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Parental language mixing: Its measurement and the relation of mixed input to young bilingual children's vocabulary size*


Is parental language mixing related to vocabulary acquisition in bilingual infants and children? Bilingual parents (who spoke English and another language; n = 181) completed the Language Mixing Scale questionnaire, a new self-report measure that assesses how frequently parents use words from two different languages in the same sentence, such as borrowing words from another language or code switching between two languages in the same sentence. Concurrently, English vocabulary size was measured in the bilingual children of these parents. Most parents reported regular language mixing in interactions with their child. Increased rates of parental language mixing were associated with significantly smaller comprehension vocabularies in 1.5-year-old bilingual infants, and marginally smaller production vocabularies in 2-year-old bilingual children. Exposure to language mixing might obscure cues that facilitate young bilingual children's separation of their languages and could hinder the functioning of learning mechanisms that support the early growth of their vocabularies.

Corresponding author
Address for correspondence: Concordia University, Department of Psychology, 7141 Sherbrooke St. West, Montreal, Quebec, H4B 1R6,
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This work was funded by a Canada Graduate Scholarship from the Natural Sciences and Engineering Research Council of Canada. Data were collected during doctoral studies at the University of British Columbia, with advising from Janet F. Werker. Thank you to Ferran Pons and Janet F. Werker for their helpful comments on earlier versions of this manuscript. Special thanks to all of the members of the Infant Studies Centre at the University of British Columbia and the Concordia Infant Research Laboratory for their support.

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