Poster A70, Thursday, August 16, 10:15 am – 12:00 pm, Room 2000AB
Age of acquisition of L2 affects alpha power during bilingual speech in noise processing
Angela Grant1,2, Kristina Coulter1,2, Shanna Kousaie2,3, Annie C. Gilbert2,3, Shari Baum2,3, Vincent Gracco2,3,4, Denise Klein2,3, Debra Titone2,3, Natalie Phillips1,2;1Concordia University, 2Centre for Research on Brain, Language, and Music, 3McGill University, 4Yale University
Research on bilingualism has grown exponentially in recent years. Yet, little of that research has investigated a common aspect of language comprehension: understanding speech in noise. Electroencephalography (EEG) studies conducted in monolingual participants have revealed that listening to speech in noise results in increased alpha power, which is thought to be due to increased attentional demands (e.g., Obleser et al., 2012). It remains unclear whether these results would extend to processing in bilinguals. In the current study, we tested English/French bilinguals who did not significantly differ in L2 proficiency as measured by letter and category fluency. These bilinguals were split into groups of 17 early (L2 acquired by age five) and 18 late (L2 acquired after age 5) sequential bilinguals, as well as 15 simultaneous bilinguals. Participants were presented with highly semantically constrained auditory sentences such as “We saw a flock of wild geese” in both languages and in both noise (16-talker babble) and in quiet. EEG was recorded while participants listened to the sentences and repeated the final word. Only sentences where the final word was produced correctly were analyzed. The data was segmented for time-frequency analyses from 0-1000ms after the terminal word, with a 500ms pre-stimulus baseline. We conducted a 2 (Language) x 3 (Age of Acquisition) x 2 (Listening Condition) x 3 (Electrode) x 6 (Time quantified in 100ms intervals from 100ms to 700ms) mixed ANOVA of power in the alpha band. We found a significant main effect of Language, such that alpha power was higher in the L2. That main effect was qualified by a trending interaction with Time, such that the effect of Language was driven by differences in an early (100-200ms) window. We also observed an interaction of Listening Condition by Age of Acquisition (AoA), such that processing speech in noise elicited more alpha power in late bilinguals compared to simultaneous bilinguals. Early bilinguals did not differ from either group, in quiet or noise. Our results, when interpreted in the theoretical context where alpha power indexes attentional control (e.g. Wostmann et al., 2017), suggest that listening in the second language requires additional attentional control compared to the first language, particularly early in processing during word identification. Additionally, although our participants did not differ in their L2 proficiency, our results suggest that under difficult processing demands, AoA modulates the amount of attention required to process the L2.
Topic Area: Multilingualism