bergstrom, for many helpful comments, particularly in improving the Proof of Lemma 1. Edward Cartwright also acknowledges the support of ESRC Grant RES-000-22-1999, “Why some people choose to be leaders.” Amrish Patel also acknowledges the support of a Jan Wallander and Tom Hedelius postdoctoral research fellowship.


Whether motivated by reciprocity or conformity, imitation is common in public good contexts. We consider the incentive for an agent to contribute to a public good if he expects imitation from others. Using a sequential public good game with exogenous ordering, we show that agents early enough in the sequence who believe imitation to be sufficiently likely would want to contribute. By contributing, they expect total contributions to increase significantly. We also show that preferences determine how early an agent need be, that the observed share of imitators in experiments is sufficiently high to warrant contribution and that an increase in group size reduces the incentive to contribute.