Word deafness with preserved number word perception

ABSTRACT

We describe the performance of an aphasic individual, K.A., who showed a selective impairment affecting his ability to perceive spoken language, while largely sparing his ability to perceive written language and to produce spoken language. His spoken perception impairment left him unable to distinguish words or nonwords that differed on a single phoneme and he was no better than chance at auditory lexical decision or single spoken word and single picture matching with phonological foils. Strikingly, despite this profound impairment, K.A. showed a selective sparing in his ability to perceive number words, which he was able to repeat and comprehend largely without error. This case adds to a growing literature demonstrating modality-specific dissociations between number word and non-number word processing. Because of the locus of K.A.’s speech perception deficit for non-number words, we argue that this distinction between number word and non-number word processing arises at a sublexical level of representations in speech perception, in a parallel fashion to what has previously been argued for in the organization of the sublexical level of representation for speech production.

KEYWORDS:

• Aphasia
• numerosity
• category-specific deficits
• speech perception

Acknowledgements

Research was supported by National Institute of Deafness and Communication Disorders of the National Institutes of Health under award number R21DC01671 to S.F.B. and F32DC016812 to H.D. We would like to thank K.A. and his family for their time and effort in participating in this project.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 The one exception to this pattern is that he showed no noticeable impairment in repeating days of the week. However, given his repetition performance with the other stimuli types, and his difficulties with days of the week in the other tasks, we interpret this null result as a Type 2 error, rather than a selective sparing of only days of the week only in repetition.

2 While K.A. had a severe prelexical phonological processing deficit, a comparison between syllable and word discrimination and auditory single word picture matching suggest that K.A. had an additional lexical-semantic deficit at least for non-number words. This raises the possibility that K.A.’s problems with non-number words could be caused by the interaction of multiple deficits. Under this account, the difference between number and non-number word processing is that K.A. does not have a lexical-semantic deficit for number words. To make this account work, we would have to assume that his impaired prelexical phonological processing is good enough to support performance on all of these tasks, in the absence of an additional lexical-semantic deficit. However, given the severity of his problems with repetition and discrimination tasks, we think that this possibility is unlikely.

Additional information

Funding

Research was supported by National Institute on Deafness and Other Communication Disorders of the National Institutes of Health under award number R21DC01671 to S.F.B. and F32DC016812 to H.D.