Dark spots seem to flash on and off inside the white dots at the crossings.
Try this
- Shrink Size of the dots to 0: the flashing stops.
- Tick Make the streets black: no gray streets, no illusion.
Why it happens
Elke Lingelbach found this variant of the Hermann grid, and Michael Schrauf, Bernd Lingelbach and Eugen Wist described it in 1997. The flashes need the gray streets, the white dots and eye movements: as your eyes jump around, dots fall in your peripheral vision, where they look dark, then you look at them and they turn white again. That is why the black dots seem to appear and disappear.
Did you know?
It is one of the few illusions that seems to flicker without anything moving on the screen.
References
- SCHRAUF M., LINGELBACH B., WIST E. (1997). The Scintillating Grid Illusion. Vision Research, 37, 1033-1038. doi:10.1016/s0042-6989(96)00255-6
- Background on Wikipedia
The illusion on this page is drawn by code written for this site. Last checked 1 November 2026.
Frequently asked questions
Why do the dots in the scintillating grid flash?
The dots look dark in your peripheral vision; as your eyes move, they seem to switch between dark and white.
Try these next
Light and colorSimultaneous contrast
Two identical gray squares look different shades on different backgrounds.
Light and colorWhite’s illusion
Gray bars look darker on white stripes and lighter on black stripes, the opposite of what contrast predicts.
Light and colorHermann grid
Gray spots flicker at the crossings of the white streets, except where you look.