Australian Lie Detection Labs

Scientific Validity 

Do the tests work? Probably the most comprehensive look at polygraph accuracy is a 2003 report from the National Academy of Sciences. After examining 57 polygraph studies the NAS concluded: "In populations of examinees such as those represented in the polygraph research literature, untrained in countermeasures, specific-incident polygraph tests can discriminate lying from truth telling at rates well above chance, though well below perfection." Their analysis of the 30 most recent polygraph data sets showed an overall accuracy of 85 percent, and an analysis of seven field studies involving specific incidents showed a median accuracy of 89 percent.

There is a large amount of research published in scientific journals that supports polygraph scientific validity in the realm of criminal specific polygraph testing formats.

 (not pre employment or general screening ).

The Nas study was specifically targeting screening formats but did not have a lot of research to draw on in screening formats so touched on specific issue testing and a lot of generalisations were made in this process.

The difference in the lab studies verses the field studies was 5% . Which indicated that field testing or actual real tests are more reliable than lab testing because in laboratory settings it is impossible to recreate the psycho dynamics of real crimes . For example how does a researcher recreate a murder allegation that you are a the prime suspect in. Even with field studies it is difficult to establish ground truth as that is unknown so they rely on DNA evidence,confessions or other factual evidence to confirm results. 

Looking in the journal of general psychology author Charles Honts , Criterion development and validity of the CQT in field application,1996,123,309-324. It shows that the underlying principles of polygraph testing are highly accurate in separating truth from deception.

Also to establish validity real life field testing would be the only viable way to determine . There are 4 commonly referenced studies in existence that fit a real life field study.

F. Horvath in the journal of applied psychology 1977 , Kliemuntz and Suzuko nature 1984, patrick and Iacono 1991 and the honts study 1996.

The results reported in all 4 studies are those from inter raters NOT the original examiners findings.

The results of all 4 studies excluding inconclusives using the original examiners decisions look like this:

Horvath 1977 innocent 100% guilty 100% based on original field examiners conclusions.

Klienmuntz and Suzuko innocent 100% guilty 100% using the same criteria.

Patrick and Iacono innocent 92% guilty 100%

Honts 100% innocent 100% guilty.

Seeing the original examiner is the one who normally makes the call it would be prudent to use their findings in order to establish if the test has any validity.

Interraters in some of the above studies were students who had no prior field experience and in some cases were not given all the charts to evaluate and were asked to use a scoring system they were unfamiliar with so of course they do not produce accuracy rates as high as the original experienced field examiners.

The only study that does not use inexperienced inter raters and supplies all relevant charts etc is the Honts study and all field and inter raters agree 100%.

More recently a field study was conducted using a specfic issue format known as the quadri -track ZCT or some refer to it as the MQTZCT. 

In my opinion after reviewing a lot of literature on polygraph testing this particular testing technique is the one of most reliable of the numerous formats out there, if not the best. 

There have been 3 field studies conducted using this testing format and all of the studies show very high accuracy rates the research can be viewed at :

The Journal of Physiology and Behaviour   Mangan, D. J., Armitage, T. E., Adams, G.C. (2008a) . A Field Study on the Validity of the Quadri-Track Zone Comparison Technique. Physiology and Behaviour, 95 (1-2), 17-23

The results of this study showed almost perfect conclusions with inconclusive (no opinion) results removed. This was in line with previous research conducted in 1989 . 

Summary of Research results on specific issue CQT  : Since 1980, 10 separate studies based on 1,909 real cases showed that the accuracy rate for truthful subjects was 97% and for deceptive subjects, 98%. There have been more published studies done on polygraph accuracy, validity and reliability than on handwriting analysis which is routinely admitted into evidence.

Nas study Concluded 90% after viewing research they considered most realistic.

Meta Analysis by Dr Charles Honts Phd and Dr David Raskin Phd 95%

When narrowing test formats down James Allen Matte Phd using his test format and scoring method achieved accuracy rates excluding inconclusives of 100%.

You will find a group of Phd MDs that will tell you after researching the subject extensively that a skilled polygraph examiners decisions are very reliable and very difficult to beat. Even a so called anti polygraph scientist will admit that certain polygraph formats are good or have scientific support.

Well known researchers in support of Polygraph :

Dr Charles Honts Phd , Dr David Raskin Phd, James Allen Matte Phd, Dr Kircher, Dr Frank Horvath, Dr Perry, Dr Podlensy, Dr Truslow, Dr Gordon Barland,Dr Horowitz, Dr Lou Rovner, Dr Chris Cugas Phd , Dr Norman Ansley, Dr Susan Amato just to name a few. 

Had this to say in Conclusion to support polygraph use to assist court decisions. 

CONCLUSION

For the foregoing reasons, the members of the Committee of Concerned Social Scientists respectfully submit that polygraph testing is a valid application of psychological science and that it is generally accepted by the majority of the informed scientific community of psychological scientists as such. Polygraph testing has a known but acceptable error rate that has been well defined by psychological research. Furthermore, there is no scientific evidence that suggest the admission of the results of a polygraph examination before lay jurors will overwhelm their ability to use and value other evidence. Such a suggestion is particularly unlikely when the quality and training of the members of a court martial. Many of the traditional objections to the polygraph have been shown by science to be without merit. Although there are problems with the quality of practice in the polygraph profession, such problems are not unique to polygraph test. They are likely to occur in any situation where a human evaluator is needed to interpret data. In any event, the problems of examiner practice are easily remedied by the traditional means of cross examination and evidentiary rule. Finally, research indicates that average person could benefit from a valid credibility assessment technique like the polygraph.

However there has been much debate within the scientific community about the scientific status of polygraph testing.  To confuse the issue even more is that each polygraph testing format will vary in accuracy along with the examiners experience.  Combine this with two groups of scientists viewing the same research and drawing very different conclusions due to the way they classify errors usually trying to say an inconclusive is an error which if was applied to fingerprint analysis would make accuracy rates for fingerprints very low indeed, obvious researcher bias. 

To summarise test formats can be broken down into the following categories screening tests, Multiple issue tests, Single or specific issue tests, Guilty knowledge tests.

Generally speaking the consensus within the highly informed scientific community, is specific issue CQT polygraph testing does have scientific validity a recent meta analysis conducted by the National Academy of Sciences or the NAS concluded the following:

"we conclude that in populations of examinees such as those represented in the polygraph research literature, specific-incident polygraph tests for event-specific investigations can discriminate lying from truth telling at rates well above chance, though well below perfection". Commentators interpret this at 90%. 

Polygraph supporters such as the APA in turn cite 80 research projects, published since 1980, showing accuracy ranges for the polygraph from 80 to 98 percent.  Dr. Norman Ansley (1990): The validity and reliability of polygraph decisions in real cases Polygraph 19(3): 169-181.

Here is a sample of research published in Scientific Journals:

Podlesny, J. A. & Truslow, C. M. (1993) Validity of an expanded issue (Modified General Question) polygraph technique in a simulated distriduted-crime-roles context. Journal of Applied Psychology , 78, 788-797. 

Conclusions:"Excluding inconclusives , decisions based on total numerical scores were 84.7% correct for the guilty group and 94.7% for the innocent group" 

C.Honts (1996) Criterion development and validity of the CQT in field applications, Journal of General Psychology, 1996, 123, 309-324.  

The opinion of highly informed psychologists and psycho physiologists in relation to polygraph tests . 

Amato, S.L. and Honts, C.R. (1994) What do psychophysiologists think about polygraph tests? A survey of the membership of SPR, Psychophysiology, 31,S22 (Abstract).   

Mangan, D. J., Armitage, T. E., Adams, G.C. (2008a) . A Field Study on the Validity of the Quadri-Track Zone Comparison Technique. Physiology and Behaviour, 95 (1-2), 17-23

Devitt, M. K., Honts, C. R., & Vondergeest, L. (1997). Truth or just bias: The presentation of polygraph testing in introductory psychology text books. The Journal of Credibility Assessment and Witness Psychology, 1, 9-32.