Preschool- and Kindergarten-Age Benefits

“There is a push worldwide where English becomes like the lingua franca, so it’s important that the child be exposed to the other language early, and the younger you are, the more nativelike you’re going to sound,”

“It seems that being raised in an environment in which multiple languages are spoken, rather than being bilingual per se, is the driving factor.”

“The key difference between bilinguals and monolinguals may be more basic: a heightened ability to monitor the environment. “Bilinguals have to switch languages quite often — you may talk to your father in one language and to your mother in another language,” says Albert Costa, a researcher at the University of Pompeu Fabra in Spain. “It requires keeping track of changes around you in the same way that we monitor our surroundings when driving.” In a study comparing German-Italian bilinguals with Italian monolinguals on monitoring tasks, Mr. Costa and his colleagues found that the bilingual subjects not only performed better, but they also did so with less activity in parts of the brain involved in monitoring, indicating that they were more efficient at it.”

True bilingualism is a relatively rare and a beautiful thing, and by “true,” I mean speaking two languages with the proficiency of a native — something most of us will only dream of as we struggle with learning languages in school and beyond.

Highly competent bilingualism is probably more common in other countries, since many children growing up in the United States aren’t exposed to other languages. But the steps along the road toward bilingualism can help a child’s overall facility with language. And early exposure to more than one language can confer certain advantages, especially in terms of facility with forming the sounds in that language.

But parents should not assume that young children’s natural language abilities will lead to true grown-up language skills without a good deal of effort. Erika Hoff, a developmental psychologist who is a professor at Florida Atlantic University and the lead author of a 2015 review article on bilingual development, said: “For everybody trying to raise a bilingual child, whatever your background and reason, it’s very important to realize that acquiring a language requires massive exposure to that language.”

Pediatricians routinely advise parents to talk as much as possible to their young children, to read to them and sing to them. Part of the point is to increase their language exposure, a major concern even for children growing up with only one language. And in order to foster language development, the exposure has to be person-to-person; screen time doesn’t count for learning language in young children — even one language — though kids can learn content and vocabulary from educational screen time later on. “For bilingual development, the child will need exposure to both languages,” Dr. Hoff said, “and that’s really difficult in a monolingual environment, which is what the U.S. is.”

Pediatricians advise non-English-speaking parents to read aloud and sing and tell stories and speak with their children in their native languages, so the children get that rich and complex language exposure, along with sophisticated content and information, rather than the more limited exposure you get from someone speaking a language in which the speaker is not entirely comfortable.

Parents come up with all kinds of strategies to try to promote this kind of exposure. Some families decide that each parent will speak a different language to the child. But the child will be able to sort out the two languages even if both parents speak them both, Dr. Hoff said. “There is certainly no research to suggest that children need to have languages lined up with speakers or they get confused.” On the other hand, that rule could be a way of making sure that the non-English language is used.

If a child grows up with caretakers who speak a foreign language — perhaps a Chinese au pair or a French nanny — the child may see some benefits down the road in studying that language. But if a child grows up speaking that second language — Korean, say — with cousins and grandparents, attending a “Saturday School” that emphasizes the language and the culture, listening to music and even reading books in that language, and visits Korea along the way, that child will end up with a much stronger sense of the language.

It does take longer to acquire two languages than one, Dr. Hoff said, and that, again, comes back to the exposure.

“A child who is learning two languages will have a smaller vocabulary in each than a child who is only learning one; there are only so many hours in the day, and you’re either hearing English or Spanish,” Dr. Hoff said. The children will be fine, though, she said. They may mix the languages, but that doesn’t indicate confusion. “Adult bilinguals mix their languages all the time; it’s a sign of language ability,” she said.

Dr. Hoff works in South Florida, where there is a very educated and affluent population raising children in Spanish and English. “The children start out as baby bilinguals, but the older they get, the more English overtakes Spanish,” she said. “The ones who are successful bilinguals as adults are still much better in English than they are in Spanish — they didn’t go to school in Spanish, they don’t read books in Spanish, and when you actually measure the size of their vocabularies, or the grammar they understand, or the coherence of the narrative they produce, they are not as proficient as they are in English.”

Gigliana Melzi, a developmental psychologist and associate professor of applied psychology at New York University who studies language in Spanish- and English-speaking Latino families, agreed. “Parents will need to be mindful about introducing the child to literacy in that language,” she said. “They will need to be thoughtful about ways they will encourage the child to maintain the language.”

It’s also important, she said, to watch the individual child and make sure the child is not overloaded with demands because of parental expectations and ambitions; maybe three languages on top of a musical instrument and a serious sport is just too much.

The languages you learn as a child are important, but so are the languages you learn later in life. “We all know people who make great contributions and do great science in English and are not native speakers,” Dr. Hoff said. “The human brain is amazing, and the human capacity to acquire language is amazing.”

So what should parents do if they want to give their children a bilingual boost? “Find a native speaker and have that native speaker have fun, interesting conversations with your child, and your child will learn something,” Dr. Hoff said. “Don’t expect it will turn your child into a perfect balanced bilingual, but that’s O.K.” Whatever you do is an advantage.

Dr. Melzi said that often, a child who has been fluent in two languages in the preschool years goes to school where English is spoken, and starts using English to describe what happens there.

“There is a push worldwide where English becomes like the lingua franca, so it’s important that the child be exposed to the other language early, and the younger you are, the more nativelike you’re going to sound,” she said. On the other hand, older children may learn more easily: “The younger you are, the more head start you have,” she said. “The older you are, the more efficient learner you are, you have a first language you can use as a bootstrap.”

So true bilingualism may be rare, but parents shouldn’t be discouraged on that account, since all the skills that children acquire along the way are very valuable, Dr. Melzi said. “It’s worth it, but it’s a lot of work.”

BEING bilingual has some obvious advantages. Learning more than one language enables new conversations and new experiences. But in recent years, psychology researchers have demonstrated some less obvious advantages of bilingualism, too. For instance, bilingual children may enjoy certain cognitive benefits, such as improved executive function — which is critical for problem solving and other mentally demanding activities.

Now, two new studies demonstrate that multilingual exposure improves not only children’s cognitive skills but also their social abilities.

One study from my developmental psychology lab — conducted in collaboration with the psychologists Boaz Keysar, Zoe Liberman and Samantha Fan at the University of Chicago, and published last year in the journal Psychological Science — shows that multilingual children can be better at communication than monolingual children.

We took a group of children in the United States, ages 4 to 6, from different linguistic backgrounds, and presented them with a situation in which they had to consider someone else’s perspective to understand her meaning. For example, an adult said to the child: “Ooh, a small car! Can you move the small car for me?” Children could see three cars — small, medium and large — but were in position to observe that the adult could not see the smallest car. Since the adult could see only the medium and large cars, when she said “small” car, she must be referring to the child’s “medium.”

We found that bilingual children were better than monolingual children at this task. If you think about it, this makes intuitive sense. Interpreting someone’s utterance often requires attending not just to its content, but also to the surrounding context. What does a speaker know or not know? What did she intend to convey? Children in multilingual environments have social experiences that provide routine practice in considering the perspectives of others: They have to think about who speaks which language to whom, who understands which content, and the times and places in which different languages are spoken.

Interestingly, we also found that children who were effectively monolingual yet regularly exposed to another language — for example, those who had grandparents who spoke another language — were just as talented as the bilingual children at this task. It seems that being raised in an environment in which multiple languages are spoken, rather than being bilingual per se, is the driving factor.

You might wonder whether our findings could be explained as just another instance of the greater cognitive skills that bilingual children have been observed to have. We wondered that, too. So we gave all the children a standard cognitive test of executive function. We found that bilingual children performed better than monolingual children, but that the kids who were effectively monolingual yet regularly exposed to another language did not. These “exposure” children performed like monolinguals on the cognitive task, but like bilinguals on the communication task. Something other than cognitive skills — something more “social” — must explain their facility in adopting another’s perspective.

In a follow-up study, forthcoming in the journal Developmental Science, my colleagues and I examined the effects of multilingual exposure on even younger children: 14- to 16-month-old babies, who are hardly speaking at all. In this study, led by Zoe Liberman and in collaboration with Professor Keysar and the psychologist Amanda Woodward, babies were shown two versions of the same object, such as a banana, one of which was visible to both the infant and an adult, the other visible to the baby yet hidden from the adult’s view. When the adult asked the baby for “the banana,” the baby might hand her either object — both were bananas, after all — yet if the baby understood the social context, he would reach more often for the banana that the adult could see.

We found that babies in monolingual environments reached equally often for the two bananas. Babies in multilingual environments, including those who were exposed to a second language only minimally, already understood the importance of adopting another’s perspective for communication: They reached more often for the banana that the adult could see.

Multilingual exposure, it seems, facilitates the basic skills of interpersonal understanding. Of course, becoming fully bilingual or multilingual is not always easy or possible for everyone. But the social advantage we have identified appears to emerge from merely being raised in an environment in which multiple languages are experienced, not from being bilingual per se. This is potentially good news for parents who are not bilingual themselves, yet who want their children to enjoy some of the benefits of multilingualism.

Editor’s Note: We’re resurfacing this story from the archives to show you how learning a second language can improve how you think.

SPEAKING two languages rather than just one has obvious practical benefits in an increasingly globalized world. But in recent years, scientists have begun to show that the advantages of bilingualism are even more fundamental than being able to converse with a wider range of people. Being bilingual, it turns out, makes you smarter. It can have a profound effect on your brain, improving cognitive skills not related to language and even shielding against dementia in old age.

This view of bilingualism is remarkably different from the understanding of bilingualism through much of the 20th century. Researchers, educators and policy makers long considered a second language to be an interference, cognitively speaking, that hindered a child’s academic and intellectual development.

They were not wrong about the interference: there is ample evidence that in a bilingual’s brain both language systems are active even when he is using only one language, thus creating situations in which one system obstructs the other. But this interference, researchers are finding out, isn’t so much a handicap as a blessing in disguise. It forces the brain to resolve internal conflict, giving the mind a workout that strengthens its cognitive muscles.

Bilinguals, for instance, seem to be more adept than monolinguals at solving certain kinds of mental puzzles. In a 2004 study by the psychologists Ellen Bialystok and Michelle Martin-Rhee, bilingual and monolingual preschoolers were asked to sort blue circles and red squares presented on a computer screen into two digital bins — one marked with a blue square and the other marked with a red circle.

In the first task, the children had to sort the shapes by color, placing blue circles in the bin marked with the blue square and red squares in the bin marked with the red circle. Both groups did this with comparable ease. Next, the children were asked to sort by shape, which was more challenging because it required placing the images in a bin marked with a conflicting color. The bilinguals were quicker at performing this task.

The collective evidence from a number of such studies suggests that the bilingual experience improves the brain’s so-called executive function — a command system that directs the attention processes that we use for planning, solving problems and performing various other mentally demanding tasks. These processes include ignoring distractions to stay focused, switching attention willfully from one thing to another and holding information in mind — like remembering a sequence of directions while driving.

Why does the tussle between two simultaneously active language systems improve these aspects of cognition? Until recently, researchers thought the bilingual advantage stemmed primarily from an ability for inhibition that was honed by the exercise of suppressing one language system: this suppression, it was thought, would help train the bilingual mind to ignore distractions in other contexts. But that explanation increasingly appears to be inadequate, since studies have shown that bilinguals perform better than monolinguals even at tasks that do not require inhibition, like threading a line through an ascending series of numbers scattered randomly on a page.

The key difference between bilinguals and monolinguals may be more basic: a heightened ability to monitor the environment. “Bilinguals have to switch languages quite often — you may talk to your father in one language and to your mother in another language,” says Albert Costa, a researcher at the University of Pompeu Fabra in Spain. “It requires keeping track of changes around you in the same way that we monitor our surroundings when driving.” In a study comparing German-Italian bilinguals with Italian monolinguals on monitoring tasks, Mr. Costa and his colleagues found that the bilingual subjects not only performed better, but they also did so with less activity in parts of the brain involved in monitoring, indicating that they were more efficient at it.

The bilingual experience appears to influence the brain from infancy to old age (and there is reason to believe that it may also apply to those who learn a second language later in life).

In a 2009 study led by Agnes Kovacs of the International School for Advanced Studies in Trieste, Italy, 7-month-old babies exposed to two languages from birth were compared with peers raised with one language. In an initial set of trials, the infants were presented with an audio cue and then shown a puppet on one side of a screen. Both infant groups learned to look at that side of the screen in anticipation of the puppet. But in a later set of trials, when the puppet began appearing on the opposite side of the screen, the babies exposed to a bilingual environment quickly learned to switch their anticipatory gaze in the new direction while the other babies did not.

Bilingualism’s effects also extend into the twilight years. In a recent study of 44 elderly Spanish-English bilinguals, scientists led by the neuropsychologist Tamar Gollan of the University of California, San Diego, found that individuals with a higher degree of bilingualism — measured through a comparative evaluation of proficiency in each language — were more resistant than others to the onset of dementia and other symptoms of Alzheimer’s disease: the higher the degree of bilingualism, the later the age of onset.

Nobody ever doubted the power of language. But who would have imagined that the words we hear and the sentences we speak might be leaving such a deep imprint?

Correction: March 25, 2012 

The Gray Matter column on bilingualism last Sunday misspelled the name of a university in Spain. It is Pompeu Fabra, not Pompea Fabra.