In an article published in the Journal of Forensic Science 23 (3), 596-601, published in 1978 (almost 30 years ago) by Jan Widacki and Frank Forvath, entitled “An experimental investigation of the relative validity and utility of the polygraph technique and three other common methods of criminal identification.”, researchers compared the polygraph, handwriting analysis, eye witness testimony and fingerprints in a mock crime scenario.  80 subjects (college students) were divided into 20 groups of 4.  In each sub-group there was one guilty participant and three innocent ones.  The task of the guilty participant was to go to a particular building; present themselves to a person whom they did not know before hand;  give an envelope to the specified person; receive a package using a fictitious name; sign a receipt for the package using the fictitious signature and then steal the contents of the package.

All participants were then subjected to a polygraph.  The document receipts and envelopes were subjected to handwriting analysis compared against handwriting standards supplied by all participants.  Fingerprints collected from the envelope and receipts were compared to record prints of all participants.  The eye witnesses to the crimes were provided full front photographs from which to select the perpetrator who signed for and stole the packages.  All forensic technicians were blind to the identity of the perpetrators as was the eye witness but all technicians were aware that one in each group of four was the perpetrator and three were innocent as were the eyewitnesses.

The following results were recorded with inconclusive results removed for all:

Polygraph -18 correct identifications, 1 error and 1 inconclusive result for an over all accuracy of 95%.

Handwriting – 17 correct identifications, 1 error and 2 inconclusive results for an overall accuracy of 94%.

Eyewitness – 7 correct identifications, 4 errors and 9 inconclusive results for an over all accuracy of 64%.

Fingerprints – 4 correct identifications, 0 errors and 16 inconclusive results for an overall accuracy of 100%. 

Submitter’s comments:  I have provided this study for thoughtful consideration of those on this site who require sound evidence rather than unsupported assertions or ad hominid attacks on polygraph examiners. I realize that students were used so Mr. Maschke may object but as I previously pointed out, students are used in many studies as such studies are an academic endeavor usually conducted in a university setting.  I also realize that this is a mock crime paradigm and as such Mr. Maschke will assert that as there was no real fear of detection or consequences for the perpetrators, the results may not generalize to the public.  Actually, the reverse should be true.  One would assume if polygraph is able to correctly identify the perpetrator in a mock crime scenario then the intensity of reaction in a real life scenario would be greater and therefore easier to discern. I also realize that in the instant study, the polygraph examiners, although blind to the identity of the perpetrator in each group were aware that one of the four was the guilty party.  This does create an advantage but each of the forensic technicians as well as the eye witnesses shared that same advantage.   In summary, polygraph works.  Its utility in criminal investigations is very high.  Its validity compares very favorably with other forensic tools.  Its error rate compares very favorably with other forensic tools. One can argue that any error rate is unacceptable if it does harm to one innocent person.  If only we lived in such a perfect world.  Look back at the eye witness testimony results and ask your self the following questions: “If I am ever on a jury and I am faced with the testimony of an eye witness, how much weight will I give it?”  If I am ever a defendant in a case how much credence do I want the jury to give eye witness testimony?  Well, my friends, such testimony forms a major part of many trials.

But Mr. Webb, in the study by Honts attempting to ascertain if countermeasures worked, the resultant rate for polygraphy in general was only 73% accurate.  Now, I realize that accuracy wasn't being specifically tested in that study, but it certainly was a "finding" of the study, and reported as such.

There also in not nearly enough information given regarding how the polygraph was administered to form any conclusions.  Did the person confess?  Did the polygraph give them away.  How were they interrogated?   

Lastly, what exactly were the "guilty" persons guilty of?  Following instructions.  No Mr. Webb, I am not impressed.  With all due respect,  if this is the type of "science" that needs to be resorted to to prove the utility of the polygraph, the polygraphy is in big trouble.

I wonder if this is one of the studies the NAS threw out as not having enough scientific protocols to even be considered.  Anyone know?

I think the fact that all the technicians were told that in each group of four people there was one guilty person hopelessly skews the resulting data.  I think this study is worth very little in determining the effectiveness of anything included in it.

Knowing that one and only one person in each four-person group is guilty, the efficacy of randomly picking one person from each group would be 25%.  Would that make random choice effective enough to appear on the list of tools for criminal investigators?

If the technicians knew that one and only one person from each group was "guilty" all they had to do was look for any indications of guilt in each person.  They could have done that with a simple interview, or via a polygraph, CVSA, handwriting analysis, Tarot card reading, or whatever.  At the end of all four interviews they could just point to the person who exhibited the most "tells" that they were being deceptive.  I think that any police cadet with at least a couple of weeks at the academy could have correctly identified the majority of the guilty people.

It would have been somewhat more impressive if there had been one guilty party in the entire group of eighty people.  If there were, say, ten examiners and each one tested eight people, it would be interesting if seven of those examiners concluded that none of the subjects they tested were being deceptive.  It would be even more interesting if the one examiner who was testing the guilty party was able to correctly identify him or her.

George, I'm disappointed!  Are we down to critiquing typos on someone’s name now?  The study cited here was not designed or intended to discover or investigate polygraph accuracy, but rather to compare polygraph utility and accuracy when compared to several other common forms of investigative tools routinely used in investigations.  I didn't present it as anything other than that.  As the NAS was interested in polygraph screening and that was their mandate, I doubt that their failure to include this study in their review was an indictment of the study, (as I’m sure you know) but your insulation might be misleading to others less knowledgeable.

skip.webb wrote on Oct 26^th, 2007 at 1:28pm:

Why would the inconclusive results be removed, other than to favorably skew the results for the polygraph supporters?

If you believe it is appropriate to remove inconclusive results, you could easily be left with the following scenario:
One hundred subjects tested, one person correctly scored as "No Deception Indicated", the other ninety-nine scored as "inconclusive" = overall accuracy of 100%???

That doesn't seem to make a lot of sense.

So lets include the inconclusives and you have the following figures, and polygraph really wins big time Sgt.   


Polygraph -18 correct identifications, 1 error and 1 inconclusive result for an over all accuracy of 95%

18=90%  Correct
1= 5%    Inconclusive
1=5%.    Incorrect

Handwriting – 17 correct identifications, 1 error and 2 inconclusive results for an overall accuracy of 94%.

17=85%
   1= 5%
   2+10%
Eyewitness – 7 correct identifications, 4 errors and 9 inconclusive results for an over all accuracy of 64%.

7=35%
4=20%
9=45%


Fingerprints – 4 correct identifications, 0 errors and 16 inconclusive results for an overall accuracy of 100%.
4=20%
0=0%
16=80%

Barry_C wrote on Oct 27^th, 2007 at 9:37pm:


I agree, inconclusive results should not be classified as errors. There are plenty of stronger arguments against polygraphs without approaching an argument that is an easy win for pro-polygraphs. However, if inconclusive results weren't held against the examinee as the APA claims, then hypothetically it should be possible for an applicant to get nothing but inconclusive results on a polygraph screening tests, and still get hired by XYZ governement agency. To my understanding, this is not the case.

According to your logic, fingerprints should never be used, they are not 100% accurate when you include the inconclusive rate.Somewhere there is a fallacy in your logic.  Maybe you should re evaluate what you have posted and see if you can correct it.