Check this out on **Bad Astronomer’s **blog:
http://blogs.discovermagazine.com/badastronomy/2009/08/18/square-circle-spiral/
It is just evil. I cannot, cannot get my mind to stop perceiving this wrong: it’s both fascinating and intensely annoying at the same time.
Very cool.
I’ll be sending that to a few people.
It makes me dizzy, like I’m seeing double. Which is the point, I guess.
The center one is easy, but the rest…hoo boy!
I can see them all if I relax my eyes and just look at the very center rather than try to look directly at any one ring. Very cool.
I can see the circles when I focus on one ring at a time. Looking at the whole image? Spirals.
Following a chain of links from that post, I found this one, which is is even worse–the “blue” and “green” stripes are actually the same color.
I really didn’t believe this at first and thought I must be misreading the claim… but it’s true. Amazin’.
That one is not fair. It just isn’t.
I like the green and blue one better. I can see the green and blue.
On the first one, I saw a spiral for just a second but then saw circles. I tried to make myself see the spiral and I’d almost get there but then lose it.
I have the same problem with those magic eye pictures. I don’t see anything for a few seconds but then my eyes adjust (against my will) and I can’t see anything BUT the hidden picture.
Optical illusions are supposed to be fun dammit! That’s why I like the green and blue one.
This master page is even more amazing. There went 30 minutes!
It seems unfair until you realize thats exactly how monitors work, by combining colors to create the impression of other colors.
The first illusion is pretty good though. I can blur my eyes a bit and see concentric circles, but when i focus them, all screwy and spirally again. 
I’m not convinced by the explanation of this one. It’s initially striking, but surely it’s just that your brain/eyes average out the colours, so turquoise + purple = blue and turquoise + orange = green?
I don’t see that it is any more of an optical illusion than seeing orange when looking at an image of small red dots on an yellow background. If that’s an “optical illusion”, then surely any bit of four-colour printing using screening dots is as well? 
That is freakish. :eek:
The first time I saw this I took a screen capture, called it up in my bitmap editor and looked at the pixels. Not that I didn’t believe them or anything…
I have nearly the same reaction to that one. I don’t see concentric circles, I see overlapping circles. Before I read the description, I thought the illusion was going to be that it’s really a spiral, which I can almost see. I can’t see concentric circles at all, though.
Look at the full view. Even when you **know **that the “blue” and “green” stripes are exactly the same color, you can’t make your brain see it–they continue to look like two completely different colors. You have to go to the zoomed in view to even begin to force your brain to concede that yeah, okay, maybe they’re identical.
And yes–many ways of displaying color **are **optical illusions that take advantage of this very brain weirdness (as observed by CutterJohn).
From now on, I’m only going to wear clothes made from fabric printed with these designs.
My point is that this one is “cheating” somewhat by using colour mixing. It’s like presenting a yellow field with red dots (which looks orange from a distance) and a yellow field with blue dots (which looks green from a distance), and then saying “Ha! They’re both yellow!”.
If you want a properly amazing colour perception illusion, check these out:
http://www.echalk.co.uk/amusements/OpticalIllusions/colourPerception/colourPerception.html
especially number 2.
You could make yourself look pregnant without actually being pregnant. That would be a head turner.
:eek: :eek:
I HAD to cut & paste that one into Photoshop to make sure. I could not believe the blue & yellow were the same color.