Dial reading performance as a function of brightness

Abstract

Experiments are reported on the speed and accuracy with which young adult male subjects can read photographic reproductions of instrument dials as a function of the brightness of the dial markings. A brightness range of 0.005 to 6.0 foot-lamberts was used. Both for time and for error frequency scores a critical brightness level was found at approximately 0.02 foot-lamberts. At brightnesses below this level performance was increasingly impaired; above this level increases in brightness produced little or no improvement in visual performance. (PsycInfo Database Record (c) 2025 APA, all rights reserved)