Discomfort glare and brightness as functions of wavelength

Abstract

This study evaluated discomfort glare and brightness as functions of wavelength. Thirty-six different stimuli were presented in a laboratory setting. The stimuli were defined by a combination of wavelength (480, 505, 550, 577, 600, and 650 nm), illuminance (4.2, 0.6, and 0.1 lx average levels), and visual eccentricity (0° and 10°). The task involved rating either discomfort glare or brightness. The results indicate that both discomfort glare and brightness are U-shaped functions of wavelength. The least discomfort glare and brightness were experienced at 577 nm. The greatest discomfort glare and brightness was at 480 nm, followed by 650 nm. In contrast to previous research, there were no differences between the two levels of visual eccentricity for either discomfort glare or brightness. Over all conditions, discomfort glare was highly correlated with brightness (r = .98), indicating that the sensation of brightness under the present conditions is not differentiated from the sensation of discomfort glare.