What to see?
Only when you look at this image for even just a few seconds it feels like it would give you a headache isn’t it? But what do you see in the end? If you look long enough at the movement of the circle you will have the impression that the center pulls you in, and that everything around becomes smaller. Right after the image changes into the image of Buddha you will see that the picture becomes larger.
What to do?
All you have to do is fixate your look at the center of the circle, of the image, and try to keep it there for a few moments. The illusion of pulling you in of the circle may give you feeling that everything is trying to get into that “black hole”. Now push the “Show Image” button! What do you see when the other picture appears? The non-moving one. This one may give you the impressions that all the thing around expand, that the belly of the statue gets bigger and bigger.
How it works?
Well, if you look long enough at the motion you can easily spot the motion after-effect.
The motion after-effect or the waterfall illusion is a visual illusion which appears after we had contact for a time with a moving visual stimulus and then changing the stimulus intro a stationary one. The stationary stimulus seems to move in the opposite direction from the original stimulus. This motion after-effect is believed to be the result of motion adaptation.
The simplest example is the waterfall illusion. Try to look for a while at the movement of the water, at the way it falls, and then move your look at the stationary rocks or trees around it. What’s the effect? The stationary objects seem to move upwards slightly.
The phenomena can be explained through the neural adaptation. The neural adaptation is a particular movement that reduces the response of the neurons for a constantly moving stimulus. This adaptation also reduces the spontaneous baseline activity of the neurons when they have to respond to a stationary stimulus. Another way explaining thing is through the perception process. For instance: the neurons know that motion is possible in any direction so when we turn our look towards the stationary rocks, near the waterfall, the neural coding will tend to balance the downwards movement of the water with the downwards movement of the stationary rocks.