New research from the Massachusetts Institute of Technology (MIT) suggests that if people want to achieve native-like proficiency(流利度) in a new language, they should start learning that language before the age of ten. The researchers added that children up to the age of 17 or 18 remain adept(擅长的;精于) at learning grammar. There is bad news for those who want to pick up a new language beyond their late teens. The researchers say this is past the "critical period" when language-learning ability starts to decline(下降). Researcher Joshua Hartshorne said: "As far as a child is concerned, it's quite easy to become bilingual(双语的)....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 an analysis of results from a 10-minute online grammar quiz(测验). Over 670,000 language learners of all ages participated in the test. Researchers measured the grammatical ability of people who started learning a language at different points in their life. Professor Hartshorne focused on grammar rules that were most likely to confuse a non-native speaker as a gauge(评估，标准) of that person's proficiency. MIT researcher Josh Tenenbaum suggested people simply might be too busy to learn a language later in life. He said: "After 17 or 18, you leave home, you work full time, or you become a specialized university student. All of these might impact your learning rate for any language."