Originally published in 1977, this book considers the role language plays in psychological development. It tries to avoid general discussions of "language and thought", an approach already sufficiently developed by philosophers and (although somewhat less) by psychologists. Instead it attempts to focus specifically upon what we can learn about the topic from available research findings at the time. Theoretical considerations are developed only when necessary to clarify an issue or to facilitate the integration of presented material. The aim of the work is simple - to share with the reader the author's thoughts and understanding of available knowledge of the role of language in mental development.

First published in English in 1969, the book opens with a chapter by Pierre Oleron on intellectual activities. These fall into three groups: inductive activities (the apprehension of laws, relations and concepts), reasoning and problem solving. It describes typical methods and essential results obtained by relevant experiments. There are two chapters by Jean Piaget and his collaborator Barbel 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 Greco 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.

First published in English in 1969, the book opens with a chapter by Pierre Oleron on intellectual activities. These fall into three groups: inductive activities (the apprehension of laws, relations and concepts), reasoning and problem solving. It describes typical methods and essential results obtained by relevant experiments.

There are two chapters by Jean Piaget and his collaborator Barbel 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 Greco 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."