Multiple patterns of developmental reading disability in a shallow orthography: principles for a diagnostic screening of dyslexias

In this study we examine whether we can identify several types of developmental dyslexia (Friedmann & Coltheart, in press) in Italian readers, by using a reading test battery that includes stimuli that are sensitive to the various dyslexia types. This allowed us to detect not only surface, phonological, and deep developmental dyslexia, but also dyslexias that result from a deficit of the orthographic-visual analyzer, i.e. impaired letter identification, letter position dyslexia, and attentional dyslexia. 262 (50% Male) primary school children (from 2nd to 5th grade) participated in the study. We developed a new reading test battery, that includes lists of words, nonwords and word pairs, created to detect the various types of dyslexia, and a specific coding scheme for the classification of reading errors. In addition, we ran standard text and word/nonword reading tests, to assess the discriminative validity of this new diagnostic battery. An analysis of error types was carried out on the skilled readers’ performance, to obtain normative profiles for each grade. About 70% of errors can be referred to the functions of the orthographic-visual analyzer, whereas about 16% can be identified as phonological errors and 10% as surface errors. Other errors (about 4%) can be linked to dysfunction of the phonological buffer. The agreement between standard tests and the new assessment procedure in identifying poor readers was 94%. However, the new diagnostic assessment detected 11 children with dyslexia who were not identified with the standard diagnostic procedure. The new screening method allowed us to detect in Italian types of dyslexia described by Friedmann and Coltheart (in press). In particular, the orthographic-visual analyzer seems to be most frequently involved. The new assessment is useful in identifying specific reading impairments and offers relevant clues to develop training methods to improve reading skills in children with dyslexia.