Twisted strategy may enhance the evolution of cooperation in spatial prisoner's dilemma

Many studies of a spatial game theory have been performed to maintain cooperators because defectors tend to survive in a classical spatial game theory; therefore, various models have been proposed. In this study, the abovementioned problem is tackled using the spatial prisoner's dilemma (SPD) by considering the memory. In the proposed model, all players have a defined memory length related to the strategy update. The strategy for individual players is updated differently from the SPD model only when there are neighboring players whose strategy is the same but whose scores are higher than their own score. Under such conditions, players update to a strategy that is different from the original SPD strategy by considering their own past strategy and by adopting an unlikely strategy. This study is based on the idea of changing own behavior when the situation is not good for players. Consequently, cooperators were easily maintained in the proposed model by forming characteristic spatial patterns. Moreover, the model was unlikely to be affected by a payoff matrix parameter. Author summary In the proposed model, all players have a defined memory length related to the strategy update. The strategy for individual players is updated differently from the SPD model under a certain situation. Players sometimes update their strategy with an unlikely strategy. Results show that the proposed model exhibits characteristic spatial patterns and cooperators can survive.(c) 2023 Elsevier B.V. All rights reserved.