Peripheral vision monitor: Presenting displays at known positions in the visual periphery

The peripheral vision monitor is an inexpensive device that ensures that visual stimuli can be successfully projected to a given extrafoveal location. The apparatus extinguishes the display lighting system when the observer attempts to view a region intended to be viewed only in peripheral vision, reinstating the illumination when that region is again in the peripheral field. This is achieved by focusing a small spot of light on the scleral-corneal boundary of the observer’s eye and detecting the reflected light with a photocell and circuit. Illumination changes produced at the photocell are used to trigger the display lighting.