As a philosopher, I'm very interested in human perception, and especially by things that consistently fool us. Optical illusions are one such thing. Inspired by the art of Akiyoshi Kitaoka, I taught myself how to make a variety of different optical illusions using Adobe Illustrator. I also enjoy making gifs, like the one above, to show how they work.
In this next one, which is my favourite, all the greens are really the same shade!
This next one utilises a phenomenon called "illusory red". As the samples show, there's no swatch in this image that someone would usually call "red".