Phonemic identification defect in aphasia.

Eight-four right-handed patients with unilateral hemispheric damage (50 aphasics, 12 non-aphasic left brain-damaged and 22 right brain-damaged patients) and 53 control patients without cerebral lesions were given a test of phoneme identification which examined the S's ability to identify the acoustic boundary between the two phonemes, /d/ and /t/, expressed in terms of voice-onset time (VOT). Phonemic identification defect (PID), defined with reference to the performance of the control group, was found to be virtually limited aphasics; in over 70 per cent of them, the identification of the boundary zone between voiced and voiceless consonants along the VOT continuum was either impossible or abnormal, While neither the fluency - nonfluency dimension of speech nor the level of comprehension seemed to be crucially associated with PID, some evidence pointed to disordered phonemic output as to one dimension of aphasia that is specifically related to it.