Punish in public

Convergent evidence for detrimental effects of punishment on cooperation has been obtained in a wide variety of environments, ranging from American students facing punishment in laboratory experiments to Israeli parents facing fines for arriving late to their child‟s day care. We show here that enhancing the norm salience role of punishment can eliminate its detrimental effects. In a public goods game, we first demonstrate that privately implemented punishment reduces cooperation in relation to a baseline treatment without punishment. However, when that same incentive is implemented publicly cooperation is sustained at significantly higher rates than in both baseline and private punishment treatments. Our design ensures that this effect is not due to shame, differences in information or signaling. Rather, we focus on the fact that publicly implemented punishment reminds a greater number of people a greater number of times about the social norm. We show that this increased norm salience promotes group members‟ norm obedience. Our findings have important efficiency implications for the design of mechanisms intended to deter misconduct. Acknowledgements: The authors contributed equally to this research. An early draft of this paper was circulated under the title “Public Implementation Eliminates Detrimental Effects of Punishment on Human Cooperation”. We are grateful to Rachel Croson, Ernst Fehr, Howard Margolis, Bruno Frey, Herbert Gintis, Robin Hanson, Francesco Parisi, Alex Tabarrok and Toshio Yamagishi for useful comments. We thank seminar participants at Carnegie-Mellon University, University of Michigan, University of Pennsylvania, University of Pittsburgh, University of Zurich, University of Lyon, University of Wittenberg, University of Regensburg, Virginia Commonwealth University, University of Texas at Dallas, James Madison University, Laval University, George Mason University as well as attendees of the 2005 Economic Science Association meetings, the 2005 Southern Economic Association meetings, the 2006 Workshop on Social Institutions and Behavior at the University of Amsterdam, and the 2007 ENABLE conference at the University of Mannheim. We gratefully acknowledge that Xiaorong Zhou assisted with the software. We are grateful for grants to the first author from the Russell Sage Foundation, and to the second author from the International Foundation for Research in Experimental Economics (IFREE-103), and the National Science Foundation (SES-0339181) that supported this research.