05 Apr

How accurate are Lie Detectors

Lie detectors are electronic devices used in order to detect whether a person is telling lies or truth. We have seen these devices in movies and TV series, but are they real and do they actually work? Let’s find out here.

Lie detectors are polygraph machines. They do not work magic by telling truth or lie. Instead, they are a mere monitor that records various changes in the regular physics of the body.

In most people, telling lies or being deceptive causes discomfort and fear. This results in a change in body temperature, heart rate, sweat rate and breathing. Now, our polygraph machine works on recording these changes.

If there is an increase in these parameters, then a person can be assumed to be telling a lie. If there is no change and a person is being sincere, the body parameters remain steady.


While most cases of lie detection using lie detectors are said to be reliable, there is no shortage of cases when lie detection tests have given false positive and false negative results.

There are people in this world who aren’t affected by telling lies. Their bodies show no changes even if they lie continuously. In these cases, lie detectors are useless. On the other hand, there are also cases in which people are naturally nervous and get excited and anxious just by being asked a question. So, the reliability of lie detectors is not yet 100 percent.

Lie detector test results are not acceptable in court because of this very reason. However, lie detectors have helped investigators a lot in solving criminal cases and proceedings.

General use

Nowadays, lie detectors are not just used by the police and the government, it is also available for private use. People use lie detectors to verify various controversial situations such as those involving employees, spouse or family matters.

Some companies necessitate a  lie detector test as a  part of their interview process to choose reliable employees. In short, lie detectors have come into the public use more than the government. As technology continues to advance we may see lie detectors become more accurate.