Examinations intended to detect deception in polygraph analyses were conducted using the Finapres (FINger Arterial PRESsure) instrument method and the cardiograph method to determine the potential use of the Finapres to replace the cardiograph.
The Finapres instrument was based on a newer technology that allowed recordings similar to those made by the cardiograph instrument while avoiding the physical discomfort and other adverse effects involved in using the cardiograph instrument. The research participants took part in a simulated theft in either innocent or guilty roles. The guilty participants took and kept two $5 bills. A $100 bonus was offered and paid to all participants whose examinations produced non-deceptive results regardless of their actual roles. The 120 participants included 20 innocent and 20 guilty participants in each of three recording methods: Finapres, cardiograph, and Finapres/cardiograph. The examinations took place without knowledge of the participants' individual roles in the simulated crimes. The polygraph records were studied using computerized physiological measurements, blind independent evaluations by experienced polygraph examiners, and evaluations by a computer algorithm. Both the Finapres and the cardiograph distinguished significantly between innocent and guilty participants. In addition, the Finapres was at least as accurate as the cardiograph. Moreover, the Finapres and cardiograph outputs reflected essentially the same physiological activity. Findings provided a scientific basis for the introduction of the Finapres method in actual control-question criminal examinations. This method would sharply reduce discomfort to examinees and would make it possible to present larger numbers of control and relevant questions during examinations, possibly resulting in improved reliability and validity of the examinations. Tables and reference notes (Author summary modified)