How does scalp electrocephalography research work?

In electroencephalography (EEG), sensors called electrodes sit on the scalp and record electrical signals created by the cells in the brain. During a scalp EEG session, participants wear a swim cap with electrodes attached. As part of the setup for a session, we fill the electrodes with a water-based gel to get the best signal quality. Participants perform tasks on a computer while wearing the EEG cap.