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11 KiB
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11 KiB
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%% ========================== %%
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%% How to Beat a Lie-Detector %%
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%% ========================== %%
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%% By _The Reflex_ %%
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%% An Official_Omnipotent,_Inc._Production %%
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This file would be useful to you if you were caught by the Gestapo, uh...I
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mean Bell Security (B. S. for short).
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The polygraph test was invented by William Moulton Marston, who was,
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strangely enough, also the creator of the Wonder Woman comic strip (under the
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name Charles Moulton). The standard polygraph records only three distinct
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vital signs. A blood-pressure. Wires attached to the fingers measure changes
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in electrical resistance of the skin due to sweating. Rubber straps around the
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torso measure the breathing rate. This information is displayed as four
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squiggles on a moving strip of graph paper.
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Whether or not you believe a polygraph provides useful information (most
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psychologists have their doubts), there is a good chance you'll be asked to
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take a polygraph test. The vast majority of lie-detector tests are
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administered for employee screening -- "Have you been using the WATS line for
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personal calls?" and so forth -- not for police work. In 'A Tremor In the
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Blood: Uses and Abuses of the Lie Detector' (New York: McGraw-Hill, 1981),
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polygraph critic David Thoreson Lykken estimates that as many as one million
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polygraph examinations are performed on Americans each year. In criminal cases
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however, even the manifestly innocent may be asked to take a polygraph test.
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All Yakima County, Washington, rape victims are required to take the test;
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refusal means the case will not be prosecuted.
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At best, all the polygraph can indicate is a heightened emotional reaction
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to a question. It cannot specify what kind of an emotional reaction.
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Polygraphers try to design question formats so guilt-induced nervousness will
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be the only emotional invoked and so the subject's reaction to relevant
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questions can be compared to other, "control" questions.
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THE LIE CONTROL TEST
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~~~~~~~~~~~~~~~~~~~~
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This is the question format used in most police investigations. It
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usually starts with a card trick devised by two pioneer polygraphers, John E.
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Reid and F. E. Inbau.
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The polygrapher hooks the subject to the polygraph and takes out a deck of
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cards. The polygrapher tells the subject that he must "calibrate" the
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polygraph with a simple test. He fans the deck and asks the subject to select
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a card. The subject is told to look at the card but not to show it or mention
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its name. The polygrapher tells the subject to answer "no" to every question
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asked about the card. "Is it a black card?" the polygrapher asks. "Is it a
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high card?" and so on. After each "no" the polygrapher scrutinizes the
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tracings and fiddles with the dials. If the no answer is incorrect, the
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polygrapher disagrees. The field is soon narrowed to one card -- and it is the
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correct card.
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Needless to say, the polygrapher uses a trick deck. The point is to
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foster confidence in the machine. After identifying the card, the polygrapher
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comments that the subject's reactions are particularly easy to read and segues
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into the interrogation.
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Three types of questions are used in a lie-control test. The entire list
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is read to the subject well in advance of the test. The start of a typical
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interrogation might run like this:
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1. Is you name Sarah Elkins?
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2. Is Paris the capital of France?
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3. Have you ever failed to report more than $50 of tip, gambling or gift
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income on a single year's tax return?
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4. Is this apple red?
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5. Do you have any idea why the cash receipts for the last quarter are about
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$22,000 in error?
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6. Is there something important that you did not mention on your job
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application?
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7. Have you ever been embezzling from the company?
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The first question is always irrelevant to the matter being investigated.
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It has to be because many subjects get nervous on the first question no matter
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what. Other irrelevant questions are asked throughout the interrogation
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(questions 2 and 4 in the sample list). If the subject gives any questions to
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provide a yardstick for evaluating responses to the relevant questions.
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Actually, the irrelevant questions are there to give the subject's vital signs
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time to return to normal. They aren't the control questions.
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Questions 5 and 7 in the list above are relevant questions -- the only
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questions the examiner is really interested in. The relevant questions are
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asked in several different wordings during the test.
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Questions 3 and 6 are control questions. In the pretest discussion of the
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questions, the polygrapher explains that it is helpful to throw in a few
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"general honesty" questions. Whoever committed the serious crime, the spiel
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goes, probably committed less serious crimes in the past. Hence the inclusion
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of questions about tax cheating, lying on the job applications, stealing as a
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child, etc.
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The polygrapher affects the attitude that it would be damaging indeed to
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admit any such indiscretions. Frequently this scares the subject into
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admitting minor crimes. In that case, the polygrapher frowns and agrees to
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rewrite the question. Should the subject concede failing to report eighty
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dollars in gambling winnings, question 3 might be changes to "Have you ever
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failed to report more than a hundred dollars of tip, gambling, or gift income
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on a single years's tax return?" If necessary, several of the control
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questions may be reworded before the test -- always so that the subject will
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be able to give the "honest" response.
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In reality, the whole point of each working question is to manufacture a
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lie. It is the secret working premise of polygraphers that everyone commits
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the minor transgressions that are the subject of the usual control questions.
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All the subject's denials on the control questions are assumed to be lies. The
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polygraph tracings during these "lies" establish a base line for interpreting
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the reaction to the relevant questions.
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The reason for rewriting some control questions is so a candid subject
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will not admit to minor crimes on the test. That would be telling the truth,
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and the polygrapher wants the subject to lie. The control questions are
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intentionally broad. Even if a question is reworded to exclude the confessed
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instance, it is assumed that any denial must be a lie.
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The rationale for the lie-control test goes like this: The honest subject
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will be worried about the control questions. He'll know that he has committed
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small transgressions or suspect that he must have, even if he can't remember
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them. So he'll be afraid that the machine will detect his deception on the
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"general honesty" questions (especially in view of its success with the card
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trick). That would be embarrassing at least, and it might throw suspicion on
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him for the larger crime. In contrast, the relevant questions should be less
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threatening to the honest subject. He knows he didn't commit the crimes they
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refer to.
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The guilty person, on the other hand, should have far more to fear from
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the relevant questions. If the machine can detect lying on the relevant issue,
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it matters little that it might also implicate him in petty matters.
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By this hypothesis, an innocent person should have greater polygraphic
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response to the control questions than to the relevant questions. The guilty
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pattern is just the reverse: Greater response to the relevant questions.
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This, at any rate, is what polygraphers look for when the machine is switched
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on.
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THE RELEVANT-CONTROL TEST
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~~~~~~~~~~~~~~~~~~~~~~~~~
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The relevant-control test is the type used for most employee screenings.
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Thus it is the most common type of examination. The interrogation consists
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only of irrelevant and relevant questions. As with the lie-control test, the
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first question and a few others are irrelevant. The relevant questions usually
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test workplace honesty: "Have you ever taken home office supplies for personal
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use?" "Have you ever clocked in for someone else?"
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The premise is that no one will lie about everything. So if a few of the
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relevant questions produce heightened responses, they are presumed to be the
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questions on which the subject is lying. Unfortunately, there is no ambiguous
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way of deciding how much response is indicates a lie. Most psychologists agree
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that the relevant-control test is a poor test of deception.
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The Reid/Inbau card trick is eliminated from employee screenings: There
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is too great of a chance of coworkers comparing notes and discovering that
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everyone picked the ace of spades.
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HOW TO BEAT THE LIE-DETECTOR
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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To the extent that the polygraph works at all, it works because people
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believe it does. Many criminals confess during polygraph examinations. Many
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employees are more honest for fear of periodic screenings. But a dummy
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polygraph that hummed and scribbled preprogrammed tracings would be no less in
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these instances.
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David Thoreson Lykken estimates that lie-control polygraph tests are about
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70 percent accurate. (Remember, though, that choosing "heads" or "tails" of a
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flipped coin can be accurate 50 percent of the time.) Accuracy of 70 percent
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is not impressive, but it is high enough to talk meaningfully of beating a
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polygraph test.
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Just by having read this far, you stand a greater chance of beating a
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polygraph test. You won't be wowed by the card demonstration. You realize
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that the polygraph's powers are limited. There are two additional techniques
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for beating the polygraph. The more obvious is to learn how to repress
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physiologic responses to stressful questions. Some people are good at this
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one; others are not. Most people can get better by practicing with a
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polygraph. Of course, this training requires a polygraph, and polygraphs are
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expensive.
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The opposite approach is to pick out the control questions in the pretest
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discussion and exaggerate reactions to these questions during the test. When
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the control-question responses are greater than the relevant-question
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responses, the polygrapher must acquit the subject.
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Because breathing is one of the parameters measures, taking a deep breath
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and holding it will record as an abnormal response. Flexing the arm muscles
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under the cuff distorts the blood-pressure reading. But a suspicious
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polygrapher may spot wither ruse.
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A more subtle method is to hide a tack in one shoe. Stepping on the tack
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during the control questions produces stress reactions with no outward signs of
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fidgeting. Biting the tongue forcefully also works. Can you imagine the
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polygrapher's response to the "Is this apple red?" question when you say "red"
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and the machine starts going crazy? He'd shit his pants!
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_______________________________________________________________________________
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