The defining feature of conversation is the expectation of a response. It would just be a monologue without one. In person, or on the phone, those responses come astoundingly quickly: After one person has spoken, the other replies in an average of just 200 milliseconds.
In recent decades, written communication has caught up—or at least come as close as it’s likely to get to mimicking the speed of regular conversation (until they implant thought-to-text microchips in our brains). It takes more than 200 milliseconds to compose a text, but it’s not called “instant” messaging for nothing: There is an understanding that any message you send can be replied to more or less immediately.
But there is also an understanding that you don’t have to reply to any message you receive immediately. As much as these communication tools are designed to be instant, they are also easily ignored. And ignore them we do. Texts go unanswered for hours or days, emails sit in inboxes for so long that “Sorry for the delayed response” has gone from earnest apology to punchline.
People don’t need fancy technology to ignore each other, of course: It takes just as little effort to avoid responding to a letter, or a voicemail, or not to answer the door when the Girl Scouts come knocking. As Naomi Baron, a linguist at American University who studies language and technology, puts it, “We’ve dissed people in lots of formats before.” But what’s different now, she says, is that “media that are in principle asynchronous increasingly function as if they are synchronous.”