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Open Access Publications from the University of California

Vocabulary Growth in Infancy and Toddlerhood: The Impact of COVID-19


Early vocabulary development is heavily influenced by children’s language environment. For example, higher SES children who have frequent and rich interactions with caregivers tend to have larger vocabulary size than lower SES children who have less stable home environment (e.g., Hoff & Naigles, 2002). Because of the recent pandemic, most Canadian children have experienced dramatic changes to their day-to-day life. In the current study, we ask whether the pandemic environment affects children’s vocabulary growth. We compare the MacArthur-Bates Communicative Development Inventory (CDI) scores of 11- to 34-month-olds collected before (N=1365) and after (N=301) the onset of COVID-19. Preliminary results show that CDI scores collected for toddlers after the pandemic onset are significantly lower than those collected before. We will continue to collect additional CDI data, and examine how factors such as screen time, reading time, SES, and number of people the child has regular interaction with mediate children’s vocabulary size.

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