Swans on Tea

Optical illusions: caused by eye or brain?
For the past 200 years, researchers have debated whether the illusion of motion in a static image is caused by mechanisms in the eye, in the brain, or by a combination of both. Because measuring these kinds of physiological responses is difficult, no study has successfully measured direct and [...]

A Perspective on 3-D Visual Illusions
slideshow and article

A different lean, mean fightin’ machine. Stroboscopic effect image.
Stripes

An audio “illusion.” The pitch increases, and seems to continue when you replay the clip.
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This phenomenon is known as Shepard’s paradox; the ending tones are the same as the beginning ones, so it’s the auditory equivalent of Escher’s “Ascending and Descending” perpetual staircase.

Cool photo that’s not quite what it appears

Rotating Grid Illusion
Oh, way cool. A rotating grid looks like a bunch of smaller grids when you rotate it.

Dynamic Optical Illusions
Several cool ones, along with some standard ones.

How many cameras are you wearing? (Chandler, to Monica)
candid camera, over at Cocktail Party Physics.
Richmond’s main hypothesis, however, was that the effect stems from the fact that the camera only has one “eye” (i.e., the lens), whereas human beings have two eyes, roughly 7 to 8 centimeters apart. The camera, it seems, lacks depth [...]

Squaring the Diamond illusion at Illusion Sciences

10 optical illusions in 2 minutes
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via Neurophilosophy

The illusion business. Posting them, that is. Too much direct competition: Illusion Sciences
Illusions and explanations, by an illusion designer and psychologist
Bonus: Illusion of the year contest, top 10 finalists
via Cognitive Daily

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Of course, the real explanation here is that this is a stroboscopic effect, aka the wagon wheel effect — the rotor speed and the film speed are matched (to some ratio) so there is no apparent movement of the blades for each frame of [...]