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Parafoveal N400 fixation-related potential effects vary as function of eye movement behavior (i.e., word skipping) during natural sentence reading

Poster Session E - Monday, March 31, 2025, 2:30 – 4:30 pm EDT, Back Bay Ballroom/Republic Ballroom

Sara Milligan¹ (smilliga@usf.edu), Elizabeth Schotter²; ¹University of South Florida

Decades of neurolinguistic research using event-related brain potentials (ERPs) to study the in-the-moment language processing in the brain is limited by the use of rapid serial visual presentation (RSVP) to present the words in the sentence one word at a time. Although this research has established the N400 component, a robust and reliable response that is sensitive to semantic expectancy, it is unclear how this response relates to eye movement decisions when the reader has control over where and for how long to direct their attention, and can pre-process upcoming words before fixating them. To determine how eye movements relate to the N400, we co-registered EEG and eye tracking to measure fixation-related brain potentials during natural sentence reading. We manipulated parafoveal previews of target words so that the previewed word was either (1) expected, (2) an anomalous orthographic neighbor of the expected word, or (3) an anomalous instance of the. We split trials based on whether the reader skipped or fixated the word and found a parafoveal N400 effect in response to the anomalous neighbor, which occurred only when the word was skipped, and a parafoveal N400 effect in response to the anomalous the, which was present regardless of skipping. This pattern suggests that (1) some N400 effects are yoked to behavioral eye movement decisions, (2) eye movement behavior is largely determined prior to complete comprehension based on partial linguistic processing, and (3) language processing continues after the eyes have moved on.

Topic Area: LANGUAGE: Semantic