Bilingual Development

Many studies have shown that how monolingual caregivers talk to their infants matters for the infant’s language development. In this project, I explored how bilingual caregivers talk to their infants, and how this might affect their infant’s language acquisition patterns.

Language input to bilingual infants

We collected an audio corpus of daylong recordings by bilingual families with an infant using the LENA recording system. This audio corpus consists of three days of recordings when the child was 10-months of age, and one extra day of recording when the child was 18-months of age. We have assessed the reliability of the LENA recording system for estimating adult word counts in these recordings (Orena, Byers-Heinlein & Polka, 2019), and reported on general input characteristics to bilingual infants at 10-months of age (Orena, Byers-Heinlein & Polka, in press). Ongoing work is directed towards examining how and when bilingual caregivers mix their two languages to their infants, and how bilingual input changes or stays the same between 10- and 18-months of age.

Early speech production in bilingual infants

A large body of work has examined how language input affects early production in monolingual infants. Using the Montréal Bilingual Infant corpus, I examined how speaker and language context might influence 10-month-old bilingual infants’ early productions (Xu, Orena, Ruan, & Polka, in prep). We found that, even in naturalistic contexts, infants vocalize more often during one-to-one interactions versus when more than one adult is present or when the infant is alone. Interestingly, infants vocalized more often when interacting with their primary caregiver and when hearing their dominant language, suggesting that infants’ dominant language will play a large role in shaping their early productions.

Early speech processing in bilingual infants

A hallmark of children’s language development is their ability to recognize words in a stream of speech. Prior research has shown that monolingual infants are able to segment bi-syllabic words from sentences by 8-months of age; however, virtually nothing is known about how infants raised in bilingual homes face this difficult problem. Our study showed that when tested in a sequential dual-language task, segmenting words in both of their native languages poses a challenge for bilingual-learning 8-month-olds (Polka, Orena, Sundara, & Worrall, 2016). Recently, we showed that when tested in a simultaneous dual-language task, bilingual infants (as a group) showed word segmentation in both of their native languages by 8-months of age (Orena & Polka, 2019). Further, exploratory analyses indicate that these abilities are mediated by experience hearing language mixing from their caregivers.


Relevant articles

Xu, K., Orena,A.J., Ruan, Y., & Polka, L. (in preparation). The influence of bilingual input on infant volubility and turn-taking at 10-months of age. Data collected and analyzed, manuscript in progress.

Orena, A.J., Byers-Heinlein, K., & Polka, L. (in press). What do bilingual infants actually hear? Evaluating measures of caregiver speech to10-month-old, bilingual-learning infants. Developmental Science.

Orena, A.J., Byers-Heinlein, K., & Polka, L. (2019). Reliability of the Language Environment Analysis (LENA) in a French-English bilingual speech context. Journal of Speech, Language and Hearing Research. doi:10.1044/2019_JSLHR-L-18-0342

Orena, A.J., & Polka, L. (2019). Monolingual and bilingual infants’ word segmentation abilities in an inter-mixed dual-language task. Infancy.doi:10.1111/infa.12296

Polka, L., Orena, A.J., Sundara, M.,& Worrall, J. (2017). Segmenting words from fluent speech during infancy - challenges and opportunities in a bilingual context. Developmental Science,20(1). doi:10.1111/desc.12419


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