Jean Piaget proposed a theory of cognitive development, which revolutionized our understanding of how children acquire knowledge and understanding. He described four major stages of development. They are:

1. Sensorimotor Stage 

(Birth to 2 Years)

The sensorimotor stage lasts from birth to about 2 years of age. During this stage of cognitive development, infants start to understand the world by coordinating sensory experiences with motor actions — hence the term "sensorimotor."
In this stage, the infant progresses from primary reflexive behavior to repetitive self-initiated behavior, such as thumb sucking. One of the most important achievements of the sensorimotor stage is the development of object permanence, that is, the infant’s knowledge that an object outside his or her current sensory field continues to exist.

There are six sub-stages under this stage. They are:

① Simple Reflexes (0–1 Month)

  1. In this substage, there are no differences between self and external world.
  2. Tends to become more adaptive.

② First Habits and Primary Circular Reactions (1–4 Months)

  1. Focus on his own body.
  2. Infants coordinate sensation and two types of schemas: habits and primary circular reaction. A primary circular reaction is a schema based on the attempt to reproduce an event that initially occurred by chance.

③ Secondary Circular Reactions (4–8 Months)

  1. The infant repeats actions for the sake of its sensation.
  2. This is a secondary circular reaction — an action repeated because of its consequences.
  3. The infants become object-oriented.
  4. Becoming less self-centred.
  5. The infants imitate some simple actions.

④ Coordination of Secondary Circular Reactions (8–12 Months)

  1. Begin to use the already learned behavior.
  2. They realize that objects in the environment are clearly separate from them and have distinct qualities of their own.

⑤ Tertiary Circular Reactions (12–18 Months)

  1. This stage marks the starting point for human curiosity and interest in novelty.
  2. Infants purposely explore new possibilities within objects.

⑥ Internalization of Schemas (18–24 Months)

  1. The infant develops the ability to use primitive symbols.
  2. A symbol is an internalized sensory image or word that represents an event.

2. Preoperational Stage 

(2–7 Years of Age)

The preoperational stage, which lasts from approximately 2 to 7 years of age, is the second Piagetian stage. In this stage, children begin to represent the world with words, images, and drawings. They form stable concepts and begin to reason. This stage is called preoperational because at this time the child does not yet perform operations, which are reversible mental actions that allow children to do mentally what they could do only physically. The development of language is the most significant event during this stage. The child is progressing from a sensorimotor type of intelligence to a symbolic type of intelligence.

Limiting Characteristics of Preoperational Reasoning: The inability to perform logical operations appears to be the result of three limiting characteristics of preoperational reasoning. They are:

① Egocentrism

Egocentrism refers to a person’s inability to assume the role or viewpoint of another person. It means that the child can’t understand that other people might think or feel differently from they do. They believe that everyone sees the world just like they do. For example, if a little girl is talking to her grandmother on the phone, she might nod or point at something, forgetting that her grandmother can’t see her.

② Centration

In the second limiting characteristic, centration, the child tends to focus or center on one aspect or dimension of the situation and overlook other important aspects of the problem. For example, when shown two glasses with the same amount of water—one tall and thin, the other short and wide—a child may say the taller glass has more water, just because it's taller, ignoring the width or actual volume.

③ Irreversibility

Irreversibility means the child cannot mentally reverse an action or go backward in their thinking. They don’t yet understand that things can be done and then undone. For example, if a child sees someone flatten a ball of clay into a pancake shape, they may not understand that the clay can be rolled back into a ball. To them, once it’s flat, it’s always flat.

3. Concrete Operational Stage

 (7–11 Years)

Piaget proposed that the concrete operational stage lasts from 7 to 11 years of age. In this stage, children can perform operations (concrete operations), and they can reason logically as long as reasoning can be applied to specific or concrete examples. Here, the operations are the mental actions that are reversible, and concrete operations are operations that are applied to real, tangible objects.

In this stage, the child's thought processes (cognition) and the ability to perform mental operations (thinking) are now becoming less restricted by egocentrism, centration, and irreversibility.
However, hypothetical and abstract problems continue to present difficulty.

4. Formal Operational Stage 

(11 or 12 to 15 Years)

This is the final stage of cognitive development. It is reached after about eleven or twelve years of age. At this point, the child is capable of dealing with abstract concepts that go beyond the immediate environment.

Formal operational thought is more abstract than concrete operational thought.
Adolescents are no longer limited to actual, concrete experiences. They can imagine make-believe situations, understand proportions, and reason about events that are purely hypothetical.

They are likely to solve problems through trial and error. Adolescents begin to think like scientists, devising plans to solve problems and systematically designing solutions. This type of problem solving requires hypothetical-deductive reasoning, which involves: Creating a hypothesis, and deducing its implications — steps that provide ways to test the hypothesis.

 

Reference

  1. Sarafino, E. P., & Armstrong, J. W. (1986). Child and adolescent development. Wadsworth Publishing.
  2. Piaget, J. (1952). The Origins of Intelligence in Children. New York: International Universities Press.
  3. Piaget, J. (1972). The Psychology of the Child. Basic Books.
  4. Santrock, J. W. (2019). Life-Span Development (17th ed.). McGraw-Hill Education.
  5. Papalia, D. E., & Feldman, R. D. (2011). Human Development. McGraw-Hill Education.