Cognitive constraints and environmental supports: A multifactorial account of vocabulary breadth and depth in multilingual learners across three countries

<p>Vocabulary knowledge underpins language and literacy development, yet the factors shaping multilingual children’s vocabulary breadth and depth in the societal language remain underexplored. This study investigated 140 multilingual children (70 girls, 70 boys) aged 4;8–9;0 (M = 6;9) in the UK, the Netherlands, and France. Data was collected between March 2022 to May 2023. Vocabulary breadth and depth were modelled using measures of verbal short-term memory, verbal working memory, phonological skills, and indices of language exposure and richness derived from the Q-BEx parental questionnaire (De Cat et al., 2023). Results showed that memory skills were consistently associated with both vocabulary dimensions, and that language and literacy experiences were also associated with vocabulary outcomes. Vocabulary breadth and depth exhibited both shared and distinct predictor profiles, and the non-linear analyses suggested that different combinations of cognitive and environmental factors characterised different patterns of vocabulary performance across sociolinguistic contexts. These findings support an individual-differences approach to multilingual vocabulary development and highlight the value of considering cognitive and experiential factors jointly.Cognitive constraints and environmental supports: A multifactorial account of vocabulary breadth and depth in multilingual learners across three countries.</p>