Bilingual individuals can control which language they use, and this boosts the development of executive control processes in bilinguals.
Bilinguals must have a mechanism for controlling attention to their two language systems in order to achieve fluent performance in each language without intrusions from the other. This paper examines the evidence that the experience of controlling attention to two languages boosts the development of executive control processes in childhood for bilinguals, sustains cognitive control advantages for bilinguals through adulthood and protects bilingual older adults from the decline of these processes with ageing. Future research with bilingualism should explore these effects in a broader and more multidisciplinary context in order to provide a more detailed understanding of the functioning of the bilingual mind.
Bialystok, E., 2008. Cognitive Effects of Bilingualism: How linguistic experience leads to cognitive change. International Journal of Bilingual Education and Bilingualism, 10(3), pp. 210-223.