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Dr. Barland,

My position is the latter, Mr. Lee was branded a LIAR. He PASSED his tests, but the FBI insisted that he was "deceptive".

If he truly violated National Security, then yes he should be punished. My personal opinion is he didn't sell or pass anything to foreign agents or governments, he simply took sensitive work home, that in itself hardly warrants the treatment he was subjected to.

One last comment Dr., Yes the process missed Ames and Montes, and they continued to spy. So why do these high profile criminals slip through the cracks when you tout the polygraph as highly "accurate"? Could it be possible that they knew countermeasures?

Fred F.

Gordon,

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I agree with you that the polygraph does not detect deception per se, even as it does not detect spies per se. And yet the federal polygraph community represents to the public that polygraph "tests" detect deception. The notion is implicit in the official DoDPI term for polygraphy: "psychophysiological detection of deception."

Would you agree that CQT polygraphy also lacks "control" within the scientific meaning of the word? How can the polygrapher possibly know that he has "so structure[d] the testing environment to control extraneous responses?" That is, how can the polygrapher distinguish between the anxious but truthful subject and the anxious and deceptive subject?

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One of the standard questions asked in counterintelligence-scope polygraph screening is something similar to, "Did you ever provide classified information to any unauthorized individual?" Clearly, the person who disclosed classified information to his (uncleared) girlfriend is being deceptive when he answers that question, "No."

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Implicit in the above statement is the unfounded assumption that the polygraph examiner can actually distinguish between a lying and truth-telling in the first place.

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I don't think it has been established that the fact that a question causes a person to think of something specific every time it is asked will necessarily result in a reaction to the question that is measurable by the polygraph instrument.

With regard to the wisdom of making admissions to relevant questions, our advice in The Lie Behind the Lie Detector is not strictly speaking to "make no admissions whatsoever" with regard to the relevant questions but rather to have an explanation prepared in advance that cannot be turned into a damaging admission, as explained in the subchapter "To Explain or Not to Explain Responses to Relevant Questions" (pp. 134-35 of the 2nd ed.).

You earlier started a message thread titled CM advice on dealing with DI results misguided. I don't think that you or the anonymous polygrapher whose message you forwarded offered a convincing argument that a subject accused of deception in the course of a polygraph interrogation would benefit by making an admission against interest.

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In all the polygraph studies I've read, "deception" seems to have meant that the subject answered the question "untruthfully," in the common sense of the word. For the sake of argument, let's say that the person who provided classified information to his girlfriend who has no security clearance is asked, "Did you ever provide classified information to an unauthorized individual?" If he answers "No," he's deceptive. Similarly, if a person who has robbed the 1st National Bank is asked "Did you rob that bank?" (after it has been made clear to him which bank "that bank" is) answers "No," he's deceptive.

With this commonsense understanding of "deception" in mind, what is the sensitivity and specificity of CQT polygraphy for the detection (or inference, if you will) of deception (i.e., whether a person has answered a question truthfully)?

George,

You asked:

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That is the whole purpose of the comparison questions.  If the person knows he is being completely truthful regarding the relevant questions, but has doubts as to whether he can be completely truthful when answering the comparison questions with a simple "No," he tends to react more to the comparison questions than the controls.  They serve to protect against that cause of false positive errors.

Peace,

Gordon

George wrote:

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The commonsense understanding you described is limited to the clear-cut, black-and-white situation in which the person is either being completely truthful or completely deceptive (i.e. lies of comission).  This is often found in laboratory research paradigms, but ignores many real-world situations frequently found in security screening, which can be rife with ambiguities.  This is why the examiner often uses the term DI (deception indicated) or NDI in criminal investigations, yet uses SR (significant response) or NSR to describe the results in screening situations.

The sensitivity and specificity of the polygraph technique depends upon a number of variables, such as how deception is defined, what the test issue is, how many test issues are on a test, the ambiguities inherent in the testing situation, and whether the test is a criminal investigation or security screening.  Can you define your question more precisely?

Peace,

Gordon

George,

You're looking for a simple answer.  What I'm trying to convey is that there is none.  We can talk about the accuracy of examiner decisions (which is what the 1969 Bersh study examined), the accuracy of blind chart evaluations (which is what the more recent studies examine), the accuracy of decisions on individual questions within a multi-issue test (as opposed to overall decisions based on the test as a whole), etc.  The sensitivity and specificity vary according to what criterion you are using as a decision and how the CQT is employed. 

At the risk of repeating myself, I must stress that one of the more important variables is the definition of deception.  You  feel more comfortable with confining it to lies of commision, which is what most of the laboratory research has focused on, but which ignores the complexities of many real-life situations.

To answer your question as best I can, I know of no official government statistic regarding sensitivity and specificity.  I doubt that one exists, nor is likely to exist in the foreseeable future.  A lot depends on the situation in which the CQT is used, e.g. a single issue criminal examination versus a multi-issue screening examination.

The probabilities cited in the Nicholson case refer to how Nicholson's reactions compared to the total number of verified truthful and deceptive sets of charts in the data base used by that particular algorithm.  The size and make-up of the data base has varied over the years as more and more verified cases are added to it.

Peace,

Gordon

J.B. McCloughan wrote on Apr 13^th, 2002 at 5:09am:


The effects of amplifiers, filters, and sampling procedures
have clearly adulterated the data.... This is not a scientific project... there is no reason to believe that the [algorithm] developed at APL has any power whatsoever to discriminate between truthful and deceptive subjects... In summary, the contractors [APL] have developed, delivered, and sold an algorithm to separate DI from NDI subjects that has no demonstrated validity...

The entire article is here

George,

Specificity and sensitivity can be expressed in a controlled setting where the number of cases of each are known and can be confirmed.(i.e.. 50 truthful and 50 deceptive)  It can also be expressed in a field setting with a given sample of cases where there is a known outcome of the sample. If you set base rates based on a human assumed outcome of a population, the true percentages are bound to be skewed.  The fact is in a forensic field science there is no way of telling how many of one or another will come in a given day, month, year, etc...  

For a simple break down of the Theory of Polygraph go to: http://www.mattepolygraph.com/ ;

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As for first part of your statement, there is a known sensitivity and specificity for polygraph that has been established and proven through peer-reviewed scientific research.  The later part of your statement has little or nothing to do with the prior portion.  As has been said before, this is simply a statistical probability that a given sample is or is not.  As for ones' ability to testify based on statistical probability, DNA experts testify to just that.  They say that based on a known data base and assumed probability the chances of someone having the same DNA is 1 in (enter probable number).  Yet there is no way of being certain what the true percentage is unless the entire world were to submit to DNA testing, the samples are collected, processed, entered into a world database, and all samples are checked one against another.

Note: this post was edited to correct a formatting problem; except for this note, no words were added, deleted, or changed. --AntiPolygraph.org Administrator