Chimerism is what happens when cells from one twin are present in the other. For example, white blood cells with Y chromosomes would be found in the female twin. Vigier et. al, 1989.
Piaget's theory of cognitive development. Piaget's theory of cognitive development is a comprehensive theory about the nature and development of human intelligence. It was first created by the Swiss developmental psychologist Jean Piaget (1896â1980).
Piaget focused on cognitive development in children and adolescents. Jean Piaget's theory of cognitive development described and explained the changes in logical thinking of children and adolescents. Piaget proposed that children proceed through four stages based on maturation and experience.