Poster E51, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Single-word ERPs reveal age-related changes in incremental context processing
Brennan Payne1, Kara Federmeier1; 1University of Illinois
Event-related potential (ERP) studies looking at responses to expected and unexpected sentence-final words have reliably found that older adults (OA) show reduced effects on the N400, a component linked to meaning processing. These findings have been taken to suggest that OA are less efficient in utilizing contextual constraints. In the current study, we directly examined whether OA are less able to take advantage of accumulating contextual constraints over the course of a sentence. Linear mixed-effects models of single-word ERPs were used to examine age-related changes in the effects of context on multiple aspects of lexical processing. We recorded EEG while younger (YA) and OA read congruent sentences, syntactic prose (grammatical but nonsensical), and random word strings. In YA, open-class words elicited N400 reductions with increasing word position in congruent sentences only, replicating the classic word position effect. In OA, this effect was attenuated, suggesting a reduced sensitivity to accumulating contextual constraints in aging. Sensitivity of the N400 to lexical variation (e.g., word frequency) was overridden by accumulating semantic context in YA. In OA, the N400 was sensitive to lexical frequency, but this effect was not modulated by word position. Collectively, these findings support the claim that aging is associated with a reduced ability to build up and use context information over time and that modeling variability in single-trial event-related EEG activity can reveal mechanisms by which different sources of information simultaneously contribute to the unfolding dynamics of comprehension in the brain in real time.
Topic Area: LANGUAGE: Development & aging