It's a new person!

I gave in and bought Stumbling on Happiness by Harvard Psychologist Daniel Gilbert off of the itunes store. This was one of the psychology studies he mentioned in it:

A psychologist claiming to be a tourist walks up to a person and asks a couple questions. In the middle of the conversation two construction workers with a big board walk between them so the person being asked questions cannot see the tourist. While this happens, the psychologist runs out of the room and another person runs in without the unsuspecting stranger seeing. This second person looks nothing like the first, is dressed nothing like the first, and does not have a similar voice. However if that second person continues the conversation few people notice that they are talking to an entirely different person!

And as an extra bonus. Here is the Daniel Gilbert TED talk.