Start before the age of 10 to become fluent in a language

CHILDREN must start learning a second language before the age of 10 if they ever hope to become fluent, the largest study of its kind has found.

Scientists at the Massachusetts Institute of Technology and Boston College studied data from nearly 700,000 language learners and established there is a “critical period” up to the age of 18 where the brain is most receptive.

While this period is far longer than researchers previously thought, the data also suggest that there is a relatively young cut-off point before which children must start learning to achieve native fluency. The researchers said that while it is typical for children to pick up languages more easily than adults – a phenomenon often seen in families that migrate to a new country – the trend has been difficult to study in a laboratory setting.

Prof Joshua Hartshorne, from Boston College, who led the study, said: “We don’t see very much difference

‘This is a rare opportunity to take a new perspective and see something that other people haven’t’

between people who start at birth and people who start at 10, but we start seeing a decline after that.”

Following people as they learn a language over many years has previously been challenging for scientists.

In the study, they used a social media questionnaire to obtain snapshots of thousands of people who were at different stages of learning English. By measuring the grammatical ability of people of different ages, who started learning English at various stages in their life, they were able to gather enough data to achieve robust conclusions

“This is one of those rare opportunities in science where we could work on a question that is very old, that many smart people have thought about and written about, and take a new perspective and see something that maybe other people haven’t,” said Prof Josh Tenenbaum, an MIT professor of brain and cognitive sciences.

Steven Pinker, a professor of psychology at Harvard University, is also an author of the paper, which is published in the journal Cognition.