Piaget's (1936) theory of cognitive development explains how a child constructs a mental model of the world. He disagreed with the idea that intelligence was a fixed trait, and regarded cognitive development as a process which occurs due to biological maturation and interaction with the environment. Piaget's work has undergone severe criticism and has been subject to numerous objections, there is no disputing his contributions to the area of child psychology and cognitive development. Although he may have underestimated childhood abilities and also the age at which cognitive development occurs, it is not disputed that the changes in fact do happen. Therefore, piaget's work has been both important and significant. Compare and contrast Piaget's theory of cognitive development with: Vygotsky Theory of cognitive development: (you