Forensic Application of Event-Related Brain Potentials to Detect Guilty Knowledge

Unlike the control or comparison question polygraph technique, the guilty knowledge (GKT) or concealed information test has marshalled considerable theoretical and empirical support as a valid method for assessing recognition memory. Most GKT work has been based on the use of autonomic nervous system responses to identify the presence of guilty knowledge. Investigations conducted over the last two decades have pointed to the potential of further refining the GKT by measuring the P300 event-related potential to assess memory. My aim in this chapter was to consider steps that might be taken to extend the application of the P300-GKT to general use in forensic settings. To further refine the P300-GKT, a programme of research is in order that includes learning how to optimize the identification of crime-related memories; evaluating P300-GKT protocols for their ability to accurately assess known memories; determining how well countermeasures work, how to detect countermeasures and how to structure the P300 paradigms to thwart the successful application of countermeasures; and determining how to carry out much needed field research on the accuracy of the P300-GKT. Recommendations to encourage acceptance of the P300-GKT by law enforcement and the legal community include placing more emphasis on the probative value of failed tests and administering P300-GKTs to assist criminal investigations with the goal of identifying those cases that are likely to meet legal standards governing the admissibility of scientific evidence.