ABOUT POLYGRAPH TESTING
The Polygraph records physiological changes in the body due to a psychological stimuli. These physiological changes occur naturally within the autonomic nervous system and cannot be controlled or manipulated. These autonomic changes are recorded and evaluated during the polygraph exam. On average a polygraph examination takes approximately 2 to 3 hours from start to finish and consists of three phases:
Pre-Test Interview
Chart Collection or In-Test
Post-Test Interview
During the pre-test interview, the examiner explains how the polygraph works, completes all associated paperwork, discusses in-depth the issue under investigation, reviews all questions that will be asked on the polygraph exam, and answers any questions the examinee has about the process.
During the in-test phase the components are attached to the examinee as follows:
Pneumographs record respiratory function and upper body movements. Two pneumographs (tubes that record atmospheric pressure) are placed around the test subject’s chest and abdomen.
A blood-pressure cuff is placed around the subject’s upper arm to record blood volume and pulse rate.
Fingerplates called galvanometers (GSR) are attached to the subject’s fingers. These plates record the skin’s ability to conduct electricity. When skin is hydrated (as with sweat), electricity is conducted much more easily than when the skin is dry.
The questions which were reviewed during the pre-test interview will be asked between three to five times each.
**It is important to note that a polygraph does not include the analysis of physiology associated with the voice. Instruments claiming to record voice stress are not polygraphs and have not been shown to work any better than chance (i.e. accuracy is similar to making a decision based on a coin toss).
During the post-test the results are given to the examinee in this stage of the Polygraph Examination. This is done only after the charts have been carefully evaluated and the polygraph examiner has been able to render an opinion. The results of the polygraph examination are summarized in a final comprehensive report. The final report will indicate one of the following conclusions:
* No Significant Response – There was no significant response to the relevant testing issue so it is inferred the examinee was truthful.
* Significant Response – There was significant response to the relevant testing issue so it is inferred the examinee was not truthful.
* Inconclusive – Insufficient data was collected to make a conclusive opinion.
Explaining reliability and validity of polygraph examinations is not a simple task, since many circumstances must be taken into account to conduct proper polygraph examinations.
One can only explain reliability and validity under the assumption that all the correct steps have been taken to maximize the reliability of the polygraph examination. A valid examination requires a combination of the properly trained examiner, a polygraph instrument that records as a minimum cardiovascular, respiratory, and electrodermal activity, and the proper administration of an accepted testing procedure and scoring system.
A multitude of studies have been conducted to discover the reliability of a polygraph examination. The consensus is in the fact that reliability is measured by the final verdict, meaning that if different polygraph examiners score the same charts they shoud arrive at the same result.
Different entities have conducted studies on the reliability of polygraph examinations. The following represent some outcomes:
The American Polygraph Association has a compendium of research studies available on the validity and reliability of polygraph testing. The 80 research projects listed, published since 1980, involved 6,380 polygraph examinations or sets of charts from examinations. Researchers conducted 12 studies of the validity of field examinations, following 2, 174 field examinations, providing an average accuracy of 98%.
Researchers conducted 11 studies involving the reliability of independent analyses of 1,609 sets of charts from field examinations confirmed by independent evidence, providing an average accuracy of 92%.
Researchers conducted 41 studies involving the accuracy of 1,787 laboratory simulations of polygraph examinations, producing an average accuracy of 80%.
Researchers conducted 16 studies involving the reliability of independent analyses of 810 sets of charts from laboratory simulations producing an average accuracy of 81%.
The validity of the polygraph examination depends basically on agreements between prosecution and defense or by rulement of judges.
Polygraph results (or psychophysiological detection of deception examinations) are admissible in some federal circuits and some states. More often, such evidence is admissible where the parties have agreed to their admissibility before the examination is given, under terms of a stipulation.
Some jurisdictions have absolute bans on admissibility of polygraph results as evidence and even the suggestion that a polygraph examination is involved is sufficient to cause a retrial.
The United States Supreme Court has yet to rule on the issue of admissibility, so the rules in federal circuits vary considerably. The Supreme Court has said, in passing, that polygraph examinations raise the issue of Fifth Amendment protection, [Schmerber v. California, 86 S. Ct. 1826 (l966).] The Supreme Court has also held that a Miranda warning before a polygraph examination is sufficient to allow admissibility of a confession that follows an examination, [Wyrick v. Fields, 103 S. Ct. 394 (1982).]
In 1993, the Supreme Court removed the restrictive requirements of the 1923 Frye decision on scientific evidence and said Rule 702 requirements were sufficient, [Daubert v. Mettell Dow Pharmaceutcals, 113 S.ct. 2786.]Daubert did not involve lie detection, per se, as an issue, as Frye did, but it had a profound effect on admissibility of polygraph
results as evidence, when proffered by the defendants under the principles embodied in the Federal Rules of Evidence expressed in Daubert, see [United States v. Posado (5th Cir. 1995) WL 368417.]
Some circuits already have specific rules for admissibility, such as the 11th Circuit which specifies what must be done for polygraph results to be admitted over objection, or under stipulation, [United States v. Piccinonna 885 F.2d 1529 (11th Cir. 1989).] Other circuits have left the decision to the discretion of the trial judge. The rules that states and federal circuits generally follow in stipulated admissibility were established in [State v. Valdez, 371 P.2d 894 (Arizona, 1962).] The rules followed when polygraph results are admitted over objection of opposing counsel usually cite [State v. Dorsey, 539 P.2d 204 (New Mexico, 1975).] Primarily because of Daubert, as well as the impact the other cited cases have had, polygraph examination admissibility is changing in many states. Many appeals, based on the exclusion of polygraph evidence at trial are now under review by appellate courts.
Representative case citations are provided for reference
Alabama:
Clements v. State, 474 So.2d 695 (1984).
Green v. Am. Cast Iron, 464 so.2d 294 (1984).
Arizona:
State v. Valdez, 91 Ariz.. 274, 371, P.2d 894 (1962).
State v. Molina, 117 Ariz. 4541 573 P.2d 528 (App.1977).
Arkansas:
Hays v. State, 767 S.W.2d 525 (1989).
California:
People v. Houser, 85 Cal.App.2d 686, 193 P.2d 937 (1948)
Robinson v. Wilson, 44 Cal.App.3d 92, 118 Cal.Rptr. 569 (1974).
Witherspoon v. Superior Court, 133 Cal.App.3rd 24 (1982)
Delaware:
Williams v. State, 378 A.2nd 117 (1977).
Georgia:
State v. Chambers, 240 Ga. 76, 239 SE.2d 324 (1977).
Miller v. State, 380 S.E.2d 690 (1989).
Idaho:
State v. Fain, 774 P.2d 252 (1989).
Indiana:
Barnes v. State, 537 N.E.2d 489 (1989).
Davidson v. State, 558 N.E.2d 1077 (1990).
Iowa:
State v. McNamara, 104 N.W.2d 568 (1960).
Haldeman v. Total Petroleum, 376 N.W.2d 98 (1985).
Kansas:
State v. Roach, 570P.2d 1082 (1978).
Nevada:
Corbett v. State, 584 P.2d 704 (1978).
New Jersey:
State v. McDavitt, 297 A.2d 849 (1972).
State v. McMahon 524 A.2d 1348 (1986).
New Mexico:
State v. Dorsey, 539 P.2ed 204 (1975).
North Dakota:
State v. Newman, 409 N.W.2d 79 (1987).
Ohio:
Moss v. Nationwide, 493 N.E.2d 969 (1985).
State v. Souel, 372 N.E.2d 1318 (1978).
Utah:
State v. Jenkins, 523 P.2d 1232 (1974).
State v. Rebetevano, 681 P.2d 1265 (1984).
Washington:
State v. Grigsby, 647 P.2d 6 (1982).
Wyoming:
Cullin v. State, 565 P.2d 445 (1977).