Lexical-semantic representation in bilingual aphasia: Findings from semantic priming and cognate repetition priming

Background: While many studies have investigated the nature of language organisation in monolingual speakers with aphasia, our understanding of bilingual aphasia lags far behind. Only a handful of studies have employed on-line psycholinguistic experimental methods to explore the nature of language representation and processing in bilingual speakers with aphasia. Improving our understanding of how language is organised and processed in bilingual speakers with aphasia is central to the development of effective impairment-level language treatments. Cognate/noncognate representation and semantic representation are two key aspects of bilingual language organisation that are yet to be explored in depth in bilingual speakers with aphasia.Aims: The present study aimed to investigate (1) whether semantic representation was shared across the two languages of a bilingual speaker with aphasia and (2) whether cognate words would produce a processing advantage relative to noncognate words (as has been found in neurologically-normal younger bilingual adults).Methods & Procedures: A 70-year-old bilingual Italian/English speaker, who presented with nonfluent aphasia and apraxia of speech, completed two priming experiments: a semantic priming experiment and a cognate repetition priming experiment.Outcomes & Results: In the semantic priming experiment, the participant demonstrated large priming effects in both within-language conditions and one cross-language condition. The finding of priming in at least one of the cross-language conditions provides some corroboration for shared semantic representation in this bilingual individual with aphasia. In the cognate repetition priming experiment, the participant produced a language-specific cognate advantage in English, for words repeated in the same language. For words repeated in a different language condition (i.e., as their translation equivalent), the participant produced a processing advantage for noncognate words.Conclusions: The findings of this study provided support for shared semantic representation in bilingual speakers following aphasia; however, the results also suggested that aphasia can disrupt normal lexical access processes. Results in relation to cognate versus noncognate processing suggested that bilingual speakers with aphasia may not, necessarily, always display a cognate advantage. Overall, the present study showed that language processing in bilingual speakers with aphasia is highly complex and is dependent upon the intricate interplay between the speaker's premorbid language proficiency, inhibitory processing deficits that occur with normal aging and postmorbid language impairment and recovery patterns.