PHONOLOGICAL DYSLEXIA - LOSS OF A READING-SPECIFIC COMPONENT OF THE COGNITIVE ARCHITECTURE

In phonological dyslexia, nonword reading is impaired while the readin g of both regular and irregular words is preserved. Many phonological dyslexics are able to repeat the same nonwords that they are unable to read. This constellation of abilities and deficits has been interpret ed as the result of impairment in the ability to translate orthography to phonology, as distinct from the impairment of orthography or phono logy themselves. If this interpretation is correct, then the brain mus t contain some tissue that is dedicated to this reading-specific abili ty, that is, tissue which is necessary for this and only this ability. This, in turn, implies that school-age learning can determine the exi stence and nature of anatomically separate (hence selectively lesionab le) neural systems. Our interest in this issue has led us to consider an alternative explanation of phonological dyslexia, according to whic h it results from a general (i.e. not reading-specific) impairment of phonological representation. We explain how a patient with apparently good nonword repetition might nevertheless have a general impairment o f phonological representation that affects nonword reading, and we tes t this explanation with one such patient. We also discuss the evidence for and against this hypothesis available in other published cases of dissociated nonword reading and repetition.