Designing Social Interfaces, 2nd Edition

Chapter 5. Here We Are Now

It’s impossible to move, to live, to operate at any level without leaving traces, bits, seemingly meaningless fragments of personal information.

—WILLIAM GIBSON

HOW DO YOU KNOW SOMEONE IS PRESENT? In class, they used to call roll and each person would respond with “here” or “yo” (coincidentally a hot “phatic” presence app from the past year) or sometimes just “present.” (Phatic communication is used purely as a social lubricant and without much semantic content, such as “how do you do?” or, in German, the ubiquitous bitte). Usually you can just look around. But, how about when someone is standing behind you and he clears his throat, not because he’s feeling hoarse but as a way of letting you know he’s standing there, so he won’t startle you?

In the real world, we are tuned to all sorts of indications of who is present (either in the immediate moment or the recent stretch of time) and who is absent. If you see an unmown lawn, it might mean no one’s been home for a while, or it could mean that the homeowner is an iconoclast at war with the neighborhood association, but if you notice a pile of uncollected newspapers on the stoop, that’s a pretty good sign of absence. Likewise, if the curtains are open and they were closed earlier or a light is on that was dark before, that’s another sign that someone’s there.

Graffiti showing a nose peeking above a wall with the legend “Kilroy was here” can also imply that someone has been by, perhaps recently. In his fantastic ...