dimanche 9 décembre 2012

The Theory behind the Spinning Lady Illusion

Many people have asked me that they can’t make the spinning dancer rotate anti-clockwise. Today, I will put them out of their misery.
Today, we’re going to look into the famous spinning lady illusion made by web designer Nobuyuki Kayahara. Without any waiting, let me ask you this question: Which direction is the lady spinning; clockwise or anti-clockwise?
Spinning Dancer

The creator of this illusion has given us a tip here: “If the foot touching the ground is perceived to be the left foot, the dancer appears to be spinning clockwise; if it is taken to be the right foot, then she appears to be spinning counterclockwise.” But the problem here is if you perceive it rotating in one direction, it’s really hard to perceive otherwise. So is this a bluff?

Is this a Bluff?

No, the lady can be spinning in different direction to different people. To prove it, we present you with following figures in which you can clearly see the same lady rotating in two different directions. The central figure is the original one while the other two have lines on them. I can safely bet that you see the left one rotating clockwise and the right one spinning anticlockwise.
spinning lady

Psychology of this illusion:

This illusion has been rumored to tell which hemisphere of your brain has more growth than the other; this is a false theory. As a matter of fact in a survey of 1600 people almost two thirds see it rotating clockwise. So what is it then?
Researchers have explained this illusion with the help of bistable perception according to which you can view a two dimensional object from two different perspective. As the figure is in 2D, our brain tries to construct a third dimension around it and it may choose any one of two possible perspectives. Other illusions that work on the same principle are Face/Vase and Necker Cube (blink after each iteration) illusions.

Can I make the original illusion spin both ways?

Yes you can. Look at the spinning lady illusion for quite sometime and then blink. The spinning lady will change it’s direction as you blink your eyes. If this doesn’t work, try to look at the illusion for a longer period (maybe a minute) and then blink. It will also help if you just focus on one part of her body rather than moving your eyes abruptly. The spinning lady illusion is much difficult to perceive from both the perspectives as compared to the Face/Vase and Necker Cube ones in which you can change your perspective just by a single blink of the eye.

Want a Quick Cheat?

Scroll up to the set of three figures. If you want the lady spin clockwise, view the central figure in isolation with the left one. Similarly if you want the lady to spin in counter-clockwise direction, view the central figure in isolation with the right one.

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