A polygraph is all about the detection of deception. A device that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while a person is asked and answers a series of questions, a polygraph—also known as a lie detector—is a potentially valuable forensic tool. Indeed, it's been used by law enforcement agencies to extract information out of suspects for over a century. But a polygraph is not without its faults, and there have been some notable failures where the consequences have been tragic.
So, what exactly is the truth behind the making of this ingenious apparatus? Click through and take the test.