After staring, a ghost of the picture appears on the gray screen in different colors.
Try this
- Tick Start and keep your eyes on the black dot until the countdown ends.
- Keep looking at the dot on the gray screen. The ghost picture is a negative of the original: cyan turns reddish, yellow turns bluish, green turns pink.
Why it happens
Color-sensitive cells adapt when you stare at a color for a while and become less responsive. When the color is removed, the opposite color from the same "channel" (red against green, blue against yellow) briefly wins, so you see a negative. Shinsuke Shimojo, Yukiyasu Kamitani and Shin'ya Nishida showed in 2001 that afterimages can even appear for surfaces the brain only filled in, which suggests part of the effect happens in the brain, not just the eye.
Did you know?
Afterimages fade faster if you blink and move your eyes; keeping them still makes the ghost last longer.
References
- Shimojo S., Kamitani Y., Nishida S. (2001). Afterimage of Perceptually Filled-in Surface. Science, 293, 1677-1680. doi:10.1126/science.1060161
- 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 I see a different color afterward?
The cells that saw the original colors are tired, so the opposite colors briefly win.
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