Eye Experiment - Stare at this image while it transitions. Do you see green, blue, yellow, and maybe purple in the B&W photo?
Here is how it works. There are these little guys in your eyes that wear their primary color on the front of their shirt, and their complimentary color on their back. When they see a color like them, they run up to the front and proudly absorb it in for you. When their color goes away they turn around and run to the back. If you blink your eyes, it makes them run back faster! Obviously certain colors run faster than others.