Suggested 4 stages of cognitive development (sensorimotor, preoperational, concrete operations, formal operations) Cognitive adaptation: children continually modify their schemas in relation to their own experiences. Substage 1: basic reflex activity (birth to 1 month: infant becomes more proficient in the use of their innate reflexes. Substage 2: primary circular reactions (1 to 4 months) Infants repeat and modify actions that focus on their own bodies and that are pleasurable and satisfying: ex: a baby accidentally brings finger close to mouth and starts sucking on it. Baby finds this pleasurable and attempts to reproduce the exact behaviour. New research directions and explanations of knowledge in infancy. 2 stages of this period: preconceptual and intuitive stages. Thus, they understand object identity a qualitative attribute of objects: however, preoperational children have difficulty when it comes to object quanitity. They think that because the cups are of different sizes, they contain different volumes of water, which is not true.