Event-related potential responses of ex-combatants and war victims differ for bias stimuli

Antagonistic social identities are reflected in neurophysiological responses to implicit bias, yet empirical validation in real-life post-conflict contexts remains scarce. This cross-sectional study assessed neurocognitive responses to bias-related stimuli among 76 Colombian participants, including both victims and ex-combatants of the armed conflict. Using an Implicit Association Test combined with EEG recording and cluster-based permutation analysis, we examined group differences in event-related potentials. Results revealed differential activation patterns: a language-related N400 and an emotion-related Late Positive Potential (LPP), both showing distinct latencies and amplitudes between groups. Particularly, victims exhibited stronger LPP modulation and delayed mid-to-late components, suggesting heightened emotional processing and increased cognitive load in evaluating bias-laden content. These findings highlight how lived experiences of victimization—not merely exposure to violence—shape neurophysiological processing of intergroup bias. Our results underscore the relevance of implicit cognitive markers for informing psychosocial interventions in transitional justice and reconciliation settings.