According to Piaget’s theory, development occurs through a series of major periods or stages that contain their own sub-stages and in which psychological activity differs qualitatively from one period to the next. The main principle that makes the stage progression necessary and non-arbitrary is that the major achievement of one period sets the necessary starting condition for the next. Most secondary accounts name four major periods, although in his full elaboration of the account, Piaget identified only three periods with sub-divisions. <\/p>\n
See Formal operations<\/a>, Logical reasoning<\/a>, Mental image<\/a>, Stage<\/a>, Stage of cognitive development<\/a><\/p>\n <\/body><\/html><\/p>\n","protected":false},"excerpt":{"rendered":" According to Piaget’s theory, development occurs through a series of major periods or stages that contain their own sub-stages and in which psychological activity differs qualitatively from one period to the next. The main principle that makes the stage progression necessary and non-arbitrary is that the major achievement of one period sets the necessary starting … <\/p>\n