Watching people's action can bring you a lot closer to the truth than merely listening to what they say (which might be a cover-up). This is the "science" of kinesics, or "body language".
Reading body language is very exciting indeed! If you know how to read and interpret body language, you can predict other people's mood and thinking process.
Some of us can read it naturally and some of us are notoriously oblivious. Fortunately, with a little extra attentiveness, you can learn to read body language, and with enough practice it'll become second nature. It can be very revealing....
Some outward expressions of inner feelings:
Openness: Open hands, unbuttoned coat.
Defensiveness: Arms crossed, sideways glance, touching-rubbing nose, rubbing eyes. Buttoned coat, drawing away.
Insecurity: Pinching flesh, chewing pen, thumb over thumb, biting fingernails.
Cooperation: Upper body in sprinters position. Open hands, sitting on edge of chair, hand to face gestures, unbuttoning coat.
Confidence: Steepled hands, hands behind back, back stiffened, hand in coat pockets with thumbs out. Hands on lapels of coat.
Nervousness: Clearing throat, "whew" sound, whistling, smoking, pinching flesh, fidgeting, covering mouth, jiggling money or keys, tugging ears, wringing hands.
Frustration: Short breaths, "tsk" sound, tightly clenched hands, wringing hands, fist-like gestures, pointing index finger, rubbing hand through hair rubbing back of neck.
Noticing the signals that people send out with their body language is a very useful social skill...Don't isolate yourself by constantly examining body language when interacting with people. Otherwise, there is no reason to gain a social upper hand anyway. This is paralysis by analysis.