No ducks and hazards in the classroom

Tricks of perception are so cool. I was waiting for a bus today and watching pedestrian traffic at an intersection right near Coolidge Corner. At one point, there was a guy walking toward me, and therefore getting larger in my frame of reference. Simultaneously, someone else was walking their dog on the street perpendicular. Since the guy coming toward me was getting larger, for quite a startling number of seconds, he blocked out the dog walker - but not the dog or the leash. To me, it looked like exactly the reverse of those carnival toys, the ones that are basically a harness attached to a wire "leash". Shaken convincingly, it looks like little kids are walking invisible dogs. However, in my case today, it looked like an invisible human was walking the dog, with the leash sticking straight up and not attached to any person I could see. Pretty odd.

(Title of this entry thanks to a link off EK's links, and a rather humorous mishearing of Pink Floyd's "Another Brick in the Wall".)