Gradually he pieced together a "blueprint" for normal cognitive development in children ... the toy still existed. Piaget found four major developmental stages (with many subdivisions).

is the fourth and final stage of Jean Piaget's theory of cognitive development. It begins at approximately age 12 and lasts into adulthood. During the formal operational stage, children's thinking ...

"At four or ... preoperational stage at around two years old Despite being over 70 years old, Piaget's theory is "still one of the prevailing theories in terms of cognitive development," Dr ...

According to psychologist Jean Piaget, such skills emerge during the preoperational stage. This is the second stage in his ...