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The neural effects of semantic violations during a natural reading paradigm in deaf and hearing readers using co-registration EEG/eye tracking methodology
Poster Session A, Wednesday, September 30, 11:00 am - 1:00 pm, Wangari Maathai
Emily M. Akers1, Katherine J. Midgley1, Phillip J. Holcomb1, Karen Emmorey1; 1San Diego State University
Semantic violations in sentences are one of the most researched sentence anomalies in the event-related potential (ERP) literature and are typically measured through the N400 component. This component has consistently been shown to be modulated by semantic anomalies, whereby anomalous words produce a larger negativity than semantically appropriate words about 400ms post-word onset. Sensitivity to semantic violations has historically been measured through unnatural paradigms like RSVP (one word at a time in the center of the screen) or RSVP with flankers (three words on the screen at a time) designs. Previously, we have studied deaf and hearing skilled readers to assess whether they process semantic violations similarly, as measured by N400 amplitudes. In an RSVP experiment, deaf readers exhibited a significantly larger negativity compared to hearing readers for semantic violations on the medial matrix verb of a sentence. In an RSVP with flankers experiment, in which readers could access parafoveal information from one word to the left and one to the right of the center-fixated word, both groups showed a reduced N400 compared to the RSVP study. In the RSVP-flankers study, the parafoveal presentation appeared to cause the semantic effects to wash out across window times, particularly for hearing readers. For both studies, however, acceptability judgements indicated high behavioral sensitivity to the semantic anomalies. In the current study, we assessed semantic violations presented in the medial matrix verb position as well as in the final word (a noun) in both hearing and deaf skilled readers using a natural reading paradigm. EEG and eye tracking co-registration was recorded such that fixation-related potentials (FRPs) could be time-locked to fixations on each word throughout the sentence. Similar to our previous studies, both groups exhibited an N400 at the time of the violation; however, both groups showed N400 effects as early as two words before fixating on the target word (i.e., when the anomaly was still in the parafovea). For the semantic final noun anomalies, deaf readers exhibited an N400 when the violation was in the parafovea, which continued into the fovea when the violation was fixated, along with a weak late positivity. Hearing readers also exhibited an N400 negativity when the violation was in the parafovea and a robust late positivity that started when the violation was in the parafovea and continued and strengthened once the violation was fixated. This study marks the first time deaf readers’ semantic neural processing has been studied naturally with EEG/eye tracking methodologies. Deaf readers continue to show consistent sensitivity to semantic violations that may be distributed across their reading span, and both groups’ sensitivity to semantic anomalies in the final word resembles the standard N400 semantic response, followed by a positivity that may reflect semantic reanalysis, and which appears to be more robust for the hearing readers.
Topic Areas: Reading,