(in particular, along the top of the ring). This handles rings which contain collapsed segments.This handles coordinate lists which contain repeated points.The list of points is assumed to have the first and last points equal.Oriented counter-clockwise, using the signed area of the ring. Right? Or no? Maybe I've just been staring at a screen for too long.Tests if a ring defined by an array of Coordinates is But on the other, they seem to be implying that I'm more likely than the average person to be bitten by a snake. It's a lot to process. One the on hand, the researchers are telling me that I'm not dumb. Odds are you see that one from an above-down angle, too. So when presented with ambiguous visual information, people tend to register the images as though they're looking downward. Take another glance at the Necker cube. Here's the logic: Things, including those that could hurt us, are more likely to sit on the ground, Troje says. It's to our advantage to quickly recognize a snake stretched across a dark path, for instance. The fact that a majority of people see the girl spinning clockwise, then, likely has more to do with our hyper-vigilant subcortical system, which runs in the background, free from the tyranny of brain hemispheres. Their brains were filling in missing data with the most likely scenario, and scientists concluded that we have not one but two separate visual systems: the recently evolved corpus callosum, which links up color- and language-identifying regions of the brain, and an older subcortical system that's sensitive to movement and orientation (and presumably kicked into action when the corpus callosum was severed). Rather than see the dot disappear and reappear, the epileptics saw it as being in continuous motion, moving from left to right, despite their split hemispheres. So they tried little games, like placing a dot in the patient's left visual field, followed by a dot in their right visual field. Some patients were indeed unable to identify the objects, but others could. And the scientists were baffled. The scientists assumed that these split-brain patients would be unable to verbally name objects presented to their left visual field, because things in the left visual field hook up to the right side of the brain, which is where we process nonverbal thinking. They thought they could prevent the spread of seizures from one hemisphere to the other if they severed the connection between the right and left brain. So that's what they did: They cut the patients' corpus callosum, the connecting fibers running between the two hemispheres. Shapiro and Troje explain that seeing the girl spin one way or another likely isn't about hemispheres at all.As proof, they point me to the vast body of "split brain research," and, whoah, is it weird and gross and fascinating.īeginning in the 1960s, scientists were trying to provide relief to epileptic patients. ![]() (Did I mention that I like these guys?) Nor do my counter-clockwise tendencies provide any clues as to whether I'm right- or left-brained. "We know there are different tasks done in different hemispheres, but saying someone is more dominant one way, well, that's tricky," Shapiro says. Does that make me dumber than the average person? No, they assure me. But since I tend to see her spinning counter-clockwise, I'm imagining her above me. ![]() ![]() Shapiro and Troje tell me that most people initially see the girl spinning clockwise. Now pretend to be filming her from above." Indeed, the spinning girl moves counterclockwise if I imagine myself below her, and clockwise if I imagine myself above her. "If you want her to switch directions, look at her as if you're filming her from below. Now imagine you are physically moving up or down in space. "Cover up everything but her foot touching the ground," he says. They're game.īut before they do, they say that it's important to understand that the spinning girl falls under a class of optical illusions called reversible images. Even though she spins, she bears similarities to other static illusions, like Necker cubes.īut that feels like cheating, and Shapiro assures me that I can solve the illusion with my own brain. I tell Shapiro and Troje how frustrating it is to feel powerless over my brain, and I ask if they can help me spin the spinning lady in both directions. ![]() I'm feeling good now, because I'm realizing that you don't have to be freaking Neil deGrasse Tyson to enjoy this thing. The reason we see her spinning in different directions is actually much more complex than which side of our brain dominates. "That's just gibberish," says Shapiro, a computer science professor at American University and creator of the color wagon wheel illusion. I want to know what's going on in my brain, so I call up Arthur Shapiro and Niko Troje, a pair of scientists who dissect Kayahara's spinning girl in the forthcoming Oxford Compendium of Visual Illusions.
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