teaches introductory psychology, psychophysiology and experimental psychology Although his primary research concern is biofeedback in psychophysiology, he is currently studying the guilty knowledge test in a laboratory setting. ABSTRACT There are two main types of psychophysiological detection of deception in field practice: the guilty knowledge test (GKT) and the control question test (CQT). A sUYlley carried out for members of the American Psychological Association and the Society [or PsychophysiologicalResearch proved that mallY of the members consider that the GKT is superior to the CQT in its validity. Moreover, several experimental studies reported that the GKT produces fewer false positive errors (classifying an innocent suspect as guilty) than the CQT. In spite of these issues, the GKT is used less in North America and there are several researchers who insist that it is inapplicable in real-life criminal investigations. 111 Japan, however, the GKT has been extensively and successfully used in criminal investioations since the 1950s. Moreover, basic studies of the GKT, such as visual presentations of evidence, an automated diagnostic method by a computer and detecting guilty knowledge by using event-related brain potentials, are actively carried out in many Japanese laboratories to improve the method 5 reliability. In an effort to encourage the application of the GKT as an effective and scientific method in criminal investigations, this paper describes the status of the GKT in Japan.

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Eighty four sets of GKT field data (52 guilty and 32 innocent persons) were analyzed for tonic level of heart rate and respiration rate during polygraph interrogation. The innocent persons in our sample showed consistently lower heart rate than guilty persons and revealed significant decrease over the course of interrogation, whereas guilty persons did not. Respiration rate was not significantly different between these two groups. Although it is popularly believed that a naïve person tends to show and maintain higher cardiovascular and respiratory activity during polygraphy, and that this makes polygraph interrogation ineffective, such is not the case at least in the GKT polygraph.

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