Have you ever wondered how Santa Claus determines whether to leave you a present or a lump of coal on Christmas Eve? How he knows if you’ve been naughty or nice? I don’t have any hard evidence to back me up, but I’m pretty sure that he must be a first-class lie detector.
And, if so, here is how Santa does it:
He begins with a baseline
The first and most important step in Santa’s deception detection is learning your baseline behavior under relaxed or generally stress-free conditions so that he can compare it with the expressions, gestures, and other signals that are only apparent when you are under stress.
He watches you while you are chatting informally, noticing how your body looks when you are relaxed. (What is your normal amount of eye contact and blink rate? What kind of gestures you use most frequently? What posture do you assume when you’re comfortable? What is your pace of speech and tone of voice?
Then, after he knows your behavioral baseline, he stays alert for meaningful deviations that signal a stress reaction (and possible deception) as you go through the day.