This is not a spiral

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By Sean Michael Ragan
Posted 2010/04/04 @ 8:51 pm
Category Art & Design, Science

Slightly off-topic, here, but I see lots of these optical illusion posts on the web, and although some of them are pretty impressive, this one borders on voodoo. I had to run my mouse pointer over the blue traces a few times to persuade myself. I’ve overlaid some big yellow circles on the original image, which you can see, below, after the jump, to save you the trouble. [via Neatorama]

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6 Responses to This is not a spiral

Collin Cunningham on April 5th, 2010 at 6:15 am said:

Agreed – best one of these yet.
Thnx for the visual aid!

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Nate on April 5th, 2010 at 6:49 am said:

Even with the added yellow circles, I kept thinking, “But there’s a spiral BEHIND those rings!”

I can’t wrap my head around this one…even tracing it with my mouse, my brain won’t agree!

Doubleplus good post, Sean!

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loonquawl on April 5th, 2010 at 7:20 am said:

… There seems to be another (recurring) illusion in those posts: The distance from the point of mention to the actual item seesm to be ~20 pixels, yet it is constantly referred to as a “jump”, ergo must be much larger, possibly page-spanning in reality. Can anyone fill me in on the magic behind this?

Anyways, even more on topic: http://www.michaelbach.de/ot/ sets out a scientificy overview of optical illusions, with some fine links to papers discussing their impact on understanding visual perception.

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Carnes on April 5th, 2010 at 7:54 am said:

wow, very neat. When i keep looking at it i almost want to lie to myself and say, yep it’s spriral.. otherwise there is mental conflict about what i’m looking at.

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weendex on April 5th, 2010 at 8:24 am said:

I found if i tilted my head to the right, about 30-45 degrees the circles became quite clear.

Also, doing some one-eyed, hand half covered image helped.

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dockjames on April 5th, 2010 at 4:24 pm said:

This illusion happens because of the way the brain perceives the checkered pattern. Within the blue circles there are darker colored squares. These squares are offset between each square in the background. This gives the viewer a sense of “implied line”. Because of the color differences, the pattern is still seen as pattern and the circles as the lines. As a whole, the brain uses those clues to change the circles into a single spiraled line. Tip: follow the squares from an edge of the illusion.

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