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

"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 ...

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 ...

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