Polygraph tests have been used for a long time to detect whether or not a person is lying. They rely on respiration rate, blood pressure, pulse and anxiety levels to determine when someone is lying.
But a new kind of polygraph will used near-infrared spectroscopy to determine lies from truths. A patent was recently filed with the World Intellectual Property Organization according to the New Scientist that would use this tech. It works by shining a light through the skull to the brain. And depending on how much light is then reflected back, scientists can then determine how active the brain is, and therefore whether or not you're lying.