Image of the Week

Snakes on a Brain

  • Published21 Sep 2012
  • Reviewed21 Sep 2012
  • Author
  • Source BrainFacts/SfN

Jorge Otero-Millan, Stephen L. Macknik, and Susana Martinez-Conde. Microsaccades and Blinks Trigger Illusory Rotation in the “Rotating Snakes” Illusion. The Journal of Neuroscience, 25 April 2012, 32(17):6043-6051.

Is this brain rotating before your eyes? Actually, it’s only rotating in your brain. Rapid, involuntary eye movements paired with sharp contrast patterns in an image may cause the brain to perceive motion where there is none.

The image above is a brain-shaped version of a known “rotating snakes” optical illusion by Akiyoshi Kitaoka, a professor of psychology at Ritsumeikan University in Kyoto. Normally presented as concentric circles of distinct gradients, the image creates the illusion of rotation to many viewers.

Researchers set out to determine whether this illusion is the result of small, jerky, involuntary movements your eyes normally make as they look at an object. The researchers surmised that these movements paired with sharp, repetitive contrasts in the image trigger a motion signal in the brain, tricking you into thinking a stationary image is spinning — or slithering.

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