Abstract:  The ultimatum game is commonly used to examine fairness-related economic decision making, and the trade-off between fairness preferences and self-interest is assumed to determine whether individuals reject or accept unfair offers. With respect to the dual-system theory, there are controversial understandings on whether fairness preferences result from the automatic response in System 1 or the deliberation processes in System2. Our study discussed such controversy from three aspects of this theory, including theoretical hypotheses, influential factors, and neural mechanisms. The automatic negative reciprocity hypothesis and the social heuristics hypothesis contend that fairness preferences are automatic, whereas the controlled-processing hypothesis contends that fairness preferences are products of deliberation process that suppresses self-interest motivation. System 1 identifies and evaluates fairness via anterior insula, amygdala, and ventromedial prefrontal cortex; while System 2 reassesses and adjusts System 1 to make the final decision via dorsal anterior cingulate cortex, ventrolateral PFC, dorsomedial PFC, and left dorsolateral PFC. Individual differences and experimental task characteristics may affect individuals’ automatic responses in System 1. Future research need to further improve the experimental paradigm; explore the moderators within the dual system and its neural network.

Key words: fairness, ultimate game, dual systems theory, automatic-processing hypothesis, controlled- processing hypothesis