Title

Bilingualism and developmental language disorder shape phonological aspects of word learning

Abstract

Phonological development can be thought of as a process of learning to dimensionalize the input. Children must take in a variable acoustic signal and develop abstract linguistic knowledge. To accomplish this, they have to find meaningful dimensions and attribute them to the right levels of structure. This requires differentially attending to phonological and non-phonological changes in words and sounds. Across three lines of research, I have examined learners’ sensitivity to phonological vs. non-phonological distinctions between words and sounds. First, we report that English-learning toddlers are flexible learners, willing to learn words distinguished on both a phonological dimension (vowel quality) and a non-phonological dimension (pitch). This contrasts with older learners, who typically show more phonologically constrained responses. Second, we find increased flexibility in Mandarin-English bilinguals, who nimbly interpret pitch content in accordance with the language context. Last, we characterize learning in preschoolers with and without developmental language disorder (DLD). We find that DLD impacts mapping of sounds to meanings, and that differences in sound-meaning mapping may be driven by impairments to sound discrimination. In future work, I hope to investigate how sound-processing impairments in DLD interact with bilingual flexibility. This topic has important implications for the intersection of language-education policies and services for children with disabilities.