Hidden circles illusion

The entire universe in blog form
Sept. 16 2009 5:08 AM

Hidden circles illusion

Hidden circles illusion

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I'm pretty good with these things, and it took me a while to see the circles... and even when I did, they kept popping in and out of existence. Shading is critical in this particular illusion!

This illusion's been around awhile; I found a reference to it from 2007, and I imagine it's a lot older than that, too. Mnd man, it's one of the more maddening ones I've ever seen! The one above it on Richard's page made me a little woozy, too. I know men tend to be somewhat more prone to red/orange color blindness than women (I have a touch of it myself, but it's not bad), so I wonder how the genders break down in seeing that particular illusion. Go take a look and leave a comment on Richard's blog!

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!