Here's the link:
Indeed, the illusion they show at the beginning of the piece sure looks like it's moving, when it's not. CB bought the issue to show the birders he works with how brightness and color perception are relative. For example, do this one (credit to Edward H. Adelson of MIT):
Look at the squares labeled A and B. Are they different? They sure look different, but, no, they are the same shade of grey. You can print it out and cut out the squares if you like.
I've been thinking about the brain and all the cool gadgets that make up our sensory machinery. Mr W's had a thing lately for the "Magic School Bus" books and videos. We checked out a book on the senses and we read it every night for bedtime stories for almost three weeks. When you think about how sensory input is translated into nerve impulses, it is pretty darn amazing. Especially sight and hearing. Things most of us take for granted are incredibly complicated.
Apparently our visual system is pretty easily fooled, to which the abundance of optical illusions can attest. This is likely because shared networks in the brain. The article says:
But the same neural machinery that interprets actual sensory inputs is also responsible for our dreams, delusions and failings of memory. In other words, the real and the imagined share a physical source in the brain.