Parallels between the reading and spelling deficits of two subgroups of developmental dyslexics

Abstract

The spelling errors of third graders who fit phonological and surface profiles of developmental dyslexia were analyzed, along with the errors of younger (reading level matched) and chronologically age matched non-dyslexic comparison groups. In Study 1, errors were analyzed as phonologically constrained, unconstrained, or inaccurate and as either orthographically acceptable or unacceptable. Study 2 extended the error classifica- tion system to nonword spellings. The main finding was that different types of dyslexics produced different types of errors. Both studies found that children produced spelling errors consistent with their type of dyslexia. The phonological group showed poor knowledge of phoneme-grapheme correspondences, consistent with the existence of a phonological deficit. The surface group's spelling error profile differed from the phonological group and closely resembled the younger normal comparison group. This pattern is consistent with other evidence that surface dyslexia represents a general delay in acquiring literacy skills. The studies provide converging evidence, from a spelling task, that developmental dyslexia is a non-homogeneous category consisting of at least two major subtypes with distinct etiologies and behavioral sequelae.