The Situationist

The Situation of Spinning

Posted by The Situationist Staff on August 25, 2008

In which direction does the dancer in the image appear to be spinning? The answer:  It depends on your situation.

From Neurologica Blog:

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These kinds of optical illusions . . . reveal . . . how our brain processes visual information in order to create a visual model of the world. The visual system evolved to make certain assumptions that are almost always right (like, if something is smaller is it likely farther away). But these assumptions can be exploited to created a false visual construction, or an optical illusion.

The spinning girl is a form of the more general spinning silhouette illusion. The image is not objectively “spinning” in one direction or the other. It is a two-dimensional image that is simply shifting back and forth. But our brains did not evolve to interpret two-dimensional representations of the world but the actual three-dimensional world. So our visual processing assumes we are looking at a 3-D image and is uses clues to interpret it as such. Or, without adequate clues it may just arbitrarily decide a best fit – spinning clockwise or counterclockwise. And once this fit is chosen, the illusion is complete – we see a 3-D spinning image.

By looking around the image, focusing on the shadow or some other part, you may force your visual system to reconstruct the image and it may choose the opposite direction, and suddenly the image will spin in the opposite direction.

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For a collection of other Situationist posts providing and discussing illusions, click here.

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One Response to “The Situation of Spinning”

  1. J. Maxwell said

    Very cool. Not only can she spin left and right, but you can get her to simply swing her leg back and forth from left to right to left, never turning her back (i.e. 180 degree flips, no full rotation). Then, once you can do this, you can create the illusion of “spinning” her all the way around in the direction of your choosing, for 1 or more full spins, mixed into the left-right-left 180 degree leg kicks. What a trip. Our visual systems are sweet …

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