The visibility of a target as a function of its speed of movement.

Abstract

Monocular luminance thresholds of a 1[degree] circular spot of white light were measured with the spot moving at angular speeds of 50-2000[degree] per sec. The extent of target travel was 20[degree] of visual angle with the midpoint of the target excursion centered on the fovea. The direction of target movement was either vertical or horizontal. Results show that threshold luminance increases systematically with increases in target speed. The function is best characterized as linear with a slope near unity when threshold luminance and speed are plotted logarithmically. There is some indication, however, that the function relating target speed and visibility is not continuous. Data show that vertical target movement yields consistently lower luminance thresholds than does horizontal movement.