When trying to figure out whether someone's lying to me, I look for the typical signs: shifty, averted eyes, twitching, rapid blinking, and so forth. But most psychologists and body language experts will tell you that none of those indicate lying. In fact, pinpointing a lie based on physical cues only works about half of the time, making it a guessing game at best.
In lecture, we talked about Paul Ekman's 6 basic emotions: happiness, sadness, anger, fear, disgust, surprise. Ekman believes that we make unconscious flashes of expressions, called micro expressions, that demonstrate our true feelings. They are not something that we have total control of, and that is how it shows our true reactions. Some of these expressions are extremely difficult to decipher, but most can be broken down into these six categories.