Multiple dimensions of afx spelling complexity: analyzing the performance of children with dyslexia and typically developing controls

This study examined afx letter spelling among 6th grade Hebrew-speaking children with dyslexia compared with chronologically age-matched and reading levelmatched controls. As diferent languages are characterized by multiple dimensions of afx spelling complexity, we specifcally targeted the following unique dimensions relevant to Hebrew: (i) afx envelope transparency; (ii) afx letter prevalence; (iii) internal morpho-phonological competition; (iv) overtness of the phonologicalorthographic link; and (v) phono-morpho-orthographic consistency. The research instrument was a spelling task of 244 words containing afx letters, covering all non-root morphological roles, both infectional and derivational. Results show that for both frequent and infrequent words, 6th graders with dyslexia perform similarly to reading age-matched controls when spelling involves morphological competition or when the phonological morphological and orthographic link is inconsistent. In frequent words the similarity in performance between the groups extends to the overt phonology criterion as well. In addition, 6th graders with dyslexia were assisted by afx letter prevalence but not by demarcation of the afx envelope, compared with reading age-matched controls. Regarding these criteria, the discrepancy between regular and irregular afx spelling was diferent between dyslexic children and non-dyslexic controls. These fndings indicate that morphological knowledge in dyslexia is not a unifed system, and while some morpho-orthographic regularities are acquired more easily, other morpho-orthographic regularities are quite challenging.