The influence of proposer features on inequity aversion: A meta-analysis of event-related potential (ERP) studies.

OBJECTIVE: Identical information can be perceived differently depending on the framing in which it is presented. Consequently, individuals may exhibit varying degrees of inequity aversion toward objectively inequitable allocations depending on the proposer features. However, a precise characterization is still lacking regarding the role of proposer features in maintaining social fairness norms and their influence on the temporal dynamics of inequity aversion processing. METHOD: In this study, we conducted a meta-analysis of event-related potential studies that explored the influence of proposer features on inequity aversion using the ultimatum game. This meta-analysis aimed to provide more temporal evidence for the underlying neural mechanisms and offer more support to the dual-system processing theory. RESULTS: Using the fixed-effect model, the results revealed that proposer features induced significant amplitude changes of the feedback-related negativity (early, rapid processing of norm violations) and P300 (late, deeper processing) components. These two components respectively mapped the intuitive system (System 1) for automated processing and the deliberate system (System 2) for elaborate processing. In addition, subgroup analysis indicated that specific proposer features led to different processing patterns, which had different impacts on the feedback-related negativity and P300. CONCLUSIONS: Taken together, proposer features significantly regulated the processing of the early and late stages of inequity aversion. Following processing by both intuitive and deliberate systems, proposer features facilitated more flexible decision making in fairness-related scenarios. These findings provided more evidence for the neural mechanism of inequity aversion and supported the dual-system processing theory of unfair decision making. (PsycInfo Database Record (c) 2026 APA, all rights reserved).