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It doesn’t look like it, but the girl in the illustration above has two gray eyes. (And some vicious-looking fingernails.) This is due to the “opponent process” our brain uses to interpret signals from photoreceptors in our eyes–a process that sometimes produces weird and counterintuitive visual results. There are more illusions with full explanations in Scientific American‘s “Colors Out of Space” slideshow. Link
Image: Akiyoshi Kitaoka
The structure of your individual brain has a lot to do with how you perceive optical illusions. Researchers at University College London asked subjects how they perceived illusions of size such as the one used in this video, and then measured the size of each subject’s visual cortex -the amount of brain matter devoted to processing vision.
The researchers then took MRIs of the subjects’ brains. What they discovered astonished them – there was an almost perfect link between the size of somebody’s visual cortex was and how much the optical illusion affected them. The smaller the visual cortex, the more a person was taken in by the optical illusion. Those with the largest visual cortices were also those most able to see the circles’ true sizes.
Read more, and see the different illusions used, at io9. Link -Thanks, Greg Ross!
Bifocals and trifocals allow people with limited vision to see objects at varying distances, but only by refocusing on the object from a different vantage. A scientist named Zeev Zalevsky responded to this problem by developing a lens that allows the user to focus on any distance out from 33 centimeters:
It involves engraving the surface of a standard lens with a grid of 25 near-circular structures each 2 millimetres across and containing two concentric rings. The engraved rings are just a few hundred micrometres wide and a micrometre deep. “The exact number and size of the sets will change from one lens to another,” depending on its size and shape, says Zalevsky.
The rings shift the phase of the light waves passing through the lens, leading to patterns of both constructive and destructive interference. Using a computer model to calculate how changes in the diameter and position of the rings alter the pattern, Zalevsky came up with a design that creates a channel of constructive interference perpendicular to the lens through each of the 25 structures. Within these channels, light from both near and distant objects is in perfect focus.
“It results in an axial channel of focused light, not a single focal spot,” Zalevsky says. “If the retina is positioned anywhere along this channel, it will always see objects in focus.”
Link via DVICE | Photo (unrelated) via Flickr user Muffet used under Creative Commons license
Why do hammerhead sharks have, well, hammer-shaped heads? The mystery may now be solved: it’s all about binocular vision.
[Michelle McComb and Timothy Tricas] then placed sensors on the shark’s skin to measure its brain activity, specifically testing whether the animal would react to beams of light shone from different locations around the tank.
By doing so, they could measure each shark’s field of vision.
"This study confirmed that hammerhead sharks have anterior binocular vision," says Dr McComb.
That means they can see directly ahead while swimming and can accurately judge distance, particularly to any prey they hunt. What’s more, the researchers show that the degree of overlap between the two eyes increases with head width.
Previously on Neatorama: Stop! Hammerhead Time
Vision is another escape-from-the-room game, sure, but it’s pretty. Be sure to examine every nook and cranny – you’re going to need keys or combinations to open almost everything. And take note of the shapes of things. That’s all I’m saying! Have fun and good luck.
Link via Jayisgames
