In a study of how people talk in English, the linguist Mark Liberman analyzed a massive database of spoken language and found that one in every sixty words people pronounce is either um or uh. Depending on how fast you talk, this means you are producing two to three of these ‘fillers’ per minute.

Why do we do this? An obvious answer is that we use these fillers when we are momentarily unable to say what we want to say. We might be having trouble remembering a word or a name, or formulating our thoughts, or we might have reason to be hesitant. But there is more to it than this. Just having a problem finding the words you want to say is not enough reason to say something like um out loud. You could just as well stay silent for a moment while you work away in your head to sort out what you are saying.

The reason we say “um” and “uh” is that, in the high-speed to-and-fro of conversation, going silent won’t work. (more…)