Are Specific Language Impairment and Dyslexia Distinct Disorders?

Abstract

Purpose: The purpose of this study was to determine whether specific language impairment (SLI) and dyslexia are distinct developmental disorders. Method: Study 1 investigated the overlap between SLI identified in kindergarten and dyslexia identified in 2nd, 4th, or 8th grades in a representative sample of 527 children. Study 2 examined phonological processing in a subsample of participants, including 21 children with dyslexia only, 43 children with SLI only, 18 children with SLI and dyslexia, and 165 children with typical language/reading development. Measures of phonological awareness and nonword repetition were considered. Results: Study 1 showed limited but statistically significant overlap between SLI and dyslexia. Study 2 found that children with dyslexia or a combination of dyslexia and SLI performed significantly less well on measures of phonological processing than did children with SLI only and those with typical development. Children with SLI only showed only mild deficits in phonological processing compared with typical children. Conclusions: These results support the view that SLI and dyslexia are distinct but potentially comorbid developmental language disorders. A deficit in phonological processing is closely associated with dyslexia but not with SLI when it occurs in the absence of dyslexia.

Linking memory and language: Evidence for a serial-order learning impairment in dyslexia

“…Interestingly, poor verbal HRL and impaired learning of motor sequences (in contrast to unimpaired performance on non-sequential procedural motor Serial-order learning in dyslexia learning) has also been demonstrated in children with a Specific Language Impairment (SLI), diagnosed when oral language lags behind (Hsu & Bishop, 2014). Recent research suggests that SLI and developmental dyslexia can best be treated as distinct, yet closely associated and potentially comorbid, language disorders (see Bishop & Snowling, 2004;Catts, Adlof, Hogan, & Ellis Weismer, 2005). On the one hand, oral language deficits are commonly reported in children with dyslexia (e.g., McArthur et al, 2000;Starck & Tallal, 1988).…”

The Influence of Reading on Vocabulary Growth: A Case for a Matthew Effect

“…There are, in fact, substantial differences in word-learning achievement in prereaders (e.g., Hart & Risley, 1995), which would affect the level of vocabulary knowledge when children start to learn new words through written language. Furthermore, these individual differences in word-learning skills would be expected to covary with reading skill, given the substantial overlap between disorders of word reading and of language skills (Catts, Adlof, Hogan, & Ellis Weismer, 2005). In order to examine the specific effect of reading experience on vocabulary, it would seem wise to control for the child's general word-learning achievement.…”

Rapid Automatic Naming Performance of Young Spanish–English Speaking Children

“…A deficit in either phonological skills or naming speed is thought to result in a less severe form of reading disability than a combined deficit. While tasks such as rhyming, alliteration, categorization, phoneme blending, segmentation, elision, and nonword repetition (NWR) measure phonological skill [33,[36][37][38][39], rapid automatic naming (RAN) is the primary measure of naming speed. There exists some controversy regarding the theoretical explanations for the relationship between naming speed and reading [40], with differing key constructs thought to underly the relationship including phonological awareness [41], orthographic processing [42], and general cognitive processing or executive function [43].…”