1. Bower, T. G. R., in Brain Mechanisms and Development (edit. by Robinson, R.) (Ciba Foundation, in the press).
2. Piaget, J., Origins of Intelligence (Basic Books, New York, 1954).
3. Bruner, J. S., Processes of Cognitive Growth: Infancy (Clark Univ. Press/Barre Publishers, Worcester, Mass., 1968).
4. Fantz, R. L., Sci. Amer., 204, 66 (1961).
5. Bower, T. G., Sci. Amer., 215, 80 (1966).