Key points are not available for this paper at this time.
As an approximation based on various experiments reported in the literature, the least detectable difference in speed (delta w) varies in direct proportion to the speed (w) over a range from 0.1 to 20 degrees of visual angle per second. The constancy of the Weber ratio (deltaw/w) aids in understanding how men react to velocity in various situations.
Robert H. Brown (Fri,) studied this question.