|In the United States, lie detection tests are known as polygraph examinations as well as tests to determine psychophysiological detection of deception (PDD). Although the legal validity of polygraph examinations has been refuted on more than one occasion by the Supreme Court and other jurisdictions, PDD and other varieties of lie detection testing are used by federal and state law enforcement agents for recruitment and interrogation, often for psychological intimidation purposes.
How Polygraph Testing Works
Despite strong and widespread criticism by the scientific community, there is a certain uniformity among polygraph devices and testing procedures. Polygraphs record physiological measurements that can be obtained with rudimentary medical equipment such as pulse counters and blood pressure cuffs. Polygraph examiners can ostensibly determine if questions answered by the test subject are deceptive or not by looking at the physiological measurements.
A lie detector test is essentially a question and answer session. Many examiners ask subjects to purposely lie before the examination begins so that the polygraph can be calibrated. The number of questions and the topics will depend on the agency that requests the test and whoever conducts the examination. Seemingly, only a handful of questions are pertinent to the underlying purpose; for example, a woman named Jane who wishes to become a police officer may be asked a couple of questions about crimes that she may or may not have committed in the past; the rest of the examination may consist of control questions that may have nothing to do with anything in particular.
Common Questions in Lie Detector Tests
Is your name Jane?
Are you really 26 years old?
Were you born in 1988?
Is today Monday?
Do you live in Dubuque?
Do you have a mortgage with Bank of America?
As can be gleaned from the questions above, the expected answers are in the yes or no range. The examiners must already know the answers from Jane’s employment application and background investigation, otherwise they might not be able to differentiate truth from deception. Some examiners insist on asking questions that they think might confuse the subject and thus elicit a physiological reaction. For example, purposely mentioning an incorrect year of birth in more than one question or asking about neighboring towns that the subject may not be familiar with.