Pattern vision breaks down after a period of inspecting a diffusely contoured dark figure upon a ground of uniform brightness and texture. When the field is illuminated with flickering light it is found that the persistence of pattern vision is inversely related to flicker frequency up to the region of fusion. At low flicker frequencies complex figures persist longer than less complex ones of equivalent area, but the reverse applies at frequencies above fusion. These findings are consistent with data obtained from experiments using stabilized retinal images