Jean Piaget developed a theory that states that children develop cognitively through four developmental stages, sensorimotor, pre-operational, concrete operational, and formal. The first stage of the cognitive development theory is called the sensorimotor stage. This stage takes place from birth until the age of two. During the sensorimotor stage the infant learns by combining their senses (sight, sound, taste, touch, smell) with their motor skills. The sensorimotor infant begins with basic reflexes, then develops the ability to use more complex manipulations of objects.
The second stage of cognitive development is referred to as the pre-operational stage. The pre-operational stage takes place from the ages of two years until the age of seven years. The majority of their new learning involves the use of symbols, language, and their imagination. A child in the pre-operational stage has no sense of logic and is egocentric, they can only view the world through their own perspective
The stage following pre-operational is called concrete operational. In the concrete operational stage the child is still using symbols, however; he is able to apply logic to the symbols. Children in concrete operational do not act intuitively, they are able to use reasoning - provided that there are concrete examples.
The final cognitive developmental stage is called the formal operational stage. In this stage, the young adult is able to apply logic to abstract thinking. They are able to deal with complicated problems and apply reason. Piaget considered formal operational the final stage of cognitive development because it is the highest level of learning that the individual will achieve.