NON-FINITE CONSTRUCTIONS IN IMPAIRED BILINGUAL BRAIN: EVIDENCE FROM APHASIA AND AUTISM

Abstract

Victims of neurological disorders such as aphasia and autism manifest difficulties in language functioning at different levels including construction of syntactic structures. Existing studies have shown that verb production and the tense node are severely impaired in monolingual aphasic and autistic speeches. It is unknown whether the claims are applicable to the nonfinite tense node especially in relation to bilingual brain. Therefore, this study examines English non-finite structures in sentence production among Nigerian bilingual aphasic (NBApP) and Nigerian bilingual autistic (NBAuP) people. X-bar and control modules of Noam Chomsky’s Principles and Parameters Theory provided the framework. The qualitative approach was adopted for this descriptive and cross-sectional study. Using Kirkword’s formula for medical statistics with the epidemiology aphasia and autism in Nigeria, 11 (6 aphasic and 5 autistic) clinically diagnosed (NBApP) and (NBAuP) participants were purposively selected from 2 federal medical centres in South Western Nigeria, 1 state hospital in Ibadan Oyo State and 2 privately owned autistic support centres in Ibadan. Passage Reading Test (PRT), In-depth Interviews (IDIs) and Participant Observation (PO) were used to elicit speeches from the participants. The data were subjected to structural analysis. The study revealed that the syntax of English infinitival clauses is preserved in Nigerian bilingual aphasic brain, but selectively impaired in Nigerian bilingual aphasic brain. NBApP generated such structures in instances where they were required. They substituted the PRO-inf with PROing irrespective of whether such syntactic constituents occur in A-position as well as AI-position. Such substitution occurred without affecting the grammaticality of the sentence. NBAuP participants freely produced infinitival structures in the passage reading test (PRT) and their self-generated sentences. However, none of them produced PRO-ing structures. For PRO-ing structures in the PRT, the participants resorted to structural reprocessing and they eventually produced finite structures. This suggests that Nigerian bilingual autistic brains are sensitive to infinitival PRO but they are not sensitive to PRO-ing. It is concluded in the study that Nigerian bilingual aphasic brain is characterised by preservation of the syntax of infinitives while Nigerian bilingual autistic brain is characterised by selective impairment of the syntax of infinitives