Disks appears to rotate.pic.twitter.com/LovDvhnzFh
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It is suggested that some eye movement feeds this illusion. It will make the effect weaker to put a fixation point.
I am still very curious how to control the speed at which they appear to spin
If you would like a faster one, here is a sample. (color-dependent Fraser-Wilcox illusion)pic.twitter.com/kAdKlhbgSZ
ahh - so if you put a wide-ish thing in the middle that your eyes would naturally scan back and forth it might help
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