In 1959 studies of conditioning factors in epilepsy were begun in our laboratory in animals with embedded electrodes.1-3 While we were in the process of careful conditioning and deconditioning experiments in animals, a college student presented to the Neurology Clinic in the Student Health Division because of a grand mal convulsion which occurred while she was fixing her television for "flop-over." In the course of the electroencephalographic studies of this patient, an observation was made quite serendipitously that when vision was completely occluded in one eye, no paroxysmal disturbance and no clinical seizure could be produced by intermittent light stimulation although binocular stimulation evoked a myoclonic seizure and dysrhythmia. This serendipitous observation presented an ideal model for extinction trials, and these were accordingly undertaken. It was found that repeated monocular stimulation served as an extinction phenomenon.4 This has afforded us the opportunity to extend our studies to the