This reminded me of a previous comment (and discussion) on HN: http://news.ycombinator.com/item?id=840331

"Another way to look at this: The first time you meet someone, you learn their full name. When discussing them with someone else who knows them, you use just a single name. If they're standing right there, you don't bother using their name, but just make eye contact, and maybe a "Hey". Should be the same way with variables."