What are children capable of learning at various stages in their development? How do children develop their intellectual skills to react and interact with their environment? How do these cognitive abilities develop, and in what order?

These were some of the questions that were answered by French psychologist Jean Piaget in 1952 when he published his groundbreaking theory on cognitive development in children.

Piaget began his research simply interested in how children react to their environments, but his observations countered the current thinking of the day (which said that children have no cognition until they are old enough to learn to speak), and have, in fact, become the most well-known and influential theory of cognitive development to date.

Here are the four cognitive stages of childhood development as identified by Jean Piaget:

Sensorimotor Stage: Birth through about 2 years. During this stage, children learn about the world through their senses and the manipulation of objects.

Preoperational Stage: Ages 2 through 7. During this stage, children develop memory and imagination. They are also able to understand things symbolically and to understand the ideas of past and future.

Concrete Operational Stage: Ages 7 through 11. During this stage, children become more aware of external events, as well as feelings other than their own. They become less egocentric and begin to understand that not everyone shares their thoughts, beliefs, or feelings.

Formal Operational Stage: Ages 11 and older. During this stage, children are able to use logic to solve problems, view the world around them, and plan for the future.

According to this model, attention, short-term memory, and long-term memory are developing between the ages of 2 and 5. Auditory processing, which is critical for good reading skills, is developing between the ages of 5 and 7. Logic & reasoning also becomes more established after 5 years of age as a child becomes better able to make connections between ideas.