In the proposed research on aphasia, crosslinguistic comparisons allow disentanglement of a confounding between universal mechanisms and language-specific content. New studies are proposed of aphasic patients with lexical and/or grammatical symptoms across languages that differ in lexical and grammatical structure. Experiments are motivated by six findings of the research program over the last 12 years. 1) The same aphasic syndromes look very different from one language to another. This leads the principal investigator and colleagues to propose to compare languages that maximize linguistic contrasts of interest. The languages under study will be Chinese, English, Italian, Spanish and Russian. 2) Language-specific knowledge is largely intact in aphasic patients suggesting that the deficits are in the processes by which knowledge is accessed in real time. That is, deficits are in performance rather than in competence. This account is tested by expanded use of real-time experimental procedures that yield information about how patients arrive at a correct or incorrect response in comprehension and production. 3) Despite these cross-language differences, grammatical inflections and function words are especially vulnerable in every language. This leads to experiments that compare aspects of language that are either at risk or protected within and across language types. 4) Some aspects of grammatical vulnerability show up in every patient group. This finding leads to experiments that assess the contribution of global forms of stress (e.g., perceptual degradation and/or cognitive loads) to isolate those impairments that are specific to particular types of aphasia from those that can be induced in normals under stressed conditions. 5) Despite quantitative differences in vulnerability, the grammatical symptoms displayed by fluent and nonfluent patients are qualitatively similar to their lexical symptoms. This leads to experiments comparing the effects of lexical and grammatical context in languages that rely to different degrees on word order, inflections and/or lexical contrasts to accomplish the same communicative goals. 6) There may be 'neurolinguistic universals'--that is, contrasts among patient groups that are invariant across different language types--that will be investigated. This includes dissociations between nouns and verbs and between closed-class and content words. The proposed studies will help to move the field of aphasiology toward a new model of brain organization for language, integrating universal and language-specific symptoms. The studies also have practical significance for international communication about aphasia, for the development of test batteries for aphasics that are tailored to the specific characteristics of individual languages and for clinical services to the bilingual communities of the nation.
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