Poster A59, Saturday, March 25, 5:00 – 7:00 pm, Pacific Concourse
First Language Proficiency Modulates Individual Differences in Semantic Processing: An MEG Study.
Morgan B. Johnson1, Lisa J. Beck1, Lyam Bailey1, Tim Bardouille1,2, Aaron J. Newman1; 1Dalhousie University, 2BIOTIC, IWK Health Centre and Capital District Health Authority
Recent research has demonstrated that native language (L1) processing – in terms of proficiency and the brain networks involved – may vary between individuals. This has been shown with processing word meanings (lexical semantics) in sentence context, with standardized measures of language proficiency modulating the N400 EEG effect. The present study extended these findings by using magnetoencephalography (MEG) and investigating processing lexical semantics at the individual word, rather than sentence, level. Language proficiency was assessed using several subtests of the Test of Adult and Adolescent Language 3 (TOAL-3) and the Test of Word Reading Efficiency 2 (TOWRE-2). Results showed that incongruent trials, where audio-visual stimuli were mismatched (e.g., a picture of an apple followed by the word “chair”), elicited an enhanced N400m (the MEG equivalent of the N400) relative to congruent trials. At the group level, generalized additive mixed-effects modeling (GAMM) confirmed the maximal N400m effect at left anterior sensor sites between 350-500 ms post-stimulus. However, at the individual level, scalp distribution of the N400m varied between subjects in this time window. Furthermore, GAMM revealed that scores on both the Listening Vocabulary subtest of the TOAL-3 and the Phonemic Decoding subtest of the TOWRE-2 correlated with N400m amplitude and laterality. Specifically, higher scores on both tests diminish the N400m effect in the right hemisphere. Thus people who have higher vocabularies and are more fluent readers process semantic incongruity more efficiently, and this is associated with increased left-lateralization of neural activity.
Topic Area: LANGUAGE: Semantic