Originally Posted by Dibalo Jonze
But indeed if we all look at it long enough; sometimes for 4 seconds sometimes after 4 minutes, she will change directions and anyone who is watching her with you will agree.
That's not true. The pattern of the ballerina does not change, only your perception changes. I've sat and looked at it along with two other people, and we can see it going in the opposite directions at the same time. I can make it "change direction" at will, while my wife can't seem to control it as well.
Whether all this has anything to do with right/left brain activity or dominance, I don't know. But it clearly has to do with the different perceptive tendencies people have.