History loyalty-based reward promotes cooperation in the spatial public goods game

Reward has been proved to be an effective mechanism to sustain cooperation among selfish individuals. In this paper, we propose a history loyalty-based reward in which a cooperator can gain additional reward if the time he sticks to the cooperation strategy is over a loyalty threshold. Accordingly, defectors have to bear the cost of reward subsequently. The results on the spatial public goods game show that the cooperation could be immensely enhanced when the loyalty threshold and the reward factor are suitable. Besides, the time evolution of cooperator density and the spatial distribution of cooperators and defectors are investigated. Our work extends the form of reward in the evolution of spatial public goods game. (C) 2019 Published by Elsevier B.V.