Interjections Are, Uh, More Important than We Thought

Listen carefully to a spoken conversation and you’ll notice that the speakers use a lot of little quasi-words — mm-hmm, um, huh? and the like — that don’t convey any information about the topic of the conversation itself. For many decades, linguists regarded such utterances as largely irrelevant noise, the flotsam and jetsam that accumulate on the margins of language when speakers aren’t as articulate as they’d like to be.

But…