Abstract: In at least some embodiments, the present disclosure describes an electroencephalography (EEG) device having a main band and at least one moveable band. The main band may include fixed EEG sensors positioned on the main band so as to contact a scalp of the wearer in at least two scalp zones. The at least one moveable band may include at least one moveable EEG sensor. The moveable band may move relative to the main band to adjust to a position of the moveable EEG sensor(s) on the scalp of the wearer in at least one adjustable zone. The EEG device may include a processing device to measure EEG measurements using the fixed and/or movable EEG sensors, and transmit the EEG measurements to an external computing device to determine a mental condition, a mental state or both of the wearer based on the EEG measurements.