It's the folk-rock polka music that really makes it.
What's most impressive about this illusion is how it manages to trick your brain, even after you've worked out the whole split-body, black-and-white outfit situation that makes it work. Try as you might, and conscious of the gimmick though you may be, it's more or less impossible to watch without lapsing back into the illusion.
As Susana Martinez-Conde, laboratory directors at the Barrow Neurological Institute, puts it: "our visual system insists in grouping adjacent body parts by color (and congruent motion)."
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Plus, like we said, there's the folk-rock polka music. Which adds a whole extra layer to the hypnotic nature of the experience.
[Via SciAm]