Jean Piaget in the context of International Bureau of Education

Conservation refers to a logical thinking ability that allows a person to determine that a certain quantity will remain the same despite adjustment of the container, shape, or apparent size, according to the psychologist Jean Piaget. His theory posits that this ability is not present in children during the preoperational stage of their development at ages 2–7 but develops in the concrete operational stage from ages 7–11.

Cognitive development is a field of study in neuroscience and psychology focusing on a child's development in terms of information processing, conceptual resources, perceptual skill, language learning, and other aspects of the developed adult brain and cognitive psychology. Qualitative differences between how a child processes their waking experience and how an adult processes their waking experience are acknowledged (such as object permanence, the understanding of logical relations, and cause-effect reasoning in school-age children). Cognitive development is defined as the emergence of the ability to consciously cognize, understand, and articulate their understanding in adult terms. Cognitive development is how a person perceives, thinks, and gains understanding of their world through the relations of genetic and learning factors. Cognitive information development is often described in terms of four key components: reasoning, intelligence, language, and memory. These aspects begin to develop around 18 months of age, as infants engage with their environment playing with toys, listening to their parents, watching television, and responding to various stimuli that capture their attention all of which contribute to their cognitive growth.

Jean Piaget was a major force establishing this field, forming his "theory of cognitive development". Piaget proposed four stages of cognitive development: the sensorimotor, preoperational, concrete operational, and formal operational period. Many of Piaget's theoretical claims have since fallen out of favor. His description of the most prominent changes in cognition with age, is generally still accepted today (e.g., how early perception moves from being dependent on concrete, external actions. Later, abstract understanding of observable aspects of reality can be captured; leading to the discovery of underlying abstract rules and principles, usually starting in adolescence)

Piaget's theory of cognitive development, or his genetic epistemology, is a comprehensive theory about the nature and development of human intelligence. It was originated by the Swiss developmental psychologist Jean Piaget (1896–1980). The theory deals with the nature of knowledge itself and how humans gradually come to acquire, construct, and use it. Piaget's theory is mainly known as a developmental stage theory.

In 1919, while working at the Alfred Binet Laboratory School in Paris, Piaget "was intrigued by the fact that children of different ages made different kinds of mistakes while solving problems". His experience and observations at the Alfred Binet Laboratory were the beginnings of his theory of cognitive development.

Radical constructivism is an approach to epistemology that situates knowledge in terms of knowers' experience. It looks to break with the conception of knowledge as a correspondence between a knower's understanding of their experience and the world beyond that experience. Adopting a skeptical position towards correspondence as in principle impossible to verify because one cannot access the world beyond one's experience in order to test the relation, radical constructivists look to redefine epistemology in terms of the viability of knowledge within knowers' experience. This break from the traditional framing of epistemology differentiates it from "trivial" forms of constructivism that emphasise the role of the knower in constructing knowledge while maintaining the traditional perspective of knowledge in terms of correspondence. Radical constructivism has been described as a "post-epistemological" position.

Radical constructivism was initially formulated by Ernst von Glasersfeld, who drew on the work of Jean Piaget, Giambattista Vico, and George Berkeley amongst others. Radical constructivism is closely related to second-order cybernetics, and especially the work of Heinz von Foerster, Humberto Maturana, and Francisco Varela. During the 1980s, Siegfried J. Schmidt played a leading role in establishing radical constructivism as a paradigm within the German speaking academic world.

Leon Festinger (8 May 1919 – 11 February 1989) was an American social psychologist who originated the theory of cognitive dissonance and social comparison theory. The rejection of the previously dominant behaviorist view of social psychology by demonstrating the inadequacy of stimulus-response conditioning accounts of human behavior is largely attributed to his theories and research. Festinger is also credited with advancing the use of laboratory experimentation in social psychology, although he simultaneously stressed the importance of studying real-life situations, a principle he practiced when personally infiltrating a doomsday cult. He is also known in social network theory for the proximity effect (or propinquity).

Festinger studied psychology under Kurt Lewin, an important figure in modern social psychology, at the University of Iowa, graduating in 1941; however, he did not develop an interest in social psychology until after joining the faculty at Lewin's Research Center for Group Dynamics at the Massachusetts Institute of Technology in 1945. Despite his preeminence in social psychology, Festinger turned to visual perception research in 1964 and then archaeology, history, and the human evolutionary sciences in 1979 until his death in 1989. Following B. F. Skinner, Jean Piaget, Sigmund Freud, and Albert Bandura, Festinger was the fifth most cited psychologist of the 20th century.

Positive adult development is a subfield of developmental psychology that studies positive development during adulthood. It is one of four major forms of adult developmental study that can be identified, according to Michael Commons; the other three forms are directionless change, stasis, and decline. Commons also further divided the concept of positive adult development into six distinct areas of study: hierarchical complexity (i.e., orders or stages), knowledge, experience, expertise, wisdom, and spirituality.

The development of people has focused on children and adolescence with several theories as proposed by Freud, Piaget, and Binet. Research in positive adult development supports the theory that development occurs during adulthood. Recent studies indicate that such development is useful in predicting things such as an individual's health, life satisfaction, and degree of contribution to society. Current research supports the idea that personal adjustment and personal growth are two main themes in positive adult development research. Personal adjustment refers to how well an individual can master and adapt to their environment, while personal growth refers to having the ability to have deep insight into oneself, others, and the world around them. One other benefit is allowing for changes in social policies to create effective, efficient interventions to help optimize the aging process to as many of our aging generation as possible. In these studies, adults that were older rated higher than these categories then those that were younger, thus supporting that there is indeed a positive development that occurs in adulthood.

Domain specificity is a theoretical position in cognitive science (especially modern cognitive development) that argues that many aspects of cognition are supported by specialized, presumably evolutionarily specified, learning devices. The position is a close relative of modularity of mind, but is considered more general in that it does not necessarily entail all the assumptions of Fodorian modularity (e.g., informational encapsulation). Instead, it is properly described as a variant of psychological nativism. Other cognitive scientists also hold the mind to be modular, without the modules necessarily possessing the characteristics of Fodorian modularity.

Domain specificity emerged in the aftermath of the cognitive revolution as a theoretical alternative to empiricist theories that believed all learning can be driven by the operation of a few such general learning devices. Prominent examples of such domain-general views include Jean Piaget's theory of cognitive development, and the views of many modern connectionists. Proponents of domain specificity argue that domain-general learning mechanisms are unable to overcome the epistemological problems facing learners in many domains, especially language. In addition, domain-specific accounts draw support from the surprising competencies of infants, who are able to reason about things like numerosity, goal-directed behavior, and the physical properties of objects all in the first months of life. Domain-specific theorists argue that these competencies are too sophisticated to have been learned via a domain-general process like associative learning, especially over such a short time and in the face of the infant's perceptual, attentional, and motor deficits. Current proponents of domain specificity argue that evolution equipped humans (and indeed most other species) with specific adaptations designed to overcome persistent problems in the environment. For humans, popular candidates include reasoning about objects, other intentional agents, language, and number. Researchers in this field seek evidence for domain specificity in a variety of ways. Some look for unique cognitive signatures thought to characterize a domain (e.g. differences in ways infants reason about inanimate versus animate entities). Others try to show selective impairment or competence within but not across domains (e.g. the increased ease of solving the Wason Selection Task when the content is social in nature). Still, others use learnability arguments to argue that a cognitive process or specific cognitive content could not be learned, as in Noam Chomsky's poverty of the stimulus argument for language.

Lawrence Kohlberg (/ˈkoʊlbɜːrɡ/; October 25, 1927 – January 17, 1987) was an American psychologist best known for his theory of stages of moral development.

He served as a professor in the Psychology Department at the University of Chicago and at the Graduate School of Education at Harvard University. Even though it was considered unusual in his era, he decided to study the topic of moral judgment, extending Jean Piaget's account of children's moral development from 25 years earlier. He proposed that moral reasoning develops through six identifiable stages, grouped into three levels: pre-conventional, conventional, and post-conventional, described in his framework of stages of moral development. His research showed that these stages appear in a fixed developmental sequence and reflect the increasing complexity of how people justify moral choices. In fact, it took Kohlberg five years before he was able to publish an article based on his views. Kohlberg's work reflected and extended not only Piaget's findings but also the theories of philosophers George Herbert Mead and James Mark Baldwin. At the same time he was creating a new field within psychology: "moral development".

Lawrence Kohlberg's stages of moral development constitute an adaptation of a psychological theory originally conceived by the Swiss psychologist Jean Piaget. Kohlberg began work on this topic as a psychology graduate student at the University of Chicago in 1958 and expanded upon the theory throughout his life.

The theory holds that moral reasoning, a necessary (but not sufficient) condition for ethical behavior, has six developmental stages, each more adequate at responding to moral dilemmas than its predecessor. Kohlberg followed the development of moral judgment far beyond the ages studied earlier by Piaget, who also claimed that logic and morality develop through constructive stages. Expanding on Piaget's work, Kohlberg determined that the process of moral development was principally concerned with justice and that it continued throughout the individual's life, a notion that led to dialogue on the philosophical implications of such research.