Growth and predictive relations of vocabulary and inflectional morphology in children with and without familial risk for dyslexia

Abstract

The growth and predictive relations of early vocabulary and inflectional morphology were examined in children with (N=107) and without (N=93) familial risk for dyslexia. Children's receptive and expressive vocabulary and inflectional morphological skills were assessed longitudinally at 2, 2.5, 3.5, and 5 years by using a parent report tool (the MacArthur Communicative Development Inventory), measures from a spontaneous speech sample, and standardized tests. Children with and without familial risk for dyslexia did not differ from each other, either in expressive vocabulary or in composite scores of inflectional morphology at the age of 2 years. However, language skills indicated increasing group differences with age. Inflectional morphology showed differing predictive patterns for the at-risk group and their controls. Proficiency of inflections at 2 years significantly predicted 5-year-olds' language skills in the at-risk group. In contrast, for their age-matched controls inflections were not a significant predictor until the age of 3.5 years. Our findings suggest that children from families with dyslexia risk status and low inflectional skills at an early age are at higher risk for impairments in subsequent language development than are their age-matched controls.