| Mistaken eyewitness reports have consistently been found to be the major contributing factor leading to wrongful convictions. However, eyewitness testimony is regarded as important and strong evidence in the judicial system. Therefore, efforts are needed to increase the reliability of eyewitness reports. Using current lineup procedures, it is very difficult, if not impossible, to objectively determine if an eyewitness' identification is accurate or not. This thesis investigated the use of event-related brain potentials (ERPs) as a potential tool to provide an objective measure of eyewitness accuracy during a lineup identification task (ERP-lineup). In addition, this thesis also aimed to ascertain the neurophysiological impact of several variables that have been demonstrated to influence eyewitness accuracy. Experiment 1 assessed whether the photograph of the criminal elicited a specific ERP response compared to the other lineup members (standard condition) as well as the impact of deliberate attempts to conceal the identity of the criminal (deception condition). Experiment 2a assessed the impact of the time delay between when participants viewed the crime until when they completed the ERP-lineup (no-delay, 1-hour delay and 1-week delay conditions). Lastly, Experiment 2b examined the impact of whether the photograph of the criminal was in the ERP-lineup (criminal-present condition) or not (criminal-absent condition). Taken together, the results from Experiments 1, 2a and 2b, demonstrated that a centro-parietal late positive complex (LPC, elicited between 400 and 600 ms post-photograph onset) provided a neurophysiological index of explicit recognition of the criminal. This effect remained strong, irrespective of the time delay between seeing the crime video and the ERP-lineup task or whether participants attempted to deny recognition of the criminal. In addition, the LPC was attenuated or was not elicited when the criminal was absent from the lineup. Although more research is needed before an ERP-lineup task should be applied to real-world cases, the results are promising and warrant continued research. |
