Authors: W. Quin Yow & Adam C. Oei
Abstract: Bilinguals have been shown to enjoy cognitive benefits in tasks that rely on executive control in prefrontal brain areas compared to monolinguals. However, research that compares monolinguals with bilinguals in executive control has not consistently provided evidence of the bilingual-advantage. This may be due to the multi-faceted dimension of bilingualism; bilinguals differ from each other on many language variables. Here, we utilized a within-population approach to investigate whether individual differences in bilingualism, such as more equal use (balanced usage) and equal proficiency (balanced proficiency) and switching between two languages are predictive of lower executive control costs in elderly bilinguals. Forty-five elderly bilinguals (30 females; mean age = 65.27) performed four executive control tasks (Stroop, Flanker, task-switching, and spatial 2-back). Multiple regression analyses showed a positive association between balanced usage and mixing cost in task switching, independent of cognitive health status, fluid intelligence, processing speed and age. The results therefore suggest that executive control skills associated with a lifetime of balanced dual language use may confer a cognitive reserve in task mixing skills in elderly bilinguals.
Keywords: bilingualism; balanced usage; executive control