Authors: Heinz Wimmer, Matthias Schurz.
Article: Dyslexia in regular orthographies: manifestation and causation.
Publication: Dyslexia (Wiley). 16: 283-299 2010 | DOI: 10.1002/dys.411
This article summarizes our research on the manifestation of dyslexia in German and on cognitive deficits, which may account for the severe reading speed deficit and the poor orthographic spelling performance that characterize dyslexia in regular orthographies. An only limited causal role of phonological deficits (phonological awareness, phonological STM, and rapid naming) for the emergence of reading fluency and spelling deficits is inferred from two large longitudinal studies with assessments of phonology before learning to read. A review of our cross‐sectional studies provides no support for several cognitive deficits (visual–attention deficit, magnocellular dysfunction, skill automatization deficit, and visual–sequential memory deficit), which were proposed as alternatives to the phonological deficit account. Finally, a revised version of the phonological deficit account in terms of a dysfunction in orthographic–phonological connectivity is proposed.
The ﬁeld of dyslexia research obviously does not suffer from a paucity of explanatory hypotheses. Nevertheless, we would like to add an additional one. It is based on the ﬁndings of very substantial deﬁcits of dyslexic readers on tasks such as spoonerism in both German and English dyslexic children (see Figure 3).Recently, a high error rate and very slow performance on a spoonerism task was also documented for Italian dyslexic readers (Menghini et al., 2010). As already noted, we do not consider these difﬁculties as reﬂecting a problem of phoneme awareness, as commonly assumed by phonological deﬁcit theorists. Against this interpretation, we pointed out that dyslexic children with poor performance on tasks such as spoonerism have no difﬁculty with phonemically correct transcriptions of complex pseudowords with consonant clusters.
The critical difference may be how tightly orthography and phonology is integrated, so that hearing a word in this task context automatically activates its orthography. The evidence for tight orthographic–phonological integration in competent readers is impressive. Rhyme judgements on spoken words were shown to be misled when items such as ‘pitch’ and ‘rich’ do not share identical rhyme spellings (Seidenberg & Tanenhaus, 1979). Similarly, phoneme counting is misled by the number of letters with more phonemes counted for ‘pitch’ than ‘rich’ (Ehri& Wilce, 1980).
To our knowledge, there are only two studies that examined orthographic instrusions into phonological judgements of dyslexic readers (Bruck, 1992;Landerl et al., 1996). Both found that dyslexic readers were less misled than competent readers although the dyslexic readers knowledge of the correct spellings of the critical words was controlled.
Wimmer, H. and Schurz, M. (2010), Dyslexia in regular orthographies: manifestation and causation. Dyslexia, 16: 283-299. doi:10.1002/dys.411