"Salience is the more common way that we entertain common knowledge, generated by certain common knowledge generators like direct speech, but also laughter, I argue, tears, blushing. We have nonverbal common knowledge generators and eye contact. With eye contact, you're looking at the part of the person that's looking at the part of you that's looking at the part of them, ad infinitum. Eye contact is a very powerful signal. Eye contact makes something that was private knowledge, common knowledge