Optical illusion: impossible anti-grav ramps

Koukichi Sugihara's "Impossible motion" -- a cunning arrangement of cardboard ramps carefully skewed to create the illusion that balls roll up them -- won top honors at the Meiji Institute for Advanced Study of Mathematical Sciences' Best Visual Illusion of the Year Contest 2010. It has a delightful 3D physicality, being a real object made out of atoms, that makes it especially wonderful.

Impossible motion: magnet-like slopes (via Neatorama)


  1. That is far more convincing than I expected. I was grinning like a mad man when the piece rotated to expose the forced perspective.

  2. Ladies and gentlemen… start your Insane Clown Posse references! Be nice if there were plans online to make your own.

  3. Is this an example of Youtube’s Spoilermatic auto function? The placeholder frame for the video is the giveaway view of the sculpture…

  4. I agree with Scott. Very bad placeholder frame.

    I wonder how convincing the illusion is if you’re actually in the room with the object.

    Still, very cool stuff.

    1. @Xopher – Probably not convincing at all, unless you can only see the piece through a hole with one eye. Part of the illusion comes from having no real perspective, causing your brain to make assumptions about the position and arrangements of the parts. If you can see it with both eyes, the perspective becomes that of four differently sized, differently shaped, and differently oriented ramps. Even using just one eye, if your head moves much at all, you lose the illusion as the distortion begins to become apparent.

      This reminds me of a film I saw in a high school class where a wedge shape cut to resemble a window frame rotated on an axis. Because of it’s shape, it looked as though the window was cycling back and forth. When a red bar was placed through one opening in the window frame, the illusion was mind boggling. Some viewers saw the bar “jump” through the side of the frame when it started its retrograde motion – others saw the bar stretch into an “S” shape to accommodate the two different aspects of the “reality” we saw before us.

  5. I think it could work in person. These Dragon illusions


    are just as amazing in person as they are in online videos. You just have to keep it a couple feet away and not walk around too much.

    I was disappointed by the default frame too. I thought they were going to roll out of the center and up the sides when I pressed play.

    As you see it rotate, it’s neat how the supports look square on the illusion side, and how many paper tabs on the back side that took.

  6. Even with the spoiler, it’s so well done I *can’t* make myself see it when in the start position.

  7. There’s a hill in Nova Scotia, and a couple of other “Magnetic Hills” around the world, built on similar principles. You take your brakes off at the “bottom” of the hill and your car trundles “up” it.

  8. I was a bit disappointed actually – VSS (the Vision Science Society) hosts this illusion showcase every year and this is far from being all that compelling – usually they pick a better one. This one breaks with any variation in point-of-observation (lots of modern illusions are more robust than this) and you can see that it’s wrong even from the right perspective, because the balls take different times to travel apparently identical distances.

    I’m not just a grumpy old man on the internet, for what its worth :) I study perception (and action) for a living and visual illusions aren’t as interesting as scientists think; they do reveal some boundaries on vision, but they only ever work by breaking a key rule and so don’t tell us anything about vision ‘in the wild’.

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