Cognitive Effects of Bilingualism

Research over the past 50 years has explored the possibility that bilingual experience reshapes cognitive ability and brain systems. The earliest studies asked simple questions about the relation between bilingualism and intelligence in children, but current studies use the multifaceted tools of cognitive psychology and neuroscience to uncover the complex and often subtle effects of this experience across the entire lifespan. Inevitably, the results of these studies are complex, sometimes contradictory, and cannot be reduced to a single binary conclusion, as was the goal in the earliest research. This chapter reviews the main results that have been reported, highlighting specific points in the lifespan. In addition, the areas of controversy are noted in order to extract a consistent theme that describes these effects. The conclusion is that more attention must be paid to uncovering the underlying mechanism that is responsible for these modifications in order to fully understand the complex patterns of results.