Watch this for more than 30 seconds. Pretty cool, eh?

If you see this lady turning in clockwise then you are using the creative side or right side of your brain. If you see it going counter-clockwise then you are using the logical side or left side of your brain. Some people can see her turning both ways, but most people see it only one way. If you try to see it the other way and if you do see, your IQ is above 160 which is almost a genius. Then see if you can make her go one way and then the other by shifting the brain's current. BOTH DIRECTIONS CAN BE SEEN

According to New Scientist, "Some people see her spinning clockwise, some see her moving counterclockwise, and most, if they stare long enough, see her switch direction. Some can make her change at will. But no-one, it seems, can make her move in two directions at once.

All pretty spooky since she is an unchanging animation of only 34 frames in a constant loop. What seems to be happening is that the two-dimensional image does not contain enough three-dimensional information to tell the brain which way she is spinning. So your brain helpfully fills this in, as brains do in many optical illusions. Only, in this case the brain can do it one of two ways.

How about the stopping? Well, perception of time is pretty subjective, and our experience of inertia is that when things make a 180-degree change in direction, they have to slow and stop first.

What this animation does not involve is different sides of the brain, as the initial post claims. What you see is purely due to your perceptual and cognitive flexibility."