Jean Piaget (1896-1980) was a Swiss developmental psychologist known for his epistemological studies with children. His theory of cognitive development and epistemological view are known as "genetic epistemology". Bärbel Inhelder (1913-1997) was a Swiss developmental psychologist; she was probably Piaget's most well-known co-worker.
The authors state in the Preface, "In this volume we have tried to present, as briefly and as clearly as possible , a synthesis, or summing up. of our work in child psychology. A book such as this seemed to us particularly desirable since our published studies have been spread out over a number of volumes, some of them quite lengthy and some of them fairly difficult to read. This little book, of course, is not meant to be a substitute for reading the other volumes. But it represents, we believe, a useful introduction to the questions we have studied and will enable the reader to gain an adequate understanding of what we have learned in our investigations."
Here are some representative quotations from the book:
"(O)ne might be tempted to consider the expressions 'child psychology' and 'genetic psychology' to be synonymous, but there is an important distinction between them: Whereas child psychology deals with the child for his own sake and does not consider his eventual development into an adult, we tend today to use the term 'genetic psychology' to refer to the study of the developmental processes that underlie the mental functions studied in general psychology."
"There is certainly such a thing as a sensori-motor intelligence, but it is very difficult to specify the exact moment when it appears."
"It is the random ("one-to-one") correspondences that lead to number, for they already imply numerical unity. Number must still be explained genetically, however; otherwise a vicious circle results."
"It is highly probable, then, that the social exchanges characteristic of the preoperatory level are preoperative; that is, at once social from the point of view of the subject and centered upon the child and his own activity from the point of view of the observer."
"Each new mental structure, by integrating the preceding ones, succeeds both in partly liberating the individual from his past and in inaugurating new activities which at the formal operatory level are mainly oriented toward the future."