Scintillating Grid

What is happening

Move your eyes slightly while scanning across the top-right and bottom-left of the figure. A dot other than the one you’re currently looking at can appear black, and it tends to vanish the moment you try to count it. All 40 circles here are drawn in the same white. There is no processing that changes a dot’s color over time.

Why it looks that way

The combination of the white circles at the intersections, the gray lines, and the black background makes the perceived brightness of nearby dots feel unstable. Where you direct your attention and how your eyes move both play a role. It resembles the Hermann grid, but the flicker produced by the added white circles is what makes this one distinct.

How to check

Revealing the answer colors the outline of each white circle to show exactly where they’re drawn. If chasing the black dots tires your eyes, take a break. Not seeing the effect doesn’t say anything about your ability to count numbers.

Try a related illusion

For reference: Michael Bach’s explanation. The figure here is an original implementation for this site.

First described

After Elke Lingelbach, 1994

Reported as a variant of the Hermann grid.

See it in the timeline