[xoxoxoBruce]

If you have to face one they can be beaten. Doug Williams was sent to jail for teaching people how.

As an examiner, Williams saw the polygraph simply as a prop to scare confessions out of suspects, “a psychological billy club.” And over time, he came to believe that a properly trained subject could game the machine. The key realization occurred when a friend on the force came into the station describing a high-speed chase from the night before. With all the fear and adrenaline, he told Williams, the “pucker factor” had been high—he’d been “pinching doughnuts” out of the seat of his patrol car.
That vivid image made Williams wonder if the same process could run in reverse, if an intentional “pucker” could trigger the physiological stress responses a polygraph traced. That would allow a subject to manipulate his response to the control questions and rig the test. For a lark, Williams hooked himself up to the machine in his office and clenched. “Lo and behold,” he recalls, “the most beautiful blood pressure increase you ever saw, accompanied by a corresponding increase in sweat activity in my hand.” The effect was even more convincing if he simultaneously altered his breathing pattern to fool the pneumographs.