Until the 1990s, many American parents refrained from teaching their young children a second language for fear of confusing them.
In fact, as recently as 1999, researchers had published papers claiming that teaching your child a second language before they have mastered a first language could result in double semi-lingualism; i.e., the child does not develop full proficiency in either of the two languages. People who follow this school of thought on the best age to learn a second language believe that children should not be exposed to a second language until the age of approximately 11-13 years.
However, most current research suggests this fear is unfounded, and some evidence suggests that we may never be able to become perfectly bilingual if we start learning the second language after age 10.
[That being said, it's far from impossible to learn a language as an adult. Although children may have some advantages over adults when learning a language, in some ways, adults are better suited than children to learn a second language.]
All that is to say that children can learn two languages at once and there are many benefits to learning a second language as soon as possible. We'll explain why in more detail below!
Being bilingual vs. being fluent
Being bilingual and being fluent in a second language are not quite the same thing. Anyone who has taken the time to become fluent in a second language can tell you that. Becoming fluent in a second language is almost like memorizing your times tables. It can feel like second nature, but almost everyone has blanked once or twice on 7 x 8. (It's 56, in case it slipped your mind!)
For example, those who are fluent in Spanish (for example) may need to occasionally refresh themselves on when to use “por” vs. “para” (both mean “for” in English, but are used for different situations in Spanish). In contrast, being bilingual means you can think in either language easily, and misusing “por” would be akin to saying something like “There is fewer snow in Florida than New York.” A person fluent in English may confuse “less” and “fewer,” but a native or bilingual speaker would never make that mistake.
You're not going t0 be able to avoid memorization with language learning. There's a ton of vocabulary and grammar concepts that you'll need as a solid base when starting to speak and understand a new language. This is why Brainscape's spaced repetition system for foreign languages is the best way to effectively remember new concepts over the long term.
Just remember that learning a new language is and always will be much more difficult than memorizing your times tables, or even memorizing thousands of new words. Because of challenges like proper pronunciation and understanding a completely different grammar structure, it's important to start as early as possible.
Language and your child’s brain
Clearly, if your goal is to have your child learn a second language, it would be preferable for your child to be bilingual as opposed to fluent. Your child will have a much easier time speaking two languages if his or her brain learns both language structures at the same time.
Let’s take a look at some of the developmental changes that occur in the brains of babies and children, when it comes to language acquisition. This information can help us make informed decisions about guiding learning.
The first month — Newborn babies develop new synaptic connections at the rate of up to three billion per second (Kotulak, 1996). Everything that a baby hears, sees, feels, tastes, and touches is absorbed by the brain.
One to six months — In this time period, babies are capable of making sounds used in all the languages in the world. However, a child will learn to talk using only the sounds and words in their environment. That’s why you may never be able to properly roll your Rs or pronounce Xhosa, an African “click” language unless you learn it very early.
Six to eight months — The baby’s brain has about 1,000 trillion synaptic connections. After this age, the number of connections begins to diminish. The brain starts to pare down the connections that are not used and strengthen ones that are used more often.
Age 10 — About half the connections have died off in the average child. The average adult has approximately five hundred trillion connections, so the number has reached a stable state.
Age 12 — Prior to about this age, the brain has been a sponge for language. It is during this period that the foundations for thinking, language, vision, attitudes, aptitudes, and other characteristics are laid down. After this stage of development, the windows close; the fundamental architecture in the brain for language is complete.
The best age to learn a second language
According to this model, it is clear why some believed it was best to start teaching a second language at the age of 11-13. The child could more easily understand the lesson, and would likely seem to make progress more quickly than a younger child. However, a child who is first exposed to a second language at this later age will not intrinsically learn it in the same way a baby or toddler would (especially when it comes to pronunciation and particular puns or nuances).
Other researchers claim that the window for language learning closes even earlier, by age 6 or 7. Therefore, the best age to learn a second language is essentially from birth, or as early as possible. There isn’t a fully complete answer to this question, but most linguists now agree: the sooner you get started, the better.
Better late than never
Remember that you can still learn a new language past the "window of opportunity" period. There are tons of benefits to exercising your brain by practicing a new language, so don’t be put off by the idea that you’ll never speak on a native level. Tools like Brainscape's foreign language flashcards can make it fun and easy to drill vocab and grammar and learn a second language at any age!
Byers-Heinlein, K. & Lew-Williams, C. (2013). Bilingualism in the early years: What the science says. LEARNing landscapes, 7(1), 95. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6168212/
De Houwer, A. (1999). Two or More Languages in Early Childhood: Some General Points and Practical Recommendations. ERIC Digest. https://eric.ed.gov/?id=ED433697
Dryden, G., & Vos, J. (1997). The learning revolution. Monterey Institute of International Studies.
Flege, J. E., Yeni-Komshian, G. H., & Liu, S. (1999). Age constraints on second-language acquisition. Journal of Memory and Language, 41(1), 78-104. https://doi.org/10.1006/jmla.1999.2638
Genesee, F., Nicoladis, E., & Paradis, J. (1995). Language differentiation in early bilingual development. Journal of Child Language, 22(3), 611-631. https://doi.org/10.1017/S0305000900009971
Kotulak, R. (1997). Inside the brain: Revolutionary discoveries of how the mind works. Andrews McMeel Publishing.