How to make a bilingual child

Clue: Just add language!


Many couples come from different countries, bringing with them diverse language backgrounds.

Common questions about language arise:

“Which language should we use at home?”
“What if I don’t understand my partner’s language? Or that of my in-laws?”

Consider Anja and Luiz:

They are expecting their first child.
They married in 2014, and live and work in Colorado. Anja was born in Finland, and moved to the US when she was three. Luiz spent most of his childhood in Brazil, but has lived in Colorado since high school.
One of their biggest questions regards the language they should use with their child.
Anja’s mother Kati is fluent in Finnish and English. She will move in with the couple to tend the baby while they work.
Anja understands most of what her Finnish-speaking mother says. But she answers only in English. Thus, she doesn’t want her mother to speak Finnish to their child. She thinks it will confuse the child, or worse yet, delay speech.
Luiz speaks both Portuguese and English fluently. He is of the mind that the child should be exposed to all three languages. For him, learning two languages at the same time required no effort.

What would you do?

The building blocks of language and memory are falling into place during the last weeks in the womb.

The fetus is able to hear several weeks before birth. Infants can recognize a poem or a story, for example, their mother read aloud during her last trimester of pregnancy. They probably recognize the melody of the language, rather than specific words.

Newborns also prefer the familiar over the foreign. For example, they like hearing their mother’s voice over voices of stranger. And their native tongue (over a foreign language) at birth.

This tells us that even the youngest infants learn from what they hear.
And as soon as they are born, their brains are primed to learn any language.
So, is there a preferred way to “teach” children more than one language?

The short answer is: talk to and with them early, often, and keep it up. Important factors include:

  1. Age of exposure — At birth, babies can learn any speech sound, from the Spanish “ñ,” the Zulu clicks like “ʘ,” or the rolled “r” of German. So for native-like competence, exposure during the first year of life is better. Babies can just as easily learn two languages as one, if they are part of their natural environments.
  2. Quality of exposure — There are no hard and fast rules, but a child needs to take part in language to become fluent. Sitting in front of a television does not “teach” language, even though a child may learn something. As with their first language (see link to post below), they need a communicative partner. Another “quality” factor is the competence of the adult speaker.
  3. Duration of exposure — For native-like fluency, a child should practice with a 2nd language until they can express themselves verbally, which would be about the 5-years-old if they have been exposed from birth. Naturally, if they don’t continue using it, it will fade.

To explore a longer answer, we turn to researchers interested in “critical periods” of brain development for language learning, and those who study 2nd language learners.

In 1967, Eric Lenneberg proposed that language acquisition is hard-wired in humans, as language occurs about the same age for healthy children all over the world. Furthermore, he proposed a “critical period” for language learning that extended from infancy and puberty.

Later, this hypothesis was tested with 2nd language learners (Newport & Johnson, 1989).

Korean-English bilinguals who immigrated to the US between the ages of 3–39 were the focus of this study. Half of them arrived before the age of 15, the other half arrived after 17 (they had lived in the US between 3–26-years). Given Lenneberg’s theory, we would assume those 17-and-over would not do so well in English, and those 15-and-under would become fluent.

The learners were divided into four groups based on age of arrival (3–7-yrs, 8–10-yrs, 11–15-yrs, 17–39-yrs). They took a grammar test, for example, Which is correct: “The pigs is in the pen,” or “The pig is in the pen.”

The results show that the youngest group performed just as well as the native speakers, and that after seven, performance diminished. The authors thus proposed a “critical period” for 2nd language extending from infancy to 7-years-old.

Newport & Johnson, 1989

Brain development also proceeds differently depending on age of exposure to a 2nd language.

In those who have early exposure, both their native and 2nd language share common real estate in the left front part of the brain that is preferentially related to speaking. However, in late learners, a spatially separated area is engaged for 2nd language.

In a left posterior brain — associated with comprehension — there is little effect of age of acquisition.

These studies only touch on the research related to 2nd language learning, and many researchers have extended and refined these findings. They don’t change the underlying messages, however:

Early exposure is better.

Children can easily learn more than one language when young.

And naturally, more exposure is better than less.

For the record, I would side with Luiz. They should expose their child to all three languages, and Kati Their baby will undoubtedly make errors along the way, mixing Finnish with Portuguese and English, but that is part of the learning process, and it will go away. There are few things Anja and Luiz can give their children that are so easy, and will benefit them in many ways for the rest of their lives.


The jury is still out on that question, at least in terms of brain development and cognitive benefits. In fact, a recent review of the literature shows little to no effect of bilingualism and higher achievement.

However, people who speak two languages will likely tell you that they have benefitted greatly from being able to communicate with others’ in their native language. And it’s a gift you can give to your child for free.

Note: Saxton, Mathew. Child Language. Sage Publications (UK), 2/2010. VitalBook file.

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