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).
Around this time, another psychologist was offering his views on child cognitive development. Lev Vygotsky offered an alternative to Piaget's stages of cognitive development. Vygotsky's Sociocultural Theory of Development became a major influence in the field of psychology and education (Woolfolk, A., 2004).ev Vygotsky offered an alternative to Piaget's stages of cognitive development. Vygotsky's Sociocultural Theory of Development became a major influence in the field of psychology and education (Woolfolk, A., 2004).