[fan4ever]

Originally Posted by DaFace

Each of the diamonds is identical, but they are all shaded from lightest on the top to darkest on the bottom. Our minds are "anchored" into thinking that the top row is dark by the light background. As you've seen with the other two examples of this phenomenon in the thread, our eyes perceive color relative to their surroundings, so the rest of it seems like it's getting lighter because each row is comparing a darker color (bottom of the diamond) to a lighter color (top of the diamond).

I loaded this up in Photoshop and copied the diamond from one row and then just moved it all over the place. Sure enough - it blends right in no matter where you put it.

Thanks for 'splaining...