Jean Piaget’s prominent work is his Theory on the four stages of cognitive development.
He was one of the most influential researchers in the area of developmental psychology in the 20th century whose primary interest was in biological influences on how we come to know, and the developmental stages we move through as we acquire this ability (Singer & Revenson, 1997).
Piaget (1973) believed that the child plays an active role in the growth of intelligence and learns by doing. He regarded the child as a philosopher who perceives the world only as he has experienced it.
Therefore, most of Piaget’s inspiration in cognitive and intellectual development came from observations of children. In fact, Piaget observed and studied his own three children through each stage of their cognitive development.
The Theory of Cognitive Development focuses on mental processes such as perceiving, remembering, believing, and reasoning. Reasoning is the essence of intelligence, and reasoning is what Piaget studied in order to discover “how we come to know” (Singer & Revenson, 1997). Piaget believed that cognitive development is cumulative; that is, understanding a new experience grows out of a previous learning experience.