New research suggests that to achieve native-like proficiency in a new language, people should start learning before the age of ten. Researchers said children up to the age of 18 remain skilled at learning grammar. Unfortunately, those who want to pick up a new language beyond their late teens are past the "critical period" when language-learning ability starts to decline. A researcher said: "As far as a child is concerned, it's quite easy to become bilingual....That's when you're best at learning languages. It's not really something that you can make up later."
The research was based on the results of 670,000 people taking a 10-minute online grammar quiz. Researchers measured the grammatical ability of people who started learning a language at different points in their life. The test had grammar rules that were likely to confuse non-native speakers. These measured a person's proficiency. Another researcher suggested older people might be too busy to learn a language. He said after 17 or 18, people leave home, go to university or start work. All of these could affect how well someone learns a language.