The Sensorimotor Stage: During this stage, infants and toddlers acquire knowledge through sensory experiences and manipulating objects. It was his observations of his daughter and nephew that heavily influenced his conception of this stage. At this point in development, a child's intelligence consists of their basic motor and sensory explorations of the world. Piaget believed that developing is known as object permanence or object constancy, the understanding that objects continue to exist even when they cannot be seen, was an important element at this point of development. By learning that objects are separate and distinct entities and that they have an existence of their own outside of individual perception, children are then able to begin to attach names and words to objects.

The first stage of Piaget's theory lasts from birth to approximately age two and is centered on the infant trying to make sense of the world. During the sensorimotor stage, an infant's knowledge of the world is limited to his or her sensory perceptions and motor activities. Behaviors are limited to simple motor responses caused by sensory stimuli. Children utilize skills and abilities they were born with (such as looking, sucking, grasping, and listening) to learn more about the environment.

The Preoperational Stage: At this stage, kids learn through pretend play but still struggle with logic and taking the point of view of other people. They also often struggle with understanding the ideal of constancy. For example, a researcher might take a lump of clay, divide it into two equal pieces, and then give a child the option of choosing two pieces of clay to play with. One piece of clay is rolled into a compact ball while the other is smashed into a flat pancake-shape. Since the flat shape looks larger, the preoperational child will likely choose that piece even though the two pieces are exactly the same size.

The preoperational stage occurs roughly between the ages two and seven. Language development is one of the hallmarks of this period. Piaget noted that children in this stage do not yet understand concrete logic, cannot mentally manipulate information, and are unable to take the point of view of other people, which he termed egocentrism.

During the preoperational stage, children also become increasingly adept at using symbols, as evidenced by the increase in playing and pretending. For example, a child is able to use an object to represent something else, such as pretending a broom is a horse. Role playing also becomes important during the preoperational stage. Children often play the roles of "mommy," "daddy," "doctor" and many other characters.

The Concrete Operational Stage: Kids at this point of development begin to think more logically, but their thinking can also be very rigid. They tend to struggle with abstract and hypothetical concepts. At this point, children also become less egocentric and begin to think about how other people might think and feel. Kids in the concrete operational stage also begin to understand that their thoughts are unique to them and that not everyone else necessarily shares their thoughts, feelings, and opinions.

The concrete operational stage begins around age seven and continues until approximately age eleven. During this time, children gain a better understanding of mental operations. Children begin thinking logically about concrete events, but have difficulty understanding abstract or hypothetical concepts.

The Formal Operational Stage: The final stage of Piaget's theory involves an increase in logic, the ability to use deductive reasoning, and an understanding of abstract ideas. At this point, people become capable of seeing multiple potential solutions to problems and think more scientifically about the world around them.

The formal operational stage begins at approximately age twelve to and lasts into adulthood. During this time, people develop the ability to think about abstract concepts. Skills such as logical thought, deductive reasoning, and systematic planning also emerge during this stage.

References

Piaget, J., & Cook, M. T. (1952). The origins of intelligence in children. New York, NY: International University Press.