Piaget’s stages of cognitive development and impact on child psychology

Piaget’s Stages of Cognitive Development as part of his theory have had a monumental impact on contemporary child developmental psychology.

Jean Piaget’s Stages of Cognitive Development have had a monumental impact on contemporary developmental psychology. Despite challenges to his theory of four stages of cognitive development and later advances in understanding, his work remains a foundation for the modern understanding of child development.

Piaget’s stages of cognitive development are frequently misunderstood. They are best not understood as something that a child is “in” at a particular moment in time, with parents anxiously testing their children to see if they are ahead or behind the ‘correct’ stage. The point is that there is a continual process of building cognitive abilities where later skills are built on earlier skills. Piaget was interested in the sequence. As a guide to what changes and how, his four cognitive development stages describe one part of his great legacy.

Part of the delight of Piaget’s work is his enormously insightful observations of children and endless playful experimentation with them, including his own three children, about whom he wrote three books.

The process underlying Piaget’s stages of cognitive development

Piaget endorsed a view of the development of knowledge known as “constructivism”. In 1970, he wrote: “In order to know objects, the subject must act upon them and, therefore, transform them.” Children come to understand the world through learning what they can do with it. Thus, perception is not just a passive process: “To perceive a house is not to look at an image which has just got into your eye, but to recognise a solid shelter for you to get into,” in his words.

Driving the four stages of cognitive development is a perpetual iterative process that results in progress.

As children develop knowledge, they learn activity patterns consisting of emotion, sensation, motor movement, and perception, learned in response to a particular interaction with the world (schemes). Once they develop a scheme within particular interaction, children extend it to slightly different situations: “They cast the net of their schemes out into the world and what they catch depends on the structure of the net.”

Piaget describes two inter-linked processes in the development of knowledge:

Assimilation: The child understands new experience in terms of past experience (i.e., schemes). For example, when a baby sees a rattle she will assimilate it to her grasping scheme based on her past experience with rattles and have expectations based on that previous experience.

Accommodation: But because each new experience is somewhat different the child will accommodate to those differences and thus extend her knowledge in new ways. In other words new knowledge may change the child’s thinking fundamentally – she comes to think in a new way.

Piaget’s stages of cognitive development

The cognitive development stages: 1. Sensorimotor (during the first two years)

This stage links action to thinking during the first 18 months. Babies employ action schemes like sucking, pushing, hitting and grasping, in order to explore and manipulate the world. At the outset, the newborn has no self-consciousness and no clear awareness of what effects she produces. By coordinating her actions and through imitation of others, she learns a sense of self and how she relates to people and things. Piaget described a series of 6 sub-stages within this stage.

Sub-stage 1: Reflex activity

The baby sucks, roots, grasps, touches, cries, moves arms and legs, and gets better at all of these actions.

Sub-stage 2: Primary circular reactions

Activity focuses on the body (hence “primary”), as in the previous stage, but it is repetitive (hence “circular”) and carried out with more intent: the baby is actively exploring.

Piaget stages of development

Photo: Shutterstock.

Sub-stage 3: Secondary circular reactions

The baby starts to engage with objects and events (hence “secondary”). In the case of Piaget’s own daughter, repeated kicking in the cot made dolls that were hung up on the cot sway. The baby was not intending to make the doll sway, just enjoying that they did and learning about the link between the swaying and the kicking. At this stage of development, babies are learning by accidental discovery.

Sub-stage 4: Coordination of secondary schemes

At this point, the baby starts to combine schemes to achieve a desired result – in the case of Piaget’s own child, pulling a string in order to get hold of a piece of paper attached to it.

Sub-stage 5: Tertiary circular reactions

The baby starts active experimentation. The child will apply a scheme to achieve a result; if it does not work, the baby will try another scheme in the repertoire.

Sub-stage 6: Invention of new means

Toddlers start to find new ways of doing things on their own initiative. In the case of Piaget’s own child, instead of backing away awkwardly after bumping a toy pram into a wall, the toddler walked round the pram to the wall and pushed the pram away.

The first stage comes to an end when the baby develops the ability to think through a problem without actually having to test it out physically.

The cognitive development stages: 2. Pre-operational (between 2 and 7 years)

This starts with “pre-conceptual thought” which includes pretend play, drawing, using simple language and imitating things even when they are not present and visible. A child at this stage does not distinguish between individuals and the category they belong to. In the case of Piaget’s own child, every slug was “the slug”, the very one that was seen further back along the path.

Photo: Shutterstock.

Then comes the “intuition” sub-stage. The child starts to combine schemes in order to infer things. The classical experiment is having two identical glasses of water with the same amount of water in each, then pouring one glass into a narrower glass, so the water is higher. The child, operating in one dimension only, deduces on the basis of existing schemes that a higher water level means more water.

The cognitive development stages: 3. Concrete operational (7-11 years)

At this stage, the child understands the principle of conservation: there must be the same amount of water in each glass, because none was added or taken away. The child starts to apply logic, working things out through thought, not just action. A child will group, count and measure objects at this stage.

The cognitive development stages: 4. Formal operational (12-15 years)

The child is now systematically experimenting, forming hypotheses and testing them out by trying out alternatives, just like scientists do. Piaget recognised that not everyone expresses skills at this stage as if they were scientists in a laboratory. He thought that every adult may reach this stage in their own area of expertise – farmers, bakers, mechanics and so on.

Criticisms of the Piaget’s stages of cognitive development

The criticisms of Piaget’s four stages of cognitive development tend to focus on misunderstandings or non-essential features that do not undermine the central tenets of his theory. Some have claimed his experiments were too difficult for children, but making them easier would not change the underlying sequence of development he was describing. Others have criticised the ages associated with the stages and have pointed to diversity among children. Again, for Piaget, it was the sequence that was important, not the precise age at which a child reaches a particular point. Another criticism is that children are inconsistent in each stage and can move backwards for particular tasks or in particular situations. Again, Piaget observed that himself, without undermining the theory.

The idea of cognitive development stages is often criticised for underestimating the social factors that are part of cognitive development. Piaget is sometimes compared to Vygotsky, who so strongly emphasised social aspects. But Vygotsky was not of that view: he criticised Piaget’s early work for being too focused on social factors!

The bottom line is that the Piaget stages of cognitive development remain the greatest foundation of modern developmental psychology. Further discoveries are serving to confirm the central thrust of his argument rather than to challenge it.


 Carpendale J, Lewis C & Muller U (2018), The development of children’s thinking: Its social and communicative foundations.