2016 年 31 巻 3 号 p. 193-199
Using evolutionary simulation, Yokota and Nakanishi (2012) have shown that majority syncing (generalized tit-for-tat strategy) is an adaptive strategy in intergroup conflict situations. When intergroup conflict is mild, agents who cooperate with ingroup members and ensure their behavior conforms to other members’ cooperation rates facilitate cooperation in their own group. This finding is supported by multi-group selection theory and by cultural group selection theory. However, this model addresses only majority-syncing as a social influence strategy. The current study introduced a minority-syncing strategy to Yokota and Nakanishi’s (2012) model. There were four conditions: Majority-syncing (agents conformed to the majority, but not to the minority), no conformity (agents did not conform), minority-syncing (agents conformed to the minority, but not to the majority), and mixed (both majority- and minority-syncing strategies were used). Computer simulation revealed that the cooperation rate decreased when minority-syncing was introduced. The cooperation rate of the no-conformity condition was higher than of both the minority and the mixed conditions. We discuss the implications of minority-syncing.