The Other Side of the Coin: Recipient Norms and Their Impact on Indirect Reciprocity and Cooperation

Human cooperation depends on indirect reciprocity. In this work, we explore the concept of indirect reciprocity using a donation game in an infinitely large population. In particular, we examine how updating the reputations of recipients influences cooperation. Our work adds a time-scale parameter for updating donor and recipient reputations. We find a trade-off between the level of cooperation and evolutionary stability influenced by social norms. Forgiving' recipient norms enhance cooperation but increase susceptibility to defectors, whereas unforgiving’ norms reduce cooperation but defend against invasion by defectors. Expanding to include gossip groups allows us to analyze the evolutionary dynamics of the time-scale parameter, identifying generous' norms that support cooperation, and strict’ norms that discourage such generosity, ultimately showing vulnerability to defector invasions and potential cooperation collapse.