A simple lie detector consists of an electric circuit, often from one finger to another. A sensitive meter shows the cur - rent that flows when a small voltage is applied. How does this technique indicate that a person is lying? (And when doesn't this technique indicate when someone is lying?)

This technique indicates when a person is lying because when a person is under stress, the person tends to perspire more, hence the person will become more conductive. this means that the sensitive meter will get a higher reading of current trough his fingers indicating that the person is lying.