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Enigma |
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Fixate on the center of this image. Explanation Fixation on the center induces in most, but not all, people a strong perception of motion occurring within the rings. The motion is in opposite directions in different rings and can change direction in any one ring during one viewing. French artist Isia Leviant created this image and titled it "Enigma", because scientists were mystified about why the effect occurs. Semir Zeki, a neuroscientist at University College, London took PET brain scans of people observing this image, with remarkable results. A specific region of the cortex, close to the area responsible for the perception of motion, was active when subjects had been viewing the display. Therefore, the effect takes place fairly early on in visual processing, after the image is detected, but just before the higher level cortical processing stages where these images are interpreted in terms of previous learning. However, it is still not fully understood what causes the apparent motion of the spots. |
