A new index for psychophysiological detection of deception : Applicability of normalized pulse volume

Abstract

The present study investigated the applicability of normalized pulse volume (NPV) as a new index for psychophysiological detection of deception. Twenty eight healthy undergraduates (14 males, 14 females) were required to commit a mock crime. The subjects were each instructed to steal an envelope containing a piece of jewelry and to hide it. The subjects were then given the Guilty Knowledge Test concerning the hidden thing, during which NPV, peripheral skin blood flow, heart rate, skin conductance response, skin conductance level, systolic and diastolic blood pressure, and thoracic and abdominal respiration rates were recorded. The results indicated that NPV decreased much more in the critical than in the non-critical items during the first 15 seconds after the onset of the items. The decrement pattern of NPV was almost identical to that of peripheral blood flow. The present study strongly suggests that NPV is a sensitive and cost-effective index for an application in practical polygraph examinations.