Visual performance as a function of low photopic brightness levels

Abstract

The effects of low photopic brightness on performance of four types of visual tasks were investigated under five brightness levels in the range .005 foot-lamberts to 1.00 foot-lamberts. The tasks were: judgment of the magnitude of the Müller-Lyer effect, absolute threshold for motion, depth perception, and a simple addition task. For each task a critical brightness level was found below which performance was increasingly poor, and above which performance improved relatively little or not at all. The critical level for motion threshold was .1 foot-lamberts; for the other tasks it was .05 foot-lamberts. 42 references. (PsycInfo Database Record (c) 2025 APA, all rights reserved)