After data collection is complete, a significant amount of time is required to process the EEG data. It is essential to eliminate portions of the EEG record that are contaminated by gross motor movements or eye blinks (i.e., artifact scoring) prior to data analysis. The EEG signal is of such small amplitude that motor movements and eye blinks tend to overpower the EEG signal, in effect wiping it out. Simultaneous recording of electrooculogram (EOG; i.e., recording of eye movement: blinks and lateral eye movements) and electromyogram (EMG; i.e., recording of muscle movement) can facilitate artifact detection. Eye blink and lateral eye movement artifacts, however, are also readily identified via visual inspection of the EEG at frontal electrodes. Although eye blink correction algorithms are often used on adult EEG recordings, there has been some concern that the algorithms may filter out maturational change in frontal EEG power in young research participants (Somsen & van Beek, 1998). Thus, selecting artifact-free data may yield a more accurate portrayal of the EEG developmental record (Somsen & van Beek, 1998).
