A lie detector is a device or procedure used to obtain information from a person through physiological responses. It is usually done by measuring changes in blood pressure, respiration, and skin conductivity. The machine records these changes in the form of a graph or trace, which can be later interpreted by a trained operator.
How do polygraphs work?
A polygraph machine measures multiple physiological responses at once, including blood pressure, heart rate, respiration, and skin conductivity. The theory is that when a person lies, they experience stress which causes these bodily functions to change. The machine records these changes and produces a graph or trace that can be interpreted by a trained operator.
There are two types of polygraphs: control question and guilt detection. Control question polygraphs are used to screen applicants for government jobs or security clearance. The questions asked are designed to elicit a known stress response (e.g., “Have you ever been arrested?”). If the applicant’s physiological responses to the control questions are similar to their responses to other questions, it’s assumed they’re telling the truth. Guilt detection polygraphs are used in criminal investigations and are based on the theory that liars will experience more stress when answering questions about the crime than when asked control questions.
Choosing a lie detector provider
When choosing a lie detector provider, it’s important to make sure they’re accredited by the American Polygraph Association (APA) or the American Association of Police Polygraphists (AAPP). These organizations have strict standards for training and equipment. It’s also important to choose a provider who has experience with the type of test you’re taking. For example, if you’re taking a control question test for a government job, you’ll want to choose a provider who has experience administering this type of test.
Preparing for your polygraph
It’s important to be well rested and comfortable on the day of your polygraph. You should also avoid caffeine and alcohol, as these can affect your physiological responses. Be sure to tell the polygraph operator if you’re taking any medication that could affect your results.
During the polygraph
You’ll be asked a series of questions by the polygraph operator. The questions will usually be about your personal history and may include both control and guilt detection questions. It’s important to answer all questions honestly and without hesitation. If you try to withhold information or lie, it will likely show up in your physiological responses.
After the polygraph
The polygraph operator will interpret your results and provide a report to whoever requested the test (e.g., your employer). The report will either state that you passed or failed the polygraph. If you failed, you may be asked to take another polygraph at a later date.
What if I’m not comfortable with the polygraph?
If you’re not comfortable with the polygraph, you can refuse to take the test. However, this may have negative consequences if you’re taking the test for a job or security clearance. If you’re taking a criminal guilt detection test, you can’t be forced to take the polygraph against your will.
Conclusion
Lie detectors can be useful in some situations, but they’re not perfect. There’s always a chance of false positives or negatives, so it’s important to interpret the results carefully. If you’re considering taking a polygraph, make sure you choose a reputable provider and prepare for the test.