Asymmetric costs of individual and social learning and the evolution of cooperation in spatial prisoner’s dilemma games

Strategy updating rules (or learning rules) are particularly important in modeling the evolution of cooperation. Individual learning is widely assumed to be more costly than social learning, as it requires direct environmental exploration and trial-and-error learning, whereas social learning involves copying others’ behaviors without such exploration effort—an assumption widely adopted in the literature. This study investigated how this asymmetry in learning costs affects the evolution of cooperation in spatial prisoner’s dilemma games by building and analyzing agent-based models. The results suggested that, where individual learning was no more costly than social learning, individual learners were better at bolstering cooperation than social learners. However, where individual learning was more costly than social learning, cooperation was facilitated to a greater degree in a mixed population of individual and social learners than in a population composed of a single type of learners. In particular, the facilitation was more evident in mixed population dominated by social learners than in those dominated by individual learners. Mixed populations with a moderate-to-high fraction of social learners exhibited endure-expand dynamics that promoted cooperation. Additionally, spatial arrangements in which individual learners surrounded social learners were found to facilitate cooperation. When social learners employed critical social learning (CSL), however, a large fraction of CSL agents hindered the evolution of cooperation under costly individual learning conditions. These findings contribute to the understanding of the role of learning types and their costs in the evolution of cooperation and its spatial mechanisms, highlighting the need for an appropriate proportion of individual learners in fostering cooperation. Limitations of this study and directions for future research are also discussed.