Spinning Wireframes

What is happening

A solid drawn only in lines turns slowly around a vertical axis. Every line has the same width and brightness, so nothing in the picture says which lines are near and which are far.

That is why the picture has two readings:

• You are looking down from above, and the near edges move right
• You are looking up from below, and the near edges move left

Either way, the lines on the screen move in exactly the same way. Neither reading is the true one.

How to flip it

It helps to open “Reveal the answer” first. The two pictures there are the same drawing. Only the lines read as near (thick orange) are different.

1. Check which reading you have now. If the near edges move right, you are looking down. If they move left, you are looking up
2. Assume the other reading. If you see it from above, tell yourself: “I am right underneath it, looking up”
3. Keep watching. When the near edges start moving the other way, it has flipped

If it does not work, set “Speed” below the work to 0.5×. Slower is easier. Looking away and back again also helps.

Focusing on one part of each shape makes it easier still:

• Cube: watch only the square face at the top. Switch from “the lid of a box, seen from above” to “the ceiling of a room, seen from below”
• Octahedron: watch only the square across the middle and switch it the same way as the cube
• 4D cube: watch only the large outer cube and use the cube method. You can ignore the inner one
• Tetrahedron: the hardest shape. Compare the left and right pictures in the answer, then picture the one you are not seeing while you watch

Why it can be flipped

When the brain sees a picture that fits two readings, it picks one and holds it steady. But nothing in the picture supports that choice, so simply assuming the other reading is enough to switch. It is the same mechanism as the still Necker cube, carried over to the direction of the spin.

The reverse is also true. Make the near lines thicker and only one reading is left. That is why, in the answer, you can only see the reading where the thick lines are in front.

Compared to the dot version

Spinning Point Clouds are made of dots, so the shape itself is fuzzy. Here the shape is easy to read, yet its direction is not fixed.

The 4D cube also turns in the fourth dimension, so its inner and outer cubes trade places as it spins. Even so, the direction of the vertical spin is just as open as for the other shapes.

First described

After Hans Wallach / D. N. O'Connell, 1953
Source: “The kinetic depth effect”, Journal of Experimental Psychology

Showed that depth can be read from the shadow of a rotating wire figure. The ambiguity of a still line drawing is known from Louis Albert Necker’s 1832 description of the cube.

See it in the timeline