# Tetrahedron Optical Illusion

Many people have a hard time grasping what the meaning behind an optical illusion really is. I am no exception to the rule although I try my best to decipher the true meaning behind these works of art! Depending on the illusion, I can sit there for what seems like forever and never really get to the bottom of it. This Tetrahedron wasn’t any different for me. After looking at it for a little while, I still couldn’t quite grasp what the whole point of it was. It only appeared to be a spinning triangle that boasted a variety of colors in the image itself.

You tell me. What did you get out of this animated gif? Am I totally missing something in this simplistic piece of art? Did you notice how the color changes as the Tetrahedron spins around? The way the light reflects through the image is pretty cool and not something I would have ever thought of on my own. In reality, this thing is so simple that it shouldn’t be as intriguing as it is. Yet, I find myself sitting here and staring at the thing as it rotates round and round changing color along the way.

From green to brown to green to brown, the color changing technology in this Tetrahedron is something that you have to watch and observe to gain a full understanding of the illusion. Even though it looks like a triangle to me, that doesn’t mean you are going to think the same thing. Everyone has their own opinion on what optical illusions are cool and which ones they find boring or uninteresting.  Take the time to explore this rotating shape and see what you get out of it. Maybe you will see something that I didn’t, but for me, it really was something simple and amazing all at the same time.

## 36 Replies to “Tetrahedron Optical Illusion”

1. JMJDave says:

It’s like the ballerina illusion. You can get it to spin both directions by focusing your eyes away from the image (say looking at the words on the page).

2. Errol says:

This is like that spinning dancer; which direction is it spinning ~ right or left? Both? Depending on which direction you look at it determines which direction it spins. The colors have nothing to do with it and yet they seem to help either or both directions. Good option for an optical illusion.

3. Lak says:

You can see it rotating clockwise or anti clockwise.

4. Barry says:

The only saving grace is that if you work at it, it can rotate either way.

Barry

5. nando says:

It’s actually pretty cool… depending on which of the top corners you focus on, it will seem to change the direction it is spinning!

6. yah says:

Hi,

I am a big fan of your website though I never commented on it

This time, …

The illusions comes from the rotating, try see if you could change the direction of the rotation (it’s interchageable)

7. Jazzizhep says:

Very cool. It took a few minutes for the “change” to occur, and another few minutes to figure what causes that change. COntinue reading if you want my thoughts on what happens.

The rotation of the object can reverse its direction depending on where you perceive the “brown” panels location o be at any moment. IF the object is rotating clockwise (from a top-down perspective) the brown panel appears the the right of the object. If the object is rotating counter-clockwise (again from a top-down view), the brown panel panel appears to be at the rear of the object.

I tried to force the change at a point of my choosing and was unsuccessful.

8. Yannick says:

The illusion his simple, it’s the same as the dancer we seen a year or 2 ago. Ask yourself this question,does the shape turn clockwise or the oposite? Now try to look at it and change the rotation direction…

To understand how it works you have to look at depth perception. Does the summit of the shape his passing in front or in the back of it. If you say in front, the shape turn clockwise…

9. Anonymous says:

If you look at it right, it can change what way it rotates, like the spinning girl illusion.

10. Glass Joe says:

You can view it spinning either to the right or the left.

11. Rocco says:

It’s not about the colors though I’m sure that’s what causes the effect of it seemingly changing its spin direction.

12. q says:

its a glass pane

13. ryan says:

It can spin either direction, clockwise or counter clockwise, depending how your eyes focus on it. Very similar to the spinning ballerin

14. Rémy says:

Amazing one! It rotates in both ways !

15. dh says:

It is like the spinning girl–is it spinning clockwise or counterclockwise? Every time I look it seems to be going the other direction.

16. ebbhyen says:

I do not know if this has to do with just having one eye, but the object changes when I mentally cause the direction of the object to change. When it is spinning left to right; I see the walls change color as they spin and the top is green. When it is spinning right to left; I see a green wall, then a brown wall and then the third wallis clean and the back is painted brown, and the top is clear.

17. ebbhyen says:

I left out the most obvious, it is impossible for it to be rotating in two colors. The color would be green – wall 1, brown – wall 2, green – wall 3; but then as it should repeat, the wall is now the opposite color.

18. bandit885 says:

in addition to “changing directions” there are times I see it pointing inward as well as outward.

19. JohnE says:

I can perceive it to spin in opposite directions by looking at the grey panel on top when it circles around. If I imagine I’m looking through the tetrahedron and the grey panel is the on the inside, and the top of the grey corner is pointing towards me, it rotates counter-clockwise. If I imagine the grey panel is on the outside of the object and the top of the triangle is pointing away, then it rotates clockwise.

I wonder if the initial perception depends on where the object is in its rotation when you first see it, or perhaps left/right eye dominance?

Sometimes difficult to make it rotate back the other direction once you see it one way.

20. Suzanne says:

This is so much prettier and easier to look at than the dancer. I can’t force this one to spin the other way – it does it on it’s own.

It’s beautiful.

21. Vincent says:

The illusion here is that the triangle changes direction, not changes color.

22. Hanna says:

It can spin either way

23. Thelma Huss says:

It will change directions.

24. Ian says:

I managed to flip the directions by asking myself, are the “up and down” lines / edges , the lines moving to the left and to the right closer or farther away. Are the lines that are moving to the right closer or father away than the lines moving to the left?

25. Craig Schaff says:

CORRECTION PEOPLE… this is NOT like the dancing ballerina. That was a silloette that one could have spin either way.

This is a 3d looking object with a BLACK LINE at the angles that is ACTUALLY moving IN FRONT of the object in a clockwise (across the viewers front from viewers right to left).
If you focus ONLY on the upper point, yes you can get it to spin in the other direction until you take your eyes away.

Unknown what this purpose is other than to confuse a LOT of people into false thinking.

26. The image originates from Wikipedia, where you can find many animations of Platonic solids: http://en.wikipedia.org/wiki/Platonic_solid

In the original post, James Dean writes: “It only appeared to be a spinning triangle”. But the whole point is that it is not a one dimensional triangle, but a three dimensional polyhedron. In particular, it is a tetrahedron that consists of four triangles: http://en.wikipedia.org/wiki/Tetrahedron

When drawing an image of 3D figure on a 1D surface (or a computer screen), we are prone to an optical illusion, similar to other ambiguous (or reversible) figures. A typical example is the Necker Cube: https://en.wikipedia.org/wiki/Necker_Cube

A drawing of a tetrahedron can cause a similar ambiguity, in which it is not clear whether one of the vertices (angles) is directed out of or into the screen. (See also the comment by bandit885.)

To help us interpret the line drawing as a 3D image, the faces of the tetrahedron have been colored in a semitransparent way. But the colouring itself still allows for two interpretations (inwards/outwards). (See also the comments by Jazzizhep, ebbhyen, and JohnE.)

So, yes, I agree with the majority of previous commenters: it is a lot like the spinning ballerina illusion. Although a cool thing about this one is that was probably not intended to cause such a reversible image! :-)

However, I also agree with Craig Schaff’s remark: if you look more closely (for instance, at the larger version at Wikipedia), you can determine that the tetrahedron ‘actually’ rotates from right to left all the time! You can see this thanks to the semitransparency of the faces: if an edge is pointing out of the plane it will look darker than when pointing into the plane.

27. It’s true you can make it spin either way, but here’s how:

Look at the top left-hand corner of the paragraph above the triangle (don’t look directly at the triangle). You’ll noticed in your peripheral vision the triangle appears to spin towards the direction you’re looking. After a few seconds, move your eye to the opposite, right-hand corner of the top paragraph. The triangle reverses direction and again appears to spin toward the direction you’re looking. Pretty cool! :)

28. Based on the rotating tetrahedron illusion, which was unintentional, you can create another illusion: the impossible tetrahedron, as a variation on Penrose’s triangle or the impossible cube. I sketched one here: http://www.sylviawenmackers.be/blog/2013/11/onmogelijk-viervlak/

Small correction to my previous post: Where I said “1D”, it should have been “2D”.[img]http://www.sylviawenmackers.be/images/Blog/ImpossibleTetrahedronSmall.jpg[/img]

29. HTFCuddles says:

It’s like the Spinning Ballerina illusion. It goes both ways.

30. kennie lewis says:

I definitely got into this one, actually if your concentration is on the upper corners it appears to change directions however when I concentrate on the lower point it stayed going in one direction.
The simplicity of some objects can make them complicated if looking at the wrong points.

31. suor de sapo says:

You are right. It spins clockwise all the time. I can check it by the length and transparency of the edge that was supposed to be close is actually away (shorter and blurred) when I manage to see spinning reverse.

32. Ed says:

This triangle does NOT change direction, and in that sense it is not at all like the “spinning girl” (or whatever it’s called) illusion. If you imagine it from above, this object is spinning clockwise the whole time. Just look at the top surface, which is tilted towards you part of the time: it is ONLY spinning clockwise. In the part of the spin when you can actually see the entire top surface, the front corner moves right-to-left and only right-to-left; i.e. clockwise. I’m actually not sure what the illusion here is meant to be. Perhaps that you could see this as a solid (though kind of transparent) tetrahedron, or as “hollow,” i.e. with a face or faces missing so that you can see inside it as it turns… not my favorite here.

33. Matthew brand says:

This is more important to 4th dimensional understanding than you know, If we ignore depth for a second and assume that the line in front is actually behind we can see the triangle from the opposite direction but inverted, so if in one eye we saw the correct rotation and in the other we say the inverted triangle in the opposite rotation then we would actually be perceiving it in the 4 dimension-ally. We would see the entire object outside and in. This is hard to explain and makes more sense in my mind.