Seeing Ourselves as More Honest and Moral: How the mPFC Relates to Self-Other Trait Judgments

Despite the central role of honesty in moral cognition, a critical question remains: what neural patterns underlie our self-favorable judgments when evaluating our own honesty compared to that of others? To investigate this, a behavioral study and a functional Magnetic Resonance Imaging (fMRI) study were conducted. In Study 1 (N = 506), participants evaluated honesty-related traits, moral traits other than honesty, and other traits in relation to themselves or the majority. Results showed that participants believed they possessed more and higher levels of both honest and moral traits compared to the majority, with honesty demonstrating stronger internalized identification. Study 2 (N = 62) employed functional magnetic resonance imaging (fMRI) to examine neural activity during trait evaluation tasks. Significantly stronger medial prefrontal cortex (mPFC) activity was found during self versus majority trait judgments, specifically for other traits. However, participants with stronger internalization of honest identity showed greater mPFC engagement when evaluating whether honest traits described themselves. Further exploratory representational similarity analyses showed that the mPFC differentiates between the three trait categories in a nuanced manner. Together, these findings highlight that honesty plays a central role in self-concept, and the mPFC supports self-referential trait differentiation, with its involvement in honesty-related processing varying across individuals.