Grid Illusion - Scintillating Grid Illusion

The scintillating grid illusion is an optical illusion, discovered by E. Lingelbach in 1994, that is usually considered a variation of the Hermann grid illusion (see section below).

It is constructed by superimposing white discs on the intersections of orthogonal gray bars on a black background. Dark dots seem to appear and disappear rapidly at random intersections, hence the label "scintillating". When a person keeps his or her eyes directly on a single intersection, the dark dot does not appear. The dark dots disappear if one is too close to or too far from the image.