Jean Piaget (1896-1980) studied the correlation between children's cognitive development and age. According to Paget, children undergo four stages of cognitive development, proceeding sequentially through each stage although at individual rates. Children add new experiences to their knowledge and gradually gain the capacity to achieve higher order thinking. The table below summarizes the characteristics of each stage of cognitive development.  

Stage Approximate Age Characteristics
Sensorimotor 0-2 years
  • Begins to make use of imitation, memory, and thought.
  • Begins to recognize that objects do not cease to exist when they are hidden.
  • Moves from reflex actions to goal-directed activity.
Preoperational 2-7 years
  • Gradually develops use of language and ability to think in symbolic form.
  • Able to think operations through logically in one direction.
  • Has difficulties seeing another person's point of view.
Concrete operational 7-11 years
  • Able to solve concrete (hands-on) problems in logical fashion.
  • Understands laws of conservation and is able to classify and seriate.
  • Understands reversibility.
Formal operational 11-15 years
  • Able to solve abstract problems in logical fashion.
  • Becomes more scientific in thinking.
  • Develops concerns about social issues, identity.

Source: Adapted from B. Wadsworth, Piaget's Theory of Cognitive and Affective Development: Foundations of Constructivism, 5/e © 1996. Published by Allyn and Bacon, Boston, MA. Copyright © 2004 by Pearson Education. Reprinted by permission of the publisher.