"In each of these optical illusions you see things that are--literally-- all in your mind. In the first illusion, called the subjective contour effect, your brain "fills in" the gaps in the rectangle between four corners, creating completed lines where there are no lines at all. Your brain engages in this bit of creative fiction to help you make sense of what you're seeing. For example, if you were out in the woods hunting deer, you might first catch a partial glimpse of your prey through dense vegetation that blocked you from seeing the whole animal. But you'd know what you were seeing was a deer, and not a collection of disconnected shapes, because your brain synthesized the fragmented parts of the image into an integrated whole The second illusion, sometimes called the neon effect, also is an example of your brain filling in gaps, but this time with colors. You perceive solid (albeit faint) color in the white spaces between the green lines because your brain, in attempt to help you see a whole vs. a collection of parts, compels you to see a solid whole where there actually are only disparate parts. In the final illusion, your brain guesses-erroneously as it turns out-that spots wink in and out of existence. This scintillating grid illusion arises from neural artifacts in the way your brain estimates the brightness in between sharply contrasting shapes. So why should we care about optical illusions? Neuroscientists have discovered that optical illusions tell us a lot about the way the human brain perceives the business world: the brain doesn't passively-- and faithfully-- report what it sees. Rather our brains create reality on the fly, based upon educated guesses about what is probably out there. The reason is that it takes much less processing power, and burns many fewer calories, for the brain to crudely sketch out what it sees based on a few simple rules such as "shapes that appear fragmented usually aren't, so fill in the gaps", than it does for the brain to rigorously process and compute complete and accurate pictures. Such shortcuts not only conserve energy (our brains consume 20% of our daily calorie usage), but speed up decision making...." - Lit

I like optical illusions. What kinds of illusions do we have that are non-optical? - Sue - Friendfeed is best

The mind perceives many things inaccurately/imperfectly actually... you should read up on perception... - Lit