What is meant by the critical period in language learning?
There is considerable research which shows that we are best able to learn languages before the age of five. The brain is more flexible when we are infants. Our language capability hasn’t yet solidified around one specific language. Theoretically we could learn any language as our native language when we are very young. As we get older, it usually becomes more difficult to develop native like competence in a second language. It takes a more deliberate effort, even though an adult can acquire a large vocabulary in a relatively short period of time.
What does this mean for language education?
Some parents and some educators think that this means that we should teach infants more than one language. I think that this can be beneficial, but in my opinion, it should not be at the expense of a normal childhood. In fact it is possible to learn a second language as a young child and then to forget this language if we don’t have the opportunity to use it later on. I think parents should not be too ambitious for their children, and let them enjoy interacting with their friends and family. Certainly I would not favour formal language instruction for young children. However, exposing them to different languages via film and song, is probably a good idea. If the child is lucky enough to have a parent or relative who speaks another language, this can also be taken advantage of.
Does the critical period imply that adults can’t learn languages?
I have learned just about all of my foreign languages as an adult. Some of the leading polyglots on the Internet like Luca and Richard Simcott, have also learned their languages as adults. Even if, in theory, a young child can acquire language more easily than an adult, I really don’t think that this should change much in our approach to language education. Language learning depends mostly on the attitude of the learner, and the willingness of the learner to spend enough time with the language. This is true of children and it is true of adults. Anyone can learn a language, regardless of their age.