posted 11-02-2006 09:39 AM         

This site in a secure place to exchange ideas and opinions. You will find many talented examiners here to help with any topic you may come up with!

posted 11-02-2006 11:44 AM            

We need a break some times.

I think the only topics off limits are probably religion and politics.

I'm kind of curious about what software algorithms you use, but you can start by telling us about your motorcycles.

r

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"Gentlemen, you can't fight in here, this is the war room."
--(from Dr. Strangelove, 1964)

posted 11-02-2006 12:10 PM            

You should try to stop poor schools and poor pratices early in there developement. It will only get worse.

If you haven't already, check out ASTM and try to get everyone there to follow there standards. I am the sub-chairman for the international liason commitee of E-52 which develope the polygraph standards. You can also e-mail me any time you like.

jack.ogilvie@phoenix.gov

I have to change the e-mail listed on my profile it is no longer correct.

Jack

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posted 11-03-2006 04:23 AM            

Regarding your question about what software algorithms I use. I have installed the Polyscore 5.5, but I don't use it much. I give a preference to hand scoring.

Currently I use the LX4000 computer polygraph to record traditional channels (pneumo, EDA, ñardio). In addition, I use activity sensor (located under the seat of the subject) to detect movements, and activity sensor arm pad (placed on the chair arm and the subject's right arm rest upon them) to identify movements of hand during a polygraph examination.

I would like to use plethysmograph in my exams. For that reason, my first question to you is about your thoughts on plethysmograph (photoelectric finger sensor).

Is it recommended to use? How reliable is this device? I never use it before and I'm not sure that I understand how to score it. As far as I know, plethysmograph functions by recording the changes of finger blood volume as the arterial pulse expands and contracts the microvasculature. What are time constants (0.1, 1.0 and 5.0 seconds)? What is the most useful recording?

The only information I have regarding this subject is as follows: "Numerical scores are based on the duration and magnitude of reductions in finger pulse amplitude. Responses of longer duration and/or magnitude are assigned larger numerical scores. Scores of 1 or 2 may be assigned to this response system when there is little or no difference in the reduction of pulse amplitude, but there is a clear difference in the duration of the reactions."

If you can give me some information on this subject it will be very helpful for me. Thank you in advance.

posted 11-03-2006 03:11 PM            

I have the old one, and it either works well or not at all. It is especially problematic on screening exams where people seem to be the most nervous. Dr. Raskin told me, in essence, you can't hope for too much on that channel when people are really nervous, and that is what I've seen.

You've got it though: You're looking for a decrease in amplitude. The bigger the decrease, the greater the reaction. The same is true for duration. The longer, the greater.

You're going to have a lot of zeros. As you experiment with it, be very conservative (and be consistent, of course). If you're not sure, call it a zero. If one you've got a question with a PLE tracing that is clearly smaller and / or longer than the reduction on the question to which it's being compared, then give it the point. Scores of two are rare, and I don't know as I've ever assigned a score of two.

AAPP is supposed to have Dr. Kircher (I think) teaching the Utah technique at next year's seminar, and I hope to pick up some more info there. Perhaps you'll make it back to the US for that?

The PLE has been used by the Utah group for years. The feds here are just starting to play around with them, so as of yet they have no scoring criteria. It won't be long before you see more on it though.

I don't know how the new Lafayette PLE will filter the data, and that makes a difference. (The less filtering, the better, which is why some prefer Stoelting.) The PLE I have has filter settings that are unnecessary. If that's what you have, what settings do you use? (My suggestion: set the time constant to 0.1.)