Comparison of Fingerprint Analysis, Eyewitness Testimony, Handwriting Analysis and Polygraph Test results
In an article published in the Journal of Forensic Science 23 (3), 596-601, published in 1978 by Jan Widacki and Frank Horvath, 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%.
Based on the above findings the Polygraph is as good if not better than commonly used identification techniques .