3. The Polygraph (Lie Detector) Test

People are still under the notion that Scott Peterson refused to take a polygraph (lie detector) test. They are mistaken. From Modesto Police Department's own records, it is clear that within the first few hours of Laci’s disappearance, he agreed not once, but twice to take a polygraph.

First time. From interview held with Detective Brocchini 24-25 December 2002:

BROCCHINI: Would you be willing to take a polygraph?

PETERSON: Sure.

BROCCHINI: So what you’re telling me Scott is there no, you have no idea where Laci is.

PETERSON: None.

In the above, Brocchini didn’t determine when this test would take place.  How could Scott have known that Brocchini didn’t have the intention to immediately take him to be tested that evening? And yet, further into the interview, he agreed again with no mention of consulting an attorney or any other person first: 

BROCCHINI: Would you be willing to take a polygraph?

PETERSON: Yeah . . . They're accurate, right?

BROCCHINI: Yeah, yeah, I mean I, it's not nothing that can be used against you, but yea, I believe they're accurate.

PETERSON: No, I'm certainly willing.

BROCCHINI: It wouldn't be now, it'd be, ya now, in a day or two.

PETERSON: Now . . .

BROCCHINI: It's just like the next step in this thing.

PETERSON: Sure. 

According to Catherine Crier's book "A Deadly Game", by the next day Lee Peterson had advised his son against taking a polygraph and Scott subsequently relented to take the test.

Later on in the investigation, Scott Peterson again consented to taking a polygraph. This time at the request of Amber Frey. He arranged an appointment with Melvin King for February 1, 2003. He was due to meet Amber Frey at the office of Expert Polygraph Services, but upon arrival Peterson saw Brocchini and could not see Frey in attendance. No doubt feeling that she was in collusion with Law Enforcement and that this was a set up, Peterson left.

The Truth about Polygraphs & How they Work

"There are no whole truths: all truths are half-truths. It is trying to treat them as whole truths that plays the devil"  Alfred North Whitehead

There is no science involved in polygraph testing. Even the test itself is based upon the deception of the polygrapher.  

Here, in simple terms, is how a polygraph works. The polygrapher, will warn the examinee that all their answers must be truthful, however, the truth is that he/she actually assumes that denials in response to certain questions will be untrue, or that the examinee will at least have doubts. These questions are known as “control questions”. In other words, they are questions designed for the examinee to (probably) lie to when answering.

For example, in the instance of a polygraph being undertaken for employment purposes, the control question could be "Have you ever lied to a person of authority?" Now both we and the Polygrapher know that we have ALL at some time or another lied to someone of authority, be it a teacher at school or a police officer, but by implying that a person who would do so is unsuitable for the prospective job, the polygrapher tries to maneuver the examinee into responding untruthfully. The answer is known as the “probable lie”.

All answers to subsequent questions are then compared to the control question/probable lie. The polygrapher scores the test by comparing physiological reactions to these probable-lie control questions with reactions to relevant questions such as, "Have you ever used an illegal drug?" If the reactions to the control question are greater than that of the relevant question, the examinee passes; if the reactions to the relevant question are greater than that of the control question, he fails. If reactions to both are approximately equal, then the result is “inconclusive”.

Having read this, it is easy to see that this test is bias AGAINST those who are honest honest. The person that answers truthfully to the control question is the most likely to fail!

On the other hand the “liar” can easily beat the test by secretly enhancing their physiological reactions to the “control” questions.

Why Polygraphs are Deemed Unreliable
 

The physiological reactions the polygraph measures are based on variations in breathing, pulse rate, blood pressure and perspiration. Those that are advocates of the polygraph, assert that these are all relative indicators of deception, however, there has yet to be a compelling theory found connecting these measurements and none of the above has been validated by scientific research. According to the American Civil Liberties Union:

“those physiological changes can  be triggered by a wide range of emotions such as anger, sadness, embarrassment and fear.  In addition, a variety of medical conditions  such as colds, headaches and neurological and muscular problems can distort the results.”

In addition, lack of food and/or sleep or, interrogation immediately prior to the polygraph are all likely to affect the outcome of any test.

The American Medical Association has such grave doubts about these relative indicators of deception that one expert testifying before Congress in support of the 1988 Employee Polygraph Protection Act (EPPA) was forced to  pronounce: "The [lie detector]  cannot detect lies much better than a coin toss." (The EPPA prohibits the use of polygraphs by private companies in the hiring process).

Can individuals deceive the Polygraph? In a word – yes! And very easily. Techniques are simple to learn – they are known as Countermeasures and are considered very successful. According to retired Supervisory Special Agent Dr. Drew C. Richardson who holds a Doctorate in physiology, is a graduate of the Department of Defence Polygraph Institute (DoDPI) basic polygraph examiner’s course and worked in the Bureau’s now obsolete polygraph research unit, “…anyone can be taught to beat this type of polygraph exam in a few minutes.”

Browse the internet and you’ll find countless companies freely offering information on how to defeat the test. Those that charge do so with money back guarantees. Polygraphers have claimed they can detect such countermeasures, but to date, there has been no evidence provided to back up this claim.

Advocates of the Polygraph

The groups which hold belief in the Polygraph’s viability are Law Enforcement, Government Agencies at federal, state and local level and the American Polygraph Association (who of course have a vested interest).

Law Enforcement and Government Agencies alike are equally partial to the polygraph because although it may be unreliable, it encourages confessions/admissions. Having said that, the Federal Bureau of Investigation (FBI) hold reservations about the polygraph and has some stern advice:

"The FBI uses the polygraph as an investigative tool and cautions that the results should not be relied upon to the exclusion of other evidence or knowledge obtained during the course of an investigation. This policy is based upon the fact that, a) the polygraph technique has not reached a level of acceptability within the relevant scientific  community, b) scientific research has not been able to establish the true validity of polygraph testing in criminal applications, c) there  is a lack of standardization within the polygraph community for training and for conducting polygraph examinations." James Murphy, Director FBI Polygraph Unit

So to, does the Central Intelligence Agency (CIA):

“Polygraph is more art than science, and unless an admission is obtained, the final determination is frequently what we refer to as a scientific wild-ass guess (SWAG)" Retired CIA Examiner John F. Sullivan

"[The CIA's] reliance on the polygraph is truly insane"
Former CIA Director John M. Deutch

Proponents often claim that Polygraph results are 95-99% accurate, however the studies quoted have received no scientic reviews and have usually been conducted by those with a vested interest in the results.

Opponents of the Polygraph

The list of those who have voiced both opposition and concern at the use of the Polygraph and it’s unreliability is great. It includes the American Civil Liberties Union, Professor David T. Lykken, former President of the Society for Psychophysiological Research and now the US's foremost expert on the failings of polygraphy, the National Academy of Sciences National Research Council,  the American Health Foundation, members of the Society for Psychophysiological Research and Fellows of the American Psychological Association and an array of former FBI and CIA Special Agents to name but a few.

Dr Drew C Richardson, former Supervisory Special Agent at the FBI Laboratory Division, is another adversary of the Polygraph. He asserts that; "[Polygraph screening] is completely without any theoretical foundation and has absolutely no validity...the diagnostic value of this type of  testing is no more than that of astrology or tea-leaf reading."

In 1997 Journal of Applied Psychology survey put the polygraph test's accuracy rate at only 61%, and, according to William G. Iacono, Ph.D., Professor of Psychology and Neuroscience University of Minnesota who gave evidence to the U.S. Senate Judiciary Committee Hearing, 2001 entitled "Issues Surrounding the Use of Polygraphs", Polygraphs are defective with approximately 40% of those innocent, unsuccessful in passing: "The best studies of polygraph tests, using real-life cases and published in top scientific journals, find that innocent people fare  little better than chance on these tests, with 40% or more failing on average."

Conclusion

In short, the Polygraph is an interrogation tool. It's main purpose is to intimidate the examinee. The fact that it is not admissible in court proves that even Law Enforcement and it's agencies do not hold it’s results as unequivocal. With reference to criminal cases, it is not used to clear suspects, it’s sole purpose is only to attempt to elicit a confession which CAN be used in a court of law.

So back to the Peterson case. Having read the above, had Scott Peterson taken a test, would you accept as 100% true the results, irrelevant of whether he passed or failed?

This series is authored by Nadia Taze