Piaget was born in 1896 in Neuchâtel, in the Francophone region of Switzerland. His father, Arthur Piaget, was a professor of medieval literature at the University of Neuchâtel. Piaget was a precocious child who developed an interest in biology and the natural world. He was educated at the University of Neuchâtel, and studied briefly at the University of Zürich. During this time, he published two philosophical papers that showed the direction of his thinking at the time, but which he later dismissed as adolescent thought. His interest in psychoanalysis, at the time a burgeoning strain of psychology, can also be dated to this period. Piaget moved from Switzerland to Paris, France after his graduation and he taught at the Grange-Aux-Belles Street School for Boys. The school was run by Alfred Binet, the developer of the Binet intelligence test, and Piaget assisted in the marking of Binet's intelligence tests. It was while he was helping to mark some of these tests that Piaget noticed that young children consistently gave wrong answers to certain questions. Piaget did not focus so much on the fact of the children's answers being wrong, but that young children consistently made types of mistakes that older children and adults did not. This led him to the theory that young children's cognitive processes are inherently different from those of adults. Ultimately, he was to propose a global theory of cognitive developmental stages in which individuals exhibit certain common patterns of cognition in each period of development. In 1921, Piaget returned to Switzerland as director of the Rousseau Institute in Geneva.

In 1923, he married Valentine Châtenay; together, the couple had three children, whom Piaget studied from infancy. In 1929, Jean Piaget accepted the post of Director of the International Bureau of Education and remained the head of this international organization until 1968. Every year, he drafted his “Director's Speeches” for the IBE Council and for the International Conference on Public Education in which he explicitly addressed his educational credo.

In 1964, Piaget was invited to serve as chief consultant at two conferences at Cornell University (March 11–13) and University of California, Berkeley (March 16–18). The conferences addressed the relationship of cognitive studies and curriculum development and strived to conceive implications of recent investigations of children's cognitive development for curricula.

In 1979 he was awarded the Balzan Prize for Social and Political Sciences.

Henry Beilin described Jean Piaget's theoretical research program as consisting of four phases:

1. the sociological model of development,
2. the biological model of intellectual development,
3. the elaboration of the logical model of intellectual development,
4. the study of figurative thought.

The resulting theoretical frameworks are sufficiently different from each other that they have been characterized as representing different "Piagets."

First Piaget: The Sociological Model of Development

Piaget first developed this stage in the 1920s. He investigated the hidden side of children’s minds. Piaget proposed that children moved from a position of egocentrism to sociocentrism. For this explanation he combined the use of psychological and clinical methods to create what he called a semiclinical interview. He began the interview by asking children standardized questions and depending on how they answered, he would ask them a series of nonstandard questions. Piaget was looking for what he called “spontaneous conviction” so he often asked questions the children neither expected nor anticipated. In his studies, he noticed there was a gradual progression from intuitive to scientific and socially acceptable responses. Piaget theorized children did this because of the social interaction and the challenge to younger children’s ideas by the ideas of those children who were more advanced.

This work was used by Elton Mayo as the basis for the famous Hawthorne Experiments. For Piaget, it also led to an honorary doctorate from Harvard in 1936.

Second Piaget: The Sensorimotor/Adaptive Model of Intellectual Development

In this stage, Piaget described intelligence as having two closely interrelated parts. The first part, which is from the first stage, was the content of children's thinking. The second part was the process of intellectual activity. He believed this process of thinking could be regarded as an extension of the biological process of adaptation. Adaptation has two pieces: assimilation and accommodation. To test his theory, Piaget observed the habit in his own children. He argued infants were engaging in an act of assimilation when they sucked on everything in their reach. He claimed infants transform all objects into an object to be sucked. The children were assimilating the objects to conform to their own mental structures. Piaget then made the assumption whenever one transforms the world to meet individual needs or conceptions; one is, in a way, assimilating it. Piaget also observed his children not only assimilating objects to fit their needs, but also modifying some of their mental structures to meet the demands of the environment. This is the second division of adaption known as accommodation. To start out, the infants only engaged in primarily reflex actions such as sucking, but not long after, they would pick up actual objects and put them in their mouths. When they do this, they modify their reflex response to accommodate the external objects into reflex actions. Because the two are often in conflict, they provide the impetus for intellectual development. The constant need to balance the two, triggers intellectual growth.

Third Piaget: The Elaboration of the Logical Model of Intellectual Development

In the model Piaget developed in stage three, he argued the idea that intelligence develops in a series of stages that are related to age and are progressive because one stage must be accomplished before the next can occur. For each stage of development the child forms a view of reality for that age period. At the next stage, the child must keep up with earlier level of mental abilities to reconstruct concepts. Piaget concluded intellectual development as an upward expanding spiral in which children must constantly reconstruct the ideas formed at earlier levels with new, higher order concepts acquired at the next level.

It is primarily the Third Piaget that was incorporated into American psychology when Piaget's ideas were "rediscovered" in the 1960s.

Fourth Piaget: The Study of Figurative thought

Piaget studied areas of intelligence like perception and memory that aren’t entirely logical. Logical concepts are described as being completely reversible because they can always get back to the starting point. The perceptual concepts Piaget studied could not be manipulated. To describe the figurative process, Piaget uses pictures as examples. Pictures can’t be separated because contours cannot be separated from the forms they outline. Memory is the same way. It is never completely reversible. During this last period of work, Piaget and his colleague Inhelder also published books on perception, memory, and other figurative processes such as learning during this last period."Piaget, Jean." Encyclopædia Britannica. 2008. Encyclopædia Britannica Online. 3 November 2008 .

• Sensorimotor stage: from birth to age 2. Children experience the world through movement and senses (use five senses to explore the world). During the sensorimotor stage children are extremely egocentric, meaning they cannot perceive the world from others' viewpoints. The sensorimotor stage is divided into six substages: "(1) simple reflexes; (2) first habits and primary circular reactions; (3) secondary circular reactions; (4) coordination of secondary circular reactions; (5) tertiary circular reactions, novelty, and curiosity; and (6) internalization of schemes."

Simple reflexes is from birth to 1 month old. At this time infants use reflexes such as rooting and sucking.

First habits and primary circular reactions is from 1 month to 4 months old. During this time infants learn to coordinate sensation and two types of scheme (habit and circular reactions). A primary circular reaction is when the infant tries to reproduce an event that happened by accident (ex: sucking thumb).

The third stage, secondary circular reactions, occurs when the infant is 4 to 8 months old. At this time they become aware of things beyond their own body; they are more object oriented. At this time they might accidentally shake a rattle and continue to do it for the sake of satisfaction.

Coordination of secondary circular reactions is from 8 months to 12 months old. During this stage they can do things intentionally. They can now combine and recombine schemes and try to reach a goal (ex: use a stick to reach something). They also understand object permanence during this stage. That is, they understand that objects continue to exist even when they can't see them.

The fifth stage occurs from 12 months old to 18 months old. During this stage infants explore new possibilities of objects; they try different things to get different results.

During the last stage they are 18 to 24 months old. During this stage they shift to symbolic thinking.

Some followers of Piaget's studies of infancy, such as [[Kenneth Kaye]] argue that his contribution was as an observer of countless phenomena not previously described, but that he didn't offer explanation of the processes in real time that cause those developments, beyond analogizing them to broad concepts about biological adaptation generally.

• Preoperational stage: from ages 2 to 7 (magical thinking predominates. Acquisition of motor skills). Egocentrism begins strongly and then weakens. Children cannot conserve or use logical thinking.

• Concrete operational stage: from ages 7 to 12 (children begin to think logically but are very concrete in their thinking). Children can now conserve and think logically but only with practical aids. They are no longer egocentric.

• Formal operational stage: from age 12 onwards (development of abstract reasoning). Children develop abstract thought and can easily conserve and think logically in their mind.

Jean Piaget defined himself as an epistemologist, interested in the process of the qualitative development of knowledge. As he says in the introduction of his book "Genetic Epistemology" (ISBN 978-0-393-00596-7): "What the genetic epistemology proposes is discovering the roots of the different varieties of knowledge, since its elementary forms, following to the next levels, including also the scientific knowledge."

He believed answers for the epistemological questions at his time could be answered, or better proposed, if one looked to the genetic aspect of it, hence his experimentations with children and adolescents. Piaget considered cognitive structures development as a differentiation of biological regulations. In one of his last books, "Equilibration of Cognitive Structures: The Central Problem of Intellectual Development" (ISBN 978-022666781), he intends to explain knowledge development as a process of equilibration using two main concepts in his theory, assimilation and accommodation, as belonging not only to biological interactions but also to cognitive ones.

Stages

The four development stages are described in Piaget's theory as:

• Sensorimotor stage: from birth to age 2. Children experience the world through movement and senses (use five senses to explore the world). During the sensorimotor stage children are extremely egocentric, meaning they cannot perceive the world from others' viewpoints. The sensorimotor stage is divided into six substages: "(1) simple reflexes; (2) first habits and primary circular reactions; (3) secondary circular reactions; (4) coordination of secondary circular reactions; (5) tertiary circular reactions, novelty, and curiosity; and (6) internalization of schemes."

Simple reflexes is from birth to 1 month old. At this time infants use reflexes such as rooting and sucking.

First habits and primary circular reactions is from 1 month to 4 months old. During this time infants learn to coordinate sensation and two types of scheme (habit and circular reactions). A primary circular reaction is when the infant tries to reproduce an event that happened by accident (ex: sucking thumb).

The third stage, secondary circular reactions, occurs when the infant is 4 to 8 months old. At this time they become aware of things beyond their own body; they are more object oriented. At this time they might accidentally shake a rattle and continue to do it for sake of satisfaction.

Coordination of secondary circular reactions is from 8 months to 12 months old. During this stage they can do things intentionally. They can now combine and recombine schemes and try to reach a goal (ex: use a stick to reach something). They also understand object permanence during this stage. That is, they understand that objects continue to exist even when they can't see them.

The fifth stage occurs from 12 months old to 18 months old. During this stage infants explore new possibilities of objects; they try different things to get different results.

During the last stage they are 18 to 24 months old. During this stage they shift to symbolic thinking.

Some followers of Piaget's studies of infancy, such as [[Kenneth Kaye]] argue that his contribution was as an observer of countless phenomena not previously described, but that he didn't offer explanation of the processes in real time that cause those developments, beyond analogizing them to broad concepts about biological adaptation generally.

• Preoperational stage: from ages 2 to 7 (magical thinking predominates. Acquisition of motor skills). Egocentrism begins strongly and then weakens. Children cannot conserve or use logical thinking.

• Concrete operational stage: from ages 7 to 12 (children begin to think logically but are very concrete in their thinking). Children can now conserve and think logically but only with practical aids. They are no longer egocentric.

• Formal operational stage: from age 12 onwards (development of abstract reasoning). Children develop abstract thought and can easily conserve and think logically in their mind.

The developmental process

Piaget provided no concise description of the development process as a whole. Broadly speaking it consisted of a cycle:

• The child performs an action which has an effect on or organizes objects, and the child is able to note the characteristics of the action and its effects.
• Through repeated actions, perhaps with variations or in different contexts or on different kinds of objects, the child is able to differentiate and integrate its elements and effects. This is the process of "reflecting abstraction" (described in detail in Piaget 2001).
• At the same time, the child is able to identify the properties of objects by the way different kinds of action affect them. This is the process of "empirical abstraction".
• By repeating this process across a wide range of objects and actions, the child establishes a new level of knowledge and insight. This is the process of forming a new "cognitive stage". This dual process allows the child to construct new ways of dealing with objects and new knowledge about objects themselves.
• However, once the child has constructed these new kinds of knowledge, he or she starts to use them to create still more complex objects and to carry out still more complex actions. As a result, the child starts to recognize still more complex patterns and to construct still more complex objects. Thus a new stage begins, which will only be completed when all the child's activity and experience have been re-organized on this still higher level.

This process is not wholly gradual, however. Once a new level of organization, knowledge and insight proves to be effective, it will quickly be generalized to other areas. As a result, transitions between stages tend to be rapid and radical, and the bulk of the time spent in a new stage consists of refining this new cognitive level. When the knowledge that has been gained at one stage of study and experience leads rapidly and radically to a new higher stage of insight, a is said to have occurred.

It is because this process takes this dialectical form, in which each new stage is created through the further differentiation, integration, and synthesis of new structures out of the old, that the sequence of cognitive stages are logically necessary rather than simply empirically correct. Each new stage emerges only because the child can take for granted the achievements of its predecessors, and yet there are still more sophisticated forms of knowledge and action that are capable of being developed.

Because it covers both how we gain knowledge about objects and our reflections on our own actions, Piaget's model of development explains a number of features of human knowledge that had never previously been accounted for. For example, by showing how children progressively enrich their understanding of things by acting on and reflecting on the effects of their own previous knowledge, they are able to organize their knowledge in increasingly complex structures. Thus, once a young child can consistently and accurately recognize different kinds of animals, he or she then acquires the ability to organize the different kinds into higher groupings such as "birds", "fish", and so on. This is significant because they are now able to know things about a new animal simply on the basis of the fact that it is a bird — for example, that it will lay eggs.

At the same time, by reflecting on their own actions, the child develops an increasingly sophisticated awareness of the "rules" that govern in various ways. For example, it is by this route that Piaget explains this child's growing awareness of notions such as "right", "valid", "necessary", "proper", and so on. In other words, it is through the process of objectification, reflection and abstraction that the child constructs the principles on which action is not only effective or correct but also justified.

One of Piaget's most famous studies focused purely on the discriminative abilities of children between the ages of two and a half years old, and four and a half years old. He began the study by taking children of different ages and placing two lines of sweets, one with the sweets in a line spread further apart, and one with the same number of sweets in a line placed more closely together. He found that, “Children between 2 years, 6 months old and 3 years, 2 months old correctly discriminate the relative number of objects in two rows; between 3 years, 2 months and 4 years, 6 months they indicate a longer row with fewer objects to have "more"; after 4 years, 6 months they again discriminate correctly” (Cognitive Capacity of Very Young Children, p. 141). Initially younger children were not studied, because if at four years old a child could not conserve quantity, then a younger child presumably could not either. The results show however that children that are younger than three years and two months have quantity conservation, but as they get older they lose this quality, and do not recover it until four and a half years old. This attribute may be lost due to a temporary inability to solve because of an overdependence on perceptual strategies, which correlates more candy with a longer line of candy, or due to the inability for a four year old to reverse situations.

By the end of this experiment several results were found. First, younger children have a discriminative ability that shows the logical capacity for cognitive operations exists earlier than acknowledged. This study also reveals that young children can be equipped with certain qualities for cognitive operations, depending on how logical the structure of the task is. Research also shows that children develop explicit understanding at age 5 and as a result, the child will count the sweets to decide which has more. Finally the study found that overall quantity conservation is not a basic characteristic of humans' native inheritance.

Genetic epistemology

According to Jean Piaget, genetic epistemology "attempts to explain knowledge, and in particular scientific knowledge, on the basis of its history, its sociogenesis, and especially the psychological origins of the notions and operations upon which it is based"[5]. Piaget believed he could test epistemological questions by studying the development of thought and action in children. As a result Piaget created a field known as genetic epistemology with its own methods and problems. He defined this field as the study of child development as a means of answering epistemological questions.

Schemes

A Schema is a structured cluster of concepts, it can be used to represent objects, scenarios or sequences of events or relations. The original idea was proposed by philosopher Immanuel Kant as innate structures used to help us perceive the world.

The physical microstructure of “schemes”

In his “Biology and Knowledge” (1967+ / French 1965), Piaget tentatively hinted at possible physical embodiments for his abstract “scheme” entities. At the time, there was much talk and research about RNA as such an agent of learning, and Piaget considered some of the evidence. However he did not offer any firm conclusions, and confessed that this was beyond his area of expertise. Piaget died in 1980, and by then the RNA theory had lost its appeal.

Piaget wanted to revolutionize the way research methods were conducted. Although he started researching with his colleagues using a traditional method of data collection, he was not fully satisfied with the results and wanted to keep trying to find new ways of researching using a combination of data, which included: naturalistic observation, psychometrics, and the psychiatric clinical examination, in order to have a less guided form of research that would produce more genuine results.As Piaget developed new research methods, he wrote a book called The Language of Thought of the Child, which aimed to synthesize the methods he was using in order to study the conclusion children drew from situations and how they arrived to such conclusion. The main idea was to observe how children responded and articulated certain situations with their own reasoning, in order to examine their thought processes(Mayer, 2005).

Piaget administered a test in 15 boys with ages ranging from 10—14 years-old in which he asked participants to describe the relationship between a mix bouquet of flowers and a bouquet with flowers of the same color. The purpose of this study was to analyze the thinking process the boys had and to draw conclusions about the logic processes they had used, which was a psychometric technique of research. Piaget also used the psychoanalytic method initially developed by Sigmund Freud. The purpose of using such method was to examine the unconscious mind, as well as to continue parallel studies using different research methods. Psychoanalysis was later rejected by Piaget, as he thought it was insufficiently empirical (Mayer, 2005).

Piaget argued that children and adults used speech for different purposes. In order to confirm his argument, he experimented analyzing a child’s interpretation of a story. In the experiment, the child listened to a story and then told a friend that same story in his/her own words. The purpose of this study was to examine how children verbalize and understand each other without adult intervention. Piaget wanted to examine the limits of naturalistic observation, in order to understand a child’s reasoning. He realized the difficulty of studying children's thoughts, as it is hard to know if a child is pretending to believe their thoughts or not. Piaget was the pioneer researcher to examine children’s conversations in a social context - starting from examining their speech and actions - where children were comfortable and spontaneous(Kose, 1987).

Issues and possible solutions

After conducting many studies, Piaget was able to find significant differences in the way adults and children reason; however, he was still unable to find the path of logic reasoning and the unspoken thoughts children had, which could allow him to study a child’s intellectual development over time (Mayer, 2005).In his third book, The Child’s Conception of the World, Piaget recognized the difficulties of his prior techniques and the importance of psychiatric clinical examination. The researcher believed that the way clinical examinations were conducted influenced how a child’s inner realities surfaced. Children would likely respond according to the way the research is conducted, the questions asked, or the familiarity they have with the environment. The clinical examination conducted for his third book provides a thorough investigation into a child’s thinking process. An example of a question used to research such process was: “Can you see a thought?” (Mayer, 2005, p. 372).

The Development of new methods

Piaget recognized that psychometric tests had its limitations, as children were not able to provide the researcher with their deepest thoughts and inner intellect. It was also difficult to know if the results of child examination reflected what children believed or if it is just a pretend situation. For example, it is very difficult to know with certainty if a child who has a conversation with a toy believes the toy is alive or if the child is just pretending.Soon after drawing conclusions about psychometric studies, Piaget started developing the clinical method of examination. The clinical method included questioning a child and carefully examining their responses -in order to observe how the child reasoned according to the questions asked - and then examine the child’s perception of the world through their responses. Piaget recognized the difficulties of interviewing a child and the importance of recognizing the difference between “liberated" versus “spontaneous” responses (Mayer, 2005, p. 372).

Criticism of Piaget's research methods

"The developmental theory of Jean Piaget has been criticized on the grounds that it is conceptually limited, empirically false, or philosophically and epistemologically untenable." (Lourenco & Machado, 1996, p. 143) Piaget responded to criticism by acknowledging that the vast majority of critics did not understand the outcomes he wished to obtain from his research (Lourenco & Machado, 1996).

Development of research methods

Piaget wanted to research in environments that would allow children to connect with some existing aspects of the world. The idea was to change the approach described in his book The Child’s Conception of the World and move away from the vague questioning interviews. This new approach was described in his book The Child’s Conception of Physical Causality, where children were presented with dilemmas and had to think of possible solutions on their own.Later, after carefully analyzing previous methods, Piaget developed a combination of naturalistic observation with clinical interviewing in his book Judgment and Reasoning in the Child, where a child's intellect was tested with questions and close monitoring. Piaget was convinced he had found a way to analyze and access a child’s thoughts about the world in a very effective way. (Mayer, 2005)Piaget’s research provided a combination of theoretical and practical research methods and it has offered a crucial contribution to the field of developmental psychology (Beilin, 1992).

Despite ceasing to be a fashionable psychologist, the magnitude of Piaget's continuing influence can be measured by the global scale and activity of the Jean Piaget Society, which holds annual conferences and attracts very large numbers of participants. His theory of cognitive development has proved influential in many different areas:

• Developmental psychology
• Education and Morality
• Historical studies of thought and cognition
• Evolution
• Philosophy
• Primatology
• Artificial Intelligence

Developmental psychology

Piaget is without doubt one of the most influential developmental psychologists, influencing not only the work of Lev Vygotsky and of Lawrence Kohlberg but whole generations of eminent academics. Although subjecting his ideas to massive scrutiny led to innumerable improvements and qualifications of his original model and the emergence of a plethora of neo-Piagetian and post-Piagetian variants, Piaget's original model has proved to be remarkably robust (Lourenço and Machado 1996).

Education and development of morality

During the 1970s and 1980s, Piaget's works also inspired the transformation of European and American education, including both theory and practice, leading to a more ‘child-centered’ approach. In Conversations with Jean Piaget, he says: "Education, for most people, means trying to lead the child to resemble the typical adult of his society . . . but for me and no one else, education means making creators. . . . You have to make inventors, innovators...not conformists" (Bringuier, 1980, p. 132).

Piaget's influence is strongest in early education and moral education.

His theory of cognitive development can be used as a tool in the early childhood classroom. According to Piaget, children developed best in a classroom with interaction.

Piaget believed in two basic principles relating to moral education: that children develop moral ideas in stages and that children create their conceptions of the world. According to Piaget, "the child is someone who constructs his own moral world view, who forms ideas about right and wrong, and fair and unfair, that are not the direct product of adult teaching and that are often maintained in the face of adult wishes to the contrary" (Gallagher, 1978, p. 26). Piaget believed that children made moral judgments based on their own observations of the world.

Piaget's theory of morality was radical when his book, The Moral Judgment of the Child, was published in 1932 for two reasons: his use of philosophical criteria to define morality (as universalizable, generalizable, and obligatory) and his rejection of equating cultural norms with moral norms. Piaget, drawing on Kantian theory, proposed that morality developed out of peer interaction and that it was autonomous from authority mandates. Peers, not parents, were a key source of moral concepts such as equality, reciprocity, and justice.

Piaget attributed different types of psychosocial processes to different forms of social relationships, introducing a fundamental distinction between different types of said relationships. Where there is constraint because one participant holds more power than the other the relationship is asymmetrical, and, importantly, the knowledge that can be acquired by the dominated participant takes on a fixed and inflexible form. Piaget refers to this process as one of social transmission, illustrating it through reference to the way in which the elders of a tribe initiate younger members into the patterns of beliefs and practices of the group. Similarly, where adults exercise a dominating influence over the growing child, it is through social transmission that children can acquire knowledge. By contrast, in cooperative relations, power is more evenly distributed between participants so that a more symmetrical relationship emerges. Under these conditions, authentic forms of intellectual exchange become possible; each partner has the freedom to project his or her own thoughts, consider the positions of others, and defend his or her own point of view. In such circumstances, where children’s thinking is not limited by a dominant influence, Piaget believed "the reconstruction of knowledge", or favorable conditions for the emergence of constructive solutions to problems, exists. Here the knowledge that emerges is open, flexible and regulated by the logic of argument rather than being determined by an external authority. In short, cooperative relations provide the arena for the emergence of operations, which for Piaget requires the absence of any constraining influence, and is most often illustrated by the relations that form between peers (for more on the importance of this distinction see Duveen & Psaltis, in press; Psaltis & Duveen, 2006, 2007).

Historical studies of thought and cognition

Historical changes of thought have been modeled in Piagetian terms. Broadly speaking these models have mapped changes in morality, intellectual life and cognitive levels against historical changes (typically in the complexity of social systems).

Notable examples include:

• Michael Horace Barnes' study of the co-evolution of religious and scientific thinking
• Peter Damerow's theory of prehistoric and archaic thought
• Kieran Egan's stages of understanding
• James W. Fowler's stages of faith development
• Suzy Gablik's stages of art history
• Christopher Hallpike's studies of changes in cognition and moral judgment in pre-historical, archaic and classical periods ... (Hallpike 1979, 2004)
• Lawrence Kohlberg's stages of moral development
• Don Lepan's theory of the origins of modern thought and drama
• Charles Radding's theory of the medieval intellectual development
• Jürgen Habermas's reworking of historical materialism.

Non human development

Neo-Piagetian stages have been applied to the maximum stage attained by various animals. For example spiders attain the circular sensory motor stage, coordinating actions and perceptions. Pigeons attain the sensory motor stage, forming concepts.

Origins

The origins of human intelligence have also been studied in Piagetian terms. Wynn (1979, 1981) analysed Acheulian and Oldowan tools in terms of the insight into spatial relationships required to create each kind. On a more general level, Robinson's Birth of Reason (2005) suggests a large-scale model for the emergence of a Piagetian intelligence.

Primatology

Piaget's models of cognition have also been applied outside the human sphere, and some primatologists assess the development and abilities of primates in terms of Piaget's model.

Philosophy

Some have taken account of Piaget's work. For example, the philosopher and social theorist Jürgen Habermas has incorporated Piaget into his work, most notably in The Theory of Communicative Action. The philosopher Thomas Kuhn credited Piaget's work with helping him to understand the transition between modes of thought which characterized his theory of paradigm shifts. Yet, that said, it is also noted that the implications of his later work do indeed remain largely unexamined. Shortly before his death (September, 1980), Piaget was involved in a debate about the relationships between innate and acquired features of language, at the Centre Royaumont pour une Science de l'Homme, where he discussed his point of view with the linguist Noam Chomsky as well as Hilary Putnam and Stephen Toulmin.

Artificial intelligence

Piaget also had a considerable effect in the field of computer science and artificial intelligence. Seymour Papert used Piaget's work while developing the Logo programming language. Alan Kay used Piaget's theories as the basis for the Dynabook programming system concept, which was first discussed within the confines of the Xerox Palo Alto Research Center, or Xerox PARC. These discussions led to the development of the Alto prototype, which explored for the first time all the elements of the graphical user interface (GUI), and influenced the creation of user interfaces in the 1980s and beyond.

• Gary L. Drescher' Made-Up Minds: A Constructivist Approach to Artificial Intelligence

Piaget's theory, however vital in understanding child psychology, did not go without scrutiny. A main figure who's ideas contradicted Piaget's ideas was the Russian psychologist Lev Vygotsky. Vygotsky stressed the importance of a child's cultural background as an effect to the stages of development. Because different cultures stress different social interactions, this challenged Piaget's theory that the hierarchy of learning development had to develop in succession. Vygotsky introduced the term Zone of proximal development as an overall task a child would have to develop that would be too difficult to develop alone.

Also, the so called neo-Piagetian theories of cognitive development maintained that Piaget's theory does not do justice either to the underlying mechanisms of information processing that explain transition from stage to stage or individual differences in cognitive development. According to these theories, changes in information processesing mechanisms, such as speed of processing and working memory, are responsible for ascension from stage to stage. Moreover, differences between individuals in these processes explain why some individuals develop faster than other individuals (Demetriou, 1998).

Curiously, Piaget had published a novel at the age of 20, before he'd begun any research in psychology, in which he stated what would later be the "conclusions" from decades of studying the development of intelligence in children.

In the list below, the following definitions have been used:

• Exemplars: More than 5,000 citations in Google Scholar
• Super-Classics: More than 2,500 citations in Google Scholar
• Classics: More than 1,000 citations in Google Scholar
• Major Works: More than 500 citations in Google Scholar
• Works of Significance: More than 250 citations in Google Scholar

The references have been presented in order of their impact according to Google Scholar.

Exemplars

• Piaget, J. (1952). The Origins of Intelligence in Children. New York: International University Press. (Original work published 1936.)
• Piaget, J. (1932). The Moral Judgment of the Child. London: Kegan Paul, Trench, Trubner and Co. (Original work published 1932.)

Super-classics

• The construction of reality in the child
• Piaget, J. (1962). Play, Dreams and Imitation in Childhood. New York: Norton.
• The language and thought of the child
• Piaget, J., and Inhelder, B. (1962). The Psychology of the Child. New York: Basic Books.
• Inhelder, B. and J. Piaget (1958). The Growth of Logical Thinking from Childhood to Adolescence. New York: Basic Books.
• Piaget, J. (1928). The Child's Conception of the World. London: Routledge and Kegan Paul.
• Piaget, J. (1951). The Psychology of Intelligence. London: Routledge and Kegan Paul

Classics

• Piaget, J., and Inhelder, B. (1967). The Child's Conception of Space. New York: W.W. Norton.
• Piaget, J. (1983). Piaget's theory. In P. Mussen (ed.). Handbook of Child Psychology. 4th edition. Vol. 1. New York: Wiley.
• Piaget, J. (1952). The Child's Conception of Number. London: Routledge and Kegan Paul.
• Piaget, J. (1970). Structuralism. New York: Harper & Row.
• Genetic epistemology
• The early growth of logic in the child
• The origin of intelligence in the child

Major Works

• Piaget, J. (1971). Biology and Knowledge. Chicago: University of Chicago Press.
• Science of education and the psychology of the child
• The child's conception of physical causality
• Intellectual evolution from adolescence to adulthood
• Six psychological studies
• Piaget, J. (1985). The Equilibration of Cognitive Structures: The Central Problem of Intellectual Development. Chicago: University of Chicago Press. (New translation of The Development of Thought)
• Child's Conception of Geometry
• Development and learning
• To understand is to invent: The future of education
• The development of thought: Equilibration of cognitive structures (see Equilibration of Cognitive Structures)
• Language and learning: the debate between Jean Piaget and Noam Chomsky
• The Principles of Genetic Epistemology

Works of significance

• Piaget, J. (1977). The Grasp of Consciousness: Action and concept in the young child. London: Routledge and Kegan Paul.
• Piaget, J. (1955). The Child's Construction of Reality. London: Routledge and Kegan Paul.
• The mechanisms of perception
• Piaget, J. (1972). Psychology and Epistemology: Towards a Theory of Knowledge. Harmondsworth: Penguin.
• The child's conception of time
• Piaget, J. (1953). Logic and Psychology. Manchester: Manchester University Press.
• Memory and intelligence
• Piaget, J. (1975). The Origin of the Idea of Chance in Children. London: Routledge and Kegan Paul.
• Mental imagery in the child
• Piaget, J. (1981). Intelligence and Affectivity. Their Relationship during Child Development. Palo Alto: Annual Reviews.
• Piaget, J., and Garcia, R. (1989). Psychogenesis and the History of Science. New York: Columbia University Press.
• Beth, E. W., and Piaget, J. (1966). Mathematical Epistemology and Psychology. Dordrecht: D. Reidel.
• The growth of the mind

New translations

• Piaget, J. (1995). Sociological Studies. London: Routledge.
• Piaget, J. (2001). Studies in Reflecting Abstraction. Hove, UK: Psychology Press.