Word-level spelling of children with dyslexia and developmental language disorder

Abstract

Spelling is challenging for children with dyslexia and for children with Developmental Language Disorder (DLD), but it is not clear as yet whether the difficulties are the same in both groups of children, as few direct comparisons between spelling outcomes of these groups have been reported. We therefore compared the mean word dictation spelling outcomes of children (age range 8.2-10.4 years) with dyslexia (n=31), DLD (n=30) and typically developing (TD) age-matched peers (n=31) as well as the error types. Additionally, we divided the group of children with DLD into those with (DLD+RD, n=18) and without word reading difficulties (DLD-only, n=12). Finally, we conducted concurrent regression analyses to establish which language- and literacy-related abilities contribute to spelling. 
Both the groups with dyslexia and DLD displayed spelling problems. These were most pronounced for the subgroup of children with DLD+RD. The error type analyses showed that the groups with dyslexia and DLD made more errors in all categories than the TD group. Furthermore, the dyslexia, DLD-only and DLD+RD groups showed similar errors with phoneme-grapheme associations that were not entirely transparent (gauw [quick] as *gouw), with mappings of phonology-orthography and morphology (pittig [spicy] as *pitteg), and errors concerning spelling rules (metro [metro] as *meetro). The dyslexia and DLD+RD groups also showed more errors in transparent phonology-grapheme mappings (boek [book] as *beok) and orthographic knowledge (loanwords, hyphenation). The regression analysis showed a strong contribution of word reading and rapid automatized naming to spelling. When these measures were excluded, morphology contributed significantly, but to a lesser extent.  
The findings confirm the spelling problems of children with dyslexia and with DLD, especially the severe problems of children with DLD+RD. They also point to the importance of word-reading ability and rapid automatized naming for spelling, as well as to a smaller contribution of morphology. Together, the findings show the need for systematic spelling instruction and intervention for children with dyslexia and DLD, as well as support of oral language.  Keywords: Spelling, Dyslexia, Developmental Language Disorder, Reading, Language.