Verbal comprehension after brain damage :a psycholinguistic investigation with special reference to cerebro-vascular accident

Abstract

A review of theory and practice in the examination of verbal comprehension in brain-dairiaged adults leads to the conclusion that this underdeveloped area of study can benefit from the application of theories from linguistics. An experimental investigation of (principally) adults who had suffered cerebro -vascular accident applied, amoxigst other linguistic theories, the division of language into phonological, syntactic and semantic levels of organization. The main findings were: a) Semantic abilities in speech and comprehension corresponded; syntactic abilities in speech corresponded with those in reading comprehension, but not aural comprehension; comprehension of phonemic distinctions corresponded with phonetic articulatory abilities, but not with degree of phonemic paraphasia. Tests of verbal comprehension which required simple manipulations of-objects or tokens were contaminated by gesture dyspraxia. Functional comprehension was not a reliable predictor of results on linguistic tests. b) Piphasic adults with left-brain damage experienced significantly more difficulties in comprehension when sequence was critical to the meaning of a word or sentence. At the syntactic level this occurred with reading as well as with aural input, indicating a central difficulty rather than one which is modality-specific. in aural comprehension, unlike all types of control subjects including children, aphasic adults found sentences with reversible elements in surface structure harder than sentences in which reversible deep relations are not made explicit in surface structure sequence. Sequencing appears to be a significant influence on verbal comprehension after left-brain damage. c) Right-brain-damaged adults who were not aphasic in speech, and who were familial right-handers, were selectively impaired in semantic comprehension. Semantic comprehension may be bilaterally represented in the brain, although comprehension at syntactic and phonological levels may depend principally on mechanisms lateralized to the left hemisphere.