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Oscillatory signatures of Sentence Processing under varying Working Memory Conditions
Poster Session B, Friday, September 12, 4:30 - 6:00 pm, Field House
Eleonora Rossi1, Yanina Prystauka2, Megan Nakamura3; 1University of Florida, 2University of Bergen, 3Pennsylvania State University
Recent work on neural oscillatory correlates of sentence processing suggests power decreases in alpha and beta can be associated with the processing of syntactic and semantic violations (Kielar et al., 2014). Some findings also suggest changes in alpha may reflect neural processes underlying Working Memory (WM) (Wianda & Ross, 2019). More recently, Rossi & Prystauka (2020) found that when individuals process linguistic information in their second language (L2), alpha and beta oscillations decline earlier in time than in native speakers. The authors hypothesized that processing in the L2 taxes WM resources, and that this reduction might be at the basis of the observed shortening of the oscillatory duration. Goal: The present study tests this hypothesis by manipulating WM itself in native, monolingual English speakers to create a ‘taxing condition’ while processing in their native language. Method: Fifty-seven monolingual English college aged students participated in the study (f =28; mean age =19.5). Participants were randomly assigned to one of two groups: A NonMemory group (N = 28) completed a single-task version of a Sentence Judgement Task (SJT) while EEG was recorded. The Memory group (N =29) completed a dual-task version of the SJT with an additional ongoing working memory task which required participants to memorize a sequence of three words at the beginning of each sentence, monitor the sentence for those words, and randomly recall if a specific word was present in the sentence. The SJT consisted of 60 correct sentences, 60 items with syntactic violations, and 60 items with semantic violations. Results: Time-frequency representations (TFRs) of EEG data were computed using the FieldTrip toolbox. Continuous data were epoched (−750 to 1800 ms) and TFRs (2–30 Hz, 2 Hz steps) were computed using the mtmconvol method with a 500 ms Hanning-tapered sliding window in 10 ms steps. Relative baseline correction (−0.5 to −0.1 s) was applied. Statistical analysis was conducted using a cluster-based permutation test, for the two memory groups separately. Following Rossi & Prystauka, three time-windows: 450-750 ms, 750-1050 and 1050-1300 – were analyzed within the 4-30 Hz frequency range. Sentences with a syntactic violation elicited an increase in theta power (4-6Hz) and a decrease in alpha-beta power (10-22 Hz) in both groups in the first time window. The decrease in alpha-beta power continued in the second, and third time window for both groups alike. Sentences with a semantic violations elicited an increase in theta power (4-6Hz) in both groups in the first-time window. In the second time window a decrease in beta power was observed for both groups, but it was maintained only in the third time window for participants who completed the task without memory load. Discussion: These results provide preliminary support for the idea that shorter oscillatory reverberations might reflect reduced working memory resources during sentence processing.
Topic Areas: Syntax and Combinatorial Semantics, Meaning: Lexical Semantics