Group Formation through Indirect Reciprocity

Cooperative behavior can be observed widely in our society. An important aspect of cooperation is that people can maintain mutual cooperation even if they are faced with social dilemma, which means the situation that people fail to cooperate although entire cooperation gives better payoff to everyone. Several mechanisms are pointed out to be important to overcome the social dilemma, and reciprocity is one of them [1]. Especially indirect reciprocity (cooperation to someone enhance his probability to have a cooperative response from others) is a key when partners of interaction are flexible [3]. It is necessary for this mechanism to work that people monitor what others do to others and appropriately judge whom they should cooperate with. Otherwise free riding behavior spreads and cooperation is abandoned.