Activation of the Phonological Lexicon for Reading and Object Naming in Deep Dyslexia

Abstract

Poor oral reading in some cases of deep dyslexia could be due to difficulty in inhibiting the phonological lexical entries of words semantically related to the correct reading responses. If this is the case, then additional activation of the correct phonological entries should improve reading performance, whereas additional activation of competing entries should lead to errors. This should hold true for object naming as well as for reading, since both depend on a semantically mediated lexical route. These predictions were borne out with an “output” deep dyslexic patient, who made many semantic errors in both reading and naming. Providing phonetic cues (the initial portions of the correct responses) increased his reading and naming accuracy, and providing miscues (the initial portions of words related semantically to the correct responses) led to errors. Furthermore, when the patient was shown a printed word or pictured object and the examiner spoke a correct reading or naming response in isolation, the patient almost always accepted the response as correct, but he also judged that many semantically related foils were correct. Finally, a comparison of reading and naming errors suggested that “visual” errors may sometimes have a phonological basis.