Working memory predicts receptive vocabulary: a two-year longitudinal study of children with intellectual disabilities

Existing studies have suggested concurrent correlations between working memory and linguistic skills for children with intellectual disabilities; however, evidence for the longitudinal relationship is sparse. This study collected longitudinal data on working memory and linguistic skills from 103 Chinese school-aged children with intellectual disabilities. At the first time of testing, children were 6 to 16 years old and completed measurements of working memory and receptive vocabulary. The same measurements were administered 1 and 2 years later. Children’s working memory was assessed by backward digit span and starting position selection, and receptive vocabulary was measured using the Peabody Picture Vocabulary test. The random intercept cross-lagged panel model results demonstrated that working memory scores significantly predicted changes in receptive vocabulary for children with intellectual disabilities over time, but the reverse pattern was not evident. To some extent, our findings suggested that interventions targeting boosting working memory may subsequently enhance receptive vocabulary in children with intellectual disabilities.