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Ninio, J. and Stevens, K. A., Variations on the Hermann Grid: An Extinction Illusion // Facebook

Your Brain Won’t Let You See Every Dot in This Illusion at Once

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Ninio, J. and Stevens, K. A., Variations on the Hermann Grid: An Extinction Illusion // Facebook

Stare at the above image long enough and you’ll start to notice something peculiar: When your eyes focus on one of the gray intersections in the picture, two or three black dots will appear. But as you hold your gaze, the dots in your periphery seem to fade from view, and if your direct your vision elsewhere, they’ll hop to a different area altogether.

This optical illusion has been baffling the internet since it was shared by Japanese psychology professor Akiyoshi Kitaoka on Sunday, September 11. Most people are incapable of seeing all 12 black dots in the image at once, a phenomenon The Verge reports is due to humans’ poor peripheral vision.

Because our eyes can’t process the visual information in our peripheries as well as what’s directly in front of us, our brains make guesses with what's available to fill in any mental gaps, according to researchers who first introduced the world to the illusion. So when we stare at a black dot surrounded by a pattern of gray lines against a white background, our mind assumes what the intersection of the gray lines will look like without adding a black dot in the center.

A paper published in 2000 in the journal Perception, where the optical illusion first appeared, explains how our brains react to the image:

“When the white disks in a scintillating grid are reduced in size, and outlined in black, they tend to disappear. One sees only a few of them at a time, in clusters which move erratically on the page. Where they are not seen, the grey alleys seem to be continuous, generating grey crossings that are not actually present.”

Seeing objects in our periphery isn't the only task the human eye struggles with. The imperfect way we process color also makes for some mind-bending optical illusions.

[h/t The Verge]

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Belly flops are the least-dignified—yet most painful—way of making a serious splash at the pool. Rarely do they result in serious physical injury, but if you’re wondering why an elegant swan dive feels better for your body than falling stomach-first into the water, you can learn the laws of physics that turn your soft torso a tender pink by watching the SciShow’s video below.

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What's the Saltiest Water in the World?
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iStock // lucamato

Saltwater is common around the world—indeed, salty oceans cover more than two-thirds of the globe. Typical saltwater found in our oceans is about 3.5% salt by weight. But in some areas, we find naturally occurring saltwater that's far saltier. The saltiest water yet discovered is more than 12 times saltier than typical seawater.

Gaet’ale is a pond in Ethiopia which currently holds the record as the most saline water body on Earth. The water in that pond is 43.3% dissolved solids by weight—most of that being salt. This kind of water is called hypersaline for its extreme salt concentration.

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For the paper Poliakoff describes, check out this abstract.

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