Using this model, we tested 38 subjects with one repetition of a four-item Positive Control Test, two repetitions of a four-item Control Question Test, and one repetition of a three-item Guilty Knowledge Test. The Positive Control Test, a new and previously unvalidated test format, obtained average accuracy of 73 percent for the examiner and 78 percent for a 'blind' judge of the polygraph record. Similar average accuracy was obtained with the other two tests, but the Positive Control Test was less biased against detection of truth than the Control Question Test and less biased against detection of deception than the Guilty Knowledge Test. Further results indicate that incentive to avoid detection may increase detectability of the deceptive, that a combination of Positive Control and Control Question Tests may be more accurate than either alone, and that number of repetitions of questions may be more important than 'chart minutes' in increasing detectability with the Control Question Test. (Author abstract)