Which came first, the trick or the machine?
The following is from the Winter 2004 edition of Invention & Technology Volume 19 Number 3...
One of Keeler's (Leonarde Keeler was the developer of the modern polygraph) innovations was the "stimulation" test. This was intended to convince the subject, before the main part of the examination began, that the polygraph was infallible. The object, which remains the key to all successful lie detection, was to increase the subject's emotional response, to make him or her fearful that any deception would be immediately apparent to the polygraph operator.
This response could be generated in a number of ways. The subject might be asked to select a playing card, examine it, and answer no to everything the operator asked about it. The operator would ask questions ("is it a red card? Is it a face card?") and tell the subject whether the answer was a lie or the truth, eventually announcing what the card was. To make sure the test worked, the operator used a marked deck.
While I'm here, props to Pete Biro for turning me on to this wonderful magazine when he wrote about it on the Magic! BBS.