Developmental changes in phonological awareness in Chinese-English bilingual children: An fNIRS longitudinal study

Learning to read triggers a cascade of changes in children's minds and brains, changes that lead to the formation of the "reading brain". Importantly, the developmental trajectory of these changes differs across languages. The development of phonological literacy skills comes first for learners of alphabetic languages such as English. In Chinese, however, phonological literacy skills take longer to finetune due to the character's phonological opacity. Bilingualism theories, however, suggest that such developmental trajectories are plastic and subject to change due to cross-linguistic interactions between bilinguals' two languages. Our study puts these theoretical assumptions to the test by examining neurodevelopmental changes in phonological literacy skills in young Chinese-English bilinguals and Chinese monolinguals (27 monolinguals and 40 bilinguals). At two time points, in grades one and three, the children completed an auditory phonological awareness initial sound-matching task during functional Near Infrared Spectroscopy (fNIRS) neuroimaging (27 monolinguals and 40 bilinguals). In line with bilingual transfer theories, bilingual children showed a more robust fine-tune of the phonological or dorsal neural literacy pathway relative to monolinguals. Moreover, we used prediction over time to demonstrate the additional recruitment of the phonological pathways as English proficiency increased in bilinguals. The lower English phonological skills at time 1 were predictive of age-related increases in STG activation along the dorsal pathway in the Chinese task. The findings inform theories of brain development for learning to read by revealing the plasticity in foundational literacy pathways as a function of early and systematic dual-language literacy instruction.