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Posted by J.B. McCloughan
- Apr 16, 2002, 03:15 AMGeorge,
Matte's site has a downloadable file that is a supplement for his book.
I believe Gordon was directing his answer to your specific question about the known field sensitivity and specificity of CQT polygraph.
I will reiterate what both Gordon and I have stated, sensitivity and specificity are established in a controlled research setting and the outcome dependent on the variables measured and accounted for. I am not avoiding your question. I plan to respond to your more recent post in the separate thread where this discussion belongs.
Matte's site has a downloadable file that is a supplement for his book.
I believe Gordon was directing his answer to your specific question about the known field sensitivity and specificity of CQT polygraph.
I will reiterate what both Gordon and I have stated, sensitivity and specificity are established in a controlled research setting and the outcome dependent on the variables measured and accounted for. I am not avoiding your question. I plan to respond to your more recent post in the separate thread where this discussion belongs.
Posted by George W. Maschke
- Apr 15, 2002, 03:37 AMJ.B.,
Where on the website http://www.mattepolygraph.com did you find a theoretical explanation of CQT polygraphy?
You also write:
To whom is the sensitivity and specificity of CQT polygraphy known? It appears to be unknown to the U.S. Government. (As Gordon wrote, "...I know of no official government statistic regarding sensitivity and specificity.")
And what precisely is the "known" sensitivity and specificity of CQT polygraphy, J.B.? This is a question you have avoided answering in the message thread The Scientific Validity of Polygraph, which you initiated. In addition, please specify on the basis of what peer-reviewed research the sensitivity and specificity of CQT polygraphy is known.
Where on the website http://www.mattepolygraph.com did you find a theoretical explanation of CQT polygraphy?
You also write:
Quote...there is a known sensitivity and specificity for polygraph that has been established and proven through peer-reviewed scientific research.
To whom is the sensitivity and specificity of CQT polygraphy known? It appears to be unknown to the U.S. Government. (As Gordon wrote, "...I know of no official government statistic regarding sensitivity and specificity.")
And what precisely is the "known" sensitivity and specificity of CQT polygraphy, J.B.? This is a question you have avoided answering in the message thread The Scientific Validity of Polygraph, which you initiated. In addition, please specify on the basis of what peer-reviewed research the sensitivity and specificity of CQT polygraphy is known.
Posted by J.B. McCloughan
- Apr 15, 2002, 02:54 AMGeorge,
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/
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
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/
Quote
If the sensitivity and specificity of CQT polygraphy are not known (and, as you admit, not likely to be known in the foreseeable future), then is it not a fraud on the court for any polygrapher to testify, based on analysis of the charts collected during a CQT polygraph examination, as to the probablity of a subject's having been deceptive?
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
Posted by George W. Maschke
- Apr 14, 2002, 05:37 AMGordon,
The diagnostic test for which no sensitivity and specificity can be specified is a very strange one indeed. All the more strange in that it seems to have no compelling theoretical explanation, either.
If no sensitivity or specificity can be specified for CQT polygraphy, then how can any predictive validity be determined for it when applied as a screening test to any particular population group? Or is that somehow not important?
The answers to these questions are crucial to any rational consideration of what is more effective than the polygraph.
If the sensitivity and specificity of CQT polygraphy are not known (and, as you admit, not likely to be known in the foreseeable future), then is it not a fraud on the court for any polygrapher to testify, based on analysis of the charts collected during a CQT polygraph examination, as to the probablity of a subject's having been deceptive?
QuoteTo 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 diagnostic test for which no sensitivity and specificity can be specified is a very strange one indeed. All the more strange in that it seems to have no compelling theoretical explanation, either.
If no sensitivity or specificity can be specified for CQT polygraphy, then how can any predictive validity be determined for it when applied as a screening test to any particular population group? Or is that somehow not important?
The answers to these questions are crucial to any rational consideration of what is more effective than the polygraph.
QuoteThe 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.
If the sensitivity and specificity of CQT polygraphy are not known (and, as you admit, not likely to be known in the foreseeable future), then is it not a fraud on the court for any polygrapher to testify, based on analysis of the charts collected during a CQT polygraph examination, as to the probablity of a subject's having been deceptive?
Posted by beech trees
- Apr 13, 2002, 01:20 AMQuote from: J.B. on Apr 13, 2002, 01:09 AMThe "mathematical certainty", as you so call, is a computerized score based on confirmed polygraph data. The data collected is then compared to the known data to arrive at a 'probability', not 'certainty', of deception, inconclusive, or truthfull.
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
Posted by J.B. McCloughan
- Apr 13, 2002, 01:09 AMGeorge,
The "mathematical certainty", as you so call, is a computerized score based on confirmed polygraph data. The data collected is then compared to the known data to arrive at a 'probability', not 'certainty', of deception, inconclusive, or truthfull.
The "mathematical certainty", as you so call, is a computerized score based on confirmed polygraph data. The data collected is then compared to the known data to arrive at a 'probability', not 'certainty', of deception, inconclusive, or truthfull.
Posted by Gordon H. Barland
- Apr 13, 2002, 12:03 AMGeorge,
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
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
Posted by George W. Maschke
- Apr 11, 2002, 02:46 PMQuoteCan you define your question more precisely?
Gordon, CQT polygraphy is represented as a science-based diagnostic test for the detection of deception. If that's true, then it follows that, independent of the base rate of deception in any particular population group being tested, it must have a knowable sensitivity and a specificity for the detection of deception. I'm asking you to state what that sensitivity and specificity are.
For example, in the Affidavit in U.S. v. Harold J. Nicholson which you cited above, the probability of deception is stated with mathematical certainty:
QuotePolygraphs
10. On or about October 16, 1995, and October 20, 1995, NICHOLSON underwent polygraph examinations administered by CIA polygraphers as part of his routine security update. A computerized review the examination results indicated a .97 (out of 1.0) probability of deception on two questions: (1) Are you hiding involvement with a Foreign Intelligence Service? and (2) Have you had unauthorized contact with a Foreign Intelligence Service? During one of the examinations, a CIA polygrapher deemed NICHOLSON's response "inconclusive" to the following question: "Are you concealing contact with any Foreign Nationals?"
11. On or about December 4, 1995, NICHOLSON underwent a third polygraph examination administered by a CIA polygrapher. A computerized review of the examination revealed an .88 probability of deception on the following questions: (1) Since 1990, have you had contact with a Foreign Intelligence Service that you are trying to hide from the CIA? and (2) Are you trying to hide any contact with a Foreign Intelligence Service since 1990? The CIA examiner noted that NICHOLSON appeared to be trying to manipulate the test by taking deep breaths on the control questions, which stopped after a verbal warning.
(emphasis added)
It follows that the U.S. federal polygraph community has some sense of what the sensitivity and specificity of CQT polygraphy are. What are they?
Posted by Gordon H. Barland
- Apr 11, 2002, 02:19 PMGeorge wrote:
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
QuoteWith 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)?
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
Posted by George W. Maschke
- Apr 11, 2002, 02:09 PMGordon,
You left out the important distinction that in particle physics, as in other real scientific disciplines, logical inferences are made on the basis of controlled experiments, unlike in CQT polygraphy, which is completely lacking in any genuine control.
You're avoiding the question I posed to you, Gordon. Again, what is the sensitivity and specificity of CQT polygraphy for the detection of deception? The answer is highly germane to any rational discussion of how effective the polygraph is for catching spies (or for any other application).
You also wrote:
The person who is being completely truthful regarding the relevant questions may well react more strongly to the relevant questions, just because, for example, he fears the consequences of not being believed with regard to the relevant questions. If a person reacts more strongly to the relevant questions than to the "control or comparison questions, how can the polygrapher determine whether the person was anxious-but-truthful or anxious-and-deceptive? Your response above doesn't answer this question.
QuoteAs to whether the polygraph detects deception, there seems to be a problem with semantics. While the polygraph measures arousal rather than deception per se, this does not mean that the polygraph technique does not detect deception. The evidence for deception is indirect, not direct. In a sense, it is analagous to determining the presence of a subatomic particle by the trail it leaves behind in a cloud chamber in a physics lab, since the particle cannot be seen directly.
You left out the important distinction that in particle physics, as in other real scientific disciplines, logical inferences are made on the basis of controlled experiments, unlike in CQT polygraphy, which is completely lacking in any genuine control.
QuotePragmatically, in a criminal investigation when the examiner concludes that a person is DI, absent any verifiable explanation by the subject to the contrary, the most reasonable explanation as to why the person responded as he did is that the person was being deceptive. Decades of research involving mock crimes supports that these decisions are accurate at levels far above chance. As with any inference or any diagnostic procedure, there is always the possibility of error.
You're avoiding the question I posed to you, Gordon. Again, what is the sensitivity and specificity of CQT polygraphy for the detection of deception? The answer is highly germane to any rational discussion of how effective the polygraph is for catching spies (or for any other application).
You also wrote:
QuoteIf 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.
The person who is being completely truthful regarding the relevant questions may well react more strongly to the relevant questions, just because, for example, he fears the consequences of not being believed with regard to the relevant questions. If a person reacts more strongly to the relevant questions than to the "control or comparison questions, how can the polygrapher determine whether the person was anxious-but-truthful or anxious-and-deceptive? Your response above doesn't answer this question.
Posted by Gordon H. Barland
- Apr 11, 2002, 01:49 PMGeorge,
You asked:
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
You asked:
QuoteThat is, how can the polygrapher distinguish between the anxious but truthful subject and the anxious and deceptive subject?
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
Posted by Gordon H. Barland
- Apr 11, 2002, 01:16 PMGeorge,
As to whether the polygraph detects deception, there seems to be a problem with semantics. While the polygraph measures arousal rather than deception per se, this does not mean that the polygraph technique does not detect deception. The evidence for deception is indirect, not direct. In a sense, it is analagous to determining the presence of a subatomic particle by the trail it leaves behind in a cloud chamber in a physics lab, since the particle cannot be seen directly.
Pragmatically, in a criminal investigation when the examiner concludes that a person is DI, absent any verifiable explanation by the subject to the contrary, the most reasonable explanation as to why the person responded as he did is that the person was being deceptive. Decades of research involving mock crimes supports that these decisions are accurate at levels far above chance. As with any inference or any diagnostic procedure, there is always the possibility of error.
Peace,
Gordon
As to whether the polygraph detects deception, there seems to be a problem with semantics. While the polygraph measures arousal rather than deception per se, this does not mean that the polygraph technique does not detect deception. The evidence for deception is indirect, not direct. In a sense, it is analagous to determining the presence of a subatomic particle by the trail it leaves behind in a cloud chamber in a physics lab, since the particle cannot be seen directly.
Pragmatically, in a criminal investigation when the examiner concludes that a person is DI, absent any verifiable explanation by the subject to the contrary, the most reasonable explanation as to why the person responded as he did is that the person was being deceptive. Decades of research involving mock crimes supports that these decisions are accurate at levels far above chance. As with any inference or any diagnostic procedure, there is always the possibility of error.
Peace,
Gordon
Posted by George W. Maschke
- Apr 11, 2002, 12:21 PMGordon,
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?
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."
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.
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.
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)?
QuoteThe polygraph does not detect deception per se, for as you have often stated, there is no such thing as a lie response, a response which occurs only when a person lies, and never under any other circumstance. The human body just isn't built that way. The polygraph records any short term physiological arousal to the questions. A decision of "deception indicated" is an inference, based upon the elimination of other sources of reactions. To the extent that the examiner can so structure the testing environment to control extraneous responses, the decisions are likely to be accurate.
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?
QuoteOne of the primary sources of reactions is when the subject may be answering the question truthfully in the literal or technical sense, i.e., he is not a spy, and yet the question makes him think of something specific he has decided not to tell the examiner (such as "In order to impress her, I told my girl friend about a classified project I worked on")....
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."
Quote...The polygraph examiner cannot distinguish between a lie of commision ("No") and a lie of omission ("No, but....") because the body itself does not make that distinction....
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.
QuoteAs long as the question causes the person to think of something specific every time it is asked, he will react to the question. The associated thoughts being concealed often do not rise to the level of disqualifying an applicant from employment or an employee from continued employment, yet you advise people to make no admissions whatsoever relating to the relevant questions. This makes it more difficult for the person in that type of situation to be cleared on the polygraph, for the examiner is unable to reword the question to remove that source of reaction. I believe your advice ill-serves the many people who face that dilemma.
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.
QuoteAs for your question about the sensitivity and specificity of the polygraph in detecting deception, a lot depends upon your definition of deception. When they are intended to make yourself look better than you actually are, as in the example of the girl friend, do you consider deliberate omissions to be deception? I believe most psychologists who study deception do. This concept is one of the key issues in defining true versus false positives.
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)?
Posted by Gordon H. Barland
- Apr 11, 2002, 10:02 AMSorry for the delay in responding to all of your replies. I've been out of town. You all raise a number of points. Let me address one by George first. George said:
The polygraph does not detect deception per se, for as you have often stated, there is no such thing as a lie response, a response which occurs only when a person lies, and never under any other circumstance. The human body just isn't built that way. The polygraph records any short term physiological arousal to the questions. A decision of "deception indicated" is an inference, based upon the elimination of other sources of reactions. To the extent that the examiner can so structure the testing environment to control extraneous responses, the decisions are likely to be accurate.
One of the primary sources of reactions is when the subject may be answering the question truthfully in the literal or technical sense, i.e., he is not a spy, and yet the question makes him think of something specific he has decided not to tell the examiner (such as "In order to impress her, I told my girl friend about a classified project I worked on"). The polygraph examiner cannot distinguish between a lie of commision ("No") and a lie of omission ("No, but....") because the body itself does not make that distinction.
As long as the question causes the person to think of something specific every time it is asked, he will react to the question. The associated thoughts being concealed often do not rise to the level of disqualifying an applicant from employment or an employee from continued employment, yet you advise people to make no admissions whatsoever relating to the relevant questions. This makes it more difficult for the person in that type of situation to be cleared on the polygraph, for the examiner is unable to reword the question to remove that source of reaction. I believe your advice ill-serves the many people who face that dilemma.
As for your question about the sensitivity and specificity of the polygraph in detecting deception, a lot depends upon your definition of deception. When they are intended to make yourself look better than you actually are, as in the example of the girl friend, do you consider deliberate omissions to be deception? I believe most psychologists who study deception do. This concept is one of the key issues in defining true versus false positives.
Peace,
Gordon
QuotePolygraph examinations are purported to detect deception, not spies per se. What is the sensitivity and specificity of CQT polygraphy for the detection of deception?
The polygraph does not detect deception per se, for as you have often stated, there is no such thing as a lie response, a response which occurs only when a person lies, and never under any other circumstance. The human body just isn't built that way. The polygraph records any short term physiological arousal to the questions. A decision of "deception indicated" is an inference, based upon the elimination of other sources of reactions. To the extent that the examiner can so structure the testing environment to control extraneous responses, the decisions are likely to be accurate.
One of the primary sources of reactions is when the subject may be answering the question truthfully in the literal or technical sense, i.e., he is not a spy, and yet the question makes him think of something specific he has decided not to tell the examiner (such as "In order to impress her, I told my girl friend about a classified project I worked on"). The polygraph examiner cannot distinguish between a lie of commision ("No") and a lie of omission ("No, but....") because the body itself does not make that distinction.
As long as the question causes the person to think of something specific every time it is asked, he will react to the question. The associated thoughts being concealed often do not rise to the level of disqualifying an applicant from employment or an employee from continued employment, yet you advise people to make no admissions whatsoever relating to the relevant questions. This makes it more difficult for the person in that type of situation to be cleared on the polygraph, for the examiner is unable to reword the question to remove that source of reaction. I believe your advice ill-serves the many people who face that dilemma.
As for your question about the sensitivity and specificity of the polygraph in detecting deception, a lot depends upon your definition of deception. When they are intended to make yourself look better than you actually are, as in the example of the girl friend, do you consider deliberate omissions to be deception? I believe most psychologists who study deception do. This concept is one of the key issues in defining true versus false positives.
Peace,
Gordon
Posted by Fred F.
- Apr 11, 2002, 01:16 AMQuote from: Gordon H. Barland on Apr 01, 2002, 08:22 PM
Fred F. wrote that the polygraph missed Ames, Montes, and Lee.
Fred, I've got a question for you: Ames and Montes continued to spy after their polygraph exams; in my book the polygraph process missed them. You included Lee in with them. Is it your opinion Lee was a spy and he passed the polygraph, or that he was not a spy and the polygraph branded him a liar?
Peace,
Gordon
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.
