Cognitive advantages of bilingualism

A bilingual person can traditionally be defined as an individual who uses (understands and produces) two (or more) languages on a regular basis. A bilingual person's initial exposure to both languages may have started in early childhood, e.g. before age 3, but exposure may also begin later in life. While some people assume that bilinguals must be equally proficient in their languages, perfectly equal proficiency is rarely attested, and proficiency typically varies by domain. For example, a bilingual person may have greater proficiency for work-related terms in one language, and family-related terms in another language.

Being bilingual has been linked to a number of cognitive benefits. Research has studied how a bilingual individual's first language (L1) and second language (L2) interact, and it has been shown that both languages have an influence on the function of one another, and on cognitive function outside of language. Research on executive functions such as working memory, perception, and attentional and inhibitory control, has suggested that bilinguals can benefit from significant cognitive advantages over monolingual peers in various settings. There are also age-related benefits, which seem to help older adults on the battle against cognitive decline.

Throughout the history of research into the cognitive advantages of bilingualism, views have shifted from a subtractive to an additive perspective; that is from believing that being bilingual detracts from one's abilities, to believing that being bilingual adds to an individual's abilities.

There is, however, some disagreement over how findings on this subject should be interpreted. A systematic review of studies carried out between 1999 and 2012 found that the evidence for cognitive advantages is mixed and that reporting may be subject to publication bias, which has therefore given a distorted view of the evidence.

Over the course of the past few years, the prevalence of bilinguals in the United States has increased dramatically. While the United States Census Bureau does not directly poll for bilingualism, they do poll for what languages are used in an individual's home, and if it is a language other than English, they then poll for how well that same individual speaks English. In 2012, François Grosjean, a professor of Linguistics from the University of Neuchâtel, interpreted the results from the Census Bureau as follows: 11% of the population was bilingual in 1980, 14% in 1990, and 20% in 2012. This positive increase matches the shift to more positive beliefs about the cognitive advantages of bilingualism.

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