A case study of developmental phonological dyslexia.

H.M. is a 17-year-old girl of at least average intelligence and with an above-average oral vocabulary. She is impaired at non-word reading in comparison to word reading. She is incapable of reading any long nonsense words or long unusual regular words correctly. Many of her non-word reading responses are lexicalizations. She reads non-words homophonic with real words better than she reads non-words that are not homophonic with real words. Her reading age is 10 years 11 months. A large proportion of her reading errors are derivational or visual paralexias. She makes no semantic errors or errors of regularization and few neologistic responses. H.M. is not influenced by the dimensions of spelling-to-sound regularity and word length. There is no effect of word class on single-word reading although a function word deficit is present when continuous text is read aloud. H.M. is impaired at word reading when the stimulus items are distorted in a manner that reduces the potential for global perception. H.M.'s spelling errors are primarily phonological, though more complex errors are made than those characteristic of surface agraphics. All of these features are consistent with reported cases of acquired phonological dyslexia. H.M. may be confidently regarded as a developmental phonological dyslexic.