A User's Guide to the Polygraph Exam

Oct 13, 2009 - by Daniel B. Young - 0 Comments

July 22, 2007

by Daniel B. Young

There are many examples throughout history of authorities attempting to detect deception. One of my favorites is that of certain priests in India circa 1500 B.C. A donkey's tail was covered with carbon residue from an oil lamp and placed in a dark room. The suspects were sent into the room and told that pulling the "magic" donkey's tail would reveal the liar. When the suspects came out, the priests examined their hands. Those with clean hands had not touched the donkey's tail. It was assumed that this was due to their fear of their guilt being discovered, proving they were liars. A nice theory with some psychological validity, but what if the guilty man had grabbed the donkey's tail to keep from falling in the dark or an innocent man simply couldn't find the tail in the dark? This probably would not have saved the innocent man – the test was just too convenient for the authorities.

In 1915 a Harvard professor named William Moulton Marston developed an instrument he termed a lie detector; it was a prototype polygraph based on blood pressure measurement alone. Four other men, John Larson, Leonarde Keeler, John Reid, and Fred Inbau, over decades, further developed the polygraph machine and the accompanying interrogation techniques into the modern polygraph test. Mr. Marston is not well known for his part in the development of the polygraph. But he did achieve fame in another area. He was the creator of the comic book character Wonder Woman who had a magic lasso that, when wound around a person, would force him to tell only the truth. As you will see there have been times when the magic lasso would have been preferable to the polygraph machine.

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