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).
Another way to look at human development is through cognitive development theories. Cognitive development theories are concerned with the development of thought processes and how these thought processes influence our understanding of the world around us. A major figure in cognitive development theory is Jean Piaget.