Measuring what matters: effectively predicting language and literacy in children with cochlear implants

To evaluate how well various language measures typically used with very young children after they receive cochlear implants predict language and literacy skills as they enter school.

Subjects were 50 children who had just completed kindergarten and were 6 or 7 years of age. All had previously participated in a longitudinal study from 12 to 48 months of age. 27 children had severe-to-profound hearing loss and wore cochlear implants, 8 had moderate hearing loss and wore hearing aids, and 15 had normal hearing. A latent variable of language/literacy skill was constructed from scores on six kinds of measures: (1) language comprehension; (2) expressive vocabulary; (3) phonological awareness; (4) literacy; (5) narrative skill; and (6) processing speed. Five kinds of language measures obtained at six-month intervals from 12 to 48 months of age were used as predictor variables in correlational analyses: (1) language comprehension; (2) expressive vocabulary; (3) syntactic structure of productive speech; (4) form and (5) function of language used in language samples.

Outcomes quantified how much variance in kindergarten language/literacy performance was explained by each predictor variable, at each earlier age of testing. Comprehension measures consistently predicted roughly 25-50 percent of the variance in kindergarten language/literacy performance, and were the only effective predictors before 24 months of age. Vocabulary and syntactic complexity were strong predictors after roughly 36 months of age. Amount of speech produced in language samples and number of answers to parental queries explained moderate amounts of variance in performance after 24 months of age. Number of manual gestures and nonspeech vocalizations produced in language samples explained little to no variance before 24 months of age, and after that were negatively correlated with kindergarten performance. The number of imitations produced in language samples at 24 months of age explained about 10 percent of variance in kindergarten performance, but was otherwise not correlated or negatively correlated with kindergarten outcomes.

Before 24 months of age, the best predictor of later language success is language comprehension. In general, measures that index a child's cognitive processing of language are the most sensitive predictors of school-age language abilities.