I was forwarded a link to a test to determine whether one is left or right brained (click here). I was expecting a bunch of questions followed by a score, but no: the test is merely an animated image of a woman spinning around. And she was spinning to the right. The accompanying information says if you see her spinning clockwise, you're right brained. If she's spinning counter-clockwise, you're left brained.
Wait a minute. This must be a joke. She is clearly turning clockwise, how could anyone see her turning counter-clockwise? It's impossible. And besides, we may interpret things in two ways, but the data is the data: one cannot turn both clockwise and counter-clockwise at the same time.
I forwarded the link to my co-worker, who also saw the dancer turning clockwise. Of course. But then she said, "Oh wait! No, she's turning the other way!" Suddenly the dancer started spinning counter-clockwise for my co-worker. I looked again, for a long time, but she kept turning right. Then, for a strange blip of about 30 seconds, I also saw the woman spinning counter-clockwise. Aughhhhhhhhhh!
Well, I'm a little bewildered. I don't know if this optical illusion can determine right- or left-brain propensity, but it certainly shows that things which seem utterly obvious to us can be seen a different way by other people. It's not a surprise to me that I'd be right-brained, nor is it a surprise that my co-worker would be more balanced between the two. I do wonder, however, how many people see this dancer turning counter-clockwise at first glance?