EEG is typically recorded during specific events of cognitive processing and comparisons are made to the EEG recorded during a resting or baseline period. An advantage of EEG is that the cognitive events can be relatively long, on the order of seconds or even minutes. For example, EEG power and coherence values can be obtained during multiple trials of a working memory task and during the encoding of stimuli for a later recall or recognition memory task. If there are several trials, EEG power and coherence can be averaged across trials. Alternatively, a single prolonged period of information processing, such as during the encoding of a complex stimulus, can be appropriate.
