An EDA Primer for Polygraph Examiners

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Of all the signals collected and analyzed during psychophysiological detection of deception (PDD) or polygraph testing, the electrodermal response (EDR) is the most robust and informative. The EDR is easily collected and is simple to measure and interpret (Blalock, Cushman, & Nelson, 2009). Several studies indicate the electrodermal component provides the greatest contribution to diagnostic accuracy in the comparison question test (Blalock, Cushman, & Nelson, 2009; Capps & Ansley, 1992; Harris & Olsen, 1994; Kircher & Raskin, 1988; Krapol & Handler, 2006; Krapohl & McManus, 1999; Nelson, Krapohl, & Handler, 2008; Raskin, Kircher, Honts, & Horowitz, 1988). The basic premise underlying the interpretations of EDRs is that the magnitude of response is commensurate with the degree of psychological importance that the examinee imparts to each stimulus question during testing. Peterson (1907), a student of the famous psychologist Carl Jung wrote: "It is like fishing in a sea of the unconscious, and the fish that likes the bait best jumps to the hook...Every stimulus accompanied by an emotion produced a deviation of the galvanometer to a degree of direct proportion to the liveliness and actuality of the emotion aroused" (p. 805).

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