This is sick. Sick because the spiral effect is making me sick and sick because it reminds me how flawed/awesome/trippy our colour perception is. Believe it or not, the green and the blue in this spiral is the same color.
I couldn't believe it either, but I just measured the value in Photoshop: Red 0, Green 255, Blue 150 on both. Crazy.
The reason why we are perceiving one colour as different colours is because of the other colours surrounding the stripes. Each eye has six to seven million cones, which are concentrated in a central yellow spot known as the macula (I recently got mine lasered to fix some leaking blood vessels). These cones measure colour in different wavelengths, overlapping in some of them. Our brain then compares those signals in an antagonistic manner, measuring differences in wavelengths between them. When some colours are combined, the brain can't process the info from the cones correctly and we simply get confused. [gsu and Techi]