Lie detectors
Most of us practice deception on some level in our daily
live. Sometimes, you can tell when someone's lying, but other times it may not
be so easy. we humans are no better than chance at detecting deception. Because
there is no single behaviour indicative
of deception. what if you have a machine that can make this job easy. “polygraph
“or a lie detector they monitor a person's physiological reactions. They do not
detect lies rather they can only detect
whether deceptive behaviour is being displayed.
How do they work?
When someone tells a lie, they occur certain physiological
changes in his body. Instances, Heart begins to beat faster leading to rapid
perspiration, blood pressure and breathing pattern changes . polygraph is
designed to record all these changes. So basically when a person undergoes lie
detector test, various parts of the machine are attached to his body by wires .And as a person is questioned about an event,
the examiner looks for physiological changes in comparison to normal level.
Fluctuations may indicate deception.
However, the polygraph is not wholly dependable. Its
accuracy is estimated to be about 73%.Lot depends on the examiner. Some people
who are truly unaware of the fact they are lying, cannot be caught .Moreover,
people are capable enough to control
their emotions and render the machine ineffectiveness .Because of these reasons
the result of a lie detector test cannot be accepted as an evidence.