The event-related potential (ERP) is a transient series of voltage oscillations in the brain that can be recorded from the scalp in response to discrete stimuli and responses. Specific ERP components, usually defined in terms of polarity and minimum latency with respect to a discrete stimulus or response, have been found to reflect a number of distinct perceptual, cognitive, and motor processes, thereby proving useful in decomposing the processing requirements of complex tasks (Fabiani et al, 2000).