Piaget’s Stages of Cognitive Development

Children are not little adults.  Until they reach the age of 15 or so they are not capable of reasoning as an adult.  Piaget was not a psychologist.  He was a developmental biologist who devoted his life to closely observing and recording the intellectual abilities of infants, children and adolescents.   The stages of intellectual development formulated by Piaget appear to be related to major developments in brain growth.  The human brain is not fully developed until late adolescence or in the case of males sometimes early adulthood.  We often expect children to think like adults when they are not yet capable of doing so. 


When considering intelligence, Piaget focuses on the mental processes that occur, rather than on the actual measure of the intellect.

Piaget’s biological approach focuses on the physical and mental aspects of our bodies. This includes our reflexes, how we adapt to certain situations using assimilation andaccommodation.

Assimilation occurs when new information is introduced to a person. The person begins to integrate the new information into existing files, or “schema” (how you see the world)…You try to make the new information fit what you already know.

Accommodation occurs when the person reorganizes schema to accommodate themselves with the environment….You change how you see the world to fit the new information.

The succession of stages involves the movement through four stages that Piaget has set and defined. Children must move through these stages during their childhood. These include



-Concrete operational

-Formal operational

Stage movement is an important factor of Piaget’s definition of intelligence, because Piaget states there are a specific set of criteria that must be met and mastered at each stage. In order to move from the first stage to the next, the child must master that specific set of criteria.

To define Intellectual Competence, Piaget focuses on the highest level of functioning that can occur at a specific stage. Although Piaget has approximate ages assigned to stages, a child’s competence is only measured by what stage they are in, not by age. If the child can only perform tasks that are at the preoperational stage, which is the highest level the child is at regardless of age.

Developmental Stage &Approximate Age Characteristic Behavior
Sensory Motor Period
(0 – 24 months) 
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.Through countless informal experiments, infants develop the concept of separate selves, that is, the infant realizes that the external world is not an extension of themselves.

Infants realize 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: realization that an object exists even when a child cannot see or touch it

Reflexive Stage 
(0-2 months)
Simple reflex activity such as grasping, sucking.
Primary Circular Reactions
(2-4 months)
Reflexive behaviors occur in stereotyped repetition such as opening and closing fingers repetitively.
Secondary Circular Reactions (4-8 months) Repetition of change actions to reproduce interesting consequences such as kicking one’s feet to more a mobile suspended over the crib.
Coordination of Secondary Reactions (8-12 months) Responses become coordinated into more complex sequences.  Actions take on an “intentional” character such as the infant reaches behind a screen to obtain a hidden object.
Tertiary Circular Reactions
(12-18 months)
Discovery of new ways to produce the same consequence or obtain the same goal such as the infant may pull a pillow toward him in an attempt to get a toy resting on it.
Invention of New Means Through Mental Combination 
(18-24 months)


Evidence of an internal representational system.  Symbolizing the problem-solving sequence before actually responding.  Deferred imitation.
The Preoperational Period
(2-7 years)  
The preoperational stage occurs from 2 to 6 years of age, and is the second stage in Piaget’s stages of cognitive development.Throughout most of the preoperational stage, a child’s thinking is self-centered, or egocentric = a child has difficulty understanding life from any other perspective than his own. In this stage, the child is very me, myself, and I oriented.

In the pre-operational stage, 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.

Conservation:   principle that an object does not change when its appearance is changed…i.e. play dough, water

Although the child is still unable to think in a truly logical fashion, the child may begin to treat objects as part of a group. The pre-operational child may have difficulty with classification.

In the Latter part of the preoperational stage, the child begins to have an understanding between reality and fantasy. The child also begins to understand sex roles in society.

Preoperational Phase
(2-4 years)





Increased use of verbal representation but speech is egocentric.  The beginnings of symbolic rather than simple motor play.  Transductive reasoning.  Can think about something without the object being present by use of language.
Intuitive Phase 
(4-7 years)













Speech becomes more social, less egocentric.  The child has an intuitive grasp of logical concepts in some areas.  However, there is still a tendency to focus attention on one aspect of an object while ignoring others.  Concepts formed are crude and irreversible.   Easy to believe in magical increase, decrease, disappearance.  Reality not firm.  Perceptions dominate judgment.In moral-ethical realm, the child is not able to show principles underlying best behavior.  Rules of a game not develop, only uses simple do’s and don’ts imposed by authority.
Period of Concrete Operations 
(7-11 years)  
The concrete operational stage is the third stage in Piaget’s theory. This stage typically occurs between the ages of 7 and 12.During this stage, the child begins to reason logically, and organize thoughts coherently. However, they can only think about actual physical objects, they cannot handle abstract reasoning.

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. 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

Evidence for organized, logical thought.  There is the ability to perform multiple classification tasks, order objects in a logical sequence, and comprehend the principle of conservation.  Thinking becomes less transductive and less egocentric.  The child is capable of concrete problem-solving.Some reversibility now possible (quantities moved can be restored such as in arithmetic: 3+4 = 7 and 7-4 = 3, etc.)Class logic-finding bases to sort unlike objects into logical groups where previously it was on superficial perceived attribute such as color.   Categorical labels such as “number” or animal” now available.
Period of Formal Operations
(11-15 years)  
The formal operational stage is the fourth and 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”.

Thought becomes more abstract, incorporating the principles of formal logic.  The ability to generate abstract propositions, multiple hypotheses and their possible outcomes is evident.  Thinking becomes less tied to concrete reality.Formal logical systems can be acquired.  Can handle proportions, algebraic manipulation, other purely abstract processes.  If a + b = x then x = a – b.  If ma/ca = IQ = 1.00 then Ma = CA.Prepositional logic, as-if and if-then steps.  Can use aids such as axioms to transcend human limits on comprehension.

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