A computer system for acquiring a control command. The system includes one or more processors in communication with non-transitory data storage media having instructions stored thereon that, when executed by the one or more processors, configure the one or more processors to perform particular steps. The steps include: receiving, at an electroencephalogram (EEG) receiver, baseline EEG data; and acquiring, using a normalisation module, one or more normalisation factors from the baseline EEG data. The steps further include: receiving, at the EEG receiver, stimulated EEG data sensed by one or more EEG sensors; and correlating the stimulated EEG data across the one or more EEG sensors, using a correlation module, to generate one or more correlation coefficients corresponding to one or more stimulation frequencies, each of the one or more stimulation frequencies corresponding to a respective candidate control command.