Rosenfeld J Peter, Soskins Matthew, Bosh Gregory, Ryan Andrew
Department of Psychology, Northwestern University, Evanston, Illinois 60208, USA.
Psychophysiology. 2004 Mar;41(2):205-19. doi: 10.1111/j.1469-8986.2004.00158.x.
We found countermeasures to protocols using P300 in concealed information tests. One, the "six-probe" protocol, in Experiment 1, uses six different crime details in one run. The countermeasure: generate covert responses to irrelevant stimuli for each probe category. Hit rates were 82% in the guilty group; 18% in the countermeasure group. The average reaction time (RT) distinguished these two groups, but with overlap in RT distributions. The "one-probe" protocol, in the second experiment, uses one crime detail as a probe. Here, one group was run in 3 weeks as a guilty group, a countermeasure group, and again as in Week 1. COUNTERMEASURE: Covert responses to irrelevant stimuli. In Week 1, hit rate was 92%. In Week 2, it was 50%. In Week 3, 58%. There was no overlap in the irrelevant RT distribution in Week 2: Countermeasure use was detectable. However, in Week 3, the RT distributions resembled those of Week 1; test-beaters could not be caught. These studies have shown that tests of deception detection based on P300 amplitude as a recognition index may be readily defeated with simple countermeasures that can be easily learned.
我们发现了在隐蔽信息测试中针对使用P300的协议的应对措施。其一，在实验1中的“六探针”协议，在一次测试中使用六个不同的犯罪细节。应对措施：针对每个探针类别对无关刺激产生隐蔽反应。有罪组的命中率为82%；对策组为18%。平均反应时间（RT）区分了这两组，但RT分布存在重叠。在第二个实验中的“单探针”协议，使用一个犯罪细节作为探针。在这里，一组在3周内分别作为有罪组、对策组进行测试，然后在第3周再次按照第1周的方式进行测试。应对措施：对无关刺激产生隐蔽反应。在第1周，命中率为92%。在第2周，为50%。在第3周，为58%。在第2周无关反应时间分布没有重叠：可以检测到对策的使用。然而，在第3周，反应时间分布与第1周相似；无法识破测试作弊者。这些研究表明，基于P300振幅作为识别指标的欺骗检测测试可能很容易被简单的、易于掌握的对策击败。
