The Neural Control of Vision
C. The Retina

Hermann grid illusionThe center/surround organization of retinal ganglion cells has often be used to try to explain the Hermann Grid Illusion shown in Figure 8. The illusory effect is the smudges one sees at the intersections except at the center of gaze. The smudges have been attributed to the greater center/surround antagonism in retinal ganglion cells whose receptive fields are centered at the intersections (receptive field #1) than elsewhere (#2). That this explanation does not hold water can be seen in in Figures B and C where minor changes in the figure that do not affect the center-surround organization of retinal ganglion cells eliminate the illusior effect.