"The stain, the haircut, the wrong shoes"

The mark is the audience's favourite thing. A mark on the jumper. A haircut that went shorter than you asked. Shoes that are wrong for the room. The mark is different from the general beam because it's specific, and you can point to it, and so, you assume, can everyone else. All morning it has been the most visible thing about you.

To you. The mark is salient because you've been looking at it, in the mirror and then in your mind, since you noticed it. Nobody else has that history with it. When someone sees you at eleven, they see a person in a jumper. They don't see the jumper against yesterday's jumper, or the hair against last week's hair, because they don't hold yesterday's version of you at all, and chapter 5 is about how little they hold. The haircut is a change. To see a change you need the before, and the room hasn't got it.

The 2004 paper by Nicholas Epley, Boaz Keysar, Leaf Van Boven and Thomas Gilovich, which an earlier book in this series used for reading other people's minds, describes how people work out what someone else sees. You start from what you see and adjust, in steps, and you stop at the first answer that seems plausible. With the mark, the first plausible answer is still a room that sees the mark, because you're adjusting from a morning spent looking at it. There's a paper from 2002 by Gilovich, Justin Kruger and Medvec on people overestimating how much the day-to-day variation in their appearance shows, which I couldn't read beyond the title and so won't quote, but the title is the point.

And Boothby's sixth study from chapter 7 tested the mark directly. Making people focus on a feature of their own appearance raised their belief that others were attending to that specific feature. It didn't change the wider finding that they were, overall, less observed than they believed. Both at once. When you fix on the mark, you become sure the room has fixed on it, and the room goes on doing what it was doing, which is not looking at you. The practical move is small and is in chapter 19. Before you go in, say what the mark is. Then count how many people look at it.