Optical illusions have confounded and delighted humans for thousands of years, from the Parthenon's architectural trickery to M. C. Escher's impossible realities to the spinning dancer. The enjoyable struggle to understand optical illusions is best summed up by the Greek philosopher and dramatist Epicharmus: "The mind sees and the mind hears. The rest is blind and deaf."

The following websites will open up to you the mystifying world of optical illusions. Be warned, however: once you begin to bend your brain and seek to understand them, you'll probably find it too fun to stop.

Websites With Optical Illusion Collections

A lot of optical illusion websites have been left largely alone for years and even have page designs that are real flashbacks to the early days of the internet. Mighty Optical Illusions is one of the only sites with illusions I could find that is regularly updated to this day.

Be sure to check out the categories on the right to sort the illusions into the ones you really want to see. There are 3D chalk drawings, impossible objects, scary illusons, and much more.

Elsewhere on the web you'll find Michael Bach's website, which has tons of cool illusions.

One of the neatest things about the site is that most of the illusions are interactive. This one, for example, allows you to change how blurred or in focus the faces are, which alters which one looks angry.

The other great thing about the site is that Michael Bach is a vision scientist and professor of neurobiophysics, so he often provides interesting explanations of how the illusions work.

And if you want to turn off the eyes that follow your cursor around on the main page, there's a button in the top left.

Autostereograms (a.k.a. Magic Eye)

Perhaps you recall the popular Magic Eye images from the '90s. Back then you had to purchase Magic Eye books to attempt to see really cool 3D optical illusions. But now there are lots available right on the internet - so you can give yourself a headache for free!

To start you off, Eyetricks has a huge gallery of autostereograms.

To see the three-dimensional images, most instructions tell you to try to look "through" the image and into the distance. For me, it seems to work if I cross my eyes just slightly. If it doesn't work for you, you can try getting closer to the image or printing it out. It will probably take some effort at first, but once you're successful, it should get easier.

Create Your Own Autostereograms!

Easy stereogram builder has a simple editor that lets you create your own completely custom autostereograms.

For a background, you can choose a pattern, random dots, or upload your own image. For your "mask" (the image that will appear in 3D), you can choose from the many available masks, type in some text that will appear in 3D, or upload your own black-and-white image.

If you just want more 3D images to look at, check out the site's gallery of user-submitted stereograms.

Do you know of any other great websites with optical illusions? What are your favorite illusions?

Image Credit: Mattox