Do you think you could spot a liar? Many people believe there are telltale signs that show somebody is lying, and some even claim to be human lie-detectors. A suspect's behaviour can determine how they are questioned, and influence a juror's verdict. Modern scientific techniques are even being used to spot lies in the brain and have been presented as evidence in court cases. But how good really are these methods at detecting lies? Are we risking the freedom of innocent people? Join Faye Skelton (Edinburgh Napier University) to find out what psychology has to say.