I have spent my life around different languages. At home, though I heard mostly English, there was plenty of Portuguese being thrown around, especially when my parents were talking about us. When I wasn’t at home, I was usually found at my best friend’s house, whose parents were francophone Quebecois. Another friend down the road lived with her Ukranian grandparents. I befriended the foreign students, starting with the little Italian girl who started school with us in 2nd grade. After all this, it should come as no surprise that I have spent the last 20 years focusing my attention on languages and linguistics.

When my oldest sisters started school, they spoke almost no English. After some time of watching her children become confused by hearing English at school and Portuguese at home, my mother decided that the best thing for the family would be to switch the home language to English. She did not want her children to have difficulty at school, and believed that dealing with two languages would only serve as a distraction and source of confusion for them. She wanted to make it easier to navigate this new culture and society she and my father had chosen to live in. As a result, I was born into a family that had made the transition almost completely into English, with the exception of certain kitchen commands, food terms, random traditional expressions, and ‘colorful’ phrases one would say when very angry at a small girl who has just broken the sugar bowl.

As a teenager and adult, I’ve had moderate success with second languages, but I longed for the same ease in another language as I have in English. I listen enviously to all the people I know who were lucky enough to have been brought up bilingual, and I wondered what prompted my mother – and many like her – to believe that maintaining her native language at home while her children learned English in school would have been a mistake.

These days, people generally agree that there is an advantage to being bilingual. Some of the more common reasons given are pragmatic: being more marketable in an increasingly global economy, or having an easier time with international travel. Then there are more intangible benefits that are often cited: being ‘open-minded’ or accepting of other people; understanding concepts in one language that are difficult to express in another language; being more sensitive to cultural differences. These are all benefits to be sure, but they only scratch the surface. There are, however, demonstrable cognitive advantages that go beyond what many people may expect.

The consensus of the past 20 years or so seems to be that the earlier children start to learn a second language, the better. But how is ‘early’ defined? In the United States, we generally start learning a foreign language around age 13 or 14, but at that age, we’re already working against the odds.

In this online poll, 40% of respondents believe that children should start learning between the ages of 3 and 5. One commenter gave a reason for an even later start: “Personally I remember that I was still trying to get the hang of my primary language at age 5-6 (I mean, with a great grasp.) Mixing it up might make children confuse words from the foreign language with their primary language and it might become solid in the memory that way into later in life. I suggest waiting until around 7 or so, depending on how well he/she has finally grasped their primary language.” The second most popular answer, with 24% of the vote, was age 6-9, coming only slightly ahead of age 1-2 with 21% of the vote. This suggests that ‘early’ should definitely mean before age 9 at the latest, but possibly as early as birth.

A 2008 study by Kovelman et al. was one of the first to look at the age of exposure and performance on reading tests in both languages.

They studied Early bilinguals (exposure from before the age of 3), Late bilinguals (exposure between age 3-6), and Monolingual children. They tested the children in both English and Spanish. Some of the more interesting results were that: “Early bilinguals were the only group to have high reading performance in both of their languages. On English reading tasks, Early bilinguals performed overall just as well as their classmates from monolingual English-speaking homes, and on Spanish reading tasks they performed just as well as children who were monolingual in Spanish until age 5–6.”

In addition, in order to maintain the focus on biological variables, they controlled for socioeconomic status. They found, “…despite all these similarities in SES, involving practice, instruction, home, school, and socio-cultural environments, we nonetheless observed statistically significant differences between the groups depending upon whether they had early versus late exposure to English.” In other words, not only may growing up bilingual give a child an advantage over monolingual children in literacy skills, but within their socioeconomic peer group, Early bilinguals still outperform Late bilinguals.

The work of Laura Ann Petitto gives us a clue to the biological underpinnings of these behaviors. When a child is born, he almost immediately starts to sort out human linguistic sounds from the cacophony of ambient noises he hears every day. Petitto explains: “ ‘No fetus knows if it’s going to grow up in New Jersey or grow up in Tokyo. So a human child from birth to six months has a universal capacity to discriminate any of the speech sounds in any of the world languages that it could have been exposed to.’ Between six months and a year, however, this capacity is diminished in one of the few aspects of human brain development where a child goes from better to worse, Petitto says. Instead, the capacity to distinguish the tiny variations in phonetics that are specific to the child’s own language skyrockets.”

In the brains of bilingual children exposed from birth to two languages, however, this hyperfocus on one language does not occur. The brain doesn’t ‘turn off’ to all other languages but its own. The conjecture is that this gives the brain a greater capacity for learning vocabulary in both languages, which then translates in later school years to increased literacy and general cognitive skills. “Indeed, Petitto says studies she conducted of bilingual children from some of the poorest neighborhoods in the United States showed that their reading capacity was the equal of unilingual kids from the country’s wealthiest enclaves.” The advantage, then, of bilingualism is so pronounced that it can make up for the clear disadvantages of socioeconomic class. Not only do Early bilinguals outperform their Late bilingual peers, but poorer bilingual children perform as well as wealthier monolingual children on literacy tests.

Most of the focus is on babies or school-aged children, but recent research has shown that the advantage of bilingualism  continues into adulthood, and may not only compensate for age-related declines in recognition and response speed in processing language, but can also help stave off dementia.

With the overwhelming evidence that suggests that the best case scenario is learning two languages from birth, why would anyone who had the opportunity to give their children two languages opt for giving only one? Clearly, much of this understanding is relatively new, so people of my parents’ generation would not have been privy to this information. However, in the poll mentioned above, 2% of the respondents say that a child should never learn a foreign language. This means that even now in the 21st century, there is still some resistance to child bilingualism.

What might be the disadvantages of a bilingual childhood that could outweigh the cognitive benefits? While I work on the research, tell me what you think!