Evolution of commitment in the spatial public goods game through institutional incentives

Studying social dilemmas prompts the question of how cooperation can emerge in situations where individuals are expected to act selfishly. Here, in the framework of the one-shot Public Goods Game (PGG), we introduce the concept that individuals can adjust their behaviour based on the cooperative commitments made by other players in the group prior to the actual PGG interaction. To this end, we establish a commitment threshold that group members must meet for a commitment to be formed. We explore the effects of punishing commitment non-compliant players (those who commit and defect if the commitment is formed) and rewarding commitment-compliant players (those who commit and cooperate if the commitment is formed). In the presence of commitment and absence of an incentive mechanism, we observe that conditional behaviour based on commitment alone can enhance cooperation, especially when considering a specific commitment threshold value. In the presence of punishment, our results suggest that the survival of cooperation is most likely at intermediate commitment thresholds. Notably, cooperation is maximised at high commitment thresholds, when punishment occurs more frequently. Moreover, even when cooperation rarely survives, a cyclic behaviour emerges, facilitating the persistence of cooperation. For the reward case, we found that cooperation is highly frequent regardless of the commitment threshold adopted.