Born and raised in Neuchatel, Switzerland, Jean Piaget was always interested in biology and zoology. After earning his Ph.D. in biology, he became interested in psychology, particularly in how cognition develops. While working for Binet at the Sorbonne, Piaget noticed that children don’t solve problems like adults do. Children are not miniature adults but have their own distinctive style of thinking which develops in stages.
Piaget proposed four stages of cognitive development: sensorimotor, preoperational, concrete and abstract. The sensorimotor stage occupies the first two years of a child’s life. In this stage, children acquire motor control, and learn to interact with objects and accommodate to the world.
In the peroperational stage (ages 2 to 7, children acquire language. Their thinking is egocentric and contradict themselves but are not bothered by it. They can name objects, think intuitively, and argue their point of view. They cannot argue from someone else’s point of view, and believe that tall and thin containers hold more than short, fat ones).
In the concrete operational stage (ages 7 to 12), children can manipulate numbers, develop rules for classifying objects, and acquire conservation (e.g., know that shape is not the same as quantity).
In the formal operational stage of development (ages 12 to adult), children acquire abstract thinking, can discuss hypothetical situations, and perform systematic searches for solutions.