Language mixing patterns in a bilingual individual with non-fluent aphasia.

BACKGROUND: Language mixing in bilingual speakers with aphasia has been reported in a number of research studies, but the reasons for the mixing and whether it reflects typical or atypical behaviour has been a matter of debate. AIMS: In this study we tested the hypothesis that language mixing behaviour in bilingual aphasia reflects lexical retrieval difficulty. METHODS & PROCEDURES: We recruited a Hebrew-English bilingual participant with mild-moderate non-fluent agrammatic aphasia and assessed his languages at three timepoints. We analysed the participant's Hebrew and English production for retrieval during single-word naming, sentences, and discourse, and identified all instances of language mixing. OUTCOMES & RESULTS: We found that there was a greater frequency of language mixing during production of more difficult lexical items, namely the post-morbidly less proficient language (compared to the more proficient language), function words (compared to content words), and single-word naming (compared to retrieval in the context of connected speech tasks), but not for verbs (compared to nouns). CONCLUSIONS: In this bilingual participant with non-fluent aphasia, language mixing behaviour closely resembles lexical retrieval difficulty. Thus, we suggest that bilingual speakers with aphasia may mix their languages as a strategy to maximise communication.