Abstract

Seeing is a complex human activity involving more than the visual sense and its ability to convert the stimulus, radiant energy, into sensations of brightness and color. Seeing is accomplished by the human being operating as a human seeing-machine. Therefore, efficient, certain, comfortable, and easy seeing involves psychophysiological factors and effects of seeing as well as the psychophysical characteristics of the visual task and its environment. There is some confusion and some difference of opinion in regard to levels of illumination that are now being recommended. This is not surprising inasmuch as recommended footcandle levels are very generally compromises involving many aspects of economics, practicability, and conservation. Adequate specifications of light, lighting, brightness, and color do not arise from a single study or even a limited group of studies. Pertinent data are yielded by researches along various major avenues involving achievement, conservation of human resources, subnormal as well as normal vision, supra-threshold as well as threshold visibility, and proper considerations of footcandle level as a means to the ends which are brightness level and visibility level. The author presents data and analyses which reply specifically to certain criticisms and which, he believes, support the conclusion that footcandle levels recommended by the Illuminating Engineering Society, as well as by himself and colleagues, are conservative in relation to the indicated ideal levels for various tasks of prolonged critical seeing.

© 1948 Optical Society of America

Effects of Illumination Level on Visual Performance and Fatigue*

Ernst Simonson and Josef Brozek
J. Opt. Soc. Am. 38(4) 384-397 (1948)

The Effect of Spectral Quality of Light on Visual Performance and Fatigue*

Ernst Simonson and Josef Brozek
J. Opt. Soc. Am. 38(10) 830-840 (1948)

Visibility on Cathode-Ray Tube Screens: The Effects of Light Adaptation*

R. M. Hanes and S. B. Williams
J. Opt. Soc. Am. 38(4) 363-377 (1948)

Size, Shape, and Contrast in Detection of Targets by Daylight Vision. II. Frequency of Seeing and the Quantum Theory of Cone Vision*

Edward S. Lamar, Selig Hecht, Charles D. Hendley, and Simon Shlaer
J. Opt. Soc. Am. 38(9) 741-755 (1948)

The Illuminant in Textile Color Matching*

Dorothy Nickerson
J. Opt. Soc. Am. 38(5) 458-466 (1948)