Yesterday I posted a blog about the importance of reducing clutter and maintaining a neutral surrounding color when evaluating color proofs. I linked to a website sporting some great optical illusions that nicely illustrated how surrounding colors influenced human color perception.
Staying on that same theme, today I want to add one more cool optical illusion that involves a little color theory and a phenomenon called persistence of vision and after image. After image is the ghost image that seems to float in front of your eyes often after looking at something very bright like a light bulb or Stephen Hawking. Persistence of vision relies on this afterimage to persist on the retina for around 1/25 of a second. Persistence of vision is what puts the motion in some flashing neon signs and marquee signs with chasing lights. Time Square or the Las Vegas Strip is one giant persistence of vision experience. This is also what gives the illusion of motion in a film created from a series of still frames This moving picture phenomenon can be blamed for giving us such cinematic masterpieces like "From Justin to Kelly", "Kazaam", "Stop! Or My Mom Will Shoot!", "Howard the Duck", and any movie staring Pauly Shore.
Okay, so here is the illusion. Stare at the small black cross on the center of the image below. You will see that one magenta dot will disappear from each position around the circle very quickly. As this cycles around, it will appear as a green dot is now moving around the circle. That is the afterimage of the magenta dot - green is the opposite color of magenta. As you keep your eyes fixed on the black cross a little longer, you will actually see the green dot erase all of the magenta dots, so all you see is a chasing green dot. It's kind of like when Pac Man eats all the dots as he races around the screen. Here, when the green afterimage is combined with the magenta dot, a gray dot is produced which is the exact same color of the background.
Keep your eyes very still as you stare at the black cross. First you will see a chasing green dot appear (the opposite color from magenta on the color wheel). Then in about 15 to 20 seconds, the "green" dot will erase the magenta dots. Cool, huh?
The Youtube video above shows a great application of the persistence of vision phenomenon. One can only imagine the different mobile marketing opportunities that this product might have in places like Las Vegas, New York, or any other place people are gathered after dark.