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Piaget's Stages of Cognitive Development

Background and Key Concepts of Piaget's Theory


Jean Piaget and Cognitive Development

Jean Piaget's theory has become one of the most influential theories of cognitive development.

Fondation Jean Piaget / Public Domain

According to psychologist Jean Piaget, children progress through a series of four key stages of cognitive development marked by shifts in how they understand the world. Piaget believed that children are like "little scientists" and that they actively try to explore and make sense of the world around them. Through his observations of his own children, Piaget developed a stage theory of intellectual development that included four distinct stages: the sensorimotor stage, from birth to age 2; the preoperational stage, from age 2 to about age 7; the concrete operational stage, from age 7 to 11; and the formal operational stage, which begins in adolescence and spans into adulthood.

Jean Piaget's Background

Jean Piaget was born in Switzerland in 1896. After receiving his doctoral degree at age 22, Piaget formally began a career that would have a profound impact on both psychology and education. After working with Alfred Binet, Piaget developed an interest in the intellectual development of children. Based upon his observations, he concluded that children were not less intelligent than adults, they simply think differently. Albert Einstein called Piaget's discovery "so simple only a genius could have thought of it."

Piaget's stage theory describes the cognitive development of children. Cognitive development involves changes in cognitive process and abilities. In Piaget's view, early cognitive development involves processes based upon actions and later progresses into changes in mental operations.

A Quick Summary of Cognitive Development

  • The Sensorimotor Stage: During this stage, infants and toddlers acquire knowledge through sensory experiences and manipulating objects.

  • 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.

  • 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.

  • 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.

It is important to note that Piaget did not view children's intellectual development at a quantitative process; that is, kids do not just add more information and knowledge to their existing knowledge as they get older. Instead, Piaget suggested that there is a qualitative change in how children think as they gradually process through these four stages. A child at age 7 doesn't just have more information about the world than he did at age 2; there is a fundamental change in how he thinks about the world.

In order to better understand some of the things that happen during cognitive development, it is important to first examine a few of the important ideas and concepts introduced by Piaget. The following are some of the factors that influence how children learn and grow:

Key Concepts

Schemas - A schema describes both the mental and physical actions involved in understanding and knowing. Schemas are categories of knowledge that help us to interpret and understand the world.

In Piaget's view, a schema includes both a category of knowledge and the process of obtaining that knowledge. As experiences happen, this new information is used to modify, add to, or change previously existing schemas.

For example, a child may have a schema about a type of animal, such as a dog. If the child's sole experience has been with small dogs, a child might believe that all dogs are small, furry, and have four legs. Suppose then that the child encounters a very large dog. The child will take in this new information, modifying the previously existing schema to include this new information.

Assimilation - The process of taking in new information into our previously existing schemas is known as assimilation. The process is somewhat subjective, because we tend to modify experience or information somewhat to fit in with our preexisting beliefs. In the example above, seeing a dog and labeling it "dog" is an example of assimilating the animal into the child's dog schema.

Accommodation - Another part of adaptation involves changing or altering our existing schemas in light of new information, a process known as accommodation. Accommodation involves altering existing schemas, or ideas, as a result of new information or new experiences. New schemas may also be developed during this process.

Equilibration - Piaget believed that all children try to strike a balance between assimilation and accommodation, which is achieved through a mechanism Piaget called equilibration. As children progress through the stages of cognitive development, it is important to maintain a balance between applying previous knowledge (assimilation) and changing behavior to account for new knowledge (accommodation). Equilibration helps explain how children are able to move from one stage of thought into the next.

More About Piaget's Stages of Cognitive Development

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By visiting the rest of the Psychology site you can find a wealth of free psychology articles and resources, which include:


Santrock, John W. (2008). A topical approach to life-span development (4 ed.). New York City: McGraw-Hill.

Piaget, J. (1977). Gruber, H.E.; Voneche, J.J. eds. The essential Piaget. New York: Basic Books.

Piaget, J. (1983). Piaget's theory. In P. Mussen (ed). Handbook of Child Psychology. 4th edition. Vol. 1. New York: Wiley.

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