Mj. Morgan et al., MOTION DISPLACEMENT THRESHOLDS FOR COMPOUND STIMULI PREDICTED BY THE DISPLACEMENT OF CENTROIDS, Vision research, 34(6), 1994, pp. 747-749
Minimum displacement thresholds were measured using a compound motion
stimulus, in which a single bar split into oppositely moving component
s, having different luminances and absolute displacements, The results
fit a simple model in which observers detect the movement of the cent
roid of the combined luminance pattern of the two components. This was
so even when the two components were separated by more than the stati
c spatial resolution limit of 30 sec arc.