The Critical Window of Language Acquisition

It’s usually agreed that the earlier children acquire a second language, the better their cognition and language acquisition skills in later life. In support of this, the findings of a journal recently posted to online news outlets suggest that to acquire native fluency, it is best to start before the age of 10.

This period of development is often referred to as the critical window of language acquisition; the implication is that the ability to easily pick up on grammar and its intricacies begins to decline through a person’s teens, and drops right off as they enter their twenties.

So what happens to children who have, in some way or another, missed the critical window?

In reality, the issue is much more complicated than ascribing a magic age of no return to language acquisition. It’s an issue of brain plasticity.


Your Brain is Plastic

Neural connections aren’t set in stone.

There are around 86 billion – yes, billion – neurons in the average human brain, which are in part responsible for your every thought, action, and memory. Without anything to connect these disparate cells to one another, your brain would be incapable of communicating with itself, let alone tackling the complex nuances of communicating with another human being.  

This is where brain plasticity comes in. Neuroplasticity is based around the theory that our brains are strengthened by developing and maintaining neural connections, which are born of new experiences and training. In other words, education literally rewires your brain. Conversely, when we forget or allow our skills to decline, these connections degrade or are severed to make way for new ones.

This plasticity is often likened to that of a muscle; through repetition and exploration, your mind improves its ability to perform mental tasks, just as your arms can be trained to lift heavier and heavier objects. In the same way, every time you teach a lesson to a class of students, you are strengthening and rewiring their brain.

At a young age, our brain activity is particularly malleable, and brain activity associated with various tasks can even shift to different areas over time. The fact is, as the brain ages, it begins to lose this ability. It can become physically more difficult to learn new things.

What does this mean for us as educators? Are we, and the older children in our care, doomed to a unilingual existence? Does grammar acquisition rely solely on the plasticity of your brain, which, in turn, relies solely on your age?

Well, not exactly.


Feral Children Studies

Feral children and their struggles with language acquisition can provide an extreme-case scenario to help us to understand the effects of the critical window of brain plasticity on language acquisition.

The case of Genie, who was kept in isolation until the age of 13, is particularly upsetting, but it provided linguists and psychologists with a previously unavailable insight into early language acquisition skills.

Unfortunately for Genie, this extreme isolation left her unable to acquire verbal language; it seems she is physically incapable of doing so. The area of her brain that processes verbalisations has lost its childhood plasticity, supporting the theory that it becomes considerably more difficult to learn new languages past the critical window of language acquisition.

However, it’s not all doom and gloom once you hit your teens. Other studies of feral children, such as that of Oxana Malaya, have found greater success. Raised by dogs, Oxana originally mimicked the physical behaviours of a dog, and lacked human speech. She was unsocialised, and seemed incapable of communication outside of grunts, barks, and nonverbal cues.

Thankfully, since then, she has been able to learn fluency in her native tongue, resocialise herself, and live a more fulfilling life. Her brain was still plastic enough to acquire language, despite missing out on the critical window.

It’s important to remember that these are extreme cases, in which the children never learned a primary language. Hopefully, this should be true for none of the children in your care. Instead, in our case, we need to consider the importance of formal grammar education, reading for pleasure, and learning a second (or third, or fourth, or fifth) language.


Teaching Old(er) Dogs New Tricks

There are also many cases of adult spies gaining complete fluency with foreign languages, such as in the notable case of Russian spy Castro-Grigulevich. Even though he was already in his 20s, well past the critical window, he was capable of learning Spanish to such a high level of fluency and understanding that he passed as a Costa Rican diplomat for years.

Despite this human ability to adopt new grammar structures later in life, there is still a marked benefit in teaching languages to children at a younger age. It’s certainly true that some EAL students are capable of learning and becoming fluent in English very quickly, but this is still an easier process if it’s started from a younger age. Anecdotally, many parents and teachers agree that young children who have achieved fluency in multiple languages are much more receptive to language education than their unilingual peers, even in their native language.

As a result, many primary schools are now offering MFL as a subject from an early age, and, if the critical window is to be believed, this could have a huge positive long-term effect on those students’ ability to understand and absorb the grammar structures inherent to foreign languages. In a rapidly shrinking world, multilingualism is becoming more important than ever, and children who are handed the advantage of a second language in their early years before the critical window closes will have an immediate advantage over those who haven’t.

But it’s never too late to start.


Interested in supporting language education in your school? Have a look at the languages pages in our planner page idea library.

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