Jack-o'-Lantern Afterimage
Stare at a blue pumpkin for 30 seconds and an orange jack-o'-lantern with a glowing face appears.
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What do you see?
A strange blue pumpkin with a magenta stem and a black carved face: triangle eyes, a triangle nose and a jagged grin. Press start and keep your eyes on the small white dot between the eyes for thirty seconds. When the picture changes to a blank white panel, keep looking at the dot. A ghostly jack-o'-lantern floats on the white: an orange pumpkin with a green stem and a face that seems to glow from inside, as if a candle had just been lit. A few seconds later it fades away.
How it works
What you see is a negative afterimage. Every color in the picture was chosen as the opposite of the color you end up seeing.
Your eyes have three kinds of cone cells that respond best to long, medium and short wavelengths of light, roughly red, green and blue. Their signals are then combined into opposing pairs: blue against yellow, red against green and light against dark. Scientists call this opponent processing, and it is the reason nobody has ever seen a bluish yellow.
While you stare at the blue pumpkin, the blue side of the blue-yellow pair works hard and slowly becomes less responsive. When the white panel appears, it sends the same light to every cone, but the tired blue signal answers weakly, so the balance tips toward yellow and orange. The magenta stem tires the red and blue signals and leaves a green stem behind. The black face did the opposite: those cells rested, so on the white panel they answer more strongly than their neighbors and the face looks brighter than the pumpkin around it. That is the candle glow.
Keeping your eyes still matters. The afterimage is fixed to the patch of retina that got tired, so if your eyes wander the ghost pumpkin moves with them, and blinking makes it fade sooner. Thirty seconds is usually enough; forty-five gives a stronger, longer ghost. A dim room helps too.
The effect is completely normal and harmless. It is the same process that leaves a spot in your vision after a camera flash, and within a few seconds your cells recover and the panel looks white again.
History
Afterimages were described by Aristotle and studied scientifically by Johann Wolfgang von Goethe in his 1810 Theory of Colors. Ewald Hering proposed opponent colors in the 1870s, and Leo Hurvich and Dorothea Jameson measured the opponent channels in the 1950s. The blue pumpkin is original artwork for Opticalillusions.com, made for Halloween, which falls on Saturday, October 31, 2026.
Try it
- Stare for thirty seconds without moving your eyes, then look at a white wall or a sheet of paper.
- Try it on a friend without telling them what color the pumpkin will turn.
- Look at a light gray wall instead of white and see how the ghost changes.
- Print the poster, hang it by a white door, and let trick-or-treaters try it.
Frequently asked questions
How do I see the jack-o'-lantern afterimage?
Press start and keep your eyes on the small white dot between the eyes for thirty seconds. When the white panel appears, keep looking and an orange jack-o'-lantern floats there.
Why does the blue pumpkin turn orange?
Staring at blue tires the blue side of the blue-yellow pair. On the white panel the tired signal answers weakly, so the balance tips toward yellow and orange.
Why does the face seem to glow?
The black face let those cells rest. On the white panel they answer more strongly than their neighbors, so the face looks brighter, like a candle glow.
Who studied afterimages?
Aristotle described them, and Johann Wolfgang von Goethe studied them in his 1810 Theory of Colors. Ewald Hering proposed opponent colors in the 1870s.
Sources & credits
Negative afterimages and opponent colors were described by Goethe (1810) and Ewald Hering (1870s). The pumpkin is an original drawing.
- Hurvich, L. M. & Jameson, D. (1957). An opponent-process theory of color vision. Psychological Review, 64.
- Afterimage — overview Read →
- Halloween — overview Read →
Further reading: The Illusions Index (University of Glasgow) and Michael Bach’s Optical Illusions & Visual Phenomena.
Written by K.R. for Opticalillusions.com · Updated . Illusion artwork © The Wizard Of Sales, LLC. Feel free to share a link; see our terms for reuse.
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