Be sure to gaze at the amazing checkershadow illusion. Go now, then come back here.
A cursory check with a little computer program I have (Digital Color Meter in /Applications/Utilities/ for those of you with MacOS X) verifies that the two squares which look so different are, in fact, the same 42% grey. But the surely don't look the same. The explanation is helpful.
I’m Greg Restall, and this is my personal website. I teach philosophy and logic as Professor of Philosophy at the University of Melbourne. ¶ Start at the home page of this site—a compendium of recent additions around here—and go from there to learn more about who I am and what I do. ¶ This is my personal site on the web. Nothing here is in any way endorsed by the University of Melbourne.