Steven Pinker

So there's a, I have a chapter called Laughing, Crying, Blushing, Staring, Glaring about nonverbal common knowledge.

Laughing, crying, blushing, blushing, staring, glaring, glaring.

Okay.

Now, we have dozens, maybe hundreds of facial expressions, you know, smiling and frowning and grimacing and so on.

But on top of that, we have some really conspicuous forms of nonverbal communication that have puzzled people for millennia, such as laughing.

Why do we interrupt our speech with that staccato noise?

Yes, Stephen, why?

I thought you'd never ask.

Because Chuck needs to pay his mortgage tax.

I mean, come on.

I forgot.

Yes.

So what I argue is that for these conspicuous displays, blushing is another one.

Why should blood go to your cheeks?

Crying, why should a fluid drip through your eyes?

Eyes shed tears, yeah.

Why do you shed tears?

I suggest that they are common knowledge generators.

So when you're laughing, you know you're laughing because your breathing is interrupted.

Other people know you're laughing because they can hear it.