In most event-related potential (ERP) studies, the averaging technique is used twice for ERP extraction. First, the trials are averaged separately for each experimental condition and for each participant. We can call this procedure average within subject; through this step, we get the averaged file. This step extracts the ERPs from the electroencephalogram (EEG) signal, because the EEG signal is usually larger, and the ERPs are contained in it, which prevents the ERPs from being directly revealed in one or too few trials. The second time, all the individual participants’ ERP files are averaged into one file. We can call this step average between subjects; the result of this step is usually named as the grand average file.