How Critical Is the Critical Period for Language

A new study performed at MIT suggests that children remain very skilled at learning the grammar of a new language much longer than expected — up to the age of 17 or 18. People who start learning a language between 10 and 18 will still learn quickly, but since they have a shorter window before their learning ability declines, they do not achieve the proficiency of native speakers, the researchers found.

https://news.mit.edu/2018/cognitive-scientists-define-critical-period-learning-language-0501