Jean Piaget – Stages of Development

Biographical Overview

Jean Piaget was born on August 9th, 1896 in Neuchatel, Switzerland.  “He published his first paper at age 11 and wrote over 30 volumes without any formal training or degree in psychology. “In 1918, Piaget received his Doctorate in Science from the University of Neuchâtel. He worked for a year at psychology labs in Zurich and at Bleuler’s famous psychiatric clinic. During this period, he was introduced to the works of Freud, Jung, and others, (Boeree, 2006, p. 2).”  Trained in zoology, he worked with Alfred Binet on first intelligence test, (Rosenthal, 2005).”  Criticized for his research methods, he was interested in understanding how children solved problems, (Rosenthal, 2005).   He considered himself the father of a new field called “genetic epistemology”, a field that focuses on the study of the development of knowledge, (Boeree, 2006).  He married his wife in 1921 and they had three children together.  Between 1929 and 1968 he was the director of the International Bureau of Education.  In 1940, “He became chair of Experimental Psychology, the Director of the psychology laboratory, and the president of the Swiss Society of Psycholoby, (Boeree, 2006, p. 2).”   Later in his career he was bestowed several honorary degrees and held a position as professor (Boeree, 2006).  He died on September 16, 1980 in Geneva.  Rosenthal, (2095), calls him a “Developmental Structuralist” since he believed there universal stages of psychological developmen. Rosenthal, (2005), also calls him a  Universal Constructivist – the stages of developmental are universal and the child literally constructs his/her cognitive development. Heredity is responsible for unfolding the stages.

“Forces driving Piaget’s theory[include]…(1) Piaget was an evolutionary biologist. (2) Therefore, he believed that all organisms must adapt to survive. (3) Adaptation takes place at the species level phylogenetically. (4) Adaptation also takes place at the individual level ontogenetically. (5) Intelligence happens in biological organisms. (6) Therefore, intelligence is a biological process. (7) There intelligence adapts. (8) Because intelligence adapts ontogenetically, we should be able to observe it in the development of children. (Piaget, 1952)”

Key Concepts

Genetic Epistemology

Piaget did not call himself a psychologist.  He described his research as “genetic epistemology”.  While genetic refers to mechanisms of heredity epistemology refers to the formation and development of knowledge.  In other words, Piaget is interested in universal aspects of human cognitive development that reflect how we develop knowledge of the world around us.


Piaget defines schemas as building block of knowledge that allow children to interact with their environment  (Piaget, 1952). Schemas provide mental representations of the world and help us make sense of what we encounter.  Rosenthal (2005), describes schemas as reflecting the “way a person acquires knowledge about the world….[they are comprised of] patterns of organized thought or behavior” As children grow, they develop sensorimotor skills that reflect their exploration of the environment and growing knowledge about the world (Boeree, 2006).  Piaget describes this growing knowledge as an internalized schema or mental representation of the world around him.  Later schemas grow out of earlier ones.

Assimilation & Accommodation

“Assimilation and accommodation work like pendulum swings at advancing our understanding of the world and our competency in it, (Boeree, 2006, p. 3).”  They are complementary processes that together guide the development of our cognitive processes and developing schema about the world.  Rosenthal (2005) states that “Humans strive for ‘equilibration’ between these two processes.”


“Assimilation involves learning from an existing scheme or taking inknowledge by using an existing cognitive structure, (Rosenthal, 2005).”  For example assimilating a new object into an old schema might involve learning about the texture of different objects by putting them in your mouth, (like a rattle versus a pacifier).


In contrast,  accommodation involves the development of a new cognitive structure to deal with new information or situations.  For example, a child who is breastfed must learn a new schematic approach to drinking from a cup.   In other words, while assimilation involves building upon old knowledge, accommodation involves the development of knew knowledge.

Developmental Stages

Sensorimotor Stage

“The sensorimotor stage lasts from birth to about two years old. As the name implies, the infant uses senses and motor abilities to understand the world, beginning with reflexes and ending with complex combinations of sensorimotor skills, (Boeree, 2006, p. 3).” Rosenthal, (2005), notes that behavior is reflexive in nature and learning is focused on sensory information.   Key developmental milestones during this stage include: object permanence (representational thought), time and causality (Rosenthal, 2005).

Sub Stage #1: Utilizing reflexes

Since Piaget conceived thinking [as] a biological process that allows [us] to adapt to the world, (Piaget, 1952, p. 25).” Reflexive behaviors like sucking existed as our earliest schematic and evolutionary adaptation to the environment.  As infants initiate these reflexive behaviors they are refined as a byproduct of environmental requirements.  For example, bottle fed babies learn to suck differently than Breastfed babies.

Sub Stage #2: Primary circular reactions

The second Sub-Stage occurs between the ages of one and four months and involves the utilization of reflexive behavior for purposes of enjoyment rather her than as a response to stimuli (Boeree, 2006; Piaget, 1952).  These circular reasoning actions involve activities like thumb-sucking, and serves as a stimulus to which the baby responds with the same action. (Boeree, 2006).

Sub Stage #3: Secondary circular reactions

The third sensorimotor sub-Stage occurs between 4-12 months and involves a more complex array of circular reactions (Boeree, 2006; Piaget, 1952).  During this Stage, primary circular activities involving one’s body are applied instead to the environment.  For example, babies make gut stop sucking their thumb and instead utilize a rattle or pacifier.  The point is, secondary circular reactions are functionally identical to primary circular reactions, while focused instead on the environment.

Sub Stage #4: Tertiary circular reactions

“Between 12 months and 24 months, the child works on tertiary circular reactions, (Boeree, 2006).”   At this stage, babies begin refining their schemas further in accordance with environmental feedback (Piaget, 1952).   This stage involves an “active experimentation that involves] discovering new and interesting way of [doing things], (Boeree, 2006, p. 4).”  Circular reactions in this stage, are aimed at producing new effects towards unique goals.  While previous stages are aimed at learning about the environment, this stage involves learning how aspects of our environment interact with one another (Boeree, 2006).   Gravity is a convenient example.

Sub Stage #5:  Developing mental representations

Around a year and a half, children are developing mental representations of their world.   Internalized schemas provide a template for how a child can anticipate responding to certain situations.  Holding these experiences in our memory can allow us to replicate a response when  we encounter a similar situation (Boeree, 2006).

Preoperational Stage

Lasting from ages 2-7, this stage involves the development of symbolic thinking.   Piaget describes symbols as thoughts or mental representations which represent something else.  These symbols encompass images and words as the child develops language while engaging in creative/pretend play (Boeree, 2006; Rosenthal, 2005).  The key development occurring at this age includes thinking of objects in the environment at times when they are not present.  They exist instead in the mind as symbols or schema.  This allows for the development thought – what Piaget calls an “operation” (Rosenthal, 2005).  Key characteristics of this stage include egocentric thinking, pretend play, and language development (Rosenthal, 2005).

Concrete Operational Stage

The concrete operational stage occurs from ages 7-11.  Piaget uses the words operation to refer to “logical operations or principles we can use when solving problems, (Boeree, 2006, p. 6).”  At this stage, children are able to hold symbols in their mind as mental representations of objects in the world and manipulate them.   This can allow children to comprehend the viewpoint of others and mentally manipulate objects (Rosenthal, 2005).  Key developmental tasks include an understanding of math concepts, classification, serialization, reversibility of objects, and conservation of matter (Boeree, 2006; Rosenthal, 2005).

Formal Operational Stage

Occurring between the ages of 11-15, and involves the development of abstract, hypothetical, deductive reasoning (Rosenthal, 2005).  Once symbolic play and mental imagery have developed, abstract representations are able to be reorganized into a a representative thought (Piaget, 1972).  This allows us to think of possibilities and hypotheticals as we experiment with concepts in order to solve problems and understand metaphors (Rosenthal, 2005).  For example, when investigating a problem, children at this age can assess possible solutions as follows (Boeree, 2006).   Adolescents are able to tackle subjects like algebra (Rosenthal, 2005).  Key developmental accomplishments include the presence of abstract thought and mature moral thinking.  Piaget felt that only about 50% of the population, actually reached this stage (Rosenthal, 2005).



Boeree, G. (2096). Jean Piaget.  Retrieved from:

Piaget, J. (1952). The origins of intelligence in children.  Retrieved from:

Piaget, J. (1972). Intellectual Evolution from Adolesence to Adulthood.  Retrieved from:

Piaget, J. (2013). The construction of reality in the child (Vol. 82). Routledge.

Rosenthal, H. (2005). Vital Information and Review Questions for the NCE and State Counseling Exams. Routledge.

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