Jean Piaget's ideas regarding cognitive development have been very influential in education theory. Piaget believed that humans build cognitive structures as part of the biological process. He theorized four separate stages of cognitive development in children. The first, the sensorimotor stage, occurs during infancy until approximately the age of two. During this stage, the child becomes aware of a separate identity, first learns intentional action, and comes to understand that objects continue to exist when they are not present.
According to Piaget's theories, children gain an understanding of the world through interaction and experience. As the child approaches its first year, it begins to engage in increasingly active exploration of the world. Activities and verbalizations are essentially egocentric, part of the process of exploration and experimentation. In Piaget's words, "Play, when all is said and done, is the supreme law of egocentric thought."
Lev Vygotsky was a Russian psychologist who studied the interaction of language and thought. As compared to Piaget, Vygotsky theorized a higher degree of importance to influencing factors surrounding the child, such as parents and the overall environment. Therefore, while Piaget stressed the importance of the child's internal creative process, Vygotsky believed the initial language development process relies heavily on interaction provided by caregivers. In this model, language is more a tool for social interaction, rather than a purely egocentric exercise.
More recently, Noam Chomsky and Steve Pinker have developed theories regarding language acquisition that focus on language from a biological perspective, Both Chomsky and Pinker consider language to be an innate feature of the human mind that has developed through natural selection, although they differ on details of the evolutionary process. To Pinker, language is an instinct, not an invention. Therefore, learning is a natural biological process that occurs with less regard to environment or interaction.