Even in predictable orthographies: Surface dyslexia in Turkish

Purpose: We report here, for the first time, on developmental surface dyslexia in Turkish, a very transparent orthography. Surface dyslexia is a deficit in the lexical route, which forces the reader to read words via the sublexical route, leading to regularization errors. Methods: To detect surface dyslexia, we used reading aloud of loanwords with irregular conversion of vowel length or consonant allophone, and analysed regularization errors. We also tested the properties of this dyslexia using lexical decision on pseudohomophones, repetition and reading of nonwords, and analyses of reading of different types of words. The children with surface dyslexia were identified out of 175 9–10-year-olds who were tested using a reading aloud screening task and tasks that were designed to detect sublexical (rather than lexical) reading of existing words. Results: We identified 45 fourth-graders with surface dyslexia. Reading speed was less sensitive to surface dyslexia than regularization errors, as only one-third of the children we diagnosed with surface dyslexia according to their reading errors also showed slower reading than controls. A task of lexical decision of pseudohomophones indicated that 31 of the participants had impairment in the orthographic input lexicon, whereas for 14 others the orthographic input lexicon was intact and the deficit is probably at a later stage in the lexical route–the phonological output lexicon or the connection between the lexica. Nonword reading was intact for the majority of surface dyslexia participants (35 of the 45). None of the surface dyslexia participants showed phonological deficits. Conclusions: Surface dyslexia can be identified even in transparent orthographies once the relevant stimuli and error analyses are used.