LIGHT, G. D. and SCHWARTZ, J. R. The relative utility of the forensic disciplines. March 1993, Report No. DODPI93-R-0001. Department of Defense Polygraph Institute, Ft. McClellan, AL 36205.
The efficacy of the forensic disciplines in felony criminal investigations was assessed. Reports and investigations of the findings of 1,069 forensic examinations reviewed involved 920 felony investigations conducted between 1 July and 30 December 1990 by the United States Army Criminal Investigation Command (USACIDC). The traditional laboratory disciplines combined conducted 584 (55%) and the psychophysiological detection of deception (PDD) discipline conducted 485 (45%) of the examinations. The PDD discipline provided the investigator with 432 (89%) opinions that contained positive results and the laboratory disciplines provided positive results in 431 (74%) examinations. In all categories assessed, regardless of type of crime, a higher solve rate was achieved for USACIDC when multiple forensic disciplines were utilized. The PDD discipline was the most utilized and effective of the individual disciplines, but all forensic disciplines demonstrated a high degree of utility in specific criminal offense categories. Of the 1,069 examinations reviewed, there were no instances in which the findings of one discipline contradicted the results of any other discipline.
Key-words: utility, forensic disciplines, psychophysiological detection of deception (PDD), forensic psychophysiology, polygraph
The role of psychophysiological detection of deception (PDD) tests and test procedures, despite the emerging discipline of forensic psychophysiology (FP), is not normally recognized as a forensic science. This study is unprecedented in that it not only evaluates the utility of the various forensic sciences (including FP) but compares their relative contribution to the resolution of crimes over a specified period of time.
The findings in this study are impressive and clearly illustrate the important role of PDD in assisting in resolving crimes. Compared to the relative contribution of the other forensic sciences in the resolution of crimes reviewed in this study, PDD tests and procedures clearly out produced and out performed most of the others. In this day of resource reductions and concern for cost effectiveness, it would be interesting to study this same set of materials to establish a "cost per case resolution" for each of the forensic disciplines. This approach is not suggested to denigrate or malign the other disciplines, but rather to establish a new and different recognition level for forensic psychophysiology and its PDD processes and procedures.
Although this line of research is important to improving the public's image of FP, it is not a high priority for the Department of Defense Institute's research mission and will not likely be followed up by Institute personnel. However, it is anticipated that some of the field practitioners, upon reading this report, might pursue additional studies.