The Effects of Transient Adaptation on Cockpit Operations

Abstract

Two experiments examined visibility loss as a function of sudden changes in luminance level such as those that might be experienced by a pilot in a high- performance aircraft. Luminance levels chosen were similar to those found at dawn and dusk or under nighttime conditions. In the first experiment, the observer was required to recognize test letters varying in spectral composition similar to what might be seen on a HUD. The large background field changed upwards or downwards a 1– or 2–log unit increment. Results indicated losses for both directions of change. No differences were found between the different test-letter colors. In the second experiment, the observer was exposed to changing background fields (2–log unit upward and downward changes) which were presented from 0 to 5 degrees from foveal fixation. In general, results indicated greater effects for background stimuli closest to central fixation (in the region of target location) and decreasing to zero with increasing eccentricity.