The bulk of academia seems to agree that the "Critical Period Hypothesis" is only really applicable to natural acquisition of language, and that the loss of natural faculties is compensated for by the ability to actively study language.
Kids learn language by listening, whereas adults tend not to pick up on all the details of the correct language they hear from natives until and unless their attention is drawn to it (and will therefore continue to repeat the same mistakes despite never hearing anyone else say it the way they do).
This failure to notice can at times be pretty extreme -- like the following story that genuinely happened to me.
I was teaching a private lesson to a Spanish couple. We were doing a listening lesson, which started with a "gist listening" (listening to the full passage and answering several comprehension questions) followed by "close listening" exercise where they listened to short excerpts of one or two sentences and tried to fill in the blanks.
On one sentence, they struggled. They filled in most of the gaps, until they just had two blanks left. The audio was talking about how "house prices" had increased in the speaker's village. Both of them were really confused. There were only two gaps left, but what they heard was three words: "prices of houses". I repeated it about 5 times -- they kept hearing "prices of houses", every single time. I told them it was "house prices", and they listened again and still looked a bit puzzled.
My explanation for this (personal hypothesis, I've never conducted any studies to confirm this, and really don't know how you ever could) is that as we get older, we get better at understanding people with different accents and dialects from us. It seems to me that our brains learn to understand what we hear by treating it as the closest thing that we might say ourselves.
As I see it, it's not a loss of language skill, but a
change of language skill. We're trading our ability to learn new language against the ability to understand varieties of language that are different from our own.
And this paper....
mentecuerpo wrote:Format: AbstractSend to
Cogn Psychol. 1989 Jan;21(1):60-99.
Critical period effects in second language learning: the influence of maturational state on the acquisition of English as a second language.
Johnson JS, Newport EL.
Abstract
Lenneberg (1967) hypothesized that language could be acquired only within a critical period, extending from early infancy until puberty.
Well, there are two important details here: time and place. We're talking about a study carried out in America in the late 80s. America is the home of Krashen, and the late 80s were the peak of Krashenite thinking. Krashen suggested that there is no "teaching" or "learning" of a language, only "acquisition" in the style of a first language. In that context, the critical period hypothesis is seen as having broad applicability to adults.
However, in modern times (at least outside the US and the English teaching industry) it is widely accepted that adult language learning/acquisition is fundamentally different from childhood language learning/acquisition, and the critical period hypothesis now really is only a matter of adapting techniques to move to a more "adult" style of learning as the capacity for "child" learning declines.