Questions and Answers
What is a polygraph?
The polygraph is an instrument that uses sensors such as a blood pressure cuff to measure the physical changes that are taking place the test subject’s body as an examinee answers the test questions. These changes are beyond the control of the test subject. Among the changes being measured are changes in blood pressure, in pulse rate, and in skin conductivity that are known to occur when a person is lying. The sensors that measure these changes are put on or attached to the examinee’s body externally so there is no need for the person being tested to immodestly remove clothing, or be subject to any unwelcomed inspection of their body.
How accurate is polygraph testing?
The answer a person can get to this question depends in great part on who you ask. It is Mr. Podoll’s opinion that, when it comes to research, many individuals, including some counseling professionals, have not reviewed the body or research done with regard to the accuracy of the polygraph process. If a reasonably exhaustive survey of the research literature is done, one can find a bafflingly wide range of accuracy findings. In order to decide which study is to be trusted, one would have to know something about research design, and statistical methods. For example, one should make a distinction between lab studies and field studies, and between studies employing examiners in training with little experience, and studies employing experienced examiners,
The American Polygraph Association has a compendium of 80 research projects, involving 6,380 examinations. Mr. Podoll believes this is a fair sample of studies. The researchers conducted 12 studies of the validity of field examinations, following 2,174 field examinations, providing an average accuracy of 98%. Researchers conducted 11 studies involving the reliability of independent analyses of 1,609 sets of charts from field examinations confirmed by independent evidence, providing an average accuracy of 92%.
Bersh, P. J. (1969). Journal of Applied Psychology, 53(5), 399-403.
The lie detection judgments of polygraph examiners in criminal investigations conducted by the military services were validated against unanimous guilt-innocence decisions by a panel of four Judge Advocate General (JAG) attorneys. Level of agreement was 92.4%.
Honts, C. R. (1996). The Journal of General Psychology, 123(4), 309-324.
Data from the files of 41 criminal cases were examined for confirming information and were rated by two evaluators on the strength of the confirming information. The decision of the original examiners were correct 96% of the time, and the independent evaluations were 93% correct
Patrick, C. J., & Iacono, W. G. (1991). Journal of Applied Psychology, 76(2), 229-238
Records from independent police files for 402 control question test (CQTs) conducted during a 5-year period by federal police examiners in a major Canadian city, the hit rate for identifying guilty subjects was 98%.
Raskin, Kircher, Honts, & Horowitz. (1988). Report to the National Institute of Justice.
Polygraph charts from examinations conducted by the U.S. Secret Service were sampled and blindly interpreted by polygraph examiners and by computer interpretation using algorithms
Decisions by the original examiners on individual relevant questions ranged from 91-96% correct on confirmed truthful answers and 85-95% correct on confirmed deceptive answers.
Is the test painful, harmful or hazardous to my health?
Apart from individuals with unusually low pain thresholds, the test does not involve significant pain for the great majority of people. There is mild to moderate discomfort caused by the blood pressure cuff, which squeezes the arm when it is inflated. The test does not cause any physical harm, nor will your physical health be impacted.
Can a sick person or someone who consumes medication take the test?
An Illness at its worst stage can be problematic, and my preference would be to delay testing until the illness has passed. Generally speaking, taking medications should not pose much of a problem. Mr. Podoll will discuss your physical condition with you prior to the test. Call Mr. Podoll prior to your appointment if you are feeling ill, or have questions about medications. Please, do not conceal information regarding your medical status as this information is being sought for your own benefit.
Does my nervousness and anxiety bear any effect on the test outcome?
A common concern amongst examinees is that an examiner might conclude they are lying merely because they are feeling nervous or anxious. This kind of error will not occur, and Mr. Podoll will explain why this is the case in greater detail during our session. The polygraph process is designed in such a way as to allow the examiner to differentiate between situational anxiety and any effort to lie. So if you are truthful you will pass the test and if you are lying, your body will betray the deception by responding in ways that differ from how your body responds due to any feelings of nervousness or anxiety alone.
What is the test procedure?
After verifying your identity, the procedure will be explained to you in a detailed step-by-step way. You will be questioned about any physical and/or mental health issues that could interfere with my ability to obtain quality test data, about the circumstances that led to your participating in the test in the first place, and about other historical information. Based on the information that you provide, I Mr. Podoll will phrase the questions that you will be asked in the test. Only then will the polygraph sensors will be attached to you and the test will begin. During the test, a set of questions will be presented to you multiple times in order to establish whether you are answering truthfully or whether you are lying.
Can I refuse to take the test?
ABSOLUTELY. Furthermore, your refusal to participate in testing should not be turned against you.
Are the polygraph test results admissible in court?
You should consult your lawyer for what might be a more complete or comprehensive answer but generally speaking the admissibility differs from state to state and may depend upon whether your attorney and the attorney for the state (prosecuting attorney) agree before testing that they would not object to the test results being offered as evidence in your case. A test being admitted under this kind of agreement is known as a stipulated test.
Can the test be beaten?
While this is possible, the probability of the average person being successful at making a deliberate effort to beat the test is not high. In other words, you can make the effort, but you should not expect your efforts to succeed. The typical methods that people use to attempt to produce a favorable result and thus beat the test are well known to polygraph examiners. Anything that a person might read on the Internet about trying to beat the test is the kind of thing a polygraph examiner has read as well. Without a good deal of practice, and some way of getting feedback on how the method or technique being employed to defeat the test is working during practice, most people would be so clumsy in their efforts that the examiner would be very likely detect what the test subject would be up to. The same thing may be said of any effort made to try to “help” the examiner to not make a mistake. If you are determined to try to get away with not telling the truth, it would be best for you to not take the test at all.
“I don’t want an instrument to determine my innocence or guilt.”
This concern is not founded on what history has to teach us about how polygraph test results have been used by the court system. The polygraph is ONLY a diagnostic tool. The information that it provides is almost always used along with other pieces of information about a test subject, such as psychological test data, the person’s behavioral history, and the expert opinion of professionals with expertise in evaluating individuals in your situation.