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).
It includes the functions of learning, perception, memory, and thinking; and it is influenced by biological, environmental, experimental, social, and motivational factors. A variety of theories have been proposed to explain the pattern of cognitive development observed in children. PIAGET'S THEORY OF COGNITIVE DEVELOPMENTThe Evolution of Piaget's ThinkingBeginning in the early 1960s, Piaget's theory began to replace behaviorism in America. Unlike behaviorism, this theory was seen as truly developmental because it allowed for the different capacities of children of different ages.