Computational Resilience in Human Reciprocity: An Asymmetric Intrinsic Prosocial Bias for Sustaining Cooperation under Exogenous Uncertainty

In direct reciprocity, environmentally imposed exogenous uncertainty frequently decouples benefactor's altruistic intentions from final outcomes. How do cooperative bonds remain resilient against this inevitable "noise"? Adopting a comprehensive levels-of-analysis framework across eight experiments, we integrate interpersonal paradigms, computational modeling, multivariate fMRI decoding, and third-party social evaluations to uncover a robust "asymmetric adjustment" in beneficiary's affective evaluation and reciprocity under exogenous uncertainty, systematically delineating its cognitive algorithmic rules, neural representations, and adaptive functions in sustaining human cooperation. Specifi