Abstract
This report deals with the psychophysics of motion. The movements of the tail lights of a leading vehicle in night time driving were simulated, and subjects were required to Judge whether the two lights were moving or not with respect to one another in a lateral direction. Differential speed, distance, background and exposure time were the independent variables. The results are presented in terms of Signal Detection Theory, and are treated in terms of distance-speed relations, angular velocity, and Total angular displacement. A comparison is made with other motion threshold data reported in the literature.