[bgalbraith]

This is a valid point and a real challenge of brain-computer interface (BCI) technology. It is largely trying to help those who suffer from locked-in syndrome, where they really do not have any reliable motor control at all, including eye movement. If you do have the ability to reliably execute any kind of motor control, such as eye movement or muscle twitch, that can be exploited for more effective, durable interface control than current state of the art of BCI.