All illusions
Pick one, play with the sliders, then switch the trick off.
All illusions
Size and shapeMüller-Lyer illusion
Two lines of exactly the same length look different because of the fins at their ends.
Size and shapeEbbinghaus illusion
An orange circle looks smaller among big circles and bigger among small ones.
Size and shapeDelboeuf illusion
A disk inside a snug ring looks bigger than the same disk inside a wide ring.
Size and shapePonzo illusion
The upper of two identical bars looks longer because the rails make it seem farther away.
Size and shapeVertical-horizontal illusion
Vertical lines look longer than horizontal lines of the same length. Test yourself.
Size and shapeJastrow illusion
Two identical curved shapes: the lower one always looks bigger.
Size and shapeZöllner illusion
Perfectly parallel lines look tilted when short lines cross them at an angle.
Size and shapeHering illusion
Two straight lines seem to bow outward in front of a starburst.
Size and shapePoggendorff illusion
A straight line that passes behind a bar seems to come out in the wrong place.
Size and shapeCafé wall illusion
Rows of black and white tiles make perfectly straight, parallel lines look like wedges.
Size and shapeFraser spiral illusion
Separate circles look like a spiral, because of tilted stripes.
Size and shapeKanizsa triangle
A bright white triangle appears where there is no triangle at all.
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.
Light and colorScintillating grid
Black dots flash inside the white dots, everywhere you are not looking.
Light and colorMach bands
Each strip of gray looks shaded, lighter at one edge and darker at the other. It is perfectly flat.
Light and colorCornsweet illusion
A thin edge makes two identical grays look like a light half and a dark half.
Light and colorWatercolor illusion
A thin colored line inside a darker outline paints the whole shape with a faint wash of color.
Light and colorColor assimilation
The same red looks pink on one side and orange on the other.
Light and colorNegative afterimage
Stare at an oddly colored picture for 25 seconds, then see it in different colors on a blank screen.
MotionMotion-induced blindness
Three bright yellow dots disappear while a blue pattern turns behind them.
MotionPeripheral drift
A still pattern seems to rotate in the corner of your eye.
MotionPinna-Brelstaff rings
Two rings of squares seem to spin in opposite directions as the picture zooms in and out.
MotionStepping feet
Two bars moving at the same steady speed seem to take turns stepping, like feet.
MotionMotion aftereffect (waterfall illusion)
Watch a spinning spiral for 30 seconds; when it stops, it seems to turn the other way.
MotionTroxler fading
Soft colored blobs fade away into the gray when you keep your eyes still.
Two ways to see itNecker cube
A simple line drawing of a cube flips between two different 3D shapes.
Two ways to see itRubin vase
A vase, or two faces looking at each other? You cannot see both at once.
Two ways to see itSchröder stairs
A staircase you can see going up from the floor or hanging upside down from the ceiling.
Size and shapeOrbison illusion
A perfect square looks bent when it sits on a pattern of circles.
Size and shapeWundt illusion
Two straight, parallel lines seem to bow inward toward each other.
Size and shapeSander illusion
Two diagonal lines of the same length look very different inside a parallelogram.
Light and colorEhrenstein illusion
Bright discs appear where the lines stop, though nothing is drawn there.
Light and colorNeon color spreading
Thin colored line segments make a whole glowing disk of color appear.
Light and colorChubb illusion
The same patch of texture looks less contrasty inside a busy surround.
MotionOuchi illusion
A circle seems to float and slide over the background when you move your eyes.
Light and colorBenham's top
A black and white disk shows pale colors when it spins.
MotionBarber pole illusion
Diagonal stripes moving behind a window seem to move along the window instead.
Size and shapeOppel-Kundt illusion
A space filled with marks looks longer than an empty space of the same length.