Christopher Nolan’s breakout film, Memento (2000), is a story told in reverse chronological order about a man hunting for his wife’s killer. What makes his quest difficult is that he’s suffering from short-term memory loss: he can’t remember anything that happened more than 10 minutes ago. At one point in the movie he finds a picture of his only friend; under the picture is a caption reading, “Don’t believe his lies.” As the movie goes on, the audience begins to suspect that this caption was written by someone else who is trying to deceive him.
Leonard can’t rely on memory to tell him who’s trustworthy and who isn’t. He has to rely on intuition, facial cues, and other clues. He asks people to take their sunglasses off when they talk to him so he can read their eyes. He understands the following basic rules of discerning whether someone is lying when you don’t know anything about them but their name.
12. Sudden Head Movements
Someone who is lying may use excessive hand gestures and sudden jerks of the head. They’ll do this either out of nervousness or because they wish to punctuate what they’re saying with intense body language. People who are over-emphatic or over-insistent often have something to hide.
11. Excessive Talking
Someone who is lying may be reluctant to speak, or may provide vague, terse answers because they haven’t fully thought through their story and are afraid of being found out. On the other hand, a lying person may talk too much and supply too many details out of a fear of being found out. Someone who is hurriedly providing random and unnecessary information may be lying.