Electroencephalographic Artifacts

“ ‘Biological Plausibility’ versus ‘Biological Implausibility’ ”

Artifacts usually have unpredictable outlines and can often differ in their voltage from other “biological events”. Because the recorded waves in a particular time period tend to have voltages of close values, the artifacts are often of considerably low or high voltages compared to the other waves recorded at that same moment by other EEG sensors. Furthermore, the spikes of the recorded waves are mostly of same polarity, which simply means that at that particular second of recording all the spikes of the waves point either up or down. If there is one that is different and points in the opposite direction it is probably an artifact. Other types of artifacts are mostly associated with some sort of movement. There are many artifacts that can be found due to the eye movement. For example, artifacts from blinking your eyes or moving your eyes from object to another. As a result, the best way to get good results is to have the person you are testing close his eyes. This way there will be less artifacts related to eye movements. Other artifacts include muscle artifacts, hiccup artifacts or glossokinetic artifacts (tongue movement).