Subjective contours - bridging the gap between psychophysics and physiology

Much is known about the initial stages of visual processing up to the striate cortex, but how is visual information represented and handled at subsequent stages? Phenomena of contour, color and movement perception have been used to identify functions of neurons and to reveal functional differences between cortical areas that application of classical receptive-field concepts has not suggested. These differences can be related to theoretical stages of visual processing that provide stability of perception under changing conditions of stimulation.