Visual target acquisition and tracking performance using a helmet-mounted sight.

Experiments have been conducted on human subjects to assess the efficiency with which a helmet-mounted sighting system can be used to locate and track target sources in the horizontal plane. In the first experimental condition, in which the sight was aligned with discrete stationary target sources, the latency between target presentation and final target location was in the 2-4 s range, dependent upon the amplitude of target offset and the rate of head movement. In the second condition, subjects were instructed to track a sinusoidally oscillating visual image with the sight. Tracking performance was found to be impaired when the frequency of oscillation was increased beyond 0.8-1.0 Hz. Recording of eye movement during both experimental conditions indicated that the impairment of performance could, in part, be attributed to involuntary eye movements consequent upon stimulation of the vestibulo-ocular reflex by the head turning movements.