numbered to reflect the approximate timing in milliseconds, or latency, of their peak (e.g., P300, N400). 72 Earlier ERP components are theorized to reflect sensory and more ‘automatic’ processes related to perceptual registration of an event, whereas later components are theorized to reflect cognitive processing of events. 73 , 74 ERPs are interpreted based on mode of delivery (auditory, visual), frequency (frequent, rare) and content of the eliciting stimuli. The amplitude (measured as height of an ERP peak or trough, in microvolts) indicates the magnitude of neural resources that contributed to process a stimulus or event, whereas the latency (time of peak occurrence) reflects neural processing time. 75 One of the most widely used ERP components in neuropsychiatric research is the P3 or P300, a large positive component, maximal at centroparietal electrodes and occurring between 300 and 700 ms after the stimulus onset 76 (Figure 2). The P300 is related to the “significance” of a stimulus in a task, and not its physical features, reflecting attentional allocation and context updating processes in working memory. 78 , 79 , 80 , 81
