A polygraph is a machine that is usually used as a lie detector. It is designed to sense and record changes in physiological indicators, for example, the breathing rates, conductivity, and pulse of a person. A polygraph is not that accurate given the fact that some people can lie without an increase in the heartbeat rate or without being anxious. Other people can say the truth but with anxiety. But, there are many instances where the polygraph detects correctly. Therefore, there is no clear indication of how accurate a lie detector can be. Hence, we need to understand the issue of how reliable a lie detector is in terms of detecting if a person is telling the truth or a lie.
Agrawal, Gajal S., et al. “REVIEW ON LIE DETECTION SYSTEM.” (2019).
The authors try to demonstrate that noninvasive physiology sensing can be used to detect stress and lying. The work is based on a systematic literature review used to come up with a conclusion. The non-invasive physiological features include pitch variation of the voice and variability in the heartbeat rate. The features mentioned are known to be related to high-stress levels that exist in real life. “Moreover, people who are in doubtful condition are worried and scared about taking polygraph testing. Because they try to convince employees about they are innocent. And their endeavor causes a physiological change in their body, and the result of it, they are accepted, offender. By looking at all of them, the polygraph is not a useful test for lie detecting.” (Agrawal, 1119). The artificial neural network is said to be 82% accurate when determining high-stress levels.