Poster F76, Tuesday, March 28, 8:00 – 10:00 am, Pacific Concourse
Electrophysiology of Prosodic and Lexical Influences on Sentence Processing in Broca’s Aphasia
Shannon Sheppard1, Tracy Love1,2, Katherine J. Midgley1, Phillip J. Holcomb1, Lewis P. Shapiro1; 1San Diego State University, 2University of California, San Diego
Event-related potentials (ERPs) were used to examine whether and how individuals with Broca’s aphasia use lexical and prosodic cues to predict syntactic structure in sentences containing temporary syntactic ambiguities. Participants listened to sentences containing a temporary early (correct) / late (incorrect) closure ambiguity. Prosody was manipulated to either be congruent or incongruent with the early closure structure. The temporarily ambiguous NP was manipulated to be a plausible or an implausible continuation for the subordinate verb (e.g., While the band played the song/beer pleased all the customers.). Because an implausible NP (the beer) is an implausible continuation for the subordinate verb (played), the implausible NP may provide the parser with a cue that could aid in predicting upcoming syntactic structure even in sentences containing incongruent prosody. Fifteen individuals with aphasia and 20 age-matched controls participated. The individuals with aphasia were divided into groups of High and Low Comprehenders based on the severity of their comprehension deficit. Sentences with incongruent prosody and a plausibility cue resulted in an N400-P600 complex before the critical verb at the implausible NP (the beer) in the controls and High Comprehenders. In controls, incongruent prosody without a plausibility cue elicited an N400-P600 at the critical verb. A sustained positivity was revealed at both of these points in the Low Comprehenders. These results suggest that High Comprehenders have difficulty integrating prosodic cues with underlying syntactic structure when lexical information is not available to assist the parse. Low Comprehenders have difficulty integrating prosodic and lexical-semantic cues with syntactic structure.
Topic Area: LANGUAGE: Syntax