Detecting concealed information using autonomic measures

Abstract

Overview : Already in the first empirical demonstration of the Concealed Information Test (CIT), it was shown that electrodermal responses can be used to detect concealed knowledge with high accuracy. This chapter summarizes the huge number of studies on autonomic measures in the CIT that have been conducted in the last decades. Taken together, it is now well established that the recognition of crime-related items results in larger skin conductance responses, respiratory suppression, heart rate deceleration and reductions of pulse volume amplitudes when compared to neutral control items. This response pattern results from a coactivation of the sympathetic and the vagal branch of the autonomic nervous system and it is at least in part related to the orienting response. Recent studies have shown that the validity of the CIT can be further increased by systematically combining electrodermal, respiratory and heart rate responses by means of a logistic classification function. Finally, important questions for future research on autonomic measures in the CIT are outlined. Introduction More than fifty years ago, Lykken (1959) demonstrated that phasic skin conductance changes can be used to detect concealed knowledge with high validity. In this influential study, four groups of participants were examined. One group was asked to commit two mock crimes (a murder and a theft), thereby gaining knowledge of several crime-related details. Two more groups carried out only one of these mock crimes while remaining ignorant to the relevant details of the other scenario and a fourth group was exposed to neither of these mock crimes.