Jean Piaget (1896-1980 ... the toy still existed. Piaget found four major developmental stages (with many subdivisions). For the first year and a half or two years of life, infants are only ...

children enter the 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 Sam ...

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

His work modified and expanded upon Jean Piaget's previous work but ... throughout the lifespan. Kohlberg's theory outlines six stages of moral development within three different levels.