In the behaviorist view, children imitate the language of their environment to a considerable degree, and imitation is a strong contribution factor in the language learning process. A consequence of this is that the frequency with which words and structures occur in the language of the environment, will influence the language development of the child. In addition, reinforcement is needed to arrive at a higher level of language proficiency. Parental approval is an important type of reinforcement in the language learning process: when a child produces a grammatically correct utterance which is understood by its environment, approval from the parents may serve as reinforcement for such an utterance. In this way, the environment encourages the child to produce grammatical utterances, while not encouraging ungrammatical utterances.
The linguist Norm Chomsky claims that children are biologically programmed for language and that language develops in the child in just the same way that other biological functions develop. For example, every child will learn to walk as long as adequate nourishment and reasonable freedom of movement are provided. The child does not have to be taught; most children learn to walk at about the same time; and walking is essentially the same in all normal human beings. For Chomsky, language acquisition is very similar to the development of walking. The environment makes a basic contribution --- in this case, the availability of people who speak to the child. The child, or rather, the child’s biological endowment, will do the rest. This is known as the innatist position. Chomsky developed his theory in reaction to the behaviorist theory of learning based on imitation and habit formation.