Four stages of cognitive development
•The sensorimotor stage (感覺運動期, 0-2)
•Object permanence
•Goal-directed actions
•Preoperational stage (前運思期, 2-7)
•Semiotic function (picture representation)
•Reversible thinking
•Conservation, Egocentric, Collective monologue
•Concrete operational (具體運思期, 7-11)
•Identity, compensation, reversibility
•Classification, seriation
•Formal operational (形式運思期, 11-adult)
•Hypothetico-deductive reasoning (假設演繹推理)
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