The theory of intellectual development of the Swiss biologist and philosopher Jean Piaget covers the period from infancy to adulthood. Piaget focuses on the development of the child’s thinking, and above all, the development of logical thinking. Piaget believed that the thinking of an adult differs from the thinking of a child in the first place by greater logic.
At various times, Jean Piaget named different stages of intellectual development, but most often there were four: the sensorimotor stage, the preoperational stage, the stage of concrete operations and the stage of formal operations. The sensorimotor and preoperational stages are manifestations of preconceptual thinking. At this time, the judgments of children refer only to a specific subject, something visual and known to everyone, are categorical and isolated: they are not connected by a logical chain. The child understands in the first place judgments by analogy and through a clear example. The central feature of pre-conceptual thinking is egocentrism
stage of concrete operations and develops at the stage of formal operations.
sensorimotor stage lasts from birth to 2 years and is divided into 6 substages, during which the child consistently demonstrates the following features and achievements: 1) The child has unconditioned reflexes and is not able to think, set a goal and distinguish himself from the environment; 2) Reflexes turn into repetitive actions; 3) The ability to reproduce random, pleasant and interesting results of one’s own actions appears; 4) The ability to coordinate actions aimed at prolonging the impression that aroused interest increases; 5) Discovering new ways to get interesting results; 6) The emergence of the ability to imagine missing events in symbolic form. The main achievements of this period include the formation of coordinated movements corresponding to such material structure as grouping, representational construction and intentionality. A particularly noticeable result of this stage is the construction of a permanent object, that is, the understanding of the existence of objects independent of the subject.
preoperative stage characteristic for the age from 2 to 7 years, with two substages. At the first substage, the formed new ability to represent is assimilated by sensorimotor structures, and they must adapt to it. In addition, the child establishes a number of functional laws, truths and associations regarding the environment: for example, an understanding of identity and certain dependencies and correlations. A distinctive feature of children of this age is the surprising limitation of their thinking. One gets the impression that their thought is focused exclusively on one aspect of the situation, often their own point of view (egocentrism), and all other points of view or dimensions are not taken into account. Pre-operational thought, besides focusing on the single most conspicuous aspect of an event, does not seem to follow the laws of logic or physical causality, but rather is limited to contiguity associations. Thus, children’s arguments for their actions are often absurd inventions or are the result of their desire to justify themselves at any cost.
Stage of specific operations characterizes the age from 7 to 12 years and is divided into two substages. At this stage, the mistakes that the child makes at the preoperational stage are corrected, but they are corrected in different ways and not all at once. The meaning of the definition «concrete» operation, which is included in the name of this stage, is that the operational solution of problems (i.e., a solution based on reversible mental actions) is taken separately for each problem and depends on its content. For example, physical concepts are acquired by a child in the following sequence: quantity, length and mass, area, weight, time and volume.
Formal Operations Stage occurs at the age of 12 years and older. The system of reversible operations, becoming more coordinated, enters the next stage of development, formal operations, which begins at the age of 11-12 years. The previously developed ability to classify objects develops into the ability for combinatorial thinking: analyzing a physical event, the child is able to take into account all possible aspects and change them one by one, like a qualified experimenter, in search of a logically sound answer. The ability to vary — mentally and hypothetically — aspects of a situation in a fixed order means that the child can invent objects and situations that do not actually exist. Thus, possibility takes precedence over reality, and the form is manipulated and considered in isolation from the content, i.e., not in the way a child at the stage of concrete operations does.
Within each stage and substage, Piaget often distinguished three levels: failure, partial success, and success. In the latest versions of his theory, Piaget viewed development not as a rectilinear movement from one stage to another, but as a movement in a spiral, characterized by the fact that the various forms and different content of thinking, characteristic of the previous level, are rethought, restructured and integrated, or unified, at the next higher level. The invariant quantitative aspects of the problem of transforming a clay ball are learned before others.
The fundamental question of Piaget’s theory, to which no convincing answer has been found, remains the problem of novelty and spontaneity. How, from a cognitive structure, in which any new Knowledge is completely absent, does it emerge exactly — new knowledge? Moreover, how does one come to understand that new knowledge that has arisen is necessarily connected with other knowledge?
Piaget’s other theories, supplementing his main theory, deal with the development of moral judgments, perceptual development, the development of representations and memory, all of these lines of development being considered from the point of view of the limitations imposed by the various levels and consequences of our intellectual activity.