Lie detector work?

Polygraph we see in the movie How does it work? OK, then it really work?

Lie detector, known as the "polygraph" (polygraph) invented in 1921 by John Larson, an American who was both police and medical students. The working principle of the polygraph is located on that theory. When people lie, the body will show that questionable behavior can be detected through pulse measuring device.

During the investigation, The investigation will question the suspect with a series of questions prepared. This includes questions on the investigation to know the correct answer, for example, or a family history of suspects, etc., so that the investigation can observe the response of the suspect when he speaks the truth. The investigators will also ask relevant questions, such as the pipeline closed the case of a suspect is telling the truth or lying over the air signals that polygraph results. If the signal is different from the truth as he answered there was a possibility that he was lying.

The use of polygraph in the investigation of a contentious issue in the guts. Because the signals the body is complex and many factors are involved. The suspects are innocent may feel more pressure. The nervous symptoms were interpreted as symptoms such dubious when asked directly, "Do you shoot your wife, right?" The suspect may feel threatened and I deny with intense emotions. Make signs of twitching like a man charged in the investigation so suspiciously use polygraph investigators are trained to ask questions that bordered the middle. The suspects revealed the facts of the case come out like "the dead were shot with a 9 mm., Or not?", Etc. However, the turnout like this, it does not guarantee that the polygraph is caught lying. Real good

Investigation and police agencies in the US use a polygraph in the initial investigation. But there are a few states that allow the use of polygraph operators ruling of the European countries with the tools that Polygraph government agency that the police in Thailand have used a lie detector it. but not often

The signal reveals the dubious lying

It is based on the theory of the polygraph. When people lie, our body will show signs of dubious excitement unconsciously and uncontrollable. If using a polygraph signal of a suspect currently under investigation. Police will be able to distinguish whether a suspect is telling the truth or lie some where.

Pulse and blood pressure will rise liar.

Lung bouncer to short breath frequently.

Nervousness from lying skin to sweat oozing palms and fingertips.

When we lie leg Our legs are shaking a little bit. Suspiciously because of concerns This shake is beyond the control of the mind.