Thanks, Paula! I find that I can do both IF I concentrate on the lines on the sidewalk, too. If I lose focus on that, I'm cooked. My focus on my visual cues is pretty automatic now.

However, I would not be able to walk quickly and speak at the same time. When I'm in a rush (as in catching a bus), I can't even control the muscles in my face, and I make awful grimaces as I rush along, and my eyes get all wonky, too. Not a pretty sight.