Phonological Dyslexia

Phonological dyslexia is a form of reading disorder in which the ability to read unfamiliar words, or pronounceable non-words, is selectively deficient. It occurs as both a developmental and an acquired dyslexia. The disorder therefore has implications for our understanding both of how children learn to read and of the architecture of the reading system used for normal skilled reading. This special issue describes numerous cases of phonological dyslexia, including a developmental case which has been studied in depth, and the first two published cases of the disorder in Japanese readers. The implications of data from acquired phonological dyslexia for computational models of reading the DRC and Reggia-Berndt dual-route models, and the parallel-distributed-processing model of Plaut and colleagues are discussed. Phonological dyslexia is commonly interpreted as being due to the damage of one or other of the components of the system we use for reading nonwords. But if that is correct, why has every phonological dyslexic documented so far, with the exception of only one case, shown impaired performance on phonological tasks requiring no orthographic processing? That one case did appear to have an orthographic deficit and no phonological deficit: such cases should not be rare if phonological dyslexia is due to damage at any stage of the nonword reading procedure. This is currently the major unsolved question concerning phonological dyslexia.