Poster B49, Sunday, March 25, 8:00-10:00 am, Exhibit Hall C
Two late positivities during sentence comprehension: The influence of wrap-up and cognitive control
Trevor Brothers1,2, Eddie Wlotko3, Simone Riley1, Margarita Zeitlin1, Connie Choi1, Gina Kuperberg1,2; 1Tufts University, 2Massachusetts General Hospital, 3Moss Rehabilitation Research Institute
During sentence comprehension, context can influence both the initial access of word meanings (300-500ms) and more prolonged, re-interpretive processes (500-1200ms). Here, we investigated the cognitive mechanisms underlying two late post-N400 positivities, which are known to vary as a function of plausibility and lexical constraint. In this study (N = 70), we measured ERPs as participants read sentences with predictable, unpredictable, or anomalous critical words (“Father carved the turkey with a knife/smile/beach…”). For 33 participants, critical words appeared in the sentence-final position, where “wrap-up” effects are maximal. For 37 participants, a few words were added to each sentence to delay sentence wrap-up. Finally, to probe the role of cognitive control in generating these late ERP components, we used the AX Continuous Performance Task (AX-CPT) to assess individual differences in cognitive control abilities. Unpredicted words produced a larger late anterior positivity, and anomalous words produced a larger late posterior positivity, relative to predictable words. Critically, the amplitude of the anterior positivity was larger for critical words appearing in sentence-final positions. This pattern was reversed for the late posterior positivity, with larger anomaly responses occurring in sentence-medial positions. Finally, improved performance on the AX-CPT appeared to selectively enhance the magnitude of the late anterior positivity, suggesting that the re-interpretation of unexpected (but plausible) events may depend on frontally-mediated cognitive control abilities.
Topic Area: LANGUAGE: Semantic