Early lexicon and language skills at 42 months

Previous studies have shown that early lexical development is associated with later language development. It is less clear which language domains early receptive/expressive lexicons are associated with. This study analyses these associations. The study also investigates whether children with slow/typical/fast developing early receptive/expressive lexical skills differed in their language skills at three and a half years (42 months) and the predictive value of early receptive/expressive lexical skills for later language skills. The participants of this longitudinal study were 68 healthy, monolingual Finnish-speaking children whose language development was measured using the Finnish, short-form-version of the Communicative Development Inventories at 12, 15, 18 and 24 months. At 42 months, language skills of the participants were assessed using tests measuring lexical, phonological, morphological and general receptive/expressive language skills. Early receptive lexicon was associated with later morphological skills from 15 months and onwards and with other language domains at 24 months. Early expressive lexicon was associated with later morphological skills at 15 months and onwards but with other language domains from 18 months. A trend was found that children with different early lexical growth rates differed in their language skills at 42 months. The best models for predicting later receptive/expressive language skills included variables from both early receptive and expressive lexicons. These models worked well to explain receptive/expressive language skills at 42 months (63/78% of the variance). This study provides novel information on the specific associations between receptive and expressive lexicon growth and later language skills. For clinicians, measuring both receptive and expressive lexicons provides the most representative information on children's language development.