[doc30]

Interesting links. I only took a quick look at the first to get the ghist of the subject. This experiment does demonstrate that color preception is neurological since none of those colors are actually present on the disk. It may well be related to firing rate. Butthe important point is that the receptors, in conjunction with the neurology between the receptors and the brain's perception, are stimulated in such a way that color is perceived. Your brain really senses it, but it is an interpretation of data coming from the retina.

Based on what I know, the trick is to stimulate the cones in such a way that the brain perceives a given color. There are three types of cones, each with a different spectral response. I can easily imagine that, as the disk is spinning, the constrast line between the white and black would move across the retina as a front. Since the cones (receptors) are activating at slightly different times, because no two receptors are in the exact same location, then the brain perceives this phase difference as a different ratio between different receptors and color perception is generated. It is a very interesting illusion.

[js1138]

The interesting thing is that (from my personal observation) the illusion of color is best under monochromatic light. If you can get a low pressure sodium vapor light, try it.

If the rotation of the disk is reversed, the colors swap -- red to blue, and vice-versa.