How many times have I sort of interrupted someone during a conversation to half-explain, half-apologize, “That’s really interesting, I’m just picking up my phone to type it into my notes”?

It’s a funny thing: the smartphone is so intrusive—so frequently used to indicate boredom with the other people around you—that when you are using it for something useful, like checking the time or note-taking, the other person probably won’t guess that’s what you’re using it for.

To bring up a minor relevant grudge, years ago, my old boss thought I was goofing off on my computer during a meeting when I was actually taking serious notes. That’s because he was a pen-and-paper guy, and had a bit of a newfangled devices view of phones and computers...