Do you know how a lie detector machine catches a person’s lies, and how the lie detector test is done?

Polygraph test is done to detect lies, which is also called lie detector test. The lie detection machine known as lie detector was invented in 1921 by John Augustus Larson, who was a medical student at the University of California. It is used to find out the truth. Polygraph test is considered very helpful in investigating criminal cases. But do you know how this machine works.

How is lie detector test done?

To detect lies, wires and tubes are placed on some body parts, after which experts ask questions to the accused. When the accused responds, blood pressure, breathing rate, pulse rate, hand and leg movements etc. are recorded in the machine. On the basis of this record the experts give the test results.

What is the basis of test?

It is believed that if a person is lying during a test, his blood pressure, breathing speed, pulse rate etc. increase. Wires and tubes installed in the human body send signals to the machine, which are studied and on this basis experts take decisions.

Experts start by asking simple questions to the accused, to which the man usually answers truthfully. But as time passes, experts start asking tough questions and the activities involved in answering tough questions help in getting closer to the truth. But this is not considered the final truth. Research also revealed that professional criminals escape this test through practice.