Developmental changes and effects of parental interaction on French-English bilingual infants' vocalization rates

Abstract

In prior work, we investigated how several factors—social context (Social versus Non-Social & One versus Multiple speakers), speaker context (Mother versus Father), language (English versus French) and language dominance (Dominant versus Non-Dominant) – are related to vocalization rates in 10-month-olds growing up in English/French bilingual families (n = 21). This was accomplished by analyzing naturalistic daylong recordings obtained using the Language Environment Analysis (LENA) system. Here, we examined how these factors are related to vocalization rates in older infants by analyzing LENA recordings obtained when these same infants were 18 months of age (n = 16). Similar to previous findings, preliminary analysis showed a higher proportion of infant vocalizations occurred in social contexts (i.e., presence of adult speech). Moreover, more infant vocalizations occurred in contexts with one speaker as opposed to multiple speakers. In contrast to previous findings, 18-month-olds did not vocalize more when interacting with their mothers compared to their fathers. Infant vocalization rates were comparable in French and English input contexts. However, more infant vocalizations occurred in dominant language than in non-dominant language contexts. These findings will help us understand how parent-infant interactions change over time and shape the vocal behavioral of infants being raised in bilingual families.