Bilingual and cross-cultural investigation of developmental dyslexia

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PROJECT SUMMARY/ABSTRACT Dyslexia is a neurodevelopmental disorder of literacy that affects monolinguals and bilinguals alike, including Chinese-English bilinguals, who make up >3 million of the US population (US Census Bureau, 2015). At the onset of English-dominant schooling, bilinguals with dyslexia often experience a progressive decline in home language use. Yet, bilingualism theories pose that a bilingual’s two languages interact in ways that enhance children’s global language and literacy faculties (Hernandez, 2019). To advance literacy perspectives, we seek to understand the impact of cross-linguistic interactions on literacy development in bilinguals with dyslexia. Our objective is to uncover how Chinese-English bilingualism influences literacy development in children with dyslexia. We adopt the Lexical Quality (Perfetti 2002; 2021) framework to conceptualize dyslexia as an alteration in the development of sound-to-print and meaning-to-print associations. Chinese orthography emphasizes meaning-to-print associations (McBride, 2021). Our preliminary findings suggest that neurotypical Chinese-English bilinguals form stronger meaning-to-print associations and show stronger engagement of the semantic neurocircuits than English monolinguals, in English (Sun, 2021; 2022). The project’s hypothesis is that bilingual experiences with Chinese influence dyslexia by strengthening semantic literacy skills in English. To test this hypothesis, we focus on semantic and phonological literacy skills in Chinese-English bilinguals and English monolinguals educated in the US, and Chinese monolinguals educated in Taiwan (ages 8-10, n=365 per group, n=50 with dyslexia per group). Children will complete lexical morphology and phonology functional Near Infrared Spectroscopy (fNIRS) neuroimaging tasks and literacy measures in each of their language(s). We seek to determine the effects of bilingualism on learning to read in neurotypical bilinguals (Aim 1) and bilinguals with dyslexia (Aim 2). Direct cross-linguistic comparisons of monolinguals in the US and Taiwan will help isolate language-specific effects of bilingualism in dyslexia (Aim 3). The approach will provide empirical bases to (1) uncover mechanisms that influence literacy in bilinguals with dyslexia; (2) advance theories through cross-linguistic evidence on the development of foundational reading competences in structurally- distinct orthographies; (4) specify sources of individual variability in neuro-cognitive processes during the key periods of brain development for learning to read; (5) focus on semantic literacy skills to inform lexical morphology instruction for children with dyslexia. The project will advance our understanding of children’s emerging neural architecture for learning to read in linguistically-diverse learners with and without dyslexia.