According to the study which appeared on the journal Cognition, learning in an immersion setting – living in the country where the foreign language is spoken – is also more beneficial regardless of the age of first exposure to the foreign language.

Using a sample of “unprecedented size” to isolate the trajectory of learning ability from age at first exposure, age at testing and years of experience, the researchers found that grammar-learning ability in a second language changes with age, declining slightly after age 10-12 and then more markedly after age 17-18.

“If we are going to do language instruction in school…I don’t see why it can’t start from day one”

This places the offset of the critical period for language learning “much later than previously speculated,” the authors argued.

But the earlier, the better, lead author Joshua K. Hartshorne told The PIE.

“With all other factors equal, starting earlier would be better. Keep in mind that the decline is steady – this means that starting at 12 would be better than starting at 15,” he said.

“If we are going to do language instruction in school we ought to start very young. I don’t see a reason why it can’t start from day one.”

The advantage observed for immersion learners – participants that indicated they were living in an English-speaking country – is “enormous”.

Immersion learners starting before age 10 will outperform non-immersion learners, and even if they first begin learning a language after age 20 they will still do about as well as non-immersion learners who started in their early childhood, Hartshorne explained.

“At any given age that you start, at least in our dataset, you are better off in an immersion environment.”

“If the goal is to communicate, it may not matter that you can sound exactly like a native speaker”

A total of 669,498 participants took an online quiz encompassing a diverse set of grammar features, including passivisation, agreement and preposition use.

The wide variety of aspects tested, the authors explained in the study, allowed them to erase differences brought about by the participant’s first language – an important feature, since participants listed 6,000 first languages or combinations of them.

The quiz, which was shared more than 300,000 times on Facebook, is still available on this website, where users can take other quizzes to test their language ability.

However it’s important to note that the research only examined grammar learning ability and not other aspects of language, such as pronunciation, Hartshorne said, which poses a question for teachers and students interpreting the results of the study; ‘what is your goal’?

“It’s perfectly possible to communicate with bad grammar – if the goal is to communicate, it may not matter that you can sound exactly like a native speaker,” he said.

Also, he said, it would be reasonable to expect different results when testing pronunciation.

“My expectation is that your ability to learn pronunciation declines earlier, as evidenced by other studies. It may fundamentally be harder to have two accents than two grammars,” Hartshorne concluded.

Commenting on the findings and their significance for EFL teachers and teacher trainers, CES head of teacher development Chris Farrell said classroom learners can also be offered real-life language practice if teachers are trained to do so.

“It may fundamentally be harder to have two accents than two grammars”

“Findings like this make the change from a ‘knowledge-led curriculum’ with a focus on what the learner will know at the end of their course of study, to a ‘behaviour-led curriculum’ which focuses on what the learner will be able to do better at the end of their course of study,” Farrell explained.

“Real world application can be modelled and built into language lessons quite smoothly if the teachers are trained to do so.”

He also highlighted the essentially social nature of language learning, and the importance of preserving it through a support network also for adult students, who unlike children tend to learn independently without the support of their peers.

“Having a support network of people who are all being taught at the same pace as you can only benefit language progression in the short term,” he concluded.