language acquisition device

n. The language acquisition device (LAD), or language acquisition system (LAS), is the mental mechanism that guides language acquisition. The LAD takes as input environmental stimuli in the form of language heard by the learner, which may or may not have been directed at the learner. As this input is processed, internal mechanisms trigger the growth of a language-specific grammar and lexicon. The components of the LAD include the learner's knowledge of universal grammar and a handful of principles of language acquisition, both of which bias the learner to make certain types of assumptions and not others about the system being learned. One principle of language acquisition is the whole object assumption, by which a new word is initially taken to refer to the whole object it is associated with, rather than to one of its parts, or its shape, color, and so forth. The LAD is a species-specific system hypothesized to be in place at birth. It is under debate whether the LAD's properties or operational functions remain intact from birth on or whether it is subject to critical period effects.

- EMF