Processing Speed Measures as Clinical Markers for Children With Language Impairment

Abstract

This study investigated the relative utility of linguistic and nonlinguistic processing speed tasks as predictors of language impairment (LI) in children across 2 time points. Linguistic and nonlinguistic reaction time data, obtained from 131 children (89 children with typical development [TD] and 42 children with LI; 74 boys and 57 girls) were analyzed in the 3rd and 8th grades. Receiver operating characteristic curve analyses and likelihood ratios were used to compare the diagnostic usefulness of each task. A binary logistic regression was used to test whether combined measures enhanced diagnostic accuracy. In 3rd grade, a linguistic task, grammaticality judgment, provided the best discrimination between LI and TD groups. In 8th grade, a combination of linguistic and nonlinguistic tasks, rhyme judgment and simple response time, provided the best discrimination between groups. Processing speed tasks were moderately predictive of LI status at both time points. Better LR+ than LR- values suggested that slow processing speed was more predictive of the presence than the absence of LI. A nonlinguistic processing measure contributed to the prediction of LI only at 8th grade, consistent with the view that nonlinguistic and linguistic processing speeds follow different developmental trajectories.