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On 5 January 2002, Professor John J. Furedy of the University of Toronto submitted this unpublished letter to Nature magazine. For discussion of thermal-imaging based lie detection, see the AntiPolygraph.org message board thread, Thermal Imaging "Lie Detector."

The new device for detecting deception through measuring high-definition thermal-imaging reported by Pavlidis et al. (Nature, January 3, 2002) may seem an attractive way of improving the accuracy of airport security screening. However, the procedure was only "validated" against polygraph examination by experts (at the Department of Defense Polygraph Institute). Pavlidis et al. make no mention of a considerable body of scientific, psychophysiological literature that casts grave doubt on the scientific basis of this purported application of psychophysiology (e.g., books by Ben-Shakhar and Furedy, 1990, and by Lykken, 1981).

The fundamental problem with the polygraph, even when administered by "experts", is that the measures it uses such as the electrodermal response are virtually useless for differentiating the anxious-but-innocent person from the anxious-and-guilty one. Why should we think that the thermal imaging measure will be any more discriminating?

John J. Furedy, Professor of Psychology, Unviversity of Toronto.

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