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Why Speaking Two Languages Improves Self-Control

What's the Big Idea?

Does knowing that sweets are dulces in Spanish help a child learn to resist a tasty treat? It may indeed, as people who learn two languages gain cognitive advantages that extend well beyond the ability to communicate with others.

Speaking multiple languages is challenging because the person must direct attention to one language while suppressing interference from the other. Experiments show that the brains of bilingual people automatically activate both languages even in contexts where only one is relevant. This interference causes bilingual people to be slower at retrieving words and have more tip-of-the-tongue experiences, the feeling of almost remembering a word that isn’t quite accessible.

The ability to manage such competing responses improves considerably with practice. Probably for this reason, bilingual children outperform other children on a variety of tests of self-control. As early as seven months of age, bilingual children learn abstract rules and reverse previously learned rules more easily than other children. They are less likely to be fooled by conflicting cues, such as a color word like “red” written in green ink. People who speak English and American Sign Language do not have to choose between languages because they can speak with their mouths and hands simultaneously—and they do not show an advantage in self-control, suggesting that response competition is important for building this capacity.

What's the Significance?

Older bilingual children and adults also show better cognitive control than their peers with only one language, especially on demanding attention tests. These advantages show up in nonverbal tasks, so they do not depend on language skills directly. Extensive practice at selecting appropriate behavior in two different languages seems to strengthen bilingual children’s ability to show cognitive flexibility according to context—an ability that may generalize to success in other areas of life. Recent work suggests that bilingual people may be better at monitoring the environment in general, even in situations that do not involve competing responses.

Because these studies are correlational, it remains theoretically possible that the relationship between bilingualism and self-control is caused by some characteristic of households that raise bilingual children, such as wealth or parents’ willingness to put resources into their children’s development (for instance, by paying for language lessons). This explanation seems unlikely, though, because many first-generation immigrant households are poor and the bilingual advantage is found in some studies where both groups have the same socioeconomic status.

Even in people who learn more than one language from birth, the brain appears to represent the languages at least somewhat separately. A region in the left inferior parietal cortex is larger in people who speak more than one language, and it is largest in those who learned the second language when they were young or speak it fluently.

When bilinguals switch between languages, according to an analysis of multiple functional brain imaging studies, the prefrontal cortex, basal ganglia, and sometimes anterior cingulate cortex are activated. All these brain areas are also active during self-control tasks, which may explain how practicing bilingualism strengthens self-control.

Bilingual people may exert cognitive control differently, as well as better. During a conflict task, bilingual people’s brains show activation not only in dorsolateral prefrontal cortex, which everyone uses for conflict resolution, but also in Broca’s area, the region that processes grammatical rules.

The ability to speak two languages provides benefits for a lifetime, at least in people who continue to use both of them actively through adulthood. Bilingualism substantially protects self-control against its normal tendency to decline with age in the 70s and 80s. Several studies also report that people who spoke two languages for their entire lives are diagnosed with dementia (including Alzheimer’s disease) about four years later, on average, than their peers who spoke only one language.

Another area where bilingual children outperform monolingual children is in their ability to understand what other people are thinking. This advantage may develop because bilinguals get more practice at taking the perspective of other people, as they need to choose the appropriate language for their conversational partners. Alternatively, it may simply reflect their stronger self-control, which is related to social abilities. Next week, the final post in this series will examine how building self-control improves social skills and empathy in children.

Image courtesy of Shutterstock/Stockcube.

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