Orthographies and dyslexia
Dyslexia is a complex, lifelong disorder involving difficulty in learning to read or interpret words, letters and other symbols.
[6][7] However, there is also evidence that orthography, the correspondence between the language's phonemes (sound units) and its graphemes (characters, symbols, letters), plays a significant role in the type and frequency of dyslexia's manifestations.
[8] Current psycholinguistic models of dyslexia are "largely developed on the basis of alphabetic writing systems such as English",[9] but the amount of research on some logographic orthographies, Chinese in particular,[10] is also fairly significant.
The problems underlying this type of dyslexia are related directly to memory and coding skills that allow representation of printed letters and words, not to poor phonological processing.
Despite intervention, children with orthographic dyslexia continually have lower achievement reading levels when compared to their peers.
[14] Deep orthographies are writing systems, such as those of English and Arabic, that do not have a one-to-one correspondence between sounds (phonemes) and the letters (graphemes) that represent them.
Shallow orthographies, such as Italian and Finnish, have a close relationship between graphemes and phonemes, and the spelling of words is very consistent.
[15] Research has shown that the hallmark symptoms of dyslexia in a deep orthography are a deficit in phonological awareness and difficulty reading words at grade level.
A deep orthography like English has letters or letter combinations that do not reliably map to specific phonemes/sound units, and so are ambiguous in terms of the sounds that they represent whereas a transparent or shallow orthography has symbols that (more) uniquely map to sounds, ideally in a one-to-one correspondence or at least with limited or clearly signified (as with accent marks or other distinguishing features) variation.
[21] In cross-language studies, Aro and Wimmer report differences in developmental reading skills across several alphabetic orthographies.
[22] This research provides evidence that orthographic irregularities, such as the "complex grapheme-phoneme relations" found in English, present significant difficulties in the reading development of children.
[22] However, the methodology of the experiment leaves doubt as to whether the scores correlate to actual reading ability on real words.
Because there is also a visual aspect to dyslexia, affected children often show symptoms such as mirror letter reversal (e.g. confusing "b" and "d"), which can manifest in any language regardless of orthographic depth.)
Thus dyslexics, who often rely on grapheme memorization to cope with phonological awareness deficits,[23][24] may show reduced difficulty in acquiring a language which uses a logographic system.
Rather, reading in Chinese is strongly related to a child's writing skills, which depend on orthographic awareness and on motor memory.
[19] Rapid naming is one of the best single predictors of dyslexia in all languages tested, including both alphabetic and character-based writing systems.
