The cognitive consequences of early sensory deprivation.

G>TROWTH in any field of science is almost always uneven. The past decade, for example, has been a period of turbulent growth in the field of perception, a period in which parallel inquiries in neurophysiology, physics, and psychology have each in turn thrown light upon the nature of the perceptual process, light of such an order as to dazzle us all a bit with respect to the fundamental nature of perceiving. I should like briefly to review some of these developments before turning to the principal topic of this symposium: the problems of sensory deprivation. Let me consider first the field of physics. The classical metrics of physics up to the end of the 19th century were the centimeters, grams, and seconds of classical mechanics. Until very recently in psychology,