this illusion never ceases to amaze me

[Allnatural]

If you're not familier with it, squares A and B are the same color.

[JKKDARK]

they are not the same color, or I can't understand :S

[Toasty]

Yeah, I've seen it before. If you cover the rest of the picture with your hands and just focus on one square, then the other, it's easy to see they are the same brightness. Still, a very effective illusion that I just can't get my mind... eyes? mind? eyes? to see past when looking at the whole picture. :P

[yegosimo]

How amazing.. couldn't figure it out by just seeing it, I picked both colors with a Quick HTML Color Picker, and both squares have the #787878 color.

Cool :P

[Allnatural]

they are not the same color, or I can't understand :S
Same color.

http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html

Ok, if you want to get technical there are slight variations due to jpeg artifacting (if anyone has a high-quality png please post it) but they're otherwise identical.

[Toasty]

Hmm, I was trying something else. If you stare in between the two squares and use your peripheral vision to look at the two squares, they appear the same if you look just right.

[A.I.]

Can't pick the squares being the same (colour?) brightness but I notice that the shadow moves a little.

Is there known research that these 3D/optical illusions tests screw up your eyes? I get bad headaches when I do them and I don't think they're good for your eyes...

[Agozer]

If you get headaches from that doesn't mean that these kind of images would somehow be harmful to your eyes. It's an optical illusion, nothing more.

[_Zack_]

Amazing image. Optical illusions are cool :D

[markcole]

Hello mr. allnatural.
With your wisdom might you help me understand if this one really is possible.
I just can't seem to make it work. Be it a fraud?

http://www.maniacworld.com/Spinning-Silhouette-Optical-Illusion.html

[Trotterwatch]

Pretty certain that is legit - you can download the .gif and disassemble it to look at the individual frames. Works for me.

Blinking makes it change direction again.

[Allnatural]

Hello mr. allnatural.
With your wisdom might you help me understand if this one really is possible.
I just can't seem to make it work. Be it a fraud?
I've been able to get that to "work" a few times. Seems to happen more easily when viewed on a page that scrolls, since it's easier to focus on just the feet or the top of the head. Just make sure you don't blink as you slowly reveal the entire image. :)

http://members.accesstoledo.com/allnatural/spinning.html

[markcole]

Thanks man, my brother and I had been convinced it was just a ruse.
"Haha how long can I make these rubes stare at this spinning broad?"
We stared. For a long while. Focusing on just her head worked quite nicely.

[A.I.]

Staring at her shadow is even better, the effect is almost instant. I can get her to swing left and right with ease.

[ShizZy]

Yes.. that one is indeed legit. Just focus on her foot, you can then easily see her spinning in either direction.