How the Rotating Snakes optical illusion works

 View Download Id 340263 Name  In the new Journal of Neuroscience, Barrow Neurological Institute researchers present their study exploring why Akiyoshi Kitaoka's "Rotating Snakes" optical illusion is so effective. In fact, it's the cover story! From Science News:

 Content 32 17.Cover Participants held down a button when the snakes seemed to swirl and lifted the button when the snakes appeared still. Right before the snakes started to move, participants began blinking more and making short jumpy eye movements called microsaccades, Jorge Otero-Millan, Stephen Macknik and Susana Martinez-Conde report in the April 25 Journal of Neuroscience. When volunteers’ rates of microsaccades slowed down, the visual illusion faded and the snakes were more likely to stop moving.

"Snakes swirl in blink (and jump) of an eye" (Science News)

Abstract: "Microsaccades and Blinks Trigger Illusory Rotation in the “Rotating Snakes” Illusion" (Journal of Neuroscience)


  1. I miss my Science News subscription. Parents got it for me in high school, and it was the coolest thing to get weekly science information in my backwater town of 5000.

  2. damn my “short jumpy” eyes but I’ve love visual shenanigans ever since being introduced to the work of Bridget Riley

    1. The snakes are supposed to appear to turn. For me, it doesn’t happen if I focus right on them, but is unmistakable if I glance back and forth through the surrounding text.

    2.  For me, it doesn’t work with my glasses on. If I take them off, it does- a little. I’ve seen this one before, and it seemed more effective then… maybe it’s better on paper than on a screen.

  3. Presumably this is an established optical illusion (although I haven’t heard of it before), but I’m always wary of optical illusions on web pages. How do I know it isn’t an animated GIF?

    1. To stop it, just focus on one of the blue or yellow ovals or on one of the black dots for a few seconds [as I’ve been telling my students for years]. If you keep your eyes fixed on that particular dot, all appearance of movement should grind to a halt.

    1. Yes, that would be the same Akiyoshi Kitaoka who I mentioned in the post and the same page that I link to.

  4. My very ignorant guess, before ever reading this explanation would be “Peripheral Vision” and “Eye Movement”. 

    If you actually concentrate on some of the circles in a part of the picture, they stop spinning, and the others farther away appear to start spinning.  In fact, those circles on the borders of your “focus zone” seem to have only the farthest (from your focus) half “spinning”, until you focus on them and then they stop spinning wholly. 

    But it’s just guessing. The work of researchers put in unambiguous terms and corroborated by others, is the closest we get to an objective explanation. 

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