Investigation of Lexical Retrieval in Bilingualism and Aphasia: A Multiple Case Study

Abstract

Word finding difficulties (anomia) are the most prevalent and universal symptom of aphasia in bilingual and monolingual subjects. Word finding is commonly assessed using picture naming tests with black and white line drawings, but the suitability of these assessments is disputed, especially when it comes to verb naming. Studies have shown that healthy monolingual and bilingual participants as well as monolingual and bilingual people with aphasia (PWA) have greater difficulty retrieving verbs than nouns and that bilingual participants generally perform better in their first language than in their second language. Further studies with monolingual non-impaired subjects and PWA found that naming accuracy improved when participants named items from videos as opposed to pictures. The current study investigated the word finding abilities of a German-English bilingual person with aphasia (PWA), a monolingual English PWA, a German-English bilingual non-impaired participant and a monolingual English non-impaired participant. Word retrieval for nouns and verbs was assessed using two types of stimuli; pictures and videos. The bilingual participants completed the assessment in both languages. The results showed that all four participants had more difficulty retrieving verbs than nouns which was evident in lower accuracy and slower reaction times when naming verbs than when naming nouns. Accuracy scores and reaction times from picture and video stimuli were more ambiguous. Closer investigation of the performance of the two bilingual participants showed that the non-impaired bilingual participant performed almost equally well in both languages, while the bilingual PWA performed significantly better in his L2, i.e. the language he had learned later in life but used more frequently immediately prior to the stroke. This result was contrary to most previously reported research in which bilingual PWA performed better in the language they had acquired from birth. Close examination of the factors pertaining to these participants, e.g. language use and exposure or language recovery pattern post-stroke, revealed possible explanations for the participants’ pattern of results. The results of this study in part replicate but also contradict previous evidence on lexical retrieval in healthy bilinguals and bilingual PWA and support the need for further research in this area.