Grammatical category dissociation in multilingual aphasia

Abstract

Word retrieval deficits for specific grammatical categories, such as verbs versus nouns, occur as a consequence of brain damage. Such deficits are informative about the nature of lexical organization in the human brain. This study examined retrieval of grammatical categories across three languages in a trilingual person with aphasia who spoke Arabic, French, and English. In order to delineate the nature of word production difficulty, comprehension was tested, and a variety of concomitant lexical–semantic variables were analysed. The patient demonstrated a consistent noun–verb dissociation in picture naming and narrative speech, with severely impaired production of verbs across all three languages. The cross-linguistically similar noun–verb dissociation, coupled with little evidence of semantic impairment, suggests that (a) the patient has a true “nonsemantic” grammatical category specific deficit, and (b) lexical organization in multilingual speakers shares grammatical class information between languages. The findings of this study contribute to our understanding of the architecture of lexical organization in bilinguals.

Keywords:

• Bilingualism
• Aphasia
• Noun
• Verb
• Dissociation

Acknowledgments

We wish to thank the participant N.K. for his unending patience and cooperation with all the testing. We are grateful to Grace Yeni-Komshian for input on the Lebanese Arabic translations and to Raphiq Ibrahim for the suggestion to obtain familiarity ratings for Lebanese Arabic. We thank Mohan Singh for helping to develop and test stimuli in French, in scoring responses, and with illustrations. We also wish to thank students who helped with various stages of stimulus development and testing: Jamila Darwish, Justine Taweel, Omar Chatila, and Tracey Moskatel.

Notes

¹ At the time of this study (in 2008), a Lebanese Arabic version of the BAT was unavailable, and the Jordanian Arabic version was deemed the closest in lexical morphology. Individual test items were altered in lexical and morphosyntactic aspects to follow Lebanese Arabic.

² We would like to thank an anonymous reviewer for pointing this out.

³ Action names were elicited as part of an experimental paradigm in which audiorecordings of unrelated words preceded each picture presentation. Although this is different from the manner in which object names were elicited, the lower accuracy of verbs than of nouns is unlikely to be due to the different elicitation procedures (as is seen later under Results).

⁴ To evaluate the role of syntactic variables such as number of arguments and number of subcategorizations allowed by the verbs, we submitted the verb accuracy data to a separate logistic regression analysis by including these syntactic variables. This did not reveal any significant predictors.