There's more from the original author, Akiyoshi Kitaoka. Shown below, the spirals of light green or light blue are identical (R=0, G=255, B=151; scaling may change the content):
Also, as noted by Keith Lang in his blog UI&us, there are also implications for user interfaces -- and not only because of optical illusions, but also because of what might be called "mind illusions," which Daniel Goleman has made a career out of explaining. See Lang's The Art of Expectations, and the video below from TED:
"Keith Barry shows us how our brains can fool our bodies -- in a trick that works via podcast too. Then he involves the audience in some jaw-dropping (and even a bit dangerous) feats of brain magic."
Update: For briefs on illusions relating to the perception of time, see MindHacks and a Philip Zimbardo video on The Time Paradox. And, to remain on topic, click the picture to view the motion 'after effect' from Akiyoshi Kitaoka: