Man, I used to think optical illusions were the simple, “which line is longer” sort. But I have seen some optical illusions in the past decade or so that have really caused me pause. It’s like there’s been some sort of optical illusion renaissance recently.
Here is one of the animated variety that wouldn’t have worked presented, as they were when I was young, in book form. Wow.
Okay, I was curious, what is a “gabor element”? It turns out the “Gabor filter” has an interesting mathematical (and even biological) origin.
For the creative, there is a nice online tool allowing you to create a gabor element here. It should be possible to generate a series of them out of phase and stack them with a GIF-creation tool in order to experiment with you own illusions similar to the above.