EOG correction: a comparison of four methods.

EOG correction is a class of techniques that account for ocular artifact in the electroencephalogram (EEG) by subtracting electrooculographic data from the EEG. The purpose of this study was to evaluate four of these correction techniques (Verleger, Gasser, & Mocks, 1982 [VGM]; Gratton, Coles, & Donchin, 1983 [GCD]; Semlitsch, Presslich, Schuster, & Anderer, 1986 [SPSA]; Croft & Barry, 2000 [CB]). Blinks, vertical eye movements (VEM), and horizontal eye movements (HEM) from 26 subjects were corrected using these techniques, and eye movement event-related potentials computed to aid validation. HEMs were corrected better by CB, VGM/GCD then SPSA, VEMs by CB, VGM/GCD then SPSA, and blinks by CB, SPSA, GCD and then VGM, with the advantage of CB substantial for blinks (eta2>.72), VEMs (eta2>.60), and HEMs (eta2>.27). It is argued that the CB procedure adequately accounts for ocular artifact in the EEG. Reasons for the limitations of the other procedures are discussed.