The Scintillating Grid

Abstract The scintillating grid was first presented at the European Conference on Visual Perception in Tübingen in 1995. At the time, the prevailing explanation of the Hermann grid illusion was in terms of the arrangement of the receptive fields on the retina. The minor modification of having a grey instead of a white grid with white dots at the intersections produced a strikingly new and powerful illusion. Instead of the white dots, dark black dots are seen to “blink” and appear even darker in intensity than the black printer’s ink of the square. They then disappear again to reappear immediately somewhere else. The dark diagonals that appear from time to time fitted more to low-pass filtering. The study of low-pass filtered Hermann grids led to the discovery of the scintillating grid and several variants. To this day this illusion still has not been fully explained.