For the first half of the twentieth century, researchers actually thought that bilingualism put a child at a disadvantage, something that hurt her I.Q. and verbal development. But, in recent years, the notion of a bilingual advantage has emerged from research to the contrary, research that has seemed both far-reaching and compelling, much of it coming from the careful work of the psychologist Ellen Bialystok. For many tasks, including ones that involve working memory, bilingual speakers seem to have an edge. In a 2012 review of the evidence, Bialystok showed that bilinguals did indeed show enhanced executive control, a quality that has been linked, among other things, to better academic performance. And when it comes to qualities like sustained attention and switching between tasks effectively, bilinguals often come out ahead. It seems fairly evident then that, given a choice, you should raise your child to speak more than one language.
