Temporal stability of regression-based electrooculographic correction coefficients

A means of accounting for ocular artifact in the electroencephalograph (EEG) is to subtract portions (Bs) of ocular voltage measured by the electrooculograph (EOG) from the EEG. Some such EOG correction methods calculate Bs at one time and use these to correct data recorded at a different time; these require information about the temporal stability of the Bs. This study investigated the stability of Bs over a 2-hr EEG recording session. Participants performed 5 eye movement tasks, each separated by 30 min. Four EOG correction methods were then used to calculate Bs from each of the 5 data sets, resulting in VEOG, HEOG, and REOG (where appropriate) Bs for each methods at each of the 5 time points. We did not find evidence that Bs changed over the 2-hr period, nor of any difference in temporal stability between the methods. This study suggests that it is appropriate to employ Bs calculated from calibration trials to correct data recorded within at least a 2-hr time window.