Variations on the Hermann grid: an extinction illusion.
When the white disks in a scintillating grid are reduced in size, and outlined in black, they tend to disappear. One sees only a few of them at a time, in clusters which move erratically on the page. Where they are not seen, the grey alleys seem to be continuous, generating grey crossings that are not actually present. Some black sparkling can be seen at those crossings where no disk is seen. The illusion also works in reverse contrast.
Ninio
J
J
Laboratoire de Physique Statistique, Ecole Normale Supérieure, 24 rue Lhomond, 75231 Paris cedex 05, France. jacques.ninio@lps.ens.fr
Stevens
K A
KA
D000221:Adaptation, Ocular / Q000502:physiology; D005108:Extinction, Psychological / Q000502:physiology*; D006801:Humans; D009903:Optical Illusions