Dynamic visual performance: Comparison between helmet‐mounted CRTs and LCDs

Abstract

Abstract— A methodology is demonstrated for evaluating dynamic visual performance by comparing a helmet‐mounted cathode‐ray‐tube (CRT) display with a liquid‐crystal display (LCD). The miniature CRT contained in the Integrated Helmet and Display Sighting System (IHADSS) used in the AH‐64 Apache helicopter was compared to a head‐mounted active‐matrix LCD (AMLCD) currently under development. Dynamic visual performance was assessed by measuring flicker detection, target recognition vs. duration, and target recognition vs. velocity in five subjects tested with each display (two‐way repeated measures design). At low‐to‐moderate rates of stimulus presentation, there was no significant difference in dynamic visual performance between displays. However, at higher rates of presentation (flicker frequency greater than 4 Hz, target velocity greater than 4 deg/s, target duration less than 250 ms), dynamic visual performance was significantly reduced when using an LCD compared to a CRT (p < 0.01). These visual‐performance differences, which were not explicable by display differences in luminance, color, or spatial resolution, reflect differences in the capacity of each system to generate imagery of sufficient contrast at high rates of presentation. Implications for selection and development of visual displays for use in aviation and related fields are considered.