"If grammatical structure cannot be learned, it must be innate. But different languages have different grammars. So whatever is innate has to be highly abstract -- a Universal Grammar. And the problem is then to explain how children get from this abstract knowledge to the specific language they are learning. The field became encumbered by creative but highly implausible theories, most notably the parameter-setting account, which conceptualised language acquisition as a process of "setting a switch" for a number of innately-determined parameters. Evidence that children’s grammars actually changed in discrete steps, as each parameter became set, was lacking. Reality was much messier. [S]tatistical learning and connectionism were not given serious consideration by Chomsky; they were rapidly dismissed as versions of behaviourism that can’t possibly explain language acquisition." - Adriano

Auditory perception at the root of language learning (2012): infants as young as three months of age are able to automatically detect and learn complex dependencies between syllables in spoken language -- by contrast, adults only recognized the same dependencies when asked to actively search for them. http://www.pnas.org/content... - Adriano