Poster A50, Saturday, March 24, 1:30–3:30 pm, Exhibit Hall C
A Late Slow Frontal Positivity ERP reflects the resolution of contextual ambiguity during narrative discourse comprehension
Patrick Ledwidge1, Adam Ramsey1, Jeremy Foust1; 1Baldwin Wallace University
The goal of this study was to identify the event-related potential (ERP) correlate(s) of contextual ambiguity resolution during narrative discourse comprehension. Thirty-seven neurotypical college-students read narrative discourses during 256-channel ERP recording. The contexts of the discourses were initially ambiguous if read without a descriptive title (Untitled Discourse group: n = 19), but clear if preceded by a title (Titled Discourse group: n = 18). For the Untitled Discourse group, however, the contexts became more clear after reading the last word of sentence 2 (Critical Word 2) and sentence 3 (Critical Word 3), as determined offline by a separate sample. ERPs of interest were the N400 and P600 recorded to the last word of each sentence (Critical Words 1-3). For the Untitled Discourse group, N400 amplitudes (272-452 ms) became less negative from Critical Words 1-3, suggesting greater ease of lexical-semantic retrieval as the discourses unfolded. P600 amplitudes (456-700 ms) increased from Critical Words 1-3 for the Titled Discourse group. Unexpectedly, amplitudes of a Slow Frontal Positivity (SFP) ERP (684-1000 ms) increased from Critical Words 1-3 for the Untitled Discourse group only. The SFP did not occur for the Titled Discourse group. P600 amplitudes for the Untitled Discourse group were larger to Critical Word 3 than Critical Word 2. Our results suggest that the SFP reflects the resolution or revision of contextual ambiguity during narrative discourse comprehension. Alternatively, the P600 is proposed to reflect discourse context-updating when an existing context is available or after the resolution/revision of contextual ambiguity.
Topic Area: LANGUAGE: Semantic