Unpacking language richness as a predictor of bilingual children’s language proficiency

Bilingual children’s language abilities are influenced by the richness of their language experience, which is typically estimated using parental questionnaires and often expressed as a composite score based on frequency-based variables (e.g., time spent reading). We evaluated whether the composite richness score in the Q-BEx questionnaire (De Cat et al., 2022b)was fit for purpose. Data were collected from 173 bilingual children aged between 5 and 8 in three different countries(France, the Netherlands and the UK). Parents completed the Q-BEx questionnaire and children completed proficiency tasks in their societal language. We analysed the predictive power of the original score in comparison to several alternatives, derived using a principal components analysis. We found that (i) these alternatives were no more informative than the original, (ii) scores including interlocutor diversity and proficiency in addition to frequency-based measures fared better, (iii) the latent variables underlying richness were comparable across languages, and (iv) whether SES was included made little difference.