The Lilac Chaser illusion was created by Jeremy Hinton sometime before 2005 Stare at the + sign in the middle
"The illusion involves the phi phenomenon, in which separate objects viewed in rapid succession appear to be moving along a continuous path. It also triggers negative retinal afterimages, which appear after the eye is exposed to one color in a fixed position for several seconds and then that color disappears or the eyes move away. There are several theories for why this happens, but one is that the cells that send information from the retina to the brain adapt in that short window of time, adjusting for the excessive exposure to one color — magenta, in this case. When that color disappears, the adaptation makes the leftover space appear green, the complement of magenta"
