Why Can't I Speak Spanish?: The Critical Period Hypothesis of Language Acquisition
"Ahhhhh!" I yell in frustration. "I've been studying Spanish for seven years, and I still can't speak it fluently."I enjoyed this, because I'm attempting to learn Spanish, and I've been reading a lot about the differences in the ways children learn a 2nd language, compared to the ways adults learn. Both can be successful, but it's important to find the right approach, particularly for adults, I think. Read the whole thing, for the many embedded footnotes and reference links.
"Well, honey, it's not your fault. You didn't start young enough," my mom says, trying to comfort me.
Although she doesn't know it, she is basing her statement on the Critical Period Hypothesis. The Critical Period Hypothesis proposes that the human brain is only malleable, in terms of language, for a limited time. This can be compared to the critical period referred to in to the imprinting seen in some species, such as geese. During a short period of time after a gosling hatches, it begins to follow the first moving object that it sees. This is its critical period for imprinting. (1) The theory of a critical period of language acquisition is influenced by this phenomenon.
This hypothetical period is thought to last from birth to puberty. During this time, the brain is receptive to language, learning rules of grammar quickly through a relatively small number of examples. After puberty, language learning becomes more difficult. The Critical Period Hypothesis attributes this difficulty to a drastic change in the way that the brain processes language after puberty. This makes reaching fluency during adulthood much more difficult than it is in childhood.
Noam Chomksy suggests that the human brain also contains a language acquisition device (LAD) that is preprogrammed to process language. He was influential in extending the science of language learning to the languages themselves. (4) (5) Chomsky noticed that children learn the rules of grammar without being explicitly told what they are. They learn these rules through examples that they hear and amazingly the brain pieces these samples together to form the rules of the grammar of the language they are learning. This all happens very quickly, much more quickly than seems logical. Chomsky's LAD contains a preexisting set of rules, perfected by evolution and passed down through genes. This system, which contains the boundaries of natural human language and gives a language learner a way to approach language before being formally taught, is known as universal grammar.
The common grammatical units of languages around the world support the existence of universal grammar: nouns, verbs, and adjectives all exist in languages that have never interacted. Chomsky would attribute this to the universal grammar. The numerous languages and infinite number of word combinations are all governed by a finite number of rules. (6) Charles Henry suggests that the material nature of the brain lends itself to universal grammar. Language, as a function of a limited structure, should also be limited. (7) Universal grammar is the brain's method for limiting and processing language.
A possible explanation for the critical period is that as the brain matures, access to the universal grammar is restricted. And the brain must use different mechanisms to process language. Some suggest that the LAD needs daily use to prevent the degenerative effects of aging. Others say that the brain filters input differently during childhood, giving the LAD a different type of input than it receives in adulthood. (8) Current research has challenged the critical period altogether. In a recent study, adults learning a second language were able to process it (as shown through event related potentials) in the same way that another group of adults processed their first language. (9)
So where does this leave me? Is my mom right, or has she been misinformed? The observation that children learn languages (especially their first) at a remarkable rate cannot be denied. But the lack of uniformity in the success rate of second language learning leads me to believe that the Critical Period Hypothesis id too rigid. The difficulty in learning a new language as an adult is likely a combination of a less accessible LAD, a brain out of practice at accessing it, a complex set of input, and the self consciousness that comes with adulthood. This final reason is very important. We interact with language differently as children, because we are not as afraid of making mistakes and others have different expectations of us, resulting in a different type of linguistic interaction. [...]
And if you think you are too old to learn a 2nd language, you should read these links too:
Why adults are better learners than kids (So NO, you’re not too old)
The linguistic genius of adults: Research confirms we’re better learners than kids!
Breaking Down the Language Barriers