Research shows there’s a critical cut-off age for learning a language fluently

When my first-born was born, I knew she would be raised bilingual.

She was born in Norway, but we live here in Ireland, and despite her dad not speaking a word of Norwegian, using my mother tongue when speaking to my baby is what came most natural to me. Maybe because we, as mothers, tend to very much mimic our own mothers in the way we mother our babies, but also, it was hugely important to me that she would have both languages – after all; she belongs in equal part to both countries. We were warned, I remember, how introducing a baby to two languages from the get go could result in her speech being a little delayed, but in our experience, this was not the case at all. Before she turned two, our little girl was fully able to hold conversations in both Norwegian and English with no issue swapping back and forth between the two depending on who she was speaking to. Children's brains are like total sponges at that age, and so when our little boy was born three years later, he followed much the same pattern, and spoke both languages from when he started to speak. And I love how they now have their own "secret" language. I hear them sometimes, in playgrounds, switching to Norwegian if they are chatting to each other, or if they don't want someone to know what they are saying. It also is amazing when we go to Norway, and they can run out and play with their cousins and all their little friends, instantly being included because they speak the same language. As for learning languages, the earlier you start introducing a second (or third) one, the better, apparently, as research has now discovered there is a critical cut-off age for learning a language fluently. What this means, experts now argue, is that if you want to have native-like knowledge of a language, you should ideally start before age 10. The results also found that if you haven't gottten around to learning another language before that age, it's not necessarily too late, it just might not come as easy as it does to younger children. Studies have shown people remain fairly skilled learners until 17 or 18, when ability tails off. It is unclear what causes the drop in the optimal learning rate seen at about age 18. The researchers suggest it could be because the brain becomes less changeable or adaptable in adulthood. The findings of the study, in the journal Cognition, come from an online grammar test taken by nearly 670,000 people of different ages and nationalities. The grammar quiz was posted on Facebook to get enough people to take part. Questions tested if participants could determine whether a sentence written in English, such as: "Yesterday John wanted to won the race," was grammatically correct. Users were asked their age and how long they had been learning English, and in what setting - had they moved to an English-speaking country, for example? About 246,000 of the people who took the test had grown up speaking only English, while the rest were bi- or multilingual. The most common native languages (excluding English) were Finnish, Turkish, German, Russian and Hungarian. Most of the people who completed the quiz were in their 20s and 30s. The youngest age was about 10 and the oldest late 70s. When the researchers analysed the data using a computer model, the best explanation for the findings was that grammar-learning was strongest in childhood, persists into teenage years and then drops at adulthood.   Study co-author Josh Tenenbaum, a professor of brain and cognitive sciences at the Massachusetts Institute of Technology in the US, said: "It's possible that there's a biological change. It's also possible that it's something social or cultural. "There's roughly a period of being a minor that goes up to about age 17 or 18 in many societies. After that, you leave your home, maybe you work full time, or you become a specialised university student. All of those might impact your learning rate for any language."