The Behavioristic Theory focuses on the use of imitation and practice for language acquisition. According to this theory, babies learn oral language from the humans in their environment through imitation, rewards and practice. When a baby tries to speak a word and succeeds, parents and other adults in his world often praise him. This propels the child to try harder to achieve more. Critics of this theory ask if there are no rewards, does the child's language acquisition process fail?
The Innatist Theory is more widely accepted and understood than the Behavioristic Theory. This oral language development theory states that learning is a natural process for human beings. The Innatist Theory gives rise to the Language Acquisition Device, or LAD, which is thought to be a part of the brain that enables all children to grasp language naturally. However, the Innatist Theory fails to explain why children from different cultures and environments vary in the time taken to develop oral language.
This oral language development theory is a combination of the Behaviorist and Innatist theories. The Cognitive Theory suggests that language acquisition and development are founded upon the fact that babies learn language -- Behavioristic -- but also that they learn to speak what their parents are speaking, be it English, French, Swahili or any other language -- Innatist.
Brought to light by Lev Vygotsky, the Social Constructivism Theory assumes that oral language development is influenced by a number of important factors: social, physical, linguistic and cognitive. According to Vygotsky, the social sphere surrounding a child is key to the time involved for language acquisition, since a child learns language through interaction. This theory is similar to the others, but it concentrates on interaction as the focus around which language acquisition must revolve.