Bilingual kids: what research shows about first words, the brain and moving abroad

From newborn labs to census data on immigrants, the studies agree: children who grow up with two or more languages speak on time, think more flexibly and settle into a new country more easily. Here is what the research found and what it means for a family move.

In detail

Bilingual kids are not a compromise between two languages. Decades of clinical, psychological and brain research describe them as children who listen more carefully, control their attention better and read other people more accurately, with no delay in their first words. For families planning a life in another country, that research carries a practical message. The earlier a child meets the language of the new home, the easier school, friendships and later work become. And a child who keeps the family language alongside it arrives with something extra rather than something missing. This article walks through the studies, from newborn labs to census data on immigrants, and ends with what they mean for families who want their children to grow up with four or five languages.

Bilingual from the first day of life

The story begins earlier than most parents expect. Krista Byers-Heinlein, Tracey Burns and Janet Werker tested newborns at the University of British Columbia. Babies whose mothers had spoken only English during pregnancy preferred English to Tagalog. Babies whose mothers had spoken both English and Tagalog regularly showed an equal preference for the two languages. A second experiment showed that both groups still told English and Tagalog apart, so the preference for two languages was not confusion. The authors put it plainly in Psychological Science in 2010: "The first steps toward bilingual language acquisition have already begun at birth."

A few months later, bilingual babies hold on to skills that other babies lose. Whitney Weikum and colleagues, publishing in Science in 2007, showed silent videos of faces speaking English and French. At 4 and 6 months, infants noticed when the language changed just by watching the lips. By 8 months only the French-English bilingual infants still succeeded. Growing up with two languages kept a door open that monolingual development closes.

Brain imaging shows the same pattern at 11 months. Naja Ferjan Ramírez, Patricia Kuhl and their team at the University of Washington recorded infants' brain responses to Spanish and English syllables with magnetoencephalography. Monolingual babies' brains were tuned to English. Spanish-English bilingual babies' brains responded to both languages. The team described the slower shift from raw sound to language-specific sound as "an adaptive and advantageous response to increased variability in language input" in Developmental Science in 2017. In bilingual infants these responses also reached the prefrontal and orbitofrontal cortex, regions the authors link to the executive function advantage seen in bilinguals.

First words arrive on time

The most persistent worry about bilingual kids is that two languages slow speech down or mix a child up. The research does not support it. Laura-Ann Petitto and her team at McGill University filmed six children over a year, three learning French and English and three learning French and Quebec Sign Language. In the Journal of Child Language in 2001 they reported that both groups reached their early milestones in each language at the same time, and at the same time as children learning one language. From their very first words they produced matching words for the same thing in both languages, and they changed language depending on who they were talking to. The authors concluded that "the capacity to differentiate between two languages is well in place prior to first words". Mixing was there too, and it tracked how much the parents themselves mixed.

Vocabulary follows the same logic. Erika Hoff and colleagues compared bilingual and monolingual toddlers from families with equally high incomes and education, from 22 to 30 months of age. Counted one language at a time, monolingual children were ahead. Counted across both languages, the two groups "were comparable on a measure of total vocabulary" (Journal of Child Language, 2012). A bilingual two-year-old who knows "dog" in English and a different set of words in Spanish knows as much as a monolingual peer, spread across two languages.

Krista Byers-Heinlein and Casey Lew-Williams pulled this evidence together for parents in LEARNing Landscapes in 2013, separating common myths from findings across six of the questions parents ask most often about early bilingualism. Their review is a useful answer for anyone who hears from a relative that a second language will hold a child back.

What two languages do for attention and communication

Switching between languages every day trains the mind's control system. Raluca Barac and Ellen Bialystok at York University tested 104 six-year-olds in four groups: English monolinguals and children speaking English with Chinese, French or Spanish. On a nonverbal task of executive control, the mental system that steers attention, all three bilingual groups performed alike and outperformed the monolinguals (Child Development, 2012). The groups differed in culture, schooling and how close their two languages were, which makes the shared result stronger.

The social side is just as striking. Samantha Fan, Zoe Liberman, Boaz Keysar and Katherine Kinzler gave children a task in which they had to take a speaker's point of view to work out what the speaker meant. Monolingual children misread the speaker's meaning far more often than bilingual children. Children who simply grew up hearing another language around them, without speaking it themselves, did as well as the bilinguals. "For millennia, multilingual exposure has been the norm," the authors wrote in Psychological Science in 2015. For a family about to move, the finding is direct: a child raised among languages learns early that other people see the world from a different place.

The benefit lasts a lifetime

The advantage does not fade with childhood. Ellen Bialystok, Fergus Craik and Morris Freedman examined the records of a memory clinic and focused on 184 patients diagnosed with dementia, 51 percent of them bilingual. "The bilinguals showed symptoms of dementia 4 years later than monolinguals," they reported in Neuropsychologia in 2007, with other measures equal and the same rate of decline after diagnosis. A lifetime of managing two languages built a reserve that held off the first symptoms.

Why age of arrival matters for school, work and belonging

For a family planning a move, the most practical question is timing. Jacqueline Johnson and Elissa Newport tested the English grammar of 46 native speakers of Korean and Chinese who had arrived in the United States between the ages of 3 and 39. Their Cognitive Psychology paper of 1989 found "a clear and strong advantage for earlier arrivals over the later arrivals". Up to puberty, the younger the age of arrival, the better the grammar, and the gap did not come from years of experience, motivation or identification with the new country.

A much larger study confirmed the window and showed how long it stays open. Joshua Hartshorne, Joshua Tenenbaum and Steven Pinker analysed the grammar of 669,498 native and non-native English speakers. They found that the ability to learn grammar is "preserved almost to the crux of adulthood (17.4 years old) and then declines steadily" (Cognition, 2018). Children who start early have the most years inside that window, which is why they so often end up speaking the new language like natives.

Economists see the same pattern in pay slips. Hoyt Bleakley and Aimee Chin used the fact that young children learn languages more easily to measure what the language itself is worth. In The Review of Economics and Statistics in 2004 they found "a significant positive effect of English proficiency on wages among adults who immigrated to the United States as children", with much of the gain passing through more years of education. In a follow-up based on the 2000 US census, published in the American Economic Journal: Applied Economics in 2010, the same authors linked better English among immigrants who arrived young to more marriages outside their own community and, for some groups, to living outside ethnic enclaves. Language learned early turns into family ties and a place in the wider society.

A second language also pays on its own. Albert Saiz and Elena Zoido studied a representative sample of US college graduates and measured a wage premium of 2 to 3 percent for graduates who speak a second language (The Review of Economics and Statistics, 2005). A child who keeps the family language and adds the language of the new country carries that premium into adult life.

Three, four or five languages: what the evidence shows

Many families who move do not stop at two languages. A child in Lisbon or Dubai often hears one language from each parent, another at preschool and English everywhere. Research on these children is younger, but its findings are consistent. Sophie Côté, Ana Maria Gonzalez-Barrero and Krista Byers-Heinlein at Concordia University compared 170 bilingual and 20 trilingual toddlers aged 17 to 33 months in a Canadian community where both French and English are spoken. The trilinguals produced on average two thirds as many French and English words as the bilinguals, but the gap was not statistically reliable because children varied so widely, and the amount of each language a child heard tracked the size of the vocabulary. The authors concluded in the Journal of Child Language that "similar factors contribute to vocabulary development across toddlers regardless of the number of languages being acquired".

School-age children show the same picture. Karolina Mieszkowska, Ewa Haman and colleagues tested 56 children aged 4 to 6 in the United Kingdom: Polish and English monolinguals, Polish-English bilinguals and trilinguals with a third language at home. In English, the language of school and the street, the three groups knew the same number of words (Frontiers in Psychology, 2017). The home language was weaker in the multilingual children, and the authors' advice to migrant parents was to support it actively if they want it to last.

The benefit of each added language reaches into old age. Gitit Kavé and colleagues followed 814 older Israelis with an average age of 83 across three interviews over 12 years. The more languages a person spoke, the better they scored on cognitive screening tests, beyond age, gender, education and age of immigration, and the effect held even among people with no formal schooling at all (Psychology and Aging, 2008).

Put together, these studies give parents of future polyglots one clear rule. Every language grows with its share of the child's week. Côté's team tied vocabulary to how much of each language a child heard. Stephanie Place and Erika Hoff asked the mothers of 29 Spanish-English bilingual two-year-olds to keep diaries of every language contact. The relative amount of each language predicted the child's skill in it, and for English, hearing it from several different people and from native speakers added more (Child Development, 2011). A fourth or fifth language therefore needs a small regular slot of its own, every day, rather than a long lesson now and then.

Little and often, with a person beside the child

How a language arrives matters as much as how often. Patricia Kuhl, Feng-Ming Tsao and Huei-Mei Liu gave 9-month-old American babies 12 laboratory sessions with native Mandarin speakers. The babies kept the ability to hear Mandarin sounds that their English-only peers were losing. A second group saw the same speakers on video or heard them on audio, and learned nothing. In PNAS in 2003 the team summed up that infants learn sounds "from live, but not prerecorded, exposure to a foreign language". A real person in the room, responding to the child, makes the difference.

The same team then tested the idea in public nurseries. Naja Ferjan Ramírez and Patricia Kuhl brought a play-based English programme to four public infant education centres in Madrid and enrolled 280 children aged 7 to 33.5 months. The children had one hour of English a day for 18 weeks with tutors who used the sing-song speech parents use with babies. By the end, children in the programme produced an average of 74 English words or phrases per hour, against 13 in the comparison group on the schools' standard bilingual curriculum. They kept what they had learned 18 weeks later, results were similar in low- and middle-income neighbourhoods, and their Spanish kept growing (Mind, Brain, and Education, 2017).

That is the logic behind Tatako, a first-words app for parents who are raising a child with two languages. A parent and child do each lesson together: the child hears a word, finds it on a picture and says it aloud, with nothing to read. The lesson takes a few minutes, so it fits into every day, and the family language stays at home while a new one grows one small word at a time. With Tatako, English starts from the very first words. Parents who want a plan for the first years will find one in the Tatako guide on how to raise a bilingual child.

Moving abroad with bilingual kids

The research gives families two clear advantages to protect. The first is time: the younger a child is when the family settles in the new country, the more naturally the local language takes root. The second is continuity: the home language has to keep its daily place, or it shrinks. A move that is planned around the children, with the right residence status for every family member from the first day and no months lost to paperwork, protects both.

Murblz handles the legal side of that move for the whole family. We choose the residence route that covers parents and children together, prepare and file the documents, and plan the road from residence to citizenship. For families with capital, our overview of residency by investment programmes compares the countries where an investment brings residence for the whole family. How such a road looks in practice is shown in the story of how a family got Argentine citizenship. The process is clear and transparent, with a date for each step. The cost is available on request from a manager.

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