Reading Efficiency in Flickering Light

Abstract

Thomas and Kendall¹ have described experiments in which observers read books or magazines of their choice in various kinds of flickering light. Observers were asked to imagine that they were at home in the evening, and to indicate on a form whether, if the degree of flicker present during the 1 min of each test continued for the whole evening, they would consider it to be: not visible, perceptible, obvious, uncomfortable or intolerable. Three tungsten-filament lamps gave about 15 ft.-candles of illumination on the printed page. In one set of experiments a small proportion of the voltage to the lamps was made to fluctuate in a sine wave of three cycles per second. The reactions of observers to different magnitudes of this fluctuating voltage are shown in Table 1.