I was involved with optics for a while in the 70s and 80s and had the opportunity to visit a NASA center that was studying optical illusions and space flight. Very interesting stuff. There were two teams. One was tasked with creating them (fairly easy) and the other was tasked with preventing or overcoming them (incredibly difficult). They happen all the time in our real life, these illusions, and once they are seen and "figured out" they cease or recede. If you look at the speed bump child figure above after a while you figure out that it is just clever artistry and perspective. It still might leap up at you if you are driving but you'll understand it and not freak out.
The example that follows is one you can't overcome no matter how much you understand it. The center "bar" is all the same color or shade of grey. It just changes due to the background and there is nothing you can do about it. Not no way. Not no how.
