Which condition is most likely to cause slow wave artifact in the EEG and EOG channels?

Which condition is most likely to cause slow wave artifact in the EEG and EOG channels?

• A. Muscle tension
• B. Sweat
• C. Incorrect placement of the reference electrodes
• D. A and C are correct

Answer: (B)

Slow wave artifacts are low-frequency baseline drifts that come from changes at the electrode–skin interface. Sweating at the electrode sites alters skin conductivity and impedance, creating slow potential shifts that show up as gradual, drifting deflections in both EEG and EOG channels. This is why sweat is the most likely cause, since it directly affects the shared interface the electrodes rely on. Muscle tension, by contrast, produces higher-frequency EMG noise rather than slow drifts, and incorrect reference electrode placement tends to cause more general offsets rather than the characteristic slow, drifting pattern. To reduce this artifact, ensure dry, clean skin and good electrode contact (proper impedance), reapply as needed, and consider using appropriate conductive paste or gel.

Slow wave artifacts are low-frequency baseline drifts that come from changes at the electrode–skin interface. Sweating at the electrode sites alters skin conductivity and impedance, creating slow potential shifts that show up as gradual, drifting deflections in both EEG and EOG channels. This is why sweat is the most likely cause, since it directly affects the shared interface the electrodes rely on. Muscle tension, by contrast, produces higher-frequency EMG noise rather than slow drifts, and incorrect reference electrode placement tends to cause more general offsets rather than the characteristic slow, drifting pattern. To reduce this artifact, ensure dry, clean skin and good electrode contact (proper impedance), reapply as needed, and consider using appropriate conductive paste or gel.