Piaget's Stages of Cognitive Development

The following information is based on the work of Jean Piaget, a developmental biologist who devoted his life to closely observing and recording the intellectual abilities of infants, children and adolescents. [ 1 ]. Piaget concluded that human development involves a series of stages. Given below is an outline of the four stages of Piagetian development. During each of these new abilities are gained. Each stage prepares the child for the succeeding levels.

The Sensorimotor Stage

The Sensorimotor Stage is the first stage Piaget uses to define cognitive development. During this period, infants are busy discovering relationships between their bodies and the environment. Researchers have discovered that infants have relatively well developed sensory abilities. The child relies on seeing, touching, sucking, feeling, and using their senses to learn things about themselves and the environment. Piaget calls this the sensorimotor stage because the early manifestations of intelligence appear from sensory perceptions and motor activities.

Countless informal experiments during the sensorimotor stage led to one of the important achievements. They enable the infant to develop the concept of separate selves, that is, the infant realizes that the external world is not an extension of themselves. The sensorimotor stage is also marked by the child's increasing ability to coordinate separate activities. An example of the fundamental importance of this is coordination between looking and reaching, without this an action as simple as picking up an object is not possible.

Infants realise that an object can be moved by a hand (concept of causality), and develop notions of displacement and events. An important discovery during the latter part of the sensorimotor stage is the concept of "object permanence".

Object permanence is the awareness that an object continues to exist even when it is not in view. In young infants, when a toy is covered by a piece of paper, the infant immediately stops and appears to lose interest in the toy (see figure above). This child has not yet mastered the concept of object permanence. In older infants, when a toy is covered the child will actively search for the object, realizing that the object continues to exist.

After a child has mastered the concept of object permanence, the emergence of directed groping" begins to take place. With directed groping, the child begins to perform motor experiments in order to see what will happen. During directed groping, a child will vary his movements to observe how the results will differ. The child learns to use new means to achieve an end. The child discovers he can pull objects toward himself with the aid of a stick or string, or tilt objects to get them through the bars of his playpen. The child begins to recognise cause-and-effect relationships at this stage, allowing the development of intentionally. Once a child knows what the effects of his activities will be, he can intend these effects.

The Preoperational Stage

In the preoperational stage a child will react to all similar objects as though they are identical (Lefrancois, 1995). At this time all women are 'Mummy' and all men 'Daddy'. While at this level a child's thought is transductive. This means the child will make inferences from one specific to another (Carlson & Buskist, 1997). This leads to a child looking at the moon and reasoning; 'My ball is round, that thing there is round; therefore that thing is a ball' .

From the age of about 4 years until 7 most children go through the Intuitive period. This is characterized by egocentric, perception-dominated and intuitive thought which is prone to errors in classification (Lefrancois, 1995).

Most preoperational thinking is self-centred, or Egocentric. According to Piaget, a preoperational child has difficulty understanding life from any other perspective than his own. In this time, the child is very me, myself, and I oriented.

Egocentrism [ 2 ] is very apparent in the relationship between two preschool children. Imagine two children are playing right next to each other, one playing with a colouring book and the other with a doll. They are talking to each other in sequence, but each child is completely oblivious to what the other is saying.

Julie: "I love my dolly, her name is Tina"

Carol: "I'm going to colour the sun yellow"

Julie: "She has long, curly hair like my auntie"

Carol: "Maybe I'll colour the trees yellow, too"

Julie: "I wonder what Tina's eyes are made of?"

Carol: "I lost my orange crayon"

Julie: " I know her eyes are made of glass."

These types of exchanges are called "collective monologues". This type of monologue demonstrates the "egocentrism" of children's thinking in this stage.

According to Piaget, egocentrism of the young child leads them to believe that everyone thinks as they do, and that the whole world shares their feelings and desires. This sense of oneness with the world leads to the child's assumptions of magic omnipotence. Not only is the world created for them, they can control it. This leads to the child believing that nature is alive, and controllable. This is a concept of egocentrism known as "animism", the most characteristic of egocentric thought.

Closely related to animism is artificialism, or the idea that natural phenomena are created by human beings. Such as the sun is created by a man with a match. "Realism" is the child's notion that their own perspective is objective and absolute. The child thinks from one perspective and regards this reality as absolute. Names, for example, are real to the child. The child can't realize that names are only verbal labels, or conceive the idea that they could have been given a different name.

During the pre-operational period, the child begins to develop the use of symbols (but can not manipulate them), and the child is able to use language and words to represent things not visible. Also, the pre-operational child begins to master conservation problems.

By the age of four children are developing a more complete understanding of concepts and tend to have stopped reasoning tranductively (Lefrancois, 1995). However their thought is dominated more by perception than logic. This is clearly illustrated by conservation experiments. In such an experiment a pre-operational child may be shown two balls of clay, that the child acknowledges are equal in size, one of which is then squashed. The child is now asked if both lots of clay are equal. A child at this stage will say they are no longer equal.

Although the child is still unable to think in a truly logical fashion, they may begin to treat objects as part of a group. The pre-operational child may have difficulty with classification. This is because, to a pre-operational child, the division of a parent class into subclasses destroys the parent group (Lefrancois, 1995). For example, a child has a pile of toy vehicles which are then split into trucks and cars. Next the child is asked 'Tell me, are there more trucks than vehicles, or less, or the same number?' the child will almost always say there are more trucks than vehicles!

In the latter part of the preoperational period, the child begins to have an understanding between reality and fantasy.

The Concrete Operational Stage

During this stage, children begin to reason logically, and organize thoughts coherently. However, they can only think about actual physical objects, and cannot handle abstract reasoning. They have difficulty understanding abstract or hypothetical concepts.

This stage is also characterized by a loss of egocentric thinking.

During this stage, the child has the ability to master most types of conservation experiments, and begins to understand reversibility. Conservation is the realization that quantity or amount does not change when nothing has been added or taken away from an object or a collection of objects, despite changes in form or spatial arrangement. The concrete operational stage is also characterized by the child’s ability to coordinate two dimensions of an object simultaneously, arrange structures in sequence, and transpose differences between items in a series. The child is capable of concrete problem-solving. Categorical labels such as "number" or "animal" are now available to the child.


Piaget determined that children in the concrete operational stage were fairly good at the use of inductive logic. Inductive logic involves going from a specific experience to a general principle. On the other hand, children at this age have difficulty using deductive logic, which involves using a general principle to determine the outcome of a specific event.


One of the most important developments in this stage is an understanding of reversibility, or awareness that actions can be reversed. An example of this is being able to reverse the order of relationships between mental categories. For example, a child might be able to recognize that his or her dog is a Labrador, that a Labrador is a dog, and that a dog is an animal.

A large portion of the defining characteristics of the stage can be understood in terms of the child overcoming the limits of stage two, known as the pre-operational stage. The pre-operational child has a number of cognitive barriers which are subsequently broken down, and it is important to note that overcoming these obstacles is not due to gradual improvement in abilities the child already possesses. Rather the changes are genuine qualitative shifts, corresponding to new abilities being acquired.

The first, and most discussed, of these limitations is egocentrism. The pre-operational child has a “'self-centred' view of the world” (Smith, Cowie and Blades, 2003, p. 399), meaning that she has difficulty understanding that other people may see things differently, and hence hold a differing point of view. Piaget's classic test for egocentrism is the three mountains task (Piaget and Inhelder, 1956), which concrete operational thinkers can complete successfully.

A second limitation which is overcome in the concrete operational stage is the perceptual domination of one aspect of a situation. Before the stage begins, the child's perception of any situation or problem will be dominated by one aspect; this is best illustrated by the failure of pre-operational children to pass Piaget's conservation tasks (Piaget and Inhelder, 1974).

Perhaps the most important limitation, yet the most difficult to describe and measure, is that of the turn to logical operators. A pre-operational child will use mostly simple, heuristic strategies in problem solving. Once a child reaches the concrete operational stage, they will be in possession of a completely new set of strategies, allowing problem solving using logical rules. This new ability manifests itself most clearly in children's justifications for their answers. Concrete operational thinkers will explicitly state their use of logical rules in problem solving (Harris and Butterworth, 2002). This area also indicates the way in which the concrete operational stage can be negatively defined; although children can now use logical strategies, these can only be applied to concrete, immediately present objects. Thinking has become logical, but is not yet abstract.

These shifts in the child's thinking lead to a number of new abilities which are also major, positively defined characteristics of the concrete operational stage. The most frequently cited ability is conservation. Now that children are no longer perceptually dominated by one aspect of a situation, they can track changes much more easily and recognise that some properties of an object will persevere through change. Conservation is always gained in the same order, firstly with respect to number, followed secondly by weight, and thirdly by volume.

A second new ability gained in the concrete operational stage is reversibility. This refers to the ability to mentally trace backwards, and is of enormous help to the child in both their problem solving and the knowledge they have of their own problem solving. For the former this is because they can see that in a conservation task, for example, the change made could be reversed to regain the original properties. With respect to knowledge of their own problem solving, they become able to retrace their mental steps, allowing an entirely new level of reflection.

Concrete operational children also gain the ability to structure objects hierarchically, known as classification. This includes the notion of class inclusion, e.g. understanding an object being part of a subset included within a parent set, and is shown on Piaget's inclusion task, asking children to identify, out of a number of brown and white wooden beads, whether there were more brown beads or wooden beads (Piaget, 1965).

Seriation is another new ability gained during this stage, and refers to the child's ability to order objects with respect to a common property. A simple example of this would be placing a number of sticks in order of height. An important new ability which develops from the interplay of both seriation and classification is that of numeration. Whilst pre-operational children are obviously capable of counting, it is only during the concrete operational stage that they become able to apply mathematical operators, thanks to their abilities to order things in terms of number (seriation) and to split numbers into sets and subsets (classification), enabling more complex multiplication, division and so on.

Finally, and also following the development of seriation, is transitive inference. This is the name given to children's ability to compare two objects via an intermediate object. So for instance, one stick could be deemed to be longer than another by both being individually compared to another (third) stick.

The Formal Operational Stage

The Formal Operational stage [ 3 ] is the final stage in Piaget's theory. It begins at approximately 11 to 12 years of age, and continues throughout adulthood, although Piaget does point out that some people may never reach this stage of cognitive development.

The formal operational stage is characterized by the ability to formulate hypotheses and systematically test them to arrive at an answer to a problem.

The individual in the formal stage is also able to think abstractly and to understand the form or structure of a mathematical problem.

Another characteristic of the individual is their ability to reason contrary to fact. That is, if they are given a statement and asked to use it as the basis of an argument they are capable of accomplishing the task. For example, they can deal with the statement "what would happen if snow were black".


Note 1:
Although Piaget attached ages to each stage (Sensorimotor Period - birth to 2 years, PreOperational Thought- 2 to 6 or 7 years, Concrete Operations -6/7 to 11/12, & Formal Operations - 11/12 to adult), these were only rough guidelines and it is the universal sequence of the stages, not the age, which is by far the most important aspect. Regarding the issue of cross-cultural differences, this does cause more trouble for Piaget, but he still explicitly allows for the fact that abilities may show up at different times on different tasks, but it is the underlying mechanisms and strategies that he is concerned with.
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Note 2:   Egocentrism
In psychology, egocentrism is defined as a) the incomplete differentiation of the self and the world, including other people and b) the tendency to perceive, understand and interpret the world in terms of the self. The term derives from the Greek egô, meaning "I." An egocentric person has no theory of mind, cannot "put himself in other people's shoes," and believes everyone sees what he sees (or that what he sees in some way exceeds what others see.)

It appears that this is shown mostly in younger children. They are unable to separate their own beliefs,thoughts and ideas from others. For example, if a child sees that there is candy in a box, he assumes that someone else walking into the room also knows that there is candy in that box. He reasons that "since I know it, you should too". As stated previously this may be rooted in the limitations in the child's theory of mind skills. However, it does not mean that children are unable to put their selves in someone else's shoes. As far as feelings are concerned, it is shown that children exhibit empathy early on and are able to cooperate with others and be aware of their needs and wants.

Jean Piaget (1896-1980) claimed that young children are egocentric. This does not mean that they are selfish, but that they do not have the mental ability to understand that other people may have different opinions and beliefs from themselves. Piaget did a test to investigate egocentrism called the mountains study. He put children in front of a simple plaster mountain range and then asked them to pick from four pictures the view that he, Piaget, would see. Younger children picked the picture of the view they themselves saw.

However the Mountains Study has been criticized for judging children's visual spatial awareness, rather than egocentrism. A follow up study involving police dolls showed that even young children were able to correctly say what the interviewer would see. It is thought that Piaget overestimated the levels of egocentrism in children.
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Note 3:
It is now thought that not every child reaches the formal operation stage.
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