For many years, things like lie detectors have been used in a variety of different ways - they typically require you to deal with a lot of various questions and answer sessions to ensure that the people you are talking to can get the right kind of answers back from you. It's seen as unbeatable, but many people have claimed to have a method of beating a polygraph test.
You hear about these being used in criminal investigations all the time, and their overall power and strength cannot really be questioned a lot of the time - for the normal person, they will work just fine.
However, since a polygraph test is more or less just reading things like perspiration, breathing rate, blood pressure and pulse if you can get out of the habit of these raising when you "lie" they are far less accurate in their readings.
If you stay calm and composed, as you are supposed to when you tell the truth, then they cannot really pick up the different patterns of what you are really feeling like. Therefore, it can be quite hard to judge just how successful these are in terms of helping out in the midst of a criminal investigation.
When the test actually starts, you will be asked three or four questions to help establish your baseline levels - then, the "real" questions will start and the signals are then recorded on the moving screen or paper on an older machine. A large change in the heart rate or high blood pressure/increased perspiration usually indicates that something is wrong with the answer being provided.
The idea, then, is that we all act normally when talking in simply conversation and telling the truth but when we tell a lie it comes out as far more aggressive and can cause our bodies to start racing and causing a lot of problems along the way. It's a big problem that many people can tend to face and will usually need to deal with various things like heightened blood pressure etc. to be caught out as very few people can lie under this kind of pressure.
However, the problem is that these tests answers are subjective; if the person reading it is going to interpret the answers in a different way from someone else, it can cause the test to have a bit of a subjective slant to it.
For this reason, they are rarely used in criminal investigations anymore due to the fact they can be game and that the answers are purely subjective in many ways.
About the Author:
If you are under investigation you owe it to yourself to seek out an experienced criminal defense attorney who can investigate your case and may be able to prevent your arrest. Andre Belanger is an award winning trial lawyer located in Baton Rouge, Louisiana. This former Orleans Parish homicide prosecutor has brought nearly 200 cases to trial and has litigated cases before the United States Supreme Court. You can learn more about him and his firm at http://www.manassehandgill.com