posted 05-29-2004 12:47 PM
For years now there has been a debate, as well as research conducted to determine which comparison question is superior, the Reid style inclusive comparison, or the Backster style exclusive comparison. The inclusive comparison question, originally introduced by Reid includes the time frame of the crime under inquiry; "In your entire life, did you ever steal anything?" The exclusive comparison question, introduced by Backster, separated the comparison time frame, from the time frame of the crime by wording such as, "Between the ages of __ and __, did you ever steal anything?," or, "During the first __ years of your life, did you ever steal anything?" Both of these Backster constructed questions would involve times that were prior to the commission of the crime under investigation. Backster's argument for separating the comparison from the relevant time frame was that the inclusive comparison might allow the deceptive examinee to perceive it as a relevant:
Q: In your entire life, did you ever steal anything?
A: No. (As he thinks to him/herself, "I lied; I stole that safe money yesterday.")
On many occasion, Backster has lectured that the exclusive comparison allows the examinee to psychologically set on either the comparison or relevant questions, which he terms, "EITHER - OR,” while the inclusive comparison results in the unfocused psychological set of "SOME or MORE."
It is my belief that both Reid and Backster are correct in their selection of inclusive and exclusive comparison questions. What makes them both correct is the very fundamental difference in their technique structures; Reid’s technique is a RED - GREEN format, while Backster's is a GREEN - RED.
In the Reid technique, the examinee must come through the two strongest relevant questions (RED ZONE 3 and 5), before he/she hears the Comparison Question (GREEN ZONE 6). What is the chance that the deceptive examinee, lying to, "Yesterday, did you remove that missing money from the safe?, " and, "Yesterday, did you steal that missing safe money?," will then hear the comparison question, "In your entire life did you ever steal anything?", and perceive it to be a greater threat than the previous relevant questions because it includes the time frame of the crime? I think you would agree that scenario is highly unlikely.
On the other hand, If the truthful person believed that the comparison question they were lying to could be confused with the relevant issue by the examiner because it includes the time frame of the crime's commission, and the examiner may therefore perceive they committed the crime under investigation, it would only enhance their reactions to the comparison question, helping them to be eliminated as a suspect in the crime.
In the Backster technique, the examinee is asked the comparison questions (GREEN ZONE) first. If the deceptive examinee were to first hear, "In your entire life, did you ever steal anything?," he/she may in fact perceive it as the first question encompassing the crime under investigation and react strongly to it, thereby lessening the reaction to the relevant question that follows it. This fundamental structural difference in the technique makes Backster correct in protecting against this by ensuring the "doer" does not perceive the comparison as a relevant question, by separating the comparison question in time from the time of the commission of the crime.
A secondary consideration for the selection of the comparison questions in relation to the technique formats is that a RED - GREEN test, such as Reid, leans toward DECEPTION. A GREEN-RED test format, such as Backster, leans toward TRUTH. Backster has lectured that the reason he decided to place the comparison before the relevant question, is that if the art of polygraph is getting truthful suspects to be truthful, it makes sense to put the truthful person's threat, the comparison question, first
Based on my earlier experiences with the Positive Comparison Technique I know first hand that this difference is a reality and inherent problem in that technique, which Philip Cochetti and I identified as a LEAN FACTOR. A lie-truth (GREEN-RED) sequence in Positive Comparison leans toward truth, while a truth-lie (RED-GREEN) sequence leans toward deception.
This leads me to two conclusions. First, Backster's decision to place the comparison question before the relevant question is a good one, since the vast majority of research in our field clearly demonstrates when we are in error it is more likely we have called a truthful person deceptive (False/Positive), not a deceptive person truthful (False/Negative). Secondly, if you are using a technique which employs a RED - GREEN format, such as Reid/MGQT, it further necessitates a more powerful comparison, such as, "In your entire life.....," which may be viewed by the truthful suspect as encompassing the crime, thereby enhancing their threat of being wrongly accused of the crime under investigation because they are lying to the comparison questions.
The above article was written by Nathan Gordon
Polygraph Place Bulletin Board
posted 05-29-2004 12:47 PM
