I hope this isn't a repost, but very cool.
http://www.msf-usa.org/motion.html
BTW, this is why the technique on NOT focusing on anything is SO important, as described on Twist of the Wrist II book. That is... you don't focus on a specific point, just keep aware of your entire field of vision. It works awesome. Even with this test, if you don't focus on the green dot, then you can see all the dots all the time.
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