Pretty amazing optical/brain trick: Is this dancer rotating clockwise, or counter-clockwise? “If clockwise, then you use more of the right side of the brain and vice versa.” Apparently most people see her turning counter-clockwise, but Amy, Miles, and I all saw her turning clockwise. Unlike many optical illusions, this one hits you with absolute certainty – your senses don’t lie that profoundly, right? Amy: “Anyone who says she’s turning counter-clockwise is just wrong. Just wrong.” Then, 30 seconds later – “Wait! Now she’s turning counter-clockwise!” Took me a bit longer, but then suddenly she changed direction for me as well. I could not will her to change direction – she just seemed to reverse at random. But she stayed clockwise about 80% of the time, no matter how much I stared.
How this plays into left-brain / right-brain differences is a matter for psychologists – unfortunately there is no real article to accompany it.