YDS 2014-2 Soru=59

It is pointed out in the passage that the polygraph ----.

The polygraph, or the lie detector as it is often referred
to, measures autonomic nervous system activity by
sensors attached to different parts of the body. The
sensors measure changes in breathing, cardiac activity
and sweating. The indicators only show physiological
changes, usually induced by emotion. The machine
amplifies signals picked up from sensors placed at
specific parts of the body. It detects not lies, but physical
changes that are the results of specific emotions.
People are asked ‘hot’ or relevant questions as well as
‘cool’ or control questions. The assumption is that for
innocent people there is no physical difference in the
way they respond to relevant and control questions. The
other assumption is that suspect can be identified if he
or she exhibits physical changes in his or her body.
Therefore, suspects who are to be tested by polygraph
use certain drugs to suppress autonomic nervous
system activity and make any physiological recording
inconclusive. More worryingly, people can be trained to
defeat the test with a range of techniques. Tests would
therefore not only be highly unreliable but
counterproductive: alienating and misclassifying the
innocent and letting the guilty get away without receiving
the punishment he or she deserves