Diagnostic profiles of children with developmental dyslexia in a transparent orthography.

In the present study for 108 typical and 122 atypical Dutch readers in second grade, the accuracy and speed of decoding words and pseudowords, as well as the accuracy of spelling words were assessed along with four types of phonological precursor measures: rapid naming, verbal working memory, phoneme awareness and letter knowledge. The data show that the group being diagnosed as poor readers were significantly behind in all reading and spelling measures. It was also found that the criterion measures of reading and spelling explained already two third of the variance associated with the group distinction. Finally, we found word and pseudoword efficiency in the typical group to be explained by phonological awareness (spoonerism) and rapid naming of letters, word and pseudoword accuracy by phonological awareness, and spelling by phonological awareness and letter dictation. In the group of poor readers, a much greater variety of precursor measures was involved in explaining the variance in reading and spelling abilities.