Acoustic cues for the perception of place of articulation in aphasia.

Two experiments assessed the abilities of aphasic patients and nonaphasic controls to perceive place of articulation in stop consonants. Experiment I explored labeling and discrimination of [ba, da, ga] continua varying in formant transitions with or without an appropriate burst onset appended to the transitions. Results showed general difficulty in perceiving place of articulation for the aphasic patients. Regardless of diagnostic category or auditory language comprehension score, discrimination ability was independent of labeling ability, and discrimination functions were similar to normals even in the context of failure to reliably label the stimuli. Further there was less variability in performance for stimuli with bursts than without bursts. Experiment II measured the effects of lengthening the formant transitions on perception of place of articulation in stop consonants and on the perception of auditory analogs to the speech stimuli. Lengthening the transitions failed to improve performance for either the speech or nonspeech stimuli, and in some cases, reduced performance level. No correlation was observed between the patient's ability to perceive the speech and nonspeech stimuli.

Comprehension strategies determining reference in aphasia: a study of reflexivization.

This study explored the comprehension of reference in aphasia as reflected in reflexivization. A total of 132 test sentences were used consisting of two basic syntactic frames varying in the minimal distance principle and in the type of cues available in the sentence (syntax, syntax and morphology, syntax and lexical, and syntax, morphology, and lexical) for determining pronominal reference. Fifteen patients, five Broca's, five Conduction, and five Wernicke's, were asked to point to the picture (of two) corresponding to the auditorily presented test sentence. Results indicated that aphasic patients as a whole comprehend reference; however, their performance varied depending on the nature of the cues available in the sentence. All groups were impaired when only syntactic cues were available and showed a significant decrement in performance when the test sentence violated the minimal distance principle. As additional cues other than syntactic structure were provided, performance level increased. All groups, including the Broca's aphasics, showed only slight improvement with the presence of morphological cues. Wernicke's aphasic's performance was particularly vulnerable when lexical cues were added to syntactic cues. These results suggest that evaluation of a patient's deficit in sentence comprehension requires analysis of those attributes of the sentence contributing to its overall semantic interpretation.