Proceedings of the Annual Meeting of the Cognitive Science Society

Widely regarded as the cornerstone of justice (Rawls, 1971),fairness constitutes one of the pillars of human morality. TheUltimatum Game (UG), extensively studied in behavioral eco-nomics, is the canonical task for studying fairness. In sharpcontrast to the predictions of normative standards in game the-ory, people typically reject low offers in UG. In this work,we present the first resource-rational process model of UG.Concretely, by taking into account people’s expectations, weshow that Nobandegani et al.’s (2018) resource-rational pro-cess model, sample-based expected-utility, provides a unifiedaccount of several experimental findings in UG, namely, theeffects of expectation, competition, and time pressure. Assum-ing that expectation serves as a reference point for subjectivevaluation of an offer, we show that the rejection of low offers inUG can arise from purely self-interested expected-utility max-imization. We conclude by discussing the implication of ourwork for moral decision-making and, more broadly, human ra-tionality.