Vanessa Van Edwards shares lie-detection research showing that liars restrict hand gestures because they haven't rehearsed them. Watch for incongruent nods: someone shaking their head no while saying yes. Gestures that match words make speakers seem credible and help listeners relax.
It's really hard to lie with your hands. So in our lab, we do a lot of lie detection research. We look for lying tells, and often liars restrict their gestures because they haven't practiced those, and it's really hard to lie with them. We instinctively know that if someone is not using a lot of gesture, they either don't know what they're talking about, it's memorized, or it's a lie. And a lot of liars memorize their lies. And so we love people who show congruent gestures. So if I'm here and I say, today I have a really big idea, and I hold my hands out like beach ball big— oh, it looks so big. Or if I say, oh my gosh, it's from the heart, and I touch my heart, you're like, wow, it really is from the heart. Your brain can relax because it feels like, wow, this speaker knows her content so well. She can speak to me with her words but also her gestures, and they align. There's one more that you should watch out for, is an incongruent nod. So in Western cultures, when we say yes, we shake our head vertically. We say no, we shake our head horizontally. Liars don't practice their nonverbal cues, and so they'll often say yes but shake their head no. So it looks like this: what do you think of the new girl? Oh yeah, you know, she's great. And they'll shake their while they're saying yes or they're saying great. So watch out for those incongruencies.
