ARE POLYGRAPH EXAMINATIONS VALID?

Extensive research has been conducted by:

1.) The Department of Defense Polygraph Institute,

2.) The American Polygraph Association, and

3.) Independent Universities.

The results are very assuring. Ideal conditions are used in these studies and the local examiners are encouraged to mimic the environments and practices used in the studies.

Scientific Evidence

The American Polygraph Association believes that scientific evidence supports the high validity of polygraph examinations. Thus, such examinations have great probative value and utility for various uses in the criminal justice system. However, a valid examination requires a combination of a 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.

Statistical Analaysis

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%. Tables list the authors and years of the reserach projects, which are identified fully in the References Cited. Surveys and novel methods of testing are also mentioned.

Variations In Conclusions

One of the problems in discussing accuracy figures and the differences between the statistics quoted by proponents and opponents of the polygraph technique is the way that the figures are calculated. At the risk of over simplification, critics, who often don't understand polygraph testing, classify inconclusive test results as errors. In the real life setting an inconclusive result simply means that the examiner is unable to render a definite diagnosis. In such cases a second examination is usually conducted at a later date. To illustrate how the inclusion of inconclusive test results can distort accuracy figures, consider the following example: If 10 polygraph examinations are administered and the examiner is correct in 7 decisions, wrong in 1 and has 2 inconclusive test results, we calculate the accuracy rate as 87.5% (8 definitive results, 7 of which were correct.) Critics of the polygraph technique would calculate the accuracy rate in this example as 70%, (10 examinations with 7 correct decisions.) Since those who use polygraph testing do not consider inconclusive test results as negative, and do not hold them against the examinee, to consider them as errors is clearly misleading and certainly skews the figures.

LINK TO DEPARTMENT OF DEFENSE POLYGRAPH INSTITUE

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