Polygraphs have been around forever and have been used for a very long time. Normally they are used to detect people’s psychological changes and pulses to detect lies and other fibs they may be telling. It is important that as a human it is very difficult for even the best of the best liars to get passed a lie detector. You do not want to even bother trying to get away with it because not only will you most likely fail, but you will also get charged with even more and have an even harder time in court dealing with your case.
Where did Polygraphs come from?
The polygraph was originally invented in 1921 by John Larson. Looking for a way to get better results off of interrogating people or getting another more un-biased way to see if people were being honest with the people asking questions, was the motive for this invention.
Ever since then, many companies have popped up penalizing in lie detectors and are doing quite well for themselves. (http://www.liedetectortest.uk/the-history-of-the-polygraph)
They are often hired on to take control of these parts of the investigations and are really the go to guys when trying to find the liar and honest responses in investigations or interrogations. It is important to note that not anyone can become a lie detector operator. You must pass many government standard checks, complete tests and take multiple mental health checkups. This will show that you are able and ready to take on this serious task and find the criminals in the billions of honest, good people.
If you are interested in how polygraphs work, make sure you check out that link above and take a good look around. There is a lot of interesting stuff, people and cases surrounded by these polygraphs and a lot of history has been bended and re-written because of these amazing devices.