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©  Beau Deeley, technic by Prof. Akiyoshi Kitaoka




The following own (W. Daeumler's) illusion is a gif-animation, consisting of four frames with quickly and only slightly alternating widths of black and white parts respectively
(no movement of the spiral at all), recognize two counter-rotations, a slow and a faster movement in one single image simultaneously. → original page for more versions