Jean Piaget’s Theory of Cognitive Development: Meaning & Stages

Human beings change dynamically in various ways. They change physically, socially, and cognitively.

Remember, your childhood days when you were totally confused about certain things? This was because you could not understand them.

Likewise, it was so annoying when you were unable to perform certain physical actions. One of these actions may be your inability to reach out to the kitchen cupboard for your favorite cookie.

Now, try to remember those instances when you used to make houses with pieces of rocks. And you considered sticks as people living inside those houses.

All these changes relate to three categories of development mentioned earlier. These include physical, social, and cognitive development. Physical development is the development of a human being in the prenatal and postnatal periods.

What is the Prenatal and Postnatal period of development?

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Prenatal Period of Development

The prenatal period is a stage where an embryo develops into a fetus. And then the fetus develops into a full-grown baby.

Furthermore, this stage also talks about many environmental factors. Such factors can damage the fetus and interfere with normal patterns of growth. Thus, these factors are known as teratogens.

The teratogens include infectious agents, consumption of over-the-counter drugs, alcohol, and smoking.

Postnatal Period of Development

On the other hand, postnatal development talks about physical growth during infancy. This stage of human development involves perceptual development.

Certain studies showcase that newborns are able to distinguish between various sounds, colors, tastes, and odors.

In a study, two or three days old infants showcased patterns of sucking in response to different sounds of human speech. Furthermore, such kids are also observed turning their eyes and head in the direction of the sound.

Another set of studies showcased six or seven months old infants refusing to crawl across the deep side of a patterned floor to reach their mothers.

Cognitive Development

After perceptual development, the next stage of human development is cognitive development. Cognitive development is nothing but a change in our ability to understand the world around us.

Initially, the cognitive processes of children and adults were assumed to be similar. However, the Swiss psychologist Jean Piaget challenged these assumptions.

He challenged the assumptions as a result of observing his own kids as well as other children. Thus, Piaget concluded that children do not think and reason like adults in various aspects.

In other words, their thought processes are quite discrete relative to the adults both in kind and degree. Therefore, Jean Piaget’s theory of cognitive development constitutes many important insights. These insights have guided many developmental psychologists to undertake further research in this area.

So, let’s understand what is Jean Piaget’s theory of cognitive development, Piaget’s stages of cognitive development, and improvements in Piaget’s theory.

Jean Piaget’s Theory of Cognitive Development

Piaget’s theory of cognitive development is a Stage Theory. The Stage Theory refers to a type of theory proposing that all human beings undergo an orderly and predictable series of changes. However, many psychologists question the basic aspects of Piaget’s Theory including:

  • human beings undergoing a sequence of stages
  • such changes taking place from one stage to another at specific ages
  • changes taking place in a fixed order

Now, these ideas of Piaget’s Theory are questioned on two grounds. The first one refers to the fact that individuals differ from each other in various aspects. And the second one states that the assumption of a high degree of orderliness in human development is not justified.

Now, Piaget’s theory of cognitive development was based on an important assumption called ‘Constructivism’. Constructivism refers to the fact that children are active thinkers. They consistently try to build a more accurate or advanced understanding of the world around them.

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In other words, children interact with the surrounding world to develop their knowledge about it. According to Piaget, they build such knowledge through two basic processes:

I. Assimilation

The first process refers to assimilation. This process involves the inclusion of new knowledge into existing knowledge structures or mental frameworks known as schemas. A schema is nothing but a mental framework or structure that holds knowledge and organizes the same.

II. Accommodation

The next process refers to accommodation. Accommodation involves changes made in existing schemas or knowledge structures when a child is exposed to new information or experiences.

Say, for instance, a two-year-old child observes cows. Based on such an experience, he builds a schema for cows. This schema relates to the relatively big four-legged animals.

Now, the same kid observes a horse for the very first time. Then, he includes this new information in the existing schema for cows via the assimilation process. As the child encounters more horses, he begins to observe that cows differ from horses in various aspects.

For instance, horses do not have horns and a mound as in cows. They have bushier tails as compared to cows. Thus, the child is able to develop a new schema for horses. Such a modification in the existing knowledge schemas resulting from exposure to new information is known as accommodation.

Jean Piaget suggested that cognitive development in humans is due to the occurrence of assimilation and accommodation. Furthermore, children are consistently making an effort to make sense of the complex world around them. And they are doing this in a better and more accurate manner. This is because the changes in existing knowledge structures happen via assimilation and accommodation.

Given this, let’s take a look at the various stages of cognitive development suggested by Jean Piaget.

Piaget’s Stages of Cognitive Development

I. Sensorimotor Stage

The Sensory Motor Stage is the first stage of Piaget’s cognitive development theory. During this stage, infants learn that there exists a relationship between the actions they perform and the world around them.

This stage of cognitive development lasts from birth until 18 and 24 months. Further, during this stage, infants find out that they can steer objects and hence generate certain effects.

In other words, children understand the basic concept of cause and effect during the Sensory Motor stage.

For instance, children learn that they can produce sound if they would make certain movements. And one of these movements can include shaking their hands while holding a rattle. Thus, in a way, they start experimenting with different actions.

Children engage in such experiments as they want to observe various effects that such actions generate. Thus, Jean Piaget suggested that infants try to understand the world around them during the entire sensorimotor stage. And they do this only with the help of motor activities and sensory impressions.

Lack of Mental Impressions

However, they do not have the capacity to make use of such mental impressions to portray different objects at this stage. Now, such learning generates some interesting effects.

For instance, a 4-month-old infant will not try to search for the toy if you try hiding it in front of him. This is because such infants consider that anything hidden from view is also hidden from their minds.

However, such infants start searching for hidden objects when such infants grow older. This starts happening when the infant is somewhere around 8 or 9 months of age. In other words, the infants acquire a basic idea of ‘Object Permanence’ by this age. Object permanence refers to the fact that objects continue to exist even when those are hidden from view.

II. Preoperational Stage

The Preoperational Stage of Cognitive Development is the one where a toddler gets the ability to develop mental images of objects. This is unlike the Sensory Motor Stage where the toddlers were unable to develop this ability.

Now, the Preoperational Stage occurs between 18 and 24 months. Furthermore, the toddlers also get the capacity to develop language. This capacity is to the extent that they start thinking in terms of verbal symbols or words.

Thus, such developments mark the beginning of Piaget’s second stage of cognitive development – the Preoperational Stage.

Meaning of Preoperational

The term preoperational means that infants get the ability to create mental images and develop verbal symbols.

However, they lack the ability to use logic and mental operations. Furthermore, the preoperational stage lasts until about age 7. And during this stage, children are able to perform many actions that they were unable to do previously.

For instance, children about the age of 5 or 6 can engage in symbolic play. In such a play, they pretend that one object is another. Like, they might consider a pencil to be a vehicle such as a car or an airplane.

Furthermore, symbolic play consists of three changes. These changes reveal discrete insights about the modification in children’s cognitive abilities during this period.

(i.) Decentration

The first change refers to decentration. In this stage of change, children slowly start making others the recipients of their playful actions rather than themselves. For example, they start making their soft toy take a bath, or comb its hair.

(ii) Decontextualization

Then comes the second change of decontextualization. In this stage, children substitute one object with the other. They do this to perform some playful action. For instance, a child considers a pencil as an airplane.

(iii) Integration

Finally, the third change involves integration. This stage of change combines different playful actions into a complex sequence. Such an ability to involve in a more complex set of playful actions indicates that children are growing cognitively.

In other words, children are able to picture one object as another. Furthermore, there are also able to perform playful actions. Like they consider soft toys next to humans who have feelings and thoughts of their own. And to do all of this, children require the ability to think in terms of words.


Thus, the children’s thought processes in the preoperational stage are more advanced relative to those in the sensorimotor stage. However, Piaget suggested that children in the preoperational stage are still immature in various aspects.

Though children in this stage can make use of mental symbols. But their thought processes are somewhat inflexible, illogical, incomplete, and are restricted to specific contexts.

Piaget makes such an argument on the basis of the following two aspects that bring about immaturity in children at the preoperational stage:

a. Egocentrism

It refers to the young children’s incapacity to differentiate their own perspectives from others. In other words, egocentrism is the child’s inability to understand that others may perceive the world in a different way than they do.

b. Lack of Seriation

Seriation refers to the ability of a child to organize objects in a sequence using some dimension or parameter. But, children in the preoperational stage lack seriation.

c. Lack of Understanding of Relative Terms

Children in the preoperational stage lack the ability to understand relative terms like lighter, darker, softer, etc.


In the preoperational stage, children lack an understanding of conservation. Conservation refers to a concept which states that certain physical characteristics of an object do not change. And these characteristics do not change even if the outer appearance of such an object is modified.

III. Stage of Concrete Operations

The stage of concrete operations is a cognitive development stage occurring somewhere around age six or seven. Furthermore, this stage lasts until about the age of eleven.

Thus, during this stage, logical thought starts emerging in children. In other words, challenging things or the underdeveloped capabilities of the preoperational stage start developing in this stage.

Furthermore, children get the capability to solve simple problems. These are the problems that they encounter in the preoperational stage.

Now, Piaget suggests that a child defines the beginning of the stage of concrete operations when he masters the concept of conservation. During this stage, certain important skills start emerging in children. In addition to this, children get the capability to arrange things in order.

Furthermore, they understand the relative terms as mentioned in the previous stage. In addition to this, they start understanding that physical changes done originally can be reversed. And these can be reversed by undoing the original action.

This concept is referred to as reversibility. Besides all of this, Piaget emphasizes that children reaching the stage of concrete operations also start thinking logically.

IV. Stage of Formal Operations

The stage of formal operations is the final stage of cognitive development in Piaget’s theory. Children enter this stage at about the age of twelve. During this stage, major characteristics that define an adult’s thought process start emerging in children.

As we already know, children start thinking logically during the stage of concrete operations. But, such a logical thought is only restricted to concrete events or objects.

In other words, children become aware of the permanence of objects. However, children who reach the stage of formal operations start thinking in an abstract way. The following are the various ways in which children start thinking.

(i) Hypothetico – Deductive Reasoning

Hypothetico – Deductive Reasoning refers to children’s ability to understand concrete or real events and formulate possibilities. These possibilities are nothing but the events or relationships that one can only imagine.

However, such events or relationships do not exist in reality. Furthermore, this concept emphasizes that children get the ability to formulate a hypothesis.

Additionally, they can think logically about ideas, propositions, and symbols. In other words, such type of reasoning involves formulating a generic theory. After forming a generic theory, children come up with a specific hypothesis.

(ii) Inter-Propositional Thinking

Besides Hypothetico – Deductive Reasoning, children also get the capacity to involve in inter-propositional thinking. It is a type of thinking in which a child tries to test whether the propositions formulated are valid or not.

Now, there is no doubt that the thought process of older children or adolescents is somewhere close to that of adults. But, Piaget believed that the thought process of adolescents still lacked the understanding as that of the adults.

The older children use their newly developed reasoning ability to build theories about different aspects. These include theories about human relationships, ethics, or political systems.

Now, though the reasoning behind such opinions may be logical. But the theories that adolescents or older children build are incorrect. This is because young children do not have much experience or knowledge to carry out a sophisticated task.

In addition to this, there is no guarantee that children reaching the stage of formal operations and developing the capability to engage in complex thought processes would in reality be able to think in a sophisticated way. This is because complex thought processes require a great amount of cognitive effort.

Therefore, adolescents and even adults often engage themselves in less advanced modes of thought.

Modern Assessment of Piaget’s Theory

Piaget’s theory of cognitive development provides great insights to a developmental psychologist. But, there was a need to review such a grand theory with the coming up of new evidence.

Therefore, developmental psychologists suggested certain revisions in Piaget’s Theory with regards to three significant areas.

I. Cognitive Abilities of Infants and Preschoolers

The evidence showcases that Jean Piaget underestimated the cognitive abilities of infants as well as young children in many areas. This is because of the research methods that Piaget used.

Thus, these methods made it quite challenging for infants and preschool children to portray their cognitive abilities.

Let’s take a look at two of these abilities:

(i) Object Permanence

Piaget suggested that infants as young as eight or nine months old did not have the capability of Object Permanence. Object Permanence is the ability to understand that the object continues to exist, even if it is hidden from sight.

However, new findings suggest that such incapacity arises from infants’ incapability to understand the concept ‘under’.

Say, for instance, an object is hidden under a cover. So, infants below the age of eight or nine months lack the ability to understand that an object can be placed underneath another object.

Now, suppose that the objects are hidden behind a screen or another object. So, infants as old as four or five months know that the object exists but is hidden from their sight.

Besides this, the new findings also suggest that infants also have an understanding of the physical objects far beyond their existence. Infants have a basic idea about the way physical objects would behave when exposed to various conditions.

(ii) Impossible Events

The developmental psychologist Renée Baillargeon carried out an experiment involving ‘Impossible Events’. These tasks were undertaken to test cognitive skills in infants.

Furthermore, this experiment was conducted under two conditions. One is the experimental condition and the other is the controlled condition.

1. Experimental Condition

Under the experimental condition, two types of events were carried out – possible and impossible events. In the impossible event, a gloved hand pushed an object along a platform.

This was done until the object was off the platform’s edge. Furthermore, the gloved hand did not grasp the object. Rather, it only used a finger to push the object along the platform.

Then, in the possible event condition, the hand using just a finger stopped pushing the object while it was still on the platform. It was noticed that children gazed longer at the impossible event than the possible event. This indicated that they understand that physical objects cannot remain suspended in vacant spaces.

2. Controlled Condition

Now, in the control condition, the gloved hand grasped the object and pushed it beyond the edge of the platform. During this instance, children did not gaze longer at the event and were not surprised.

However, children did seem a little surprised when (i) the gloved hand grasped the object and (ii) pushed it while stopping before reaching the edge of the platform.

Thus, such experiments go against Piaget’s assumption. They indicated that infants as small as three and a half months o understand much about the physical nature of the objects.

(iii) Egocentrism

Egocentrism refers to young children’s incapacity to understand that others perceive the world in a different way than they do. In order to study this trait in young children, Piaget showed children a model of a mountain. This model consisted of various other things such as a small stream.

The children could see the stream only from certain sides of the model. Then, Piaget made children walk around the mountain and looked at it from various angles. In addition to this, he placed a doll at different positions around the mountain.

Besides this, he asked the children to explain what the doll saw. Or he asked them to pick a photograph showcasing what that doll could see.

(iv) Observation

(a.) Accuracy

Piaget observed that children could not perform such a task with accuracy until they were six or seven years old. However, once again Piaget was misled.

This was because such a task involved objects like trees and people. And these were both differentiated and familiar.

Furthermore, children as young as three or four years old could respond accurately to such objects. In fact, children as old as fourteen to eighteen months indicated that others could not see what they could see.

For instance, such infants would look back and forth between objects and adults as they point towards the objects they want the adults to see.

(b.) Conservation

Piaget also undermined young children’s concept called conservation. Conservation is the children’s capacity to categorize objects and understand what it means to be alive.

Hence, the developmental psychologist concluded that Piaget’s theory highlights some important aspects of young children’s thought processes. However, it underestimates children’s abilities in several aspects.

II. Discrete Stages of Cognitive Development

Piaget in his theory concluded that cognitive development takes place via different stages. Furthermore, these stages are continuous or follow an order. This means that he emphasized that children must complete one stage before entering the next stage.

A modern assessment of Paiget’s theory indicates that cognitive development takes place in a gradual manner. This means that a capability that is completely absent at a certain age does not appear suddenly at another. In addition to this, the cognitive changes are domain-specific.

This means that young children may have the ability with respect to some kind of thought process. However, they may be far less advanced with respect to the other areas.

III. Social Interaction Between Children and Caregivers in the Children’s Cognitive Development

Piaget’s theory of cognitive development indicates that cognitive changes in children take place due to:

  • Their effort to draw a sense of the world around them, and
  • By the process of maturation. However, Lev Vygotsky proposed a socio-cultural theory. The Socio-Cultural Theory is another major theory of cognitive development. This theory lays emphasis on the role that social factors and language play in children’s cognitive development. These changes occur in school-aged children. Vygotsky suggested that cognitive development in such children happens in an interpersonal social context. In such a context, children advance from their level of actual development towards their level of potential development. Here the potential development level refers to young children’s capability to achieve things with the help of mentors. Whereas the level of actual development refers to the capability of children to perform actions without any help.

Also Read: Social Comparison Theory: Meaning, Examples, & Application

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