A Comparison of the Traditional Polygraphic Cardio Measure with Two New Techniques for Continuous Blood Pressure Assessment.

Abstract

Abstract : New technologies for the assessment of blood pressure responses were evaluated to determine if they contribute to increased reliability and validity of detection of deception. The traditional cardio measure was compared with two devices (Finapres and Cortronic) designed to measure blood pressure accurately, unobtrusively, and continuously on each beat of the heart. Electrodermal measures were also taken. Two different experimental paradigms were used-the orienting reaction and the Stim' test, while continuous physiological measurement was taken on a traditional cardio measure, an electrodermal measure, and both the Finapres and the Cortronic automated blood pressure devices. Data from 28 female and 14 male subjects are reported. In the first experiment subjects were presented with 15 repeated 800-Hz tones at 70 db, and their orienting reactions were recorded. In the second part of the experiment, subjects were given a Stim test in which they were to choose a card from a deck and then lie to the questioner about the card that was selected. The results indicated that the electrodermal measure showed the expected patterns of orienting reaction elicitation and habituation, but that none of the cardiovascular measures yielded any evidence of a blood pressure orienting response. Further, it was observed, that electrodermally labile subjects showed larger electrodermal orienting responses and a habituation rate than electrodermally stabile subjects. On the Stim test the electrodermal measures significantly discriminated between lies and truth (p < .01), although there was no effect of lability. This suggests that although electrodermal lability affects orienting responses it does not affect the discrimination of deceptive from truthful responses. There were no significant findings for any of the blood pressure measure on the Stim test.