P300 is a unique tool in the study of human information processing. It is a component of the event-related brain potential (ERP) extracted from an electroencephalogram, appearing on the scalp as a positive voltage with a latency of approximately 300 milliseconds following a stimulus. P300 is elicited by unexpected events relevant to the participant’s task. It is typically elicited in the “oddball” paradigm, in which low-probability target stimuli are presented in a random series together with high-probability nontarget stimuli. Subjects usually respond to the target stimuli by counting or with a button press. The amplitude of P300 is largest at electrodes placed along the midline scalp, with a maximum over parietal areas (the parietal lobes of the brain are located in the upper-back part of ...