Cognate Effects and Executive Control in a Patient with Differential Bilingual Aphasia

Abstract

We describe a case study of a French–Dutch bilingual patient with differential aphasia, showing clearly larger impairments in Dutch than in French. We investigated whether this differential impairment in both languages was due to selective damage to language-specific brain areas resulting in the “loss” of the language representation itself, or rather if it reflects an executive control deficit. We assessed cross-linguistic interactions (involving lexical activation in the most affected language) with cognates in a lexical decision (LD) task, and executive control using a flanker task. We used a generalized LD task (any word requires a “yes” response) and a selective LD task in the patient's two languages (only words in a given target language require a “yes” response). The cognate data unveil a differential pattern in the three tasks, with a clear cognate facilitation effect in the generalized LD tasks and almost no cognate effect in the selective LD tasks. This implies that a more impaired language can still affect the processing of words in the best-preserved language, but only with low cross-language competition demands (generalized LD). Additionally, the flanker task showed a larger congruency effect for the patient compared with controls, indicating cognitive control difficulties. Together, these results support accounts of differential bilingual aphasia in terms of language-control difficulties.

Key words:

• aphasia
• behavioral neuropsychology
• bilingualism
• cognates
• cognition
• control
• differential aphasia
• psycholinguistics

Notes

¹The Eriksen flanker task is one of the most frequently used tasks to assess cognitive control.

²We are aware of the fact that not all people who are able to use two languages can be regarded as fully bilingual, in the sense that language proficiency takes long periods of acculturation and assimilation to reach a deep structural level (Cummins, 1979). Such mastery should not be confused with the simple ability to use a language in social situations such as conversations. However, because the patient described here acquired both languages at a very young age, and kept using both languages equally often in his daily life, we argue that he can be regarded as a fully balanced bilingual, at least for the rather low level of (lexical) language processing that is assessed in this study. We do not assume complete equivalency of all higher linguistic levels.

*The patient showed a significant difference between the French and the Dutch scores on this subtest (p < .05).

³We are aware of the fact that the way executive functioning was evaluated in this patient is rather limited (using COWAT and the flanker task). For further research, we suggest assessing executive functions more profoundly (e.g., using the Wisconsin Card-Sorting Task, a switching paradigm, a go–no go task, etc.; see also Garcia-Molina, Tomos, Bernabeu, Junque, & Roig-Rovira, 2012; Segura et al., 2009).