Child Proof

Research on bilingualism shows that it changes kids’ brains for the better — and that even with bilingual parents, it can be hard to achieve

Elizabeth Preston

Jul 11, 2019·4 min read

There are plenty of reasons to raise a child to be bilingual. Speaking a language tied to their family origins can help a kid stay close to their heritage. It allows them to converse with relatives they might not otherwise understand. It lets them connect with a wider swath of the world. And a growing body of research suggests the way it rewires the brain may confer cognitive benefits that last into old age.

Language learning begins before a baby is even born, says Ellen Bialystok, a psychology professor at York University in Canada who studies the effects of bilingualism on the brain; in one 2013 study, infants from a few hours to a few days old already showed higher interest in the sounds of the language they heard in utero. When children grow up hearing more than one language, they may learn to pay attention in different ways than monolingual children. Bialystok’s own research has shown that as early as six months old, infants from bilingual households demonstrate stronger selective attention skills, meaning they’re better able to focus on relevant information while tuning out other stimuli to focus.

Bialystok thinks that these effects reverberate throughout the rest of the child’s life. Some studies have shown that bilingual adults do better on certain tests of attention, for example, and brain imaging studies have also found some differences in the physical architecture of their brains. But Bialystok thinks the biggest benefit comes much later in life — when bilingual adults seem to have greater resilience against dementia.

But full bilingualism takes effort — and speaking two languages at home doesn’t guarantee that your kids will do the same. The Pew Research Center found that only 57% of U.S. adults who identify as second-generation Latinx immigrants are bilingual or Spanish-dominant. That number drops to 24% in the following generation.

Despite their best efforts, many bilingual adults still end up with monolingual kids. And this isn’t only true in countries where English dominates: In a 2007 study, Annick De Houwer, a professor at the University of Erfurt in Germany surveyed nearly 2,000 bilingual families in a Dutch-speaking region of Belgium (collectively, the families spoke more than 70 other languages in addition to Dutch, but some of the more common ones were French, Turkish, English, and Arabic). In nearly a quarter of those households, children spoke only Dutch.

Some parents approach bilingualism by dividing languages between family members: Maybe Mom speaks only English to the child, while Dad speaks only Spanish. In the Belgian study, though, households using this approach were just as likely — one in four — to have monolingual children.

A better strategy, if both parents are native speakers, is for both of them to exclusively use the minority language at home. Or one parent could speak that language exclusively while the other parent uses both, De Houwer says. In general, the more exposure a child has to the minority language, the better their odds of learning it.

“My kids aren’t geniuses. They just had the opportunity.”

Simona Montanari, a professor at California State University, Los Angeles, studies bilingual and multilingual development and has conducted her own sort of experiment at home. Montanari, who’s Italian, speaks Italian to her two daughters; her American husband speaks English; and the girls had a Spanish-speaking babysitter from birth, she says. Now as teenagers, the girls are comfortable in both English and Italian, and advanced in Spanish at school. “They’re not geniuses,” Montanari says. “They just had the opportunity.”

Montanari also stresses the importance of more formal education, in addition to exposure inside the home: “It is ideal to learn language from multiple speakers,” she says. She was able to start an Italian-language immersion program at her daughters’ California school district, which also offers immersion programs in several other languages. She says finding peers for her daughters who spoke Italian was a big help, as was travel to Italy and Mexico.

If those things aren’t feasible — and for many families, they aren’t — you can help your kids learn two languages the same way you help them learn one: by talking to them a lot.

And while some parents worry that raising a child in two languages might set them behind in both, kids will have no problem learning the majority language where they live, Montanari says. “[In the U.S.], English will happen no matter what.” She says her own daughters were less proficient in English than in their other two languages when they started school, but quickly caught up.

De Houwer agrees that fears of language delay are misplaced. “There is no evidence of a general delay in language development in bilingually raised children.” And you have to add up what the child can do across both languages, she says: For example, in a 2014 study, De Houwer and her colleagues compared 31 toddlers from bilingual Dutch-French households to carefully matched kids from monolingual homes. At 13 months old, toddlers in the bilingual group understood 71% more words, on average, than the monolingual toddlers. “So there’s no delay there,” De Houwer says. “Quite the opposite.”

Even if a child doesn’t don’t become fully bilingual, smaller positive changes happen in the brain with lesser degrees of language learning, Bialystok says — and that’s doesn’t even include the other benefits of studying languages, like giving kids a broader experience of the world and its people. “It’s just good to learn other languages,” she says, “even if your brain didn’t change.”