Distinct neural routes for evaluative and informational social influence
Humans routinely revise their judgments based on input from others, yet how the brain mechanisms distinguish evaluative from informational social influence remains unclear. Using preregistered electroencephalography (EEG, N = 87) and the Judge-Advisor System, we identified distinct neurocognitive routes by which feedback and advice shape judgment revision. Participants made numerical estimates, received either feedback ("good"/"bad") or advice (alternative estimates) of varying proximity to their own judgment, and then revised their response. Feedback engaged rapid evaluative monitoring: a feedback-related negativity (FRN, 200-300ms) that decreased with confidence, indicating reflexive performance assessment. Advice triggered delayed deliberate processing: late positive complex (LPC) onset latencies that slowed when confident individuals encountered discrepant advice, indicating effortful integration of external information. Both routes converged on the P300 (250-250ms),whose amplitudes increased with proximity, consistent with the reward value of social validation. These findings reveal a dual-route architecture: feedback determines whether to revise through rapid evaluative signals, while advice specifies how much to revise through sustained integrative processes. Confidence calibrates both routes, protecting against misleading feedback while intensifying deliberation over discrepant advice. This temporal dissociation clarifies how metacognitive and social processes coordinate adaptive judgment revision.