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Kristina R. Olson, Ph.D.
Kristina R Olson Ph.D.

When Does Bilingualism Help or Hurt?

The effects of bilingualism on children’s cognition.

By Sara Guirgis and Kristina Olson

Parents are often asking what they can do to prepare their children for the increasingly globally-connected world. Often that answer has involved encouraging children to learn a second language or, for immigrant families, ensuring they pass on their native language to their children. Bilingualism (being fluent in two languages) not only allows people to communicate with others who speak those languages, but also to better understand different cultures and different ways of thinking. As such, there is no shortage of programs, language immersion schools, online materials, and other options being marketed to parents to encourage their children to become fluent in a second language.

While many of us share the intuition that learning two languages is better, or believe we’ve been told that from the media or scientific studies, the actual evidence is mixed. Dr. Ellen Bialystok, a professor of psychology at York University, has been studying the pros and cons of bilingualism for almost 40 years. She and her team have found evidence on both sides of the bilingualism argument. They find that children who regularly speak more than one language (bilinguals), on average, have slight linguistic disadvantages but also cognitive advantages as compared to children who speak only one language (monolinguals).

One of the findings from these studies was that bilinguals have minor disadvantages relative to monolinguals with regard to vocabulary. While the size of an individual’s vocabulary or lexicon varied widely, on average monolinguals had more vocabulary in their one language than bilinguals had in either of their languages alone. Also, the time (in milliseconds) it took to retrieve words when thinking was slightly longer for bilinguals. So, that feeling you get when you’re trying to think of a word and it’s just not coming to you—that’s the experience that bilinguals have more often. These slight disadvantages of bilingualism may be due to having to resolve the cognitive conflict of choosing the word from the appropriate language, rather than simply choosing the appropriate word, as monolinguals do.

However, the effort the brain has to put into the management of this “joint activation” of both languages leads to the cognitive advantages observed for bilinguals over monolinguals. Bilinguals have, on average, stronger executive control, meaning they have enhanced cognitive abilities in areas that have nothing to do with linguistics, but rather overall management of cognitive functions. This enhanced executive control boosts bilinguals’ capability in areas such as working memory, inhibitory control, cognitive flexibility, and multitasking. In particular, bilinguals are especially good at tasks that involve monitoring conflict, a skill one practices a lot if trying to use words from one lexicon while avoiding those from another.

To understand why these enhancements to the bilingual brain occur, it’s helpful to know about neuroplasticity. Neuroplasticity describes how our brains change across our lives. Connections between brain cells strengthen and weaken as we reorganize information, as we learn, and as we get older. Neuroplasticity is why patients with brain injuries are often able to at least partially recover , and why people with a deficit in one physiological sense (poor eyesight, for example) can sometimes develop a greater capacity in another one of their senses (i.e. better hearing). The executive control center of the brain is the primary area responsible for managing dual languages and resolving conflicts. As bilingual children learn and use multiple languages (appropriately monitoring and using words from the right language at the right time) they are exercising and strengthening their executive function via neuroplasticity.

So while bilingual children may have a slightly smaller vocabulary for each language as compared to their peers who speak only one language, they gain a cognitive advantage by having strengthened executive function. These findings appear to hold across ethnicity and socio-economic status. It’s important to note that these advantages were seen in fully bilingual children who use both languages regularly rather than occasionally. Also, the longer an individual is bilingual, the more cognitive benefit they get. While these benefits alone are encouraging, bilingual children may also benefit from Dr. Bialystok’s findings that suggest that bilinguals have a later onset (about 4 years on average) of dementia and Alzheimer’s disease in old age.

So while there are a host of advantages to the ‘bilingual brain’—executive control and memory benefits—applicable to a wide range of situations outside of the linguistic context and only a few minor disadvantages, it’s safe to say that bilingualism isn’t a cure-all for developing or maximizing all cognitive and linguistic skills. That said, it’s also safe to say that bilingualism has much to contribute to the developing brain. In addition to improvements in cognitive and language skills, bilingualism has many other advantages too, of course, like the ability to communicate and connect with more of the world’s population and the associated opportunities to travel. Thus, parents might consider not only the cognitive benefits but the social and experiential ones as well when deciding whether the immersion school or enrichment program makes sense for their children.

copyright 2014 Sara Guirgis and Kristina Olson

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About the Author
Kristina R. Olson, Ph.D.

Kristina R. Olson, Ph.D., is an Assistant Professor of Psychology and Cognitive Science at Yale University.

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