Do you ever wonder how to tell if a person is lying and how other people say they know someone is lying? In today's society there are many ways to try to detect if people are lying but there is no way to know with 100% certainty that someone is lying without knowing for a fact the correct answer.
A couple ways that people try to detect lies is either using humans as lie detectors or by using the polygraph test. In the TV show "Lie to Me", the psychologist in the show uses nonverbal cues to detect when someone is lying. But in reality it is best to listen to what they are saying rather than how they are saying it to detect lies, but even then humans are only right about 55% of the time when detecting lies.
Another way is the polygraph test. When using this they ask three different kinds of questions: Relevant questions, irrelevant questions, and control questions. When asking the questions they monitor blood pressure, respiration, and skin conductance to try to detect when someone is lying. What I found interesting was that the polygraph is biased against the innocent and it typically misclassifies innocent people as being guilty of crimes. Both of these tests are good ways to help detect a lie but they should not be completely relied on when proving someone guilty or not because they are not 100% accurate.