He lied. Did you see it? He moved his eyes side-to-side. What a shifty liar. Oh look, she’s lying too; she’s fidgeting like crazy. I don’t know what they’re lying about because I wasn’t paying attention, but they are definitely lying.
We all like to think we are capable of knowing what people are saying even when they are not saying a word. We believe that body language can tell us whether someone is telling the truth, whether what we’ve said has struck a nerve, whether someone is being evasive. In truth, we can only tell others are lying with accuracy every time – if their nose starts to grow in front of us. Without such a cue, it’s a crapshoot.