What is a lie detector?
Lie detector (also known as "polygraph") is a device, that is used to register physiological changes, such as: sweating (skin-galvanic reaction, GSR), temperature, pulse, heart rhythm, breathing and voice. Under the influence of emotions, characteristic changes beyond concious control take place on the graphs. Thanks to the analysis, we can make assumptions about the subject's features that are interesting to us.
Polygraphs are most commonly used in the law enforcements, allowing to verify the subject's truthfulness to a large degree (up to 90%). That is why a polygraph is very often refereed to as a "lie detector". The first polygraph was used for these purposes in 1921 by John Augustus Larson. Taking the huge potential and the practical value of tests into consideration, this device has been constantly developed since today. Theoretically, there are ways to cheat a polygraph - for example, by deliberately inflicting pain during the test which results in biased graphs. Practically, the tested subject is constantly watched during the test and it is almost impossible to manipulate one's reactions in a way that could be missed by a person who carries out the examination. When a polygraph examination is done professionally, its relevance is up to 90%.
Lie detector now
Now, a lie detector is an electronic device that works in connection with personal computers. Thanks to its compact size it can be easily carried and the data gathered during an examination is safely stored and conveniently processed. The sensitivity and the amount of data that can be obtained during this examination have been greatly increased by the use of complicated mathematical algorithms.
Polygraph is widely used in many different fields, such as:
detective, insurance and police investigations
periodical employee verification
medicine (for example - examination of the people in coma)
Legal basis for polygraph examinations in Poland
In spite of its undoubted efficiency, polygraph examination still rises many question in reference to the legality of the whole process.
In Poland, a polygraph is one of the approved devices that can be used during an investigation. Art.192a of the Criminal Code explicitly mentions the possibility of its usage. An examination can be made with the consent of the tested person In other cases, for example during a recruiting process or a periodical employee verification, a consent of a tested person is all that's needed to perform such examination. In the light of the law, it is treated as a standard psychological test.
Apart from the most commonly associated examination which is lie detecting, polygraph can also establish subject's characteristics, such as:
level of neuroticism (emotional stability)
resistance to stress
resistance to conflict situations
ability to solve intellectual problems
temper (the way that someone reacts)
empathy (the ability to feel someone else's emotions)
Because the reactions registered by a polygraph are unconscious, we are allowed to get the information that can't be obtained in any other way.
1. It can be used to establish the truth about the past events that a person wants to hide, for example, about one's competence, addictions, theft, drinking in work. It is a preventive measure that can highly increase company's safety against a dishonest behaviour of its employees. This examination can be made periodically or during the recruitment procedure.
2. Tracing of the perpetrators, for example, at the premises. A polygraph test can speed up an investigation and some times it is even unnecessary, because a person who faces this examination admits to a crime.
3. Establishing informations that are not known to the tested person, for example, the level of stress burden, emotive immunity, etc. These features can be very important while staffing managerial posts, which are connected with stress and contacts with other people. We gain confidence that this is the best person for a given job.
4. Polygraph examination is quick. Gathering the needed informations takes less time and thus, it can be used in other ways.
5. As opposed to many other psychological tests that are based on the tested person's opinions and knowledge, during a polygraph test we gain access to the information that is unbiased.
6. Verification of the candidate's CV data is often difficult or even impossible to do. Polygraph test is always made privately and the gathered informations are true and unbiased.