Patterns of Mother, Father, and Child Code-Switching and Links With Child Language Development

Code-switching, the practice of alternating between languages within a conversation or utterance, is common among bilingual speakers. However, many aspects of its role in language acquisition and the association between parent and child code-switching remain unclear. This study examined code-switching between Spanish-English toddlers and their mothers and fathers. We tested whether the amount of mother and father code-switching was associated with toddlers' code-switching and whether parent and child code-switching predicted toddlers' vocabulary and word learning skills.

Participants included 23 toddlers (23-36 months old) learning Spanish and English and their mothers and fathers. Code-switching was measured using audio samples from daylong recordings. Children's productive vocabulary in English and Spanish was measured via parent report. Word learning skills in English and Spanish were measured with a behavioral fast-mapping task.

The amount of code-switching produced by both toddlers and parents was highly variable. Mothers' and fathers' code-switching demonstrated different patterns of association with children's code-switching, both in zero-order correlations and after controlling for children's total expressive vocabulary. Children's relative language exposure and parents' total code-switching showed distinct predictive patterns for children's Spanish versus English vocabulary. Toddlers' own production of code-switching was the only significant predictor for English word learning; no significant predictors of Spanish word learning emerged.

Viewed from a translanguaging framework, findings suggest that code-switching may play a meaningful and supportive role in bilingual language development. The unique contribution of maternal and paternal code-switching and language-specific effects underscores the need to consider household linguistic input broadly within culturally informed frameworks. This work highlights the role of family dynamics in bilingual development and frames code-switching as a communicative strength that helps young bilinguals navigate and enrich their dual-language environments.