The late Jean Piaget, a Swiss developmental psychologist and philosopher, was best known for studies that led to what is now known as the cognitive development theory. Piaget theorised that a child's ...

IT is late afternoon, but the four-year-old insists: “It can’t be. I haven’t had my nap.” Such is the mind of the child, by most indications illogical and full of nonsense. Not so, says Jean Piaget, a ...