> If you look just outside the pattern and keep your eyes perfectly still, they stop moving. It seems the illusion relies on you constantly glancing from one to another.

I'm fairly sure it has something to do with the way your eyes take the first derivative of the color pattern to help interpret shapes. Eye movement would certainly make a difference. But I'm not going to check my notes.

"The Music" actually frightened me a little. The whole thing was covered with dots. I didn't get the illusion, so I had to read the instructions, and I expected a mild effect. Instead, every dot--much of the picture--just plain disappeared. It does not inspire confidence in one's senses!