People lie, that’s the fact of the matter.  They can lie about some little situation or they can lie about something very big.  It’s all just to avoid getting in trouble with a partner, a parent, a boss and even the law.  There are times when you can tell if the person you’re speaking to is lying but in many cases, it’s not going to be that easy.  To tell exactly if someone is lying, the polygraph machine was invented.  For its purpose of determining if someone is lying, it’s also called the lie detector.

Polygraph machines are made using a combination of medical devices that monitor any change occurring in the body.  Some of these markers are for blood pressure, heart rates and so on.  It’s been found that when drastic changes occur in a person, it can indicate lying but the polygraph test results have to be interpreted by a skilled examiner first.  Polygraphs are mainly used in criminal investigations and court cases.  If a person’s involvement in a crime is doubtful, he’s subject to a polygraph test to make it easier for the authorities to determine if he or she is lying.

Lie detection tests go like this, the subject has to take a seat in front of the machine and various wires and straps are hooked on to the person.  These wires and straps are actually sensors for a persons’ pulse rate, breathing rate, blood pressure and perspiration.  Any data the sensors get will be documented on a strip of moving paper known as the graph.  There are even polygraphs that can make a record of a person’s leg and arm movement.  The examiner will be asking the subject a few questions to determine the baseline of the subject.  Then the real questions are asked.

If there are any big changes in a person for specific questions, the examiner makes a note of it.  If a significant change is seen like for example, faster heart rate, the test will show that the person is lying and the police or any other authority can take other measures to close the case.  The examiner has to be highly skilled at reading the polygraph results as well as the subject’s physiological reactions to the questions asked.  By combining technology and the examiner’s skill, experience and impartiality, it can be determined if a person is demonstrating deceptive behavior or not.

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