Some patients can respond to visual stimuli presented within their clinically absolute visual field defects that have been caused by partial destruction of striate cortex. This puzzling phenomenon of looking, pointing, detecting and discriminating without seeing has been called blindsight, and has fascinated philosophers and neuroscientists alike as a spotlight on the nature of unconscious or covert awareness, and the means it provides of studying the visual information carried by pathways other than the major route through the striate cortex.