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Informative Speech (Polygraphs)

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Autor:   •  September 29, 2010  •  651 Words (3 Pages)  •  1,063 Views

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Title: The Polygraph

Speaker: Neil

Thesis: To inform my audience about polygraphs, the polygraph tests, and the controversy of them.


I. Attention Getter: For more than 15 years, Robert Hanssen had led a double life. In one life he was a 25-year veteran with the FBI who had access to some of the nation's most-classified information. In his other life, he was a spy for the Russian government. Hannssen's deception was finally discovered, and in February 2001 he was arrested, and then took a polygraph test which forced him to plead guilty to 15 espionage-related charges.

II. Thesis Statement: Today, I am here to talk to you about Polygraphs, the polygraph tests, and the controversy of them.

III. Credibility: My brother-in-law had to take a polygraph test for his job. And he was forced to prepare for it a year in advance, ever since I saw his preparation for this one test; I have forever been fascinated by this invention

IV. Preview: First of all I will give you a bit of background information on polygraphs, and then I will talk about the actual test you take. Finally, I will discuss the controversy behind a polygraph test.

(Transition: How did the Polygraph test come about?)


I. Background information

A. John A. Larson, a medical student at the University of California, was the inventor of the polygraph.

B. John invented this machine based on the theory that when a person tells a lie, he/she will have a fear of being caught and their body will react with that fear.

C. The polygraph record the amount of stress produced by measuring changes in breathing, blood pressure, pulse and perspiration, continuously and simultaneously.

(Transition: Now that you know how a polygraph works, I will now talk about the test it-self.)

II. The Test

A. The average time a polygraph test takes is from 90-120 minutes. The examiner goes through a 6 step process in order find out wheatear or not a person is telling the truth or lying.

B. All the questions asked by the examiner are "yes" or "no" questions. The examiner asks questions in sets of 3's. The first question would be a known-truth question, the second question would be a case-related question, and the third questions would be a probable-lie question

(Transition: Now that you know how a polygraph test is taken. I will now discuss the controversy of using a polygraph test.)

III. The controversy over the polygraph test

A. Polygraph tests are known to be from 80-90% accurate and are not questioned until a high profile case that uses a polygraph


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