Since social dilemmas among n-persons are often embedded in other types of social exchanges, the exclusion of defectors in social dilemmas from other exchanges functions as a costless selective incentive. Recently, such “linkage” has been considered as a promising solution to resolve the...

We experimentally study the effect of a third person enforcement on a one-shot prisoner’s dilemma game played by two persons, with whom the third person plays repeated prisoner’s dilemma games. We find that when the third person can observe these two persons’ play, the possibility of the...