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Focusing on the red cross, look carefully at this picture. What do you see? White dots wriggling around in different directions and colliding? What if we tell you that the dots are not wriggling around, but are actually moving in a straight trajectory, and even worse, they never meet each other at all!
Not convinced? Look below at the second picture that has no cross, focus on one single dot and follow it with your eyes - What do you see now? A dot moving in a straight line without coming into contact with any other dots right?
This fun optical illusion was uncovered by three scientists at Japan's Keio University who discovered that for some reason when hundreds of dots are moving in straight trajectories but random directions, our brain perceives them as wriggling around and colliding with each other. It's only when we focus on one single dot that we can see what is really going on.
And while they are unable to figure out why this happens, what they did discover was that the illusion depended on two key factors - the number of dots (the larger the better) and their proximity to each other. The things that made no difference whatsoever were the distance the dots were traveling, what type of dots they were and how the observer's eyes were moving. The scientists presented their findings in a scientific paper in late 2012, hoping that someone would be able to find the cause. But so far, all the experts remain stumped.
And if you think that is cool, how about this one? Look at the white grid drawn on the black background. if you move your eyes around the image, dark dots will magically appear and disappear at the intersections. However, focus on one intersection, and poof! - The dark dots are gone! Discovered in 1870 by German physiologist Ludimar Hermann, the reason for this illusion also remains a complete mystery.
Resources: Ncbi,nim.nhi.gov, dailymail.co.uk