On the structure of word deafness and mechanisms underlying the fluctuation of disturbances of higher cortical functions

Abstract

A case of pure word deafness was studied with special reference to the structure and dynamics of the comprehension deficit. It was found that the deficit was of an acoustic nature and that it concerned linguistic and nonlinguistic material. No lateralization was found with a dichotic listening task. The linguistic deficit was restricted to the phonemic level, and increased from the beginning to the end of a syllable and with the number of syllables. If the patient did not understand a specific verbal stimulus, he could not tell whether it was a real word or a nonsense syllable complex. When examined on three successive days with the identical material, there was little fluctuation of the deficit. It was concluded that fluctuations, as described by other authors, are concerned not with the disorder as such but with a higher-order compensatory mechanism on the semantic level, and therefore cannot be seen with isolated words or syllable material. A similar explanation for fluctuations in other disorders of higher cortical functions was discussed.