Fig. 3. A. The Hermann grid illusion. B. The unshaded area of each circle represents the inhibitory zone for the point at the center of the circle. Near fixation the inhibitory zones are small and fit within the boundaries of the white stripes. Points in the intersections and points in the stripes outside the intersections receive the same amount of inhibition. Away from fixation, the larger inhibitory zones extend into the black regions, which do not contribute to lateral inhibition. Points in the intersections receive more inhibition than points outside and therefore appear darker.