“How do you find the hidden gold mine for reading someone’s body language? Instead of focusing on your primary counterpart during a negotiation, observe one of their 'wingmen.' This person is where you’ll find the most honest, unguarded body language.
“Everyone on the other side feels it when your gaze is fixed on their primary negotiator. Instead, have your wingmen discreetly watch their wingmen, and you’ll be stunned at what they pick up.”
- Chris Voss, "How to Spot a Liar"