Methods of detecting lies and other forms of deception
are based on the fact that emotions have an impact on our body’s physiological responses, such as heart rate.
In addition, our nonverbal cues, like facial expressions, bodily movements
posture, and gestures, often betray our emotional state.
Many police interrogators believe that they can spot liars by watching for movements signaling strong emotion
such as trembling hands, twitching fingers, “shifty eyes,” or frequent blinking.
Other experts have developed lists of classic “deception gestures”
such as putting a hand over the mouth or rubbing the nose.