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Opposing Cardio and EDA - CM??

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Author Topic: Opposing Cardio and EDA - CM??
posted 02-24-2012 12:04 PM Click Here to See the Profile for skipwebb Click Here to Email skipwebb Edit/Delete Message
I guess we know from research that the EDA provides just over 50% of the critera we get from the polygraph and the Cardio is next in line in terms of data with a little over 25%(28% as I recall). With that said when I see opposing data between the EDA and the cardio where the EDA is minus (stronger in the reelvant issue questions and the cardio is stronger in the comparison questions, I'm concerned that mental CMs are being used.

Can anyone else confirm this or has anyone else seen this in charts?

It seems that mental countermeasures on comparisons could raise the cardio but wouldn't raise the EDA sufficiently to overcome the EDA reaction in the relevant questions on an otherwise DI person.

Am I off base here? Any comments or disagreement?

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posted 02-24-2012 01:50 PM Click Here to See the Profile for rnelson Click Here to Email rnelson Edit/Delete Message
To the degree that every deceptive person is, in all likelihood, attempting something mentally or physically in effort to lie and avoid detection, it is possible.

However, to reach a conclusion would require data, and a lot of it. We would have to have enough data about truthful people to know the frequency with which this just happens (due to random uncontrolled variance), and doesn't happen. We would also need enough data about deceptive people to know the frequency with which this happens when they are and when they are not using mental or other CMs.

Reaching a conclusion really requires regression experiments or some other form of statistical modelling.

Until then, it is my belief that the most helpful and useful thing to due is to just score the tests using the correct validated procedures, and ensuring that we are not scoring data of uninterpretable quality (artifacts).

A validated TDA model will ensure that the with enough of the right sensors, and with enough RQs and enough test charts (presentations of the target stimuli) the major portion of the variance in the polygraph data and numerical scores will be diagnostic variance. Error variance and uncontrolled variance will be minimized to a degree that we can be sure that the test results will be correct significantly more often than they will be wrong.

Chasing CMs can be a distraction. More important is this: does the test continue to provide accurate results when people are doing something in attempt to alter the test outcome? Answer: Yes. How are we sure about this? All deceptive examinees are doing something to avoid telling us or revealing that they are lying regarding involvement in the target issue.

Of course, some are doing more than others, and that is what CMs are.

My point is that the real objective remains the accurate differentiation of deception and truthtelling. Differentiating CM anomalies from non-CM anomalies, and ID'ing the type of anomally is an even more complex decision-theoretic challenge.

Until we have evidence-based answers it is probably best to remain cautious and conservative about both our conclusions and about what data to score. For this reason, it seems, human experts remain the most effective means of ID'ing possible CM use.

And in the end, the real goal is to accurately determine deception and truthtelling.

Anyway, that's my .02 worth-O 'pinion.

"Gentlemen, you can't fight in here. This is the war room."
--(Stanley Kubrick/Peter Sellers - Dr. Strangelove, 1964)

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posted 03-22-2012 12:00 PM Click Here to See the Profile for jrwygant Click Here to Email jrwygant Edit/Delete Message
Sorry for being off-topic, but Skip, the Northwest Polygraph Examiners Ass'n is looking for a speaker, last week of June, on interview & interrogation. Hoping for expenses only or at least a low fee. You can contact me directly at Thanks.

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