Originally published in 1974: ‘This book sets forth a theory of cognitive development based on simple but powerful processes of inference. The theory is applied with great ingenuity and freshness to complex phenomena found during intellectual development. Dr Bryant has written an important and original book.’ (J.S. Bruner) ‘In this elegant, timely and brief volume, Dr Bryant produces strong experimental evidence which not only challenges Piaget’s ideas, but even more importantly synthesizes the old and new findings into a newer theory of perceptual development. The importance of this book lies both in its demonstration of elegant experimental techniques in working with young children, and in the optimism it will eventually bring to all concerned with their education. Realizing that children can make deductive inferences at an early age, educators will have to rethink some of their approaches to the teaching of young children. The studies related to the understanding of number have crucial implications for the future teaching of mathematics. This book will cause many people to take fresh thoughts on the subjects here dealt with, and so it can be strongly recommended for all students of child development.’ (William Yule, British Journal of Psychiatry)