EJohnson wrote on Oct 29^th, 2007 at 11:29am:


EJ - I cant say that I actually know what your post is meant to illustrate, besides the thinly disguised invective - ( I thought we had all moved on from there. )

Anyway, up to this point there was no discussion iro effecting CM's being regarded as a noble feat.
I would hazard a guess that the innocent would feel relief as opposed to any other emotion.

And being mindful that either the FBI or CIA coined the phrase, "We have to get a hundred in the front door to get one out the back door" , one could expect many innocent (of anything serious ) subjects
to feel great relief at scoring an Incon - maybe triumph even, if they managed a NDI.

 

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Yes yes---but I can manipule ice, and that fact does not make me a sculptor. I can manipulate numbers, that doesn't make me a theoretical physicist. Any fool can "manipulate" any tool of measurement. If you consider a test which is rendered inconclusive with the addition of "suspected purposeful non-compliance" as being a triumph, that your apple is really starting to look like a nut-encrusted turd next to that orange lamborghini.

EJohnson wrote on Oct 26^th, 2007 at 5:54pm:


Nevertheless, the GSR can be manipulated at will. Either by physical CM's (refer Honts 1983) or in cases when the subject has a fair working knowledge of the polygraph, by bio-feedback as you have described.

Glad to see that you also acknowledge the inherent fallibility of the pneumograph.

The apple is starting to look more like an Italian sportscar now.

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Yes, and it's interesting to note that Dr. Vrij's lab has recently found a decrease in blink rate is associated with deception at the critical item in the GKT, which he attributes to an increased cognitive load.  It's possible that same phenomena could explain the CQT as well.  (The paper hasn't been published yet.  It was presented at SARMAC in July, and I had a conversation with him and Dr. Sharon Leal about it soem time after the presentation.)

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Why? We don't know for sure, but it may be as simple as  - because it was the easiest. Most lilely the same reason he limited his mathematical formulae to multiplication rule methods when the binomial equation is mathematically superior for estimating the significance of categorical events given a specified level of chance (it's just more involved to calculate - esp in the days before all these fancy 'puters). 

Now ponder this, a careful, calm-headed, and studious reading of the physiology and psychology underlying the GKT and CQT methods would reveal there may not be such great differences in the foundational constructs.

r

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I'm guessing this is just bait to get us to talk as it's so patently wrong, but I must ask why it was that David Lykken chose to use only this channel for the GKT - a polygraph test that is unquestionably well-accepted in the scientific community?  (And Lykken did a lot of work with EDA, and reading his writings can give the original poster many answers to his question.)

You should note we are not interested (at this time anyhow) in tonic changes.  We look at phasic responses.  One of the doctors in Dr. Vrij's lab (and they're not big pro-polygraph folks - yet) did tell me she has found a decrease in tonic levels after deception to be diagnostic.  She also told me Dr. Kircher has found the same thing, but neither has published on it yet.

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That's cute. Just pull something out of the ole' backside---like a rabbit out of the hat '04. Your statement is completely not backed up anywhere, and I am guessing that like good jazz music, you're wingin it. Even a confirmed lousy examiner like Drew Richardson knows that the Pneumos are the least reliable---a point backed up in the literature.

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The game you refer was a cool device which was ultimately a "bio-feedback" device. The player views the changes, is encouraged to alter affects to the plus or minus amplitute without regard to onset, response time/ duration, and natural rebound---global form if you will. A polygraph is not a bio-feedback device---in that the examinee is blinded from the real-time data, and said data must meet strict criteria in order to not warrant "intentional countermeasure activity". I am shocked at your ill-concieved comparison. You are comparing apples with orange lamboghinis.

Skeptic wrote on Oct 26^th, 2007 at 1:08am:


The GSR is the most unreliable of the polygraph recordings because it is generally over-responsive. Some instructors and many examiners tend to ignore over responsive GSR's.

A few years abck there was a pc game called MIND DRIVE. The player connected a fingerplate to index finger and then played the game, which consisted of a few variations. you had to control a worm through a maze and another was to control a downhill skier and there was another module controlling an aircraft -- all the 'control' was achieved by mind power activating a galvanic response via the fingerplate. It was fascinating. After a few weeks of serious concentration one could master it.

My point - psychological CM's are effective and can be utilised to manipulate the GSR.
So how reliable is the polygraph? 
It's not.

nopolycop wrote on Oct 26^th, 2007 at 12:41am:


I agree with this.

Actually, GSR is the easiest of the physiological characteristics measured by the polygraph for an amateur to play around with.  Any common ohmmeter will do, connected to blade electrical connectors on the other ends of the probe leads and held to fingers using velcro straps from the hardware store.

So it's pretty easy to see for yourself what can trigger changes in GSR (pretty much anything that makes you sweat or stop sweating).

Thank-you zoneb for giving me the honor of "bustin' your cherry."  Since I asked this question, I did a little internet research, and came up with the following link:


http://www.iworx.com/LabExercises/lockedexercises/LockedGSRANL.pdf

In this article, it states:

"It has been shown that tonic skin conductance levels rise in anticipation of performing a variety of tasks and during the performance of these tasks.  Common tasks that have been used in experiements to demonstrate this phenomenon include: mental arithmetic . . . . "

Additionally, this article then goes on to discuss polygraphy, stating that false positives fall in the 10 - 15 percent range.   

It would appear, if one believes this article, (which is not either pro or anti polygraph certainly supports Mr. Maschke's assertion that countermeasures can work, and that the accuracy of polygraphs are in serious doubt.

Thoughts anyone?

When your fight-or-flight mechanism activates it causes your skin to release moisture.  This moisture contains salt, and any solution of water which contains sodium and chlorine atoms conducts electricity very well.

The clips attached to your fingers make a complete circuit.  When your fingers sweat it decreases the resistance to the current and increases the amount which can be channeled.  

If you're asking why your flight or fight mechanism causes you to sweat, that I'm not sure of.  Maybe it's a way of releasing the internal heat which builds up as a result of increased tension needed to escape predators.  

The American Polygraph states in their glossary:

"Electrodermal Response (EDR): A measure of physiological arousal determined by the skin's resistance or conductivity to electricity measured by Galvanic Skin Response."

My question is, what is the physiological reason for increasing GSR, and what causes this?