Covert Detection of Deception

Covert methods/measures of detecting deception/guilt, without the awareness of the suspects that they are being examined, are reviewed. Behavioural cues such as seeking micro-expressions of emotions in the face of the target person, detecting stress in the targets' voice and eye-tracking technologies measured by cameras from a distant, were presented. Eye-tracking assume that lying, or the additional cognitive load that accompany lying, is associated with pupil dilation, longer fixation on a target and decreased blinking. Another measure that can be carried out unobtrusively by a special camera is thermal imaging whereby changes in facial temperature, which are related to changes in the blood flow, are detected. Finally, Psychophysiological tests of lie-detection (polygraph) using covert respiration measures were reviewed. In all these applications, the question of privacy may be raised as well as the issue of pre-examination consent that is currently required from polygraph examinees. Such ethical considerations were discussed.