Do you see the girl spinning clockwise? Then you’re using your right brain.
Do you see her spin counter- clockwise? You’re likely using your left brain.
Some people have the ability to see both. (If you read this post in a feed reader, it probably won’t work, please click through for the test.)
Today I can only see her turn clockwise … but they way I recall, when I first saw this a few years ago, I ssaw her turn left. Hm…changes in my brain function?
Of course it’s an optical 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.
The above explanation comes from Dr. Steven Novella, academic clinical neurologist at Yale University School of Medicine.
So now we know. But I still can’t make her turn left…
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