Interesting Optical Illusion

I found this interesting optical illusion while surfing around on HappyScrappy…

Stare at the plus sign in the middle. You’ll notice that the moving dot becomes green, and then the pink dots should disappear.

Here’s an explanation, courtesy of some college professor on the author’s dad’s friend’s e-mail list:

Pretty basic principles at work here… our eyes have so many light receptors that our brains have to do lots of work to process the input, and so we pay attention to some things that change, and not to things that are stable. There are different kinds of light receptors in different parts of the retina, and that influences what we see as well. And then our neurons tend to notice change more than steady input (that’s why we get used to smells and background noises). With light, there’s an afterimage effect. I’m sure wikipedia can explain this better than I can…