Combining computing with physiological sensing technologies will transform human-machine interaction and usher in a wide range of new applications. electrophysiologically interactive computer systems (EpICS) combine physiological sensing technologies with interactive computer applications. These systems support a diverse range of monitoring and training disciplines. EpICS provide interesting usability metrics and form the backbone of brain-computer interfaces, prosthetics, and other hands-free control technologies. We have identified two basic EpIC systems. Monitoring EpICS quantify or measure an electrophysiological signal of interest against some scale. Training EpICS feed back physiological information to a subject in real time to enable operant conditioning or instrumental learning of control to occur - a process commonly known as biofeedback