Political Orientation Diverges in Time-Locked Word Responses

People with different political orientations can hear the same political content yet interpret it differently, but it is unclear when such divergence emerges during comprehension. We recorded EEG while 35 Japanese young adults listened to naturalistic political commentary and estimated temporal response functions (TRFs). The TRFs diverged by political orientation from early N1/P2 windows through the N400 window. In the N400 window, a marker of semantic integration, right-leaning participants showed a more negative TRF component in response to morality-related words (such as fairness or harm) than in response to concrete policy terms, whereas left-leaning participants showed the opposite pattern. Earlier N1/P2-related TRF components, linked to perceptual and attentional processing, also differed across groups, especially in response to policy language. Control analyses on words immediately before and after the target revealed no comparable group differences, indicating that divergence was tightly time-locked to the target word rather than reflecting broader contextual attention. Word-locked TRF amplitudes also modestly predicted self-reported political orientation. These findings identify real-time language processing as a locus of orientation-related differences and suggest that shared exposure need not imply shared interpretation.