omg, it is too! wow! I didn't believe it so I opened it with photoshop and sampled the colors. Both squares are a (hex) 6B6B6B. Wow. that's pretty darn cool.
Saw that on OCUK, someone drew a line between the two blocks but I still didn't understand it properly.
its comparison and alteration of perception. try to look at the square without seeing the surrounding squares, you'll notice the 'real' colour...
Oh my, it is the same. I just moved a bit of the A block closer to the B blockwith MSPaint and they are the same.
this is taken from the institute of physics as level cd and is sort off the same thing. we have to learn about all this type of stuff for physics. interesting stuff
wow, freaky! One way to "see" the right thing is to not focus on anything but just stare at the image between the A and B square, then forget the lettres "A" and "B" (as they help creating the illusion I think) and you'll see it is actually the same gray!