利己的行動・利他的行動は連鎖するか

──独裁者ゲームを用いた実験的検討──

抄録

The present study compared two forms of reciprocity, namely, a selfish versus altruistic one. In two experiments, participants played two rounds of the dictator game. In the first round, they were all assigned the “recipient” role, and were either over- or under-benefited by the game partner in the “allocator” role. In the second round, the participants were instead assigned the allocator role, with the recipient being either the same partner from the first round or a new partner. The results consistently showed that those who had under-benefited in the first round in turn over-benefited in the second round, regardless of whether the partner remained the same or was replaced. In contrast, those who had over-benefited previously returned the favor, but this was the case only toward the same partner rather than the new one. Hence, selfish behavior was generalized to strangers, whereas a (an altruistic) favor was not generalized, being returned only to the original benefactor. Implications of the asymmetry in chain reactions, as well as methodological issues, are discussed.