There is a well-researched theory in linguistics known as the "critical period," which suggests that it becomes more difficult to learn a second language as we age. In particular, a critical period for phonological acquisition is widely accepted. In other words, research has shown that students who learn a second language early will be able to speak that language without an accent, which probably accounts for the push to teach a second language at an early age. Here's an interesting TED talk about this idea:
There's a lot of information out there about bilingual education, if you're interested. In general, though, the effects of learning a second language at an early age are overwhelmingly positive. Some studies even suggest that it improves overall academic ability.
I would say anytime is fine. There is a lot of research on the issue, but my wife and I raised our son in a bilingual home, Japanese/English, since he was born. My wife only spoke Japanese with him and myself English. We even made him translate between us when we wanted to talk. Not until he was 6 or 7 years old did he find out that my wife and I could talk to each other without him. Now, he is in 8th grade, he is fluent in both languages, able to switch between the two, and enjoys being bilingual. He studied Spanish last year and picked it up pretty quickly. The biggest challenge we had was when he learned we could speak to each other. He then tried to pick one language and use it. In his case he picked English since we were living in America. It took my wife about 6 months of telling him she did not understand him and to speak Japanese before he spoke both languages. That was our only problem.
As well as the second language research you should look at David Sousa, How the ELL Brain Learns and other neuroscientists. The second language is stored in a different part of the brain than the mother tongue, building more neurons and connecting more areas of the brain.
In my opinion, and from all the research I have read, I'd just teach the child both languages and help him/her become proficient in both.
Learning a second language at an early is the best way for a child to actually be fluent in both languages. I think if a child learns the language early it will stick with them and it’s easier for them to learn also. When children are young their brains are like sponges and they absorb so much. As a child my parents didn’t try too hard to teach me Spanish so I was never able to speak the language but I could understand it. So when I was in middle school and high school I took four years of Spanish but I still can’t speak the language. I think it would have been much easier for me to learn a second language in preschool or elementary school.
Great story about your son! Speaks volumes about how bilingualism is so beneficial to a child. Not just for obtaining a language but for the cognitive benefits it offers down the road of life.
I also agree with the notion - any time. Of course with pronunciation, children don't have problems later. But research also shows that adults actually have a better ability to acquire a language. Patricia Kuhl makes some good points but she isn't wearing much when she says that young children learn languages faster. What makes a young learner better at learning a language is that that's all they do - they spend so much time at it. But when you compare time spent, adults are better.
I find it interesting , all the research about brain plasticity and language (when the brain divides into two halves). that's an area that should receive more attention.
I also agree about the "sooner is better" theory.
I'm a french automotive engineer, and now live as an expatriate in Turkey, using English language for business and Turkish when talking to workers/with suppliers. We ready many books with my wife in order to decide what would be our way, with our kids.
My 4 years old baby girl (Clélia) is now fluent in Turkish as well as French, and studies in a 100% Turkish school. We decided that we would only speak french at home, and that outside the house, any of use could pick the most "consistent" language.
After loooong discussions with my wife, we finally agree last year that Clélia would also get English lessons at schools, and it works pretty well: the 3 languages are totally distinct for her.
As regards my 2.5 years old boy: he understands both Turkish and French (but he just starts talking ...), and we plan to manage language acquisition the same way as for his daughter.
Actually, I had to work quite a lot in order to get a reasonable level in Turkish in parallel with my daughter who was just... talking every day. So, to adjust what ddeubel wrote, I think kids learn quickly:
- because they practice a lot,
- and also because they don't care about vocabulary/grammar mistakes, so they give it a try whenever possible. I think the natural tendency for an adult is to avoid the difficulties in everyday life (eg going back to easier language, or just changing the subject you were talking about etc.)
Anyway, I think that if you stick to clear rules with your child so that he doesn't get mixed up between languages, it's a wonderful opportunity to get him/her talk several languages (I can just speak about "up to 3!").
Learning a second language at an early age is actually crucial for lifelong use and growth. Language development must begin as an infant for children to develop following standard growth patterns. My bilingual friends credit their language skills to a combination of two things; the fact that they begin learning young, and the fact that their surrounding macrosystems made use of the languages they were learning that way they never forgot!