9309826 De Valois The visual system is able to distinguish several spatial features of visible objects, including form, texture and motion. The visual cortex of the brain has been subdivided into a many different areas based on both anatomical and functional criteria. There are physiological recordings showing the activity responses in the brain to visual stimuli, but the nature of how that cortical organization relates to the process of "seeing" is complex and not yet clear. Psychophysical tests use quantitatively well-defined optical stimuli while measuring responses to properties such as detectability or discriminability. This project uses identical stimuli for psychophysical tests and for physiological tests to determine directly to what extent the nerve cells in various levels of the cortex participate in processing patterns. Novel stimuli are exploited that incorporate patterns with the spatial components filtered in various quantifiably specified ways. In particular, the question of whether fundamentally different processes are used in texture discrimination and form discrimination will be addressed. Results will be valuable to our understanding of how the brain processes information, and will have an impact on visual neurobiology and more broadly to neuroscience, with likely application to computational vision, to artificial vision architecture and to visual display systems. ***
