205 lines
11 KiB
Plaintext
205 lines
11 KiB
Plaintext
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% %%
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%% ========================== %%
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%% Meet and Beat the Lie Detector %%
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%% ========================== %%
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%% %%
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%% Stolen from the book %%
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%% BIG SECRETS! %%
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%% by: William Poundstone %%
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%% %%
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%% Typed By %%
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%% --==**>>THE RELFEX<<**==-- %%
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%% [Member: Omnipotent, Inc.] %%
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%% %%
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%% 80-col for Countlegger 8 and %%
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%% various typo. corrections by %%
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%% Count Lazlo Hollifeld-Nibble %%
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%% %%
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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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
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the
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name Charles Moulton). The standard polygraph records only three distinct
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vital signs. A blood-pressure cuff on the upper arm measures changes in blood
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pressure. Wires attached to the fingers measure changes in electrical
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resistance of the skin due to sweating. Rubber straps around the torso
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measure
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the breathing rate. This information is displayed as four squiggles on a
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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 like for
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personal calls?" and so forth--not <20>'r police work. In 'A Tremor In the
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Blood:
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Uses and Abuses of the Lie Detector' (New York: McGraw-Hill, 1981), polygraph
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critic David Thoreson Lykken estimates that as many as one million polygraph
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examinations are performed on Americans each year. In criminal cases however,
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even the manifestly innocent may be asked to take a polygraph test. All
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Yakima
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County, Washington, rape victims are required to take the test; refusal means
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the case will not be prosecuted.
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At best, all the polygraph can indicate is a heightened emotional
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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
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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 your 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 reciepts 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 thought to
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these questions, he assumes that they are control questions to provide a
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yardstick for evaluating responses to the relevant questions. Actually, the
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irrelevant questions are there to give the subject's vital signs time to
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return
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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
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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 comitted 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 plygrapher 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 be
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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.
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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 no 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
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subject
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will be worried about the control questions. He'll know that he has
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committted
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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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threating 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
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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 qustions.
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This,
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at any rate, is what polygraphers look for when the machine is switched 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 mos<6F>olygraph test. You
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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 measured, 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 either 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
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of
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fidgeting. Biting the tounge forcefully also works.
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--William Poundstone
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///////////////////////////////////////////////////////
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// The PIRATES' HOLLOW //
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// 415-236-2371 //
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// over 12 Megs of Elite Text Files //
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// ROR-ALUCARD //
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// Sysop: Doctor Murdock //
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// C0-Sysops: That One, Sir Death, Sid Gnarly & Finn //
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// //
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// "The Gates of Hell are open night and day; //
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// Smooth is the Descent, and Easy is the way.." //
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///////////////////////////////////////////////////////
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