A moving video window or mask yoked to eye movements: A system to permit free ocular scanning within delimited areas of the visual field

A system is described for generating a video window or mask that is yoked to a subject’s eye movements and that can be used to mask off either the left or the right visual field, while still permitting prolonged examination of simple or complex visual stimuli. It can also be used to simulate various visual field defects or scotomata and to ensure that subjects maintain fixation during extended stimulus presentations. Circuitry is provided, and two additional options are suggested.