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Auteur: Evie MALAIA

Co-Auteur(s): Nathaniel SHANNON, Sharlene NEWMAN

Cognitive effort during reading in late bilinguals: an EEG study

Abstract/Résumé: This EEG study investigated the effect of the late acquisition of Spanish (L2) on reading native English words. Two groups of native English participants – one with very limited Spanish experience and one with extensive experience performed two lexical decision tasks: an English lexical decision task (ELD), in which the participants indicated whether a letter string was an English word; and a General lexical decision task (GLD), in which the participants indicated whether a letter string was a word in either English or Spanish. During the task, high-density, continuous EEG data were collected using a 256-channel EGI Geodesic Sensor net. We conducted a frequency domain analysis of the power in the higher α band (9.7-12.8 Hz) across electrode clusters of interest. The left posterior and anterior, right posterior and anterior regions of interest, comprised of 16 channels each demonstrated significantly higher α power in the monolingual group (F(1,4)=20.9, p<0.02, ep2=.874; bilingual α power M=1.5 µV, monolingual α power M=8.9 µV). However, while the bilingual group exhibited higher α power amplitude for Spanish stimuli, bilingual group demonstrated higher α power for English stimuli (F(1,4)=25.05, p<0.015, ep2=.893; monolingual English α power M=10.5 µV, Spanish α power M=7.2 µV; bilingual English α power M=1.1 µV, Spanish α power M=1.8 µV). Based on Obleser and Weizs (2011) proposal that low, evenly distributed α power indicates a state global binding between neural regions, we interpret the data to suggest that late bilingual participants utilize visual information related to orthographic features of the stimuli for executive processing. The high α power in EEG of monolinguals exposed to Spanish stimuli likely indicates the lack of binding across ROIs, as they cannot use visual information for linguistic processing in an unfamiliar language. Higher coefficient of variation (ratio of standard deviation to the mean) in the α band power amplitude across electrode clusters of interest also corresponded to faster response times in both groups, except for GLD task responses on English stimuli. The overall results appear to confirm that orthographic representations of visually presented words are activated simultaneously for both known languages even in late bilinguals. References: Obleser, J., & Weisz, N. (2012). Suppressed Alpha Oscillations Predict Intelligibility of Speech and its Acoustic Details. Cerebral Cortex.