Ehm.. een update:
http://www.newscientist.com/blog/shorts ... -girl.html
Bring on the dancing girl
OK, hands up if you can make her change direction. No? Only clockwise? How about making her stop?
This strangely compelling, animated silhouette of a woman spinning gracefully has been doing the rounds via email lately and the New Scientist office was one of many that spent a guiltily non-productive afternoon staring at her.
Why? Because 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.
What is a little scary is how threatened by this some people clearly feel. The blogosphere is rife with arguments and ingenious explanations of the lady, with some people simply refusing to believe it isn’t an animation tick that really changes direction every few minutes.
Even more common are the people who are sure they know how to make her change direction. According to them, the trick is to hold your head or hands in certain ways, tilt the screen or look at her out of the corner of one eye. It was what they were doing when they saw her change – so it must work. Right?
Nou ja, er staat van alles wat iedereen zou kunnen zeggen, maar ook dat het niets te maken heeft met je hersenhelften.
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.
Nu weer oplossen hoe dat de wereld in is gekomen. Voor je het weet ben je schuldig aan het verspreiden van wetenschappelijk bijgeloof. De hele New Scientist redactie heeft zich hier kennelijk mee onledig gehouden.
Het beeld is in elk geval een filmpje van één omwenteling van 35 frames.
Maar in elk geval, het lukt mij wel om de draairichting die ik waarneem te veranderen door me voor te stellen hoe de contouren zouden doorlopen, die in het totaal zwarte profiel dus niet aanwezig zijn. Je moet je best doen om het voor je te zien, en hoppa, dan zwaait ze opeens haar andere been voor. Fascinerend hoor.