Channels in the Visual Nervous System: Neurophysiology, Psychophysics and Models

Spatial vision research during the 1970s was dominated by the spatial frequency channel paradigm of Campbell and Robson (1968). This article summarizes some research and current views on spatial frequency channels. By channels, we mean an array of medium bandwidth mechanisms, similar to the simple cells that are commonly found in the visual system. The viewpoint presented here provides a useful perspective, slightly different from that found in Graham's excellent book (1989). Spatial frequency channels play a central role in enabling us to discriminate small, complex objects with our constantly moving eyes. Given an image that is constantly moving on the retina, it is of great value to recode the information from the position domain to the relative position (size) domain to remove the effects of image motion.