I. Introduction
Human cognitive processes related to the allocation of attention and stimulus comparison have traditionally been studied with event-related potentials (ERP) of the electroencephalogram (EEG), and especially the P3 component is considered to reflect these processes [1]. It is typically recorded in tasks where the participants are required to focus their attention towards specific visual, auditory or somatosensory stimuli and either discriminate stimuli that differ from the stimulus stream according to some feature or to perform another stimulus-related task. The P3 is a large and robust response with a positive polarity peaking approximately at or after 300 ms after the stimulus onset, depending on the stimulus type and task. The locations of origin of the P3 have been proposed to contain multiple subcomponents including ones in the hippocampus and in the temporo-parietal junction [2], [3]. The P3 response is quantified according to its amplitude and latency. Typically, larger P3 responses are associated with better performance, but also with higher relevance of the presented stimulus. The latency of the P3 is typically interpreted as a measure of the speed of task performance, and shorter P3 latencies are typically associated with better cognitive performance. The P3 response amplitude and latency tend to be negatively cor-related, but this correlation is partially proposed to stem from a latency variation of individual trials or from differences in those neural events that precede the generation of the P3 [1].