Jean Piaget, a Swiss psychologist, whose original training was in the natural sciences, spent much of his career studying the psychological development of children, largely at the Institut J.J. Rousseau at the University of Geneva, but also at home, with his own children as subjects. The impact of this research on child psychology has been enormous, and Piaget is the starting point for those seeking to learn how children view numbers, how they think of cause-and-effect relationships, or how they make moral judgments. Piaget found that cognitive development from infancy to adolescence invariably proceeds in four major stages from infancy to adolescence: sensory-motor, preoperational, concrete operational, and formal operational. Each of these stages is marked by the development of cognitive structures, making possible the solution of problems that were impossible earlier and laying the foundation for the cognitive advances of the next stage. He showed that rational adult thinking is the culmination of an extensive process that begins with elementary sensory experiences and unfolds gradually until the individual is capable of dealing with imagined concepts, that is, abstract thought. By learning how children comprehend the world and how their intellectual processes mature, Piaget contributed much to the theory of knowledge as an active process in which the mind transforms reality. Put simply, Piaget described children from a perspective that no one before had seen.
There are two chapters by Jean Piaget and his collaborator Bärbel Inhelder. The first, on mental images, breaks new ground: it describes original experiments carried out by Piaget and associates with children of various ages. Piaget examines the relations between images and motor activity, imitation, drawing and operations. He also classifies images according to their degree of complexity and show why children have inadequate images of some processes. The second chapter is on intellectual operations and Piaget gives a summary of the main findings of a number of his earlier books, on the child’s notions of conservation, classification, seriation, number, measurement, time, speed and chance.
In the last chapter, Pierre Gréco discusses learning and intellectual structures. He describes the work of psychologists with rats in mazes and formulating theories of animal learning. Gestalt psychology and various other interpretations are examined and Greco also pays attention to Piaget’s view of ‘structural learning’ based on experience.