Roughly speaking, people are conditional cooperators. They are willing to contribute to the public good as long as others are doing so as well, but if others are free riding, contributions gradually dry up. Interestingly, if you let the members of the group talk to one another before they make their decisions, contribution rates go up.6 Subjects make speeches urging cooperation and pledging to donate themselves, and even though these pledges are not binding (economists call such statements “cheap talk”), they still help raise contribution rates and maintain them over time.
