The truth about lie detectors is…they probably don’t work. And they never did.
A polygraph is little more than a device that measures heart rate/blood pressure, breathing and skin conductivity. The questioner then uses that information to determine whether the subject is lying or telling the truth.
The problem? There is no way of proving that the "bodily arousal" measured by the machine is linked to the truth of a particular statement. Maybe my pulse went faster because I lied. Or perhaps I'm nervous. Or maybe I'm about to have a heart attack.
So why do they show in popular culture on reality tv shows and, most disturbingly, in criminal investigations?
And what are the ramifications of putting our faith in these dodgy devices and half-baked theories?
In this episode of Scamapalooza, Dr Celine Van Golde of the Not Guilty project helps uncover the truth about lies.