Piaget Stages of Development

Medically Reviewed by Dan Brennan, MD on March 12, 2023
4 min read

Piaget's stages of development are part of a theory about the phases of normal intellectual development, from infancy through adulthood. This includes thought, judgment, and knowledge. The stages were named after psychologist and developmental biologist Jean Piaget, who recorded the intellectual development and abilities of infants, children, and teens.

Piaget's four stages of intellectual (or cognitive) development are:

  • Sensorimotor. Birth through ages 18-24 months
  • Preoperational. Toddlerhood (18-24 months) through early childhood (age 7)
  • Concrete operational. Ages 7 to 11
  • Formal operational. Adolescence through adulthood

Piaget acknowledged that some children may pass through the stages at different ages than the averages noted above. He also said some children may show characteristics of more than one stage at a given time.

But he insisted that:

  • Cognitive development always follows this sequence.
  • Stages cannot be skipped.
  • Each stage is marked by new intellectual abilities and a more complex understanding of the world.

Piaget's 1936 theory broke new ground because he found that children's brains work in very different ways than adults'. Before his theory, many believed that children were not yet capable of thinking as well as grown-ups.

Some experts disagree with his idea of stages. Instead, they see development as continuous. Another criticism is that Piaget didn't consider how a child's culture and social environment affect their development.

During the early stages, according to Piaget, infants are only aware of what is right in front of them. They focus on what they see, what they are doing, and physical interactions with their immediate environment.

Because they don't yet know how things react, they're constantly experimenting. They shake or throw things, put things in their mouth, and learn about the world through trial and error. The later stages include goal-oriented behavior that leads to a desired result.

Between ages 7 and 9 months, infants begin to realize that an object exists even though they can no longer see it. This important milestone -- known as object permanence -- is a sign that memory is developing.

After infants start crawling, standing, and walking, their increased physical mobility leads to more cognitive development. Near the end of the sensorimotor stage (18-24 months), infants reach another important milestone -- early language development, a sign that they are developing some symbolic abilities.

During this stage (toddler through age 7), young children are able to think about things symbolically. Their language use becomes more mature. They also develop memory and imagination, which allows them to understand the difference between past and future, and engage in make-believe.

But their thinking is based on intuition and still not completely logical. They cannot yet grasp more complex concepts such as cause and effect, time, and comparison.

At this time, elementary-age and preadolescent children -- ages 7 to 11 -- show logical, concrete reasoning.

Children's thinking becomes less focused on themselves. They're increasingly aware of external events. They begin to realize that their own thoughts and feelings are unique and may not be shared by others or may not even be part of reality.

But during this stage, most children still can't think abstractly or hypothetically.

Adolescents who reach this fourth stage of intellectual development -- usually at age 11-plus -- are able to use symbols related to abstract concepts, such as algebra and science. They can think about things in systematic ways, come up with theories, and consider possibilities. They also can ponder abstract relationships and concepts such as justice.

Although Piaget believed in lifelong intellectual growth, he insisted that the formal operational stage is the final stage of cognitive development. He also said that continued intellectual development in adults depends on the buildup of knowledge.

Along with the stages of development, Piaget's theory has several other main concepts.

Schemas are thought processes that are essentially building blocks of knowledge. A baby, for example, knows that it must make a sucking motion to eat. That's a schema.

Assimilation is how you use your existing schemas to interpret a new situation or object. For example, a child seeing a skunk for the first time might call it a cat.

Accommodation is what happens when you change a schema, or create a new one, to fit new information you learn. The child accommodates when they understand that not all furry, four-legged creatures are cats.

Equilibrium happens when you're able to use assimilation to fit in most of the new information you learn. So you're not constantly adding new schemas.

Piaget's theory has influenced education and parenting. Here are some practical ways teachers and parents can put his ideas to work:

  • Remember that kids often learn best by doing things, rather than hearing about them. Learning to solve problems isn't something that can be taught. It must be discovered.
  • The process of learning is as important (or more so) than the end result.
  • Don't try to teach a child something they aren’t ready to learn. According to Piaget's stages, kids must master one level before they move on to the next.
  • Kids learn as much from each other as from parents or teachers. Give them projects to do together, as well as individual tasks.