Executive control of language in young and older bilinguals

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There is a growing need to understand bilingualism in younger and older adults because 35% of Canadians are bilingual and the proportion over the age of 60 is increasing. There is a varying degree of overlap between a bilingual's first (L1) and second (L2) language. This sharing of information requires executive control to correctly access and produce language-appropriate information when a bilingual is speaking or reading. Studies have shown that executive control capabilities of older bilinguals are relatively protected against age-related decline. Thus, I will investigate attentional and executive control in younger and older English/ French bilinguals specifically using language-based tasks in combination with electrical brain activity (ERPs). Study 1 will examine verbal self-monitoring during picture naming in L1 and L2 when within- and across-language phonological and semantic distractors are present. The goal is to determine whether verbal self-monitoring is greater in L2 than in L1 (due to interference from L1). Study 3 will examine whether the executive control benefits due to being bilingual have a positive effect on the activation and selection of lexically ambiguous words (i.e., words with the same spelling but two distinct meanings). Study 3 will examine language as a mechanism for directing attention (i.e., by specifying relationship between objects) in younger and older adults. Study 4 will examine the neural mechanisms of switching between two languages. There is a seemingly paradoxical asymmetrical cost, namely that it takes longer to switch from one's weaker L2 to one's stronger L1 than vice versa. This is likely due to the need to suppress L1 that is required to perform in L2, which must then be overcome to switch back to L1. Overall, this research program will make a novel and significant contribution by examining the role of executive control in both production (Study 1) and comprehension (Studies 2, 3, 4), by extending current research findings to older bilinguals who represent an extreme test of the importance of executive control, and by elucidating the neural processes involved in the control of language.