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In some countries, a machine known as a lie
detector is used to ___1___
in criminal investigation. The lie detector is used
to determine ___2___
the person involved in the crime is telling the
truth or ___3___.
How does such a machine work ? When a person ___4___
an untruth, certain body reactions may ___5___
. For example, his heart may ___6___
faster and his face may flush. His blood pressure
may ___7___
rise and his breathing may ___8___
quicker. It is the ___9___
of the lie detector to record these reactions.
Normally, the machine ___10___
record reactions which the subject has no control ___11___
, such as his blood pressure, respiration or pulse.
How reliable ___12___
these machines ? Some countries do not use lie
detectors ___13___
they feel that these machines are not totally
reliable. in fact, the success ___14___
of the lie detector depends greatly ___15___
the sensitivity of the machine.
The ability of the person ___16___
the test is also very important. The examiner must
know specifically ___17___
kinds of questions to ask his subjects. The examiner
would usually familiarize himself ___18___
the details of the case first. He then asks his
subjects ___19___
that are totally unrelated ___20___
the case. The answers to these questions would
___21___
the examiner gauge what ___22___
'normal' reactions of the subject ___23___
. After this, the examiner would ask questions of ___24___
kinds -- those that are important to the case and
those which have nothing to ___25___
with the case at all.
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