A polygraph, more commonly known as a lie detector, is an electronic instrument that measures a number of physical responses to psychological stimuli. The instrument is designed to measure heart rate, respirations, blood pressure, and galvanic stimulus responses (GSR), electrical impulses that are detected and measured on the outside of the skin. While someone being tested might be able to control their breathing, heart rate, and even blood pressure, it is unlikely that they can control all of these functions plus the involuntary electrical impulses they produce when they are being truthful and when they are being deceptive. The device is used by people who are trained specifically in administering polygraph examinations.

How It Works

In a typical investigative examination, there is a lengthy discussion between the examiner and the test subject during which all of the questions that will be asked on the test are disclosed. Oddly, there are no surprise or trick questions that are thrown at the subject while they are strapped to the box. But a law enforcement employment polygraph is different.

Law enforcement candidates are attached to the machine, and a running dialogue between the examiner and the examinee takes place. Surprise questions come from out of the blue, and the person's unconscious reactions to the questions are what the examiner is looking for. Questions about committing a criminal act often spark memories of a time in junior high school when the subject swiped a package of cupcakes from a schoolmate's locker. Although this tells the examiner that the subject probably wasn't the best friend to have in junior high school, it also suggests that as criminal acts go, that particular one wasn't much of a crime. If stealing cupcakes in eighth grade is the worst thing that the person has rumbling around in the back of their mind, then it's likely that it won't be a deterrent to their hiring.

Beating the Test

There are Web sites and books devoted to the science of fooling the polygraph. These so-called guides may have some merit in certain applications, provided the individual being tested has a narrow range of focus with their examination. However, law enforcement polygraph examinations are very broad-ranged and are conducted using a stream of consciousness of the examinee. All of the advice in the world won't help you beat this kind of examination; the only sound advice is to be yourself, and to tell the truth.

Preparing for Difficult Questions

Law enforcement polygraph examinations are often an offensive and distasteful part of the hiring process, because questions are asked that prompt dramatic responses from the person being questioned. Questions such as, “Have you ever had sex with an animal?” or, “Have you ever had sexual relations with either of your parents?” are designed to learn more than an individual's sexual preferences; they are geared to create volcanic responses on the chart for the purpose of assessing the emotional boundaries of the person. What the polygraph will tell them with reasonable accuracy is that there is an absence of deviance and depravity, and that is an absolute must for law enforcement agencies.

Like so many aspects of the law enforcement application process, the polygraph examination is a place where being yourself is essential. Obviously, being truthful will facilitate a more desirable outcome than taking a course of deception. Regardless of the questions asked and the answers given, it isn't what the examiner learns about the candidate that is most important, but what the candidate learns about himself. Applicants will find from the feedback of the examiner that they have certain elements to their character about which they were previously unaware. You can make this the most negative revelation of the entire polygraph experience, or you can use the knowledge about yourself to grow stronger and better as a person.