What is Piagets Theory

Jean Piaget (1896 – 1980) was a Swiss psychologist, who developed a theory of cognitive development in children. His theory of cognitive development in childhood is one of the most important cornerstones in contemporary psychology. Before Piaget, psychological thinking about childhood cognitive development was based on biological maturation (Nature) and environment learning (Nurture). However, Piaget focused his theory on the interaction between child’s developing natural abilities and the environment.

How was the theory developed?

Jean Piaget developed this theory by observing his own children. He witnessed how they interacted with the environment. He also detected that the children in fact interact actively with the environment, rather than as a passive recipient of external stimuli and biological development. He saw children as scientists, who experiment with the social and physical environment. For example, what happens when a glass of water is spilled on the floor or what happens when a father’s nose is pinched?

Children use these experiments to construct schemas or mini theories about how the physical world operates. In addition, children use these same experiments to develop theories about social interactions. He also observed that when a new experience doesn’t fit an existing schema, they modify that existing schema or create a new schema for that experience (Piaget & Inhelder, 1969).

What are the Piaget’s stages of cognitive development?

Piaget’s observations convinced him that childhood cognitive development can be divided into four main discrete categories.

– Sensorimotor stage (Birth to 2 Years)

In this stage, the child differentiates self from objects and other people. In addition he/she recognizes self as an agent that can interact with the environment. In this stage the child also discovers the concept of object permanence (object continues to exist; even when that object cannot be seen, felt or heard). Usually this concept is discovered at the age of eight months.  

– Preoperational stage (2 – 7 years)

In the preoperational stage, children learn to use language and they start to represent objects and people by symbols. They also discover that words can represent things. In this stage a child may treat a broomstick as a horse and play with it. In addition, children in this stage can classify objects by a single feature. They will choose and arrange items with the same height. However, they cannot arrange (sort) items with different heights.

In this stage the child’s thinking is dominated by visual stimuli or impressions. For an example, a child may not understand that the amount of water is same when the water is poured from a tall glass to a shorter one. In addition, children in this stage are egocentric. That means they cannot understand the viewpoint of others.

– Concrete operational stage (7 – 11 years)

When a child arrives at this stage, they start to think logically. In addition, they can classify objects according to several features. They can also sort items with different heights. In addition they achieve the ability to mentally represent series of actions. E.g. they can draw a map of a route. However, they cannot understand an abstract meaning of a phrase.

– Formal operational stage (11 years and up)

In this stage, children can think logically about abstract propositions and they achieve the ability to test hypotheses systematically. In addition, they start to show concern about hypothetical and ideological problems.

Critiques of Piaget’s theory

Piaget’s theory revolutionized the way psychologists think about childhood development. However, more sophisticated experiments have uncovered some errors in Paget’s theory.

Several studies have found that some infants as young as three and half months show object permanence (Baillargeon, 1987; Baillargeon & Devos, 1991). In addition, several sophisticated experiments have shown that several intellectual functions develop much earlier than the theory suggests (Markman, 1979; Artman & Cahan, 1993).


Piaget’s theory of childhood cognitive development is one of the most important discoveries in modern psychology. In this theory, childhood cognitive development is categorized into four discrete stages. They are sensorimotor stage, preoperational stage, concrete operational stage and formal operational stage. Even though sophisticated psychological experiments uncovered some errors in his theory, Jean Piaget’s theory is considered one of the most important pillars in child psychology.  


Introduction to Psychology – Atkinson & Hilgard 14th edition