The effect of survival pressure-based defector reward behavior on cooperation in spatial prisoner’s dilemma games

Research has shown that rewarding behavior can greatly facilitate the occurrence of cooperation in social dilemmas. Yet rewards entail costs, making the reward itself an altruistic behavior. The reasons for adopting rewarding behaviors then become an interesting matter, so we propose a game model in which defectors are pressured by survival to adopt rewarding behaviors. Research suggests that defector reward strategies can be used as a transition strategy for defectors to alleviate survival stress and promote cooperation in the spatial prisoner's dilemma. A small survival pressure threshold will make it altogether easier for defectors to adopt a strategy that rewards defection and thus tempts the emergence of cooperators in their neighborhood. In addition, the effect of the payment cost α and the reward amount β of the rewarding behavior on the evolution of the system will be limited by the temptation b of the defector, and the effect of each parameter on the promotion of cooperation in the system is not linear. That is, when α is fixed, b and β can still optimize the level of cooperation in a given combination. The same holds for α and β when b is fixed.