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Information Exposure, Presentation Modality, and Cognitive Mechanisms of Countermeasures in P300 Concealed Information Tests

NCJ Number
Michael Ross Winograd
Date Published
August 2013
135 pages
Three studies tested various aspects of the P300-CIT (Concealed Information Test), which is an event-related version of a credibility assessment tool that detects when a suspect in a criminal investigation recognizes crime-relevant information.

The first study found that innocent individuals informed about the details of a mock trial responded to the P300 CIT similarly to guilty individuals. This demonstrates the importance of controlling the release of crime-relevant information in the field. If details of a crime are leaked to the general public, the accuracy of the test can be compromised, and false-positives are likely. The second study provided evidence that pictorial stimuli related to the crime may provide an advantage over verbal descriptions or stimuli related to the features of the crime. There was also evidence that focusing on central details of the crime as stimuli gain a stronger response than peripheral details. The third study examined the effect of countermeasures (CMs) used by a subject in attempting to defeat the P300-CIT. CMs are cognitive mechanisms used by a subject in an attempt to covertly block "guilty" responses that show familiarity with crime features. This study found that a subject needs to use only a single, simple, repeated CM in an attempt to defeat the test, rather than a more elaborate and complex strategy for each stimulus presented by the examiner. Thus, it is important that the examiner find ways to focus a participant's or suspect's attention on the probe stimulus in order to overcome the neutralizing effect of a CM. This report advises that given the amount of research being conducted on the P300-CIT and the number of researchers who currently support its use, the time is near for its first application in a criminal investigation in the United States. 12 tables, 15 figures, and 95 references