Notion that some knowledge about language is built into the brain of the human child.

Learning theorists argue that the environments of young children everywhere are supportive of learning. All young children are surrounded by speech from the beginning: parents and others address remarks to babies, respond to their vocalizations and heap praise on their earliest attempts to say words. People adjust their own speech to accommodate the young child's needs, simplifying their vocabulary, shortening their sentences, and talking about the here-and-now, usually in a special speech "register." This motherese or parentese that cues the child that this is talk meant for the child's ears.

There are some theorists who argue that this environmental support gives the child everything necessary to "figure out" the rules of language. In other words, the child is like a miniature linguist, collecting evidence to decide among...