Neural encoding of vowels in monolingual English and bilingual Spanish-English vowels
Poster D72 in Poster Session D with Social Hour, Friday, October 7, 5:30 - 7:15 pm EDT, Millennium Hall
Yan Yu1, Karen Garrido-Nag2, Aline Durney3, Valerie Shafer3; 1St. John's University, 2Gallaudet University, 3The Graduate Center, City University of New York
Children who are exposed to two languages show a different pattern of speech perception development compared to those receiving monolingual exposure. The few studies that have used neural measures to explore speech processing in toddlers indicate a different pattern of speech development in monolingual compared to bilingual groups (e.g., Yu et al., 2021). The current study asks whether bilingual experience modulates encoding of speech sounds, in addition to discrimination of these sounds. Electrophysiological responses were recorded to the American English 250-ms vowels /ɛ/ and /ɪ/ presented in sequences of 10 stimuli with a 400 ms interstimulus interval and 1500 ms intertrain interval while brain responses were recorded from 65 scalp electrodes in 24-month-old children (15 bilingual, 16 monolingual) and 36-month-old children (15 monolingual, 14 bilingual). The monolingual and bilingual children of the same age showed remarkably similar-morphology brain responses to the stimuli. Repetition of the vowel from the first to the second stimulus led to attenuation of the P1 peak (150 ms) and N2 (200 ms) at fronto-central sites between 150 and 250 ms. On the third repetition, the P1 amplitude showed recovery, with positivity beginning earlier than for the first stimulus in a train and reaching a higher positive amplitude, suggesting prediction of the stimulus. The N2 and following waveform remained suppressed. The ERPs showed group differences only after 300 ms. The monolingual and bilingual 24-month-olds and the monolingual 36-month-olds showed significant suppression from the first to second repetition of a negativity around 400 ms (N4), whereas the bilingual 36-month-olds showed no suppression. In addition, the bilingual 36-month-olds showed a large late negativity to the deviant stimuli in the final (10th position of the train) compared to relative positivity to the standard stimuli in this position. These patterns were interpreted to reflect greater attention to the stimuli, which facilitated discrimination. These finding are consonant with other studies (e.g., Shafer et al., 2012; Datta, et al. 2020) suggesting that bilingual experience leads to increased allocation of attentional resources to the speech signal.
Topic Areas: Speech Perception, Multilingualism