It is the human nature to lie in situations when one has to protect himself. Lying is a commonlyused defense method to avoid a troublesome situation. Polygraphs are instruments developed to monitor a person’s physiological reactions. It is simply a combination of various medical equipment,which monitors the occurrence of changes in the human body. During a lie detector test, the person on trial has to face cross-questioning about a particular incident, the examiner monitors pulse rate, perspiration rate,and blood pressure levels in comparison to the normal levels of the person. Polygraphs are most commonly useful in cases of investigation and interrogation. However, some private organizations have also started using this equipment for interviewing purposes.
How do polygraphs work?
- Firstly, five to seven sensors are hooked up to the body of the suspect on trial.
- These sensors help to monitor various movements and changes in the body of the suspect.
- Before starting the test, the assessor asks common questions to make the person on trial understand about the working of the test.
- Next, the person on trial has to answer a series of questions that are relevant to the investigation.
- During the lie detector test, changes in blood pressure, respiratory rate,and pulse rate are a monitor with help of polygraph.
- The examiner then evaluates the patterns observed during the test and declares whether that person is honest or is lying.
The accuracy of polygraphs.
Polygraphs are highly accurate,however; a 100% accurate result is not achievable by use of them. The polygraph only examines the changes in the body of a person. If one is able to stay confident during the test then one might be able to deceive the machine. Most often people tend to get nervous during the trial and as a result, they are not able to control their vitals, which shows in their test results.
Polygraphs have proven themselves a worthy equipment in Lie detector test. Although, a final decision cannot be formed on basis of their results they do set a positive course for investigation.