Sherry Turkle: You watch people at dinner tables, where they’re both at their phones and talking to their dinner partners. Ask what’s happening there, and they explain to you what some call “the rule of three”: You wait for three people to have their heads up before you put your head down to your phone, so you make sure that some kind of conversation persists. But then people admit that it’s not the same as the kind of conversation they’d have if everybody were paying attention. Experimental evidence backs this up, because if you have a phone on the table between two people, the people in the conversation feel less connected to each other.