A few years ago, I could make her spin either way. I’m having trouble with her tonight. She strongly wants to spin clockwise (relative to the floor). To make her spin counterclockwise, I need to cover her top half, then focus carefully lest she slips into the clockwise spin again.
What an incredibly elegant illusion! In fact, she is one of Wikimedia Commons’ “Featured Pictures,” “which means that members of the community have identified it as one of the finest images on the English Wikipedia . . . ”
This NYT blog entry identifies the creator of this image: Nobuyuki Kayahara.
The silhouette image of the spinning dancer doesn’t have any depth cues. As a result, your eyes will sometimes see the dancer standing on her left leg and spinning to the right. And sometimes they will perceive her as standing on her right leg and spinning to the left. Most people, if they stare at the image long enough, will eventually see her turn both ways.
