

This is not a spiral - RiderOfGiraffes
http://blog.makezine.com/archive/2010/04/this_is_not_a_spiral.html

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adoyle
This is a Fraser spiral -
<http://en.wikipedia.org/wiki/Fraser_spiral_illusion>

Here's another great spiral-based visual system hack -
<http://www.youtube.com/watch?v=0JVJsPpg1-8>

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rickmode
My head just exploded.

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elblanco
I wonder why it biases in one direction? I could see this working like one of
those 2-in-1 images or the rotating ballerina, where the picture you see, or
the direction she's rotating changes depending on how you look at it, but I
couldn't make the spirals go a different direction.

Our visual systems are an amazing thing.

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jsyedidia
My guess is that the bias is caused by the black shapes. You can see that each
black shape is closer to its bigger "parent" on the left on the next row out
than it is to its bigger parent on its right. Also the connection to the
parent on the left is through dark blue, and the connection to the parent on
the right is through light blue. That's enough to give a bias.

