A while ago a friend sent me this optical illusion of a spinning dancer , who is supposed to turn one way if you're "left-brained" and the other way if you're "right-brained." I'm actually not clear if this is the case. For me, the dancer starts spinning counter-clockwise and then reverses the direction. I took the animated image apart with a graphics editing program, and it seems to me that the dancer would always start off going counter-clockwise, and the left-brain/right-brain distinction has to be in when a viewer sees her changing direction, a switch that depends on an ambiguity in the silhouette about eight frames in.
I spent a lot more time than it was worth on taking apart the image, and ultimately what became interesting to me is why I found myself so resistant to the idea that how you see this image will depend on your handed-ness. Handed-ness is a funny thing because so much of our experience of the world is defined by symmetry. The specialization in brain halves is much more pronounced in humans than in other animals, and it seems awfully hard to understand why it should exist.
On a deeper level, what bothers me about discussions of left vs. right brains is that in general we love to read about the geography of the brain, whether it involves odd stories of brain lesions or those fractal-pretty MRI images, but it's often hard to figure out exactly what to conclude from it. The brain with its fissures and gullies almost looks like a map, and we half expect there to be an "x" somewhere in there marking the treasure. The problem, however, seems to me that without more of a working theory of how the brain stores information, the conclusions that we draw from the maps are very tentative.
One way of thinking about this is to imagine the operations of a computer running Photoshop. You might scan the microprocessor and find that whenever you run Photoshop, some parts of it light up frantically. So you might conclude that those parts have a specific relationship to image processing. But you would turn out to be wrong. From a computer's point of view, photo-editing is a particularly math intensive operation, and the silicon that's working overtime when you manipulate an image is not, as you might think, the part devoted to graphics processing, but the part devoted to math. The same problem of figuring out exactly what's going on applies to the brain. If a lesion on one side of the brain causes a person to confuse words or lose the ability to read, does that mean that side of the brain is specifically given over to speech and reading? Or is there a lower-order way of describing what it does that could ultimately prove more fruitful? I just don't know, but I throw that question out there for anyone who may have a better informed perspective.
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