First published in 1980. This book is the first integrated presentation of two of the most active areas in present-day visual research. Its inspiration and nucleus were provided by two Optical Society of America symposia, one on the coding of spatial information in the visual system and the other on adaptability of the visual system. Although the two topics might seem, at first sight, only distantly related, they are actually extensively intertwined in contemporary research. Some investigators focus on mechanisms of visual analysis but rely on experimental modification of perception to reveal the nature of the coding; others focus on perceptual modification but look at analytic elements for indications about what it is that gets modified. Likewise, most of the chapters in this book combine, in varying proportions, both themes. Adult human perception is the primary concern, but illuminating data from animal, infant, and neurophysiological studies are also discussed.