Thesis defences

PhD Oral Exam - Lena Kremin, Psychology

Untangling Bilingualism: Using Code-Switching to Understand Bilingual Language Development

Thursday, June 9, 2022 (all day)

This event is free


School of Graduate Studies


Daniela Ferrer



All defences have been moved to Zoom. Refer to our COVID-19 FAQs for more information.

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.


Switching between two languages, or code-switching, is common in bilingual communities. However, little is known about the code-switching young bilinguals hear in their daily lives and how they process it. This dissertation investigated these two aspects of code-switching and proposed new models for defining bilingualism.

Bilingualism is difficult to define and model. In Chapter 2, I proposed that bilingualism researchers can integrate psychometric models, such as the factor mixture model and the grade-of-membership model, which incorporate both categorical and continuous properties. Such models can unify traditional approaches of defining bilingual groups with newer views of bilingualism as a continuous variable. These models will allow researchers to address a variety of research questions, advance theory, and lead to a deeper understanding of bilingualism.

In Chapter 3, I analyzed French–English parents’ code-switching in day-long at-home audio recordings, provided when their infant was 10 and 18 months old. Code-switching was relatively infrequent: an average of 7 times per hour (6 times/1,000 words) at 10 months, increasing to 28 times per hour (18 times/1,000 words) at 18 months. Parents code-switched more between sentences than within a sentence, and this pattern became more pronounced when infants were 18 months. Parents appeared to code-switch most frequently to bolster their infant’s understanding and teach vocabulary, suggesting that code-switching may support successful bilingual language development.

In Chapter 4, I investigated how bilingual children process code-switching, examining how 3-year-old bilinguals process sentences with code-switches at an uninformative determiner-adjective pair before the target noun (e.g., “Can you see el buen [sp. the good] duck?) compared to single-language sentences (e.g., “Can you see the good duck?”). Children were unexpectedly accurate at identifying the target noun in both sentence types, contrasting with previous findings that code-switching leads to processing difficulties. Surprisingly, exploratory results suggested that code-switching may have boosted comprehension for certain children.

In sum, this dissertation has illustrated how code-switching may support bilinguals’ language development. I discovered that parents code-switch to support their child’s learning and showed that children do not always have difficulty processing code-switching. Bilingualism is a multi-faceted phenomenon, and nuanced research is needed to capture this variability.

Back to top

© Concordia University