The Swiss Psychologist, Jean Piaget (1970, 1972) took a different approach from that of the psychometricians to understand human cognition. The psychometricians were interested in studying individual differences in cognition, but Piaget was interested in understanding the nature of intellectual development in normal children.

For nearly 50 years, Paiget observed children’s intellectual development, and suggested that all children proceed through a series of four stages in a fixed order. He said that these stages differ not only in the quantity of information acquired at each stage, but also in the quality of knowledge and understanding as well.

Cognition refers to all psychological processes used in acquiring knowledge m one’s environment. It includes learning, memory, perception, thinking, reasoning, decision-making, and problem solving. Piaget’s work provides insight into the age-related cognitive activities from early childhood to adolescence.

Piaget who initially in 1920s worked in Alfred Binet’s laboratory help standardize the early IQ tests came to believe that the standardized intelligence tests ignore the development of important qualitative aspects of children’s thought processes.


In order to examine how children think, Piaget asked children some interesting questions, such as “Where do dreams come from”? Or “Has the rock life?” He was interested not with correct answers but with the way children answer a question, even if their answers were wrong. This gave him tremendous insight about the nature of children’s thought processes, which is very different from that of the adults.

Piaget received his early training in biology and philosophy. During his mage years, his godfather introduced him into an area of philosophy called epistemology, which is concerned with analysis of various forms of knowledge only natural that his theory of cognitive development reflects a distinctively logical flavor. He believed that human beings are active organisms having a network of mental structures and constantly trying to make sense of their experiences.

He consistently observed his own three children, two daughters Jaculine, and Lucine and the son Laurent. His observations were found to be almost same in cases of all his children. His meticulous studies were put a systematic theory, which continued to be updated until his death in 1980. His careful work inspired a great deal of research on children’s cognition intelligence. Even today, Piaget’s theory of intelligence provides the most dominant framework in developmental psychology.

According to Piaget (1952), “Intelligence is a particular instance biological adaptation.” For Piaget, intelligence refers to a general me adaptability. Piaget was basically concerned with three questions: (a) what it that changes with development? (b) How cognitive changes take place? (c) What is the most systematic way of ordering the stages of cognitive development?


What is it that changes with development?

According to Piaget, specific cognitive structures or schemes change as a function of age. The infant, the schemes are motor action patterns. The newborns are equipped with only primitive schemes such as sucking, looking, and grasping etc., which guide elementary forms of behavior. These sensory motor action pattern: activated when certain objects are present. For example, when a feeding bottle is present, the child can look, grasp, or suck. Therefore there is a loc scheme, a sucking scheme, or a grasping scheme, and so on.

As the infant grows, the schemes become more complex. As the child advances in age the schemes move from an action-based level to a mental level, and bee symbolic, that is actions can be carried even when the object is not pre: At this stage, the child not just acts on objects, but shows evidence of thinking before he acts. As will be discussed later, this change marks the Trans from the sensorimotor stage to the preoperational stage.

Piaget believed that all schemes are spontaneously exercised as children have a natural tendency to use them repeatedly. As the schemes are exercised they come in contact with new situations.


Gradually, children notice the between their existing schemes, and the reality requirements, and try to re this discrepancy. Hence, the schemes are continuously modified and adapted to the environmental demands. As a result of this modification and adaptation cognitive changes take place as the child’s age increases.

Thus, what change with development are the schemes or the cognitive structures of the child.

How cognitive changes take place?

To explain how cognitive structures or schemes change, Piaget identified two important intellectual functions: adaptation and organization. The basic characteristics of these intellectual functions remain the same throughout life. Their nature and functions do not change. That is why they are known as functional invariants. These functions work together and produce a variety of schemes.



Adaption is an intellectual process of building mental representations le world by interacting with the external world. Adaptation is made up of complementary processes: assimilation and accommodation. Piaget owed these terms directly from the field of biological growth. Let us see these concepts are used in the biological sphere.

When we eat to support body, we assimilate food and transform it to make it look like ourselves. 3n we cannot fully assimilate the new objects, we accommodate to them, example, when we take a new food, we must accommodate to its new lands, by adjusting our stomach and digestion to the special properties of novel food.

Cognitive adaptation works in much the same way. During assimilation, interpret the external world in terms of our existing cognitive structures, example, when an infant sucks an artificial nipple, he assimilates the nipple le scheme of sucking. In accommodation, we modify the existing mental structures to take account of new information. The baby who sucks the edge he blankets is modifying the sucking scheme to fit a new object.


Both imitation and accommodation work together in every interaction with the environment. But the balance between these two processes varies from one situation to another. When children assimilate more than they accommodate, cognitive changes do not take place. They remain in state of cognitive equilibrium. When more accommodation is necessary, children are in a state disequilibrium or cognitive discomfort.

They modify their cognitive structures to fit to the new environmental requirements. This back-and-forth movement between equilibrium and disequilibrium is called equilibration. Each equilibration produces more complex and more effective schemes as children advance in age. This is how cognitive changes take place.


Organization is another process, which helps cognitive development, takes place internally. Once children form new cognitive structures, they rearrange them and link each other in a network of cognitive system. Thus organization refers to internal arrangement of schemes or cognitive structures to form a strong interconnected cognitive system. According to Piaget, the schemes reach a true state of equilibrium, when they become a part of broad network of structures.


Thus, cognitive changes take place through processes of adaptation a organization.

How cognitive development can be ordered?

Piaget believed that the cognitive changes take place in an orderly manner, and follow a sequent Children proceed through four qualitatively distinct stages of development (a) the sensorimotor stage (birth to 2 years); (b) the preoperational stage years to 7 years); (c) the concrete operational stage (7 years to 11 year and (d) the formal operational stage (11 years and older).

These stages dif not only in the quantity of information, but also in the quality of knowledge an understanding. This sequence of development is invariant (the stages always emerge in a fixed order), and universal (all children everywhere proceed through these stages). The four successive stages of cognitive development are described below.

Sensorimotor Stage (Birth to 2 years)

This is the first stage of cognitive development, which begins at birth and continues until the child is 2-years-old. It is called so, because child understanding of the world is limited to his sensory and motor, organs, must act on the environment to understand what it is like. He has little competence in representing the environment through images, language, and symbols.

Through his motor actions, the child gradually learns that his action produce effects on the environment. The cognitive development proceeds; such a rapid rate during these two years that Piaget has divided the sensor motor stage into six substages. This is the most complex and m important period of development in which a great deal of accommodation required to meet the environmental demands

The child masters three important capacities during this period: (a) cause­s and-effect relationship, (b) object permanence, and (c) deferred imitation. First, be acquires a basic understanding of the concept of cause-and-effect. He understands that he can manipulate his environment to produce interesting effects. Second, he develops the concept of object permanence that is the ability to understand that objects exist even when they are not visible.

At about one year of age, the child understands that even when a doll is not right there in front of him, it is somewhere in the home. If he wants, he can find and play with it. Third, he develops the capacity for deferred imitation- the ability to remember and copy behaviors of others who are not immediately present. By end of the sensorimotor period, he develops mental representations of the external world that is, he can think with mental images of absent objects and past events.

Preoperational Stage (2 Years to 7 Years)

This stage is characterized by emergence of symbolic activity. During this stage, there is an extraordinary increase in child’s representational ability – the ability to think using mental images of people and objects. The child learns to carry out symbolic thinking.

Symbolic thinking is the ability to make one thing represent, or act as a symbol for another thing. When the child points to his fingers as guns, or uses a matchbox as a telephone receiver, he is demonstrating symbolic thinking. In the preoperational stage, the child learns not only through his motor actions, but more so by thinking symbolically and reflecting on his actions.

Child’s symbolic thinking is reflected in several of his activities such as (a) acquiring and using language, (b) symbolic or make-believe play, and (c) drawings. Language is symbolic in nature, because words act as symbols for objects, events, and persons. The language helps the child to separate thought from action. As a result, thinking becomes more efficient as language helps the child to deal with the past, present, and future all at once. Through language, children form a stable, larger, and interconnected image of reality.

The second manifestation of symbolic thinking is witnessed in make-believe play. In the make-believe play, children make an object stand for another object. They enact familiar activities such as pretending to eat or go to sleep. The little children wipe out the tears from doll’s eyes, and make her sleep by singing rhymes. These are examples, where children’s sensory-motor actions turned into internal mental representations of reality. Third, children’s drawing are another important mode of symbolic thinking. They represent animals, objects, persons, and events pictorially through drawings. The drawings ref child’s mental representations.

While children’s thinking during this stage is mare advanced than that of the sensorimotor stage, Piaget believes that preoperational children still immature in several important aspects. Their thinking is qualitatively inferior to that of the adults. Piaget described preoperational children in terms of what they cannot, rather than can understand. The interesting features of children thinking during this period are: (a) egocentric thought, (b) animistic think (c) centration, (d) irreversibility, and (e) lack of classificatory ability.

Because of egocentric thinking, children cannot take another person’s perspective They see the world only in terms of their perspectives. For example, a 3-year old frequently hides himself with his face against the wall and hands covering his eyes. Though he is in plain view of the other persons, he believes that he cannot be seen as he cannot see others. Egocentric thinking is responsible for animistic thinking – the belief that inanimate objects have lifelike qualities Children at this stage imagine that objects like tables, chairs, clouds, moon, etc have thoughts wishes, feelings, and intentions. A 3-year old who bangs his head against a tabletop complains about the ‘bad table’.


Centration is the focusing of attention on one single aspect of a situation while ignoring other important features. Because of centration, preoperational children fail to understand the principle of conservation. Though there are equal amount of juice in a narrower glass, and a wider glass, the child pre to drink the juice from the narrower glass as juice in the narrower glass fill a greater height.

Here the child makes a judgment about the quantity centering his attention on the dimension of height only, ignoring the dimension of width. Centration is a weakness of preoperational thinking. Another important illogical feature of preoperational thinking is irreversibility. The preoperational children cannot reverse their thinking or trace their thought processes backward manner. They may think through a series of steps in solving a problem, but they cannot go backward mentally returning to the starting point. Because their thinking is centered, and irreversible, they cannot understand the principle of conservation.

Lastly, preoperational children lack classificatory ability. They have difficulties in grouping objects into classes and subclasses. Piaget illustrated this with his famous class-inclusion problem. Children are shown 15 flowers, most of which are yellow, and only a few are blue. When asked, “Whether there are more yellow flowers or more flowers?” the preoperational children confidently respond, “There are more yellow flowers!” This shows their inability classify objects hierarchically. They fail to understand that a subclass contains lesser (or at best equal) number of elements than that of a class.

The children overcome the above limitations, when they pass to the next stage, i.e., the concrete operational stage, which begins at about 7 years of age. Recent research suggests that preoperational children are intellectually more competent than what Piaget believed. Piaget appears to have underestimated the intellectual competence of preoperational children.

Concrete Operational Stage (7 Years to 11 Years)

The concrete operational stage which spans the years from 7 to 11 is a major turning point in cognitive development, as children at this stage think ire like adults than like younger children at earlier ages. This stage is characterized by logical thought and a loss of egocentric thinking. The concrete operational child is far more logical, flexible, and organized in his cognition. But his logical mental operations are only applied to concrete objects and events, not to propositions, which are abstract and hypothetical nature.

During this stage, children acquire a number of important skills such as conservation, (b) decentration, (c) reversibility, (d) seriation, and (e) hierarchical classification. Piaget regarded conservation as the most important achievement of the concrete operational stage.

Conservation refers to an understanding of the fact that physical characteristics of objects remain there even when their outward appearance changes. When a ball of clay is flattened to the shape of a cake, the mass of clay remains the same, even if the shape of clay changes. This is called conservation of mass. The number beads in a string remain the same, whether the string is stretched in the form of a line or rolled into a circle. The ability to achieve conservation is dependent on two other concepts: decentration and reversibility.

The child can achieve conservation if he decenters his attention from only one feat of the stimulus situation to take into account a number of features at the same time. In other words, like a preoperational child, a concrete operational child does not focus his attention on only one single aspect of the stimulus situation takes into account several important aspects in making a judgment Reversibility refers to understanding that as we can think through several steps in a problem, we can also go backward in our steps to finally return the starting point. In the conservation of mass, the child understands that i cake of clay can be again brought back to form the original ball of clay.

The concrete operational children demonstrate seriation, that is the ability to arrange a set of objects on the basis of physical characteristics such height, shape etc. Given 10 sticks of varying length, they can arrange the sticks in an order from the shortest stick to the longest one. Hierarchic classification means grouping and regrouping objects into classes subclasses using more than one attribute.

The children at this stage c understand that a subclass contains lesser or at the most equal number elements as that of a class to which it belongs. Thus, given 15 flowers most of which are yellow, and a few are blue, and asked the question, “Are the more yellow flowers or more flowers?” the child will unhesitatingly answer that there are more flowers. He can understand that yellow flowers constitute a subclass of the class of flowers.

Although, concrete operational children demonstrate logical thinking, there is still one major limitation in their thinking. Their logical thinking is most bound by the concrete physical reality of the world. Their mental operation have not yet attained a formal status in that they cannot apply their thinking questions that are abstract and hypothetical in nature.

FormaI Operational Stage (11 Years and Older)

In this final stage of cognitive development, children’s thinking becomes formal, hypothetical, and abstract like that of adults. They can deal wit possibilities and predict future events. Their thinking is no longer confined to the concrete physical realities. Suppose children are asked a question of the form, “Cycles are faster than cars, and cars are faster than aero planes; which between the two, aero plane and cycle, is slower?” A concrete operation child may answer “Cycle” or may reject the question, and refuse to apply his mental operations to answer the question, because the information is contrary to his real-world knowledge. On the other hand, a formal operational child will evaluate the logic of the statements to answer the question. This shows the abstract and hypothetical nature of formal operational child’s thought processes.

The two important characteristics of child’s thinking during the formal operational stage are: (a) hypothetico-deductive reasoning, and (b) propositional thinking. Hypothetico-deductive reasoning is a formal operational problem solving strategy.

That is, when faced with a problem, a formal operational thinker can formulate a general theory based on all possible factors and then deduce specific hypotheses from the general theory for further testing. He can test the hypotheses in an orderly fashion to examine which ones work in the real world. This form of reasoning begins with possibilities and proceeds to reality. On the other hand, concrete operational children start with examining reality, and when their examination is not confirmed, they cannot think of alternatives to solve the problem.

Piaget and Inhelder (1958) have demonstrated how children solve the ‘pendulum problem’. The problem-solver is asked to figure out what determines how fast a pendulum swings. Is it the length of the string, the weight of the pendulum or the force with which the pendulum is pushed? (The correct answer is the length of the string). Concrete operational children approach the problem in an unsystematic manner. They may simultaneously change two or more variables (e.g., the length of the string and weight of the pendulum) to examine what happens.

Since, they vary more than one factor at once; they cannot tell which factor is the critical one. In contrast, formal operational children approach the problem systematically. They behave as scientists carry out investigations. They vary one factor at a time and observe its effect on the movement of the pendulum. As a result, they are likely to identity that the critical factor is the length of the string. Thus, they carry simple experiments to rule out competing possibilities. Such kind of thinking is based on hypothetico-deductive reasoning. This is an important characteristic of formal operational thought.

A second important characteristic of this stage is propositional thinking. Children can evaluate the logic of propositions or verbal statements without referring to real-world circumstances. The statements are evaluated on their own merit even if they are contrary to the real-world knowledge. Consider the question, “If aero planes are called elephants, can elephants fly?” A concrete operational thinker will answer, “No, elephants cannot fly”, while a formal operational thinker will answer, “Yes” to the question. A formal operations thinker can say so, because he is evaluating the logical validity of verbs statements without being influenced by the concrete real-world knowledge.

Though thinking during the formal operational stage closely approaches adult thinking, yet it falls short of adult level. While the reasoning of older children may be quite logical, their theories are not very practical, because they simply do not know enough about life and its possibilities. Furthermore there is no guarantee that a child after attaining 11 years of age will demonstrate hypothetico-deductive reasoning and propositional thinking as claimed by Piaget. Even adults sometimes deviate from formal operational thinking. In some cultures, particularly in less technologically advanced societies, adult: do not reach the stage of formal operational thinking.

Evaluation of Piaget’s theory

Piaget’s theory provides the most important and powerful perspective or children’s cognitive development. It is a grand theory in developments psychology, which has inspired many researchers all over the world. Tests have been developed, and educational programs for children have been planned on the basis of Piaget’s theoretical framework. A number of researchers have confirmed Piagetian concepts and stages of cognitive development. The impact of his theory has been so great that any textbook or research reports on cognition cannot overlook Piaget’s theory of cognitive development; if they do, their work will be considered incomplete.

All said and done, Piaget’s theory has not been free from criticisms. Several of his ideas are now regarded as either incorrect or only partially correct The first criticism is against Piaget’s belief that development proceeds in a stage-like manner. Some developmental psychologists believe that development is a continuous process, and cannot be broken down in:: different stages as Piaget’s theory suggests. They believe that development is more quantitative than qualitative in nature, and that the basic nature of the underlying cognitive processes changes very little with age.

Another major criticism leveled at Piaget is that he has seriously overestimated the cognitive capacities of infants and young children. In fact, they show more advanced cognitive capacities than what Piaget believed. It is been shown that children demonstrate many concrete operational skills such as conservation, seriation, and decentration before 7 years of age. The concept of object permanence is attained much earlier than what Piaget postulated.

The third major drawback in Piaget’s theory that the universal nature of Piagetian stages is thus called into question, the development is a lifetime process. All the skills do not emerge at once en the child reaches formal operational stage at the age of 11 years. In some cultures, almost no one reaches the formal operational stage.

Fourth, Piaget’s belief that children must act on their environment to revise sir cognitive structures is too narrow a notion of how learning takes place,cognitive development is not always a self-generating activity. As noted by Vygotsky, cognitive development is shaped to a large extent by the socio cultural practices and experiences. The external social environment plays a significant 5 in shaping up and modifying cognitive structures of children. Piaget has undermined the role of societal context in the development of children’s cognitions.

Finally, Piaget has overemphasized the aspects of cognition in developing theory. There are several other important dimensions of development such social, emotional, and moral development, which have not been given due attention by Piaget. The course of human cognition cannot be completely understood without taking into account other dimensions of development, which have close linkages with human cognition.