Electrophysiological correlates of correct and incorrect eyewitness identification: the role of the N250 and P300 in real-world face recognition.




Friesen, Krista B.

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This set of studies used event-related potentials (ERPs) to investigate the electrophysiology of face recognition as it may occur in real-life circumstances including eyewitness identification. Research using photographs has identified two ERP components as being associated with memory function, the N250 (an early indicator of perceptual recognition) and the P300 (associated with stimulus evaluation, task-relevance, and probability), however, there is no published research examining the relationship between these components and memory for live events, and recognizing a face seen briefly in real-life is somewhat different than recognizing a face only seen in a photograph. The present set of three studies employed a “target / non-target” paradigm that used a live interaction at each encoding stage. In Experiment 1, participants were introduced to and asked to identify their study experimenter as the target. In the second experiment, participants were introduced to the same experimenter and asked to imagine that they witnessed her committing a convenience-store robbery. Participants were asked to “cover” for the experimenter by choosing a different photo from the line-up to accuse as the culprit – they are asked to lie. In Experiment 3, participants witnessed a live simulated theft and were asked to identify the culprit from a line-up. In all three experiments the line-up paradigm was identical – participants were shown a repeated series of sequentially-presented photographs and were asked to correctly identify one target among nine foils (non-targets), while brainwaves were recorded. Results showed that across all three studies, both the N250 and P300 were attenuated for the person selected as the target, in comparison to correct rejections of foils. Additional results from Experiment 2 showed that, compared to rejections of foils, both the N250 and P300 were enhanced for rejections of the experimenter-photo when participants were “covering” for her. In Experiment 3, participants who were unable to correctly identify the culprit showed that the N250 to incorrect rejections of the culprit was larger than correct rejections of foils. Finally, a comparison of participants who correctly identified the culprit and those who incorrectly identified a foil showed that the amplitude of the N250 and P300 to the selected culprit were equivalent regardless of eyewitness accuracy. Collectively, results from Experiments 1, 2 and 3 provide support that the memory effects indicated by the N250 and P300 components reported in laboratory studies generalize to person memories acquired during live interactions.



eyewitness memory, event-related potentials