This is a very short over view of the basic functions of a polygraph for more detail see one of our many links.
Polygraph or a "lie detector" as it is better known, is an instrument designed to detect changes in central nervous system of the human body when we feel threatened. The human body is quite amazing and reacts to things it feels may harm us. For example when you are alone walking in the dark and hear a loud noise behind you, you instantly prepare for an unknown threat. That is called a sympathetic nervous reaction. So many things are happening in the body in that instant that you are unaware of. For example, saliva thickens so we don't choke, the colon shuts down, the heart takes in more blood, breathing pattern changes and many more to numerous to list. When you discover that the noise was just a cat in the trash the par a-sympathetic system takes over and calms us back down. The balance between the two is known as homeostasis all living creatures have this built in mechanism. It is sometimes called the "Fight or Flight Syndrome". Humans unlike animals can hear and interpret a verbal or spoken threat. For example if I tell my dog I am going to shoot him, he continues on and is not scared. If I tell the clerk at 7-11 I am going to shoot you if you don't give me the money, they have a huge sympathetic reaction. The more threat the bigger the reaction.
When people attempt to lie while be questioned about something important to them a reaction is observed on the instrument. A great deal of psychology and physiology is involved in the process of polygraph testing. Question formulation and test construction are very important in a successful polygraph examination. When done properly a specific issue test is about 97 percent accurate. When you Consider that witness identification is only 60 to 70 percent accurate you see why all government agencies use the polygraph.
The newest generation of computerized polygraph have increased the number of tests performed and helped eliminate some of the early problems with interpreting charts making it more universal for all users. Anyone can go out on the internet and see hundreds, if not thousands, of sites on how to beat or cheat a polygraph test because it does not work. If it did not work, why would there be so much negative press, and anti-polygraph web sites, on how to defeat it. Polygraph testing is used by all major police agencies, FBI, CIA, the US Government and other governments of foreign countries. The polygraph tests and results there after speak for themselves when it comes to the accuracy of the instrument in the hands of a competent examiner.
If you need to know the truth, Freedom Polygraph has the examiners and integrity you need.