Cognitive development
Jean Piaget

Jean Piaget was the first psychologist and philosopher to brand this type of study as "cognitive development". Other researchers, in multiple disciplines, had studied development in children before, but Piaget is often credited as being the first one to make a systematic study of cognitive development and gave it its name. His main contribution is the stage theory of child cognitive development. He also published his observational studies of cognition in children, and created a series of simple tests to reveal different cognitive abilities in children. Piaget believed that people move through stages of development that allow them to think in new, more complex ways.
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