Costly punishment does not always increase cooperation

doi:10.1073/pnas.0905918106

Costly punishment does not always increase cooperation

^aKey Laboratory of Animal Ecology and Conservation Biology, Centre for Computational Biology and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China;
^bSchool of Mathematical Sciences, Beijing Normal University, Beijing 100875, China; and
^cDepartment of Mathematics, Wilfrid Laurier University, Waterloo, ON, Canada N2L 3C5

Edited by Brian Skyrms, University of California, Irvine, CA, and approved August 13, 2009 (received for review May 29, 2009)

Abstract

In a pairwise interaction, an individual who uses costly punishment must pay a cost in order that the opponent incurs a cost. It has been argued that individuals will behave more cooperatively if they know that their opponent has the option of using costly punishment. We examined this hypothesis by conducting two repeated two-player Prisoner's Dilemma experiments, that differed in their payoffs associated to cooperation, with university students from Beijing as participants. In these experiments, the level of cooperation either stayed the same or actually decreased when compared with the control experiments in which costly punishment was not an option. We argue that this result is likely due to differences in cultural attitudes to cooperation and punishment based on similar experiments with university students from Boston that found cooperation did increase with costly punishment.

Footnotes

¹To whom correspondence may be addressed. E-mail: yitao{at}ioz.ac.cn or rcressman{at}wlu.ca
Author contributions: R.C. and Y.T. designed research; J.-J.W., B.-Y.Z., Z.-X.Z., Q.-Q.H., and X.-D.Z. performed research; J.-J.W., B.-Y.Z., Z.-X.Z., and X.-D.Z. analyzed data; and R.C. and Y.T. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0905918106/DCSupplemental.