Shiraki, Y.（白木優馬）& Igarashi, T.（五十嵐祐） (2017). We Can’t Return Evil for Good: The Comparison between Direct and Indirect Reciprocity. 恩を仇で返せない：直接互恵性と間接互恵性の比較 Letters on Evolutionary Behavioral Science, 8(1), 4-7.
There are two distinct evolutionary mechanisms of altruistic behavior: direct and indirect reciprocity. Humans are motivated not only to reciprocate benefits to benefactors but also to behave altruistically for the maintenance or improvement of their reputation. This study compared the two evolutionary mechanisms of altruistic behavior. Three scenario-based experiments on diverse samples (Japanese undergraduates in Experiment 1, Japanese crowdsourcing workers in Experiment 2, and crowdsourcing workers worldwide in Experiment 3) were conducted by manipulating (1) reciprocity between participants and a colleague (reciprocal or non-reciprocal) and (2) the colleague’s reputation in the workplace (good or bad). When participants received a reciprocal request from their colleague to help, they tended to accept it, even if the colleague had a bad reputation among others. On the other hand, participants were less accepting of a non-reciprocal request from a colleague with a bad reputation than a colleague with a good reputation. These results clearly indicate that humans prioritize the maintenance of direct reciprocal relationships over group-based reputations.