Poster Session D, Monday, March 25, 8:00 – 10:00 am, Pacific Concourse
Distributional Changes in P600 Variants as a Result of Natural Aging
Michelle Leckey1, Kara D. Federmeier1; 1University of Illinois at Urbana-Champaign
Manipulations of syntactic processing difficulty are associated with a late, posterior positivity known as the P600. A similar positivity has been elicited to thematic role animacy violations and termed the “semantic P600”. Previous research also points to similarities between the syntactic variant of the P600 and the P3b, a domain general component sensitive to saliency, task relevance and probability, factors that also modulate the syntactic P600. Current theorizing tends to assume the two language P600 effects are variants of the same underlying process, yet there is little empirical work testing that assumption. The goal of the present work was therefore to examine the relationship among the syntactic and semantic P600 and the P3b in the same subject populations. 24 young adults and 24 older adults completed three tasks that have each previously been seen to elicit one of these positivities of interest. All participants had no history of familial sinistrality. The P3b has been shown in many studies to manifest an age-related distributional change, such that it has a posterior distribution in young adults and shifts to include more frontal sites in older adults. We replicate that pattern. The syntactic P600 has also been found to show a similar age-related shift, which we also replicate. Notably, the semantic P600 (which has never been studied in older adults) did not show the same kind of age-related shift. This pattern suggests that the two P600s may be differentiable and that it is the syntactic variant that shares underlying mechanisms with the P3b.
Topic Area: LANGUAGE: Syntax