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…