what piaget did for psychology
Psychology Today. Piagetâs Missing Cognitive Stage. The Swiss psychologist Jean Piaget was a most prolific renaissance man, publishing in biology, psychology, morality, language and philosophy. His lasting legacy has been his identification and definition of stages in childrenâs thinking.
Piaget was the first psychologist to make a systematic study of children's cognitive development. Piaget's theory included four distinct stages of development: The sensorimotor stage, from birth to age 2. The preoperational stage, from age 2 to about age 7. The concrete operational stage, from age 7 to 11, and....