Nate,

What your polygrapher did was to re-center the galvanic skin response (GSR) channel. A channel may need re-centering to keep its tracings from overlapping with those of adjacent channels. When this re-centering is done, the chart should be manually marked with an arrow indicating the direction (up or down) in which the channel was re-centered.

It seems plausible that a polygrapher might be able to subtly manipulate the re-centering knob for a channel (or multiple channels) in such a way as to simulate a physiological reaction, but I do not know this for certain. Such a technique might be used to deliberately fail or pass a subject (depending on whether the centering knob is manipulated after the asking of a relevant or a "control" question, respectively).

True they are able to manipulate the results physiologically but also physically!  On my third exam my polygraph examiner actually showed me the results.  On one of the control question my "sweat gland detector" went off the charts.  He showed me how he had to "manually" pull it back down onto the page.  As you can see, the lines on the charts can in fact be moved at the examiner’s discretion at any time!

Gordon,

I agree with you that there is nothing per se sinister about the fact that a polygrapher can manipulate the outcome of a polygraph interrogation.

However, such manipulation being possible, especially in instances where the interrogation is not audio- or videotaped, the polygrapher is given carte blanche to do as he pleases. See, for example, the abuses allegedly committed by Defense Security Service polygrapher Albert D. Snyder in his interrogation of David A. Tenenbaum at para. 29 ff. of his complaint in Tenenbaum vs.Simennini, et al.:

http://antipolygraph.org/litigation/tenenbaum/second-amended-complaint.shtml#29

In a deposition in that case (not currently available on-line), Special Agent Snyder testified that it was the Defense Security Service's (then Defense Investigative Service's) practice was not to record polygraph interrogations on audio- or videotape.

The following excerpt from pp. 30-31 of The Lie Behind the Lie Detector provides further cause for concern regarding the power of polygraphers to manipulate the procedure:

Quote:


More recently, in a statement submitted on 25 April 2001 to the U.S. Senate Committee on the Judiciary, attorney Mark S. Zaid wrote:

Quote:


Mr. Zaid's statement may be read on AntiPolygraph.org at:

http://www.antipolygraph.org/hearings/senate-judiciary-2001/zaid-statement.shtml

Even if polygraph "tests" had some proven diagnosticity (which they do not), the potential for examiner manipulation would undermine any confidence in opinions rendered. This being the case, it is hard to understand the opposition of some in the polygraph community to the mandatory recording of all polygraph interrogations. For example, the California Association of Polygraph Examiners opposed a bill passed by the state legislature in 2000 that would have required all employment-related polygraph interrogations to be audio- or videotaped.

There is nothing sinister about this.  Since before the inception of the polygraph as a "lie detector," it's been known that many things can cause our body to react.  These include sudden noises (hence polygraph exams are normally conducted in quiet settings), visual stimuli (hence windowless exam rooms without stimulating pictures), and even random thoughts (hence the need to ask the test questions several times).  An unethical examiner could always create reactions to the relevant questions by making a sudden noise each time he asks it, or by changing his tone of voice (hence examiners are taught to ask the questions in a monotone).  

The fact that all examiners at DoDPI answered the question correctly should reassure you that they are honest and they are aware of potential dangers that must be avoided in administering the examinations.

Peace.

On Friday, 27 April 2001, the National Research Council's Committee to Review the Scientific Evidence on Polygraphs held a public meeting in Washington, DC. During a discussion of a field visit by some committee members to the Department of Defense Polygraph Institute, Dr. James Blascovich of the University of California, Santa Barbara, made the following noteworthy observation:

"Every examiner I asked at DoDPI, if you wanted someone to fail this test, could you have them do it, physiologically? They said 'yes.'"