vol. 338 no. 6107 682-685
- Received for publication March 26, 2012
- Accepted for publication September 13, 2012
- 1Booth School of Business, University of Chicago, Chicago, IL 60637, USA.
- 2Department of Economics, Harvard University, Cambridge, MA 02138, USA.
- 3Department of Psychology and Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ 08544, USA.
- ↵*To whom correspondence should be addressed. E-mail: