Optical Illusions Thread
Benham's Disk

Concentrate on the spinning eye at the center of the disk. Soon, from the black-and-white image, colors will emerge. These colors are not coming from the spinning image (the spinning image stays black-and-white, we promise!) but from within your eyes, your lyin’ eyes. As the disk slows, the colors will change positions, tone, and intensity. Different people will see different colors. It’s weird.
How it works:
Scientific explanations can be a letdown. Really, was anyone happier to learn that rainbows are not the homes of leprechauns with pots of gold, but optical illusions caused by refracted light? Are we better off knowing albinos are not holy children from the moon, just regular folks lacking melanin pigment?

Indeed, sometimes scientific explanations can disappoint, which makes it even more thrilling to find some mystical magic that researchers still can’t explain. Like Benham’s Disk. Introduced in 1894 by toymaker C. E. Benham, this black-and-white patterned disk is monochrome when stationary, but when spun, unleashes a flickering array of colors. What’s weird is the colors seem entirely real, as though the disk were creating some sort of portal to another, fantastically hued world. And still, after over century, nobody knows how or why it works.

The Cafe Wall
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Stare at the pattern for a moment. Does the pattern grow distorted and funneled at the tips? Examine it closely and you’ll see the alternating black and white lines are actually completely straight and square.
How it works:
The Café Wall works by feeding our brain too much contrasting information at once. Our visual systems are not very precise when perceiving strong contrasts in color, and the strong black-and-white pattern with mortar in the middle on the Café Wall immediately overpowers the brain.

Enigma
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Stare at the image for at least a minute. Watch as the lines jittery around the circle, as the circles move up and down the line. Even weirder, most people see an alteration in the color of the circle after a few moments of intense staring.
How it works:
Barrow researchers gathered three subjects and placed each in a chair in front of Enigma. As subjects gazed into the psychedelic cluster of lines and circles, cameras took 500 pictures per second of their eyes. Subjects pressed a button when they noticed the lines in Enigma as stationary; they let go of the button when the lines began jittering again. What researchers found was that the painting appears to “jitter” when microsaccades increased; it appeared stationary as the microsaccades ceased. These involuntary movements in our eyes were, at least in part, giving Enigma its illusion of movement. What’s interesting is that unlike most of the other visual highs in this book, Enigma’s effects are not generated solely in the brain. It’s in the eyes, those lyin’ eyes.

Fraser Spiral
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Try the follow the spiral by tracing just above it with a pen or the tip of your finger. You can’t. Why? Because what you’ll be seeing is not a spiral but a set of circles. Yes, really. Check it out.
How it works:
This illusion was created by British psychologist James Fraser, who first published it in 1908. When you look at the Fraser Spiral it appears a single line is twisting its way into the center, spiraling into a funnel. Your eyes, Judas-like, are deceiving you. The Fraser Spiral works by guiding the eye through a sequence of counter-angles. The eye and brain are not accustomed to processing images this geometrically complicated, and thus try to normalize the circles by imagining them as a single line, a phantom spiral corkscrewing its way to the center.

Syd Barrett–Dedicated Fractal Acid Words

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Stare at the word. Keep staring. You’ll notice something amiss
How it works:
This visual high works under the same premise as Fraser Spiral—by overwhelming the eyes with angles and counterangles. Instead of continuing with some long-winded information in which we’d just be repeating ourselves for the fifth time.

Vomit Vectors
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Look at this illusionary high. The dots appear to be moving, undulating, and animated. Stare at Vomit Vectors for at least one minute—longer if you can stomach it. Disgusting.
How it works:
Some researchers blame our reaction to Vomit Vectors on the eyes’ neurons—the brain and body’s messenger cells. When the neurons process a white area from our eyes, they send an on/off signal to our brains. Black areas generate the opposite off/on signal. The complex map of black and white areas in Vomit Vectors overloads our brains by countering on/off with off/on signals.



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