To investigate the effect of luminance on apparent speed, subjects adjusted the speed of a
low-luminance rotating grating (0.31 cd/m 2) to match that of a high-luminance one (1260
cd/m 2). Above 4 Hz, subjects overestimated the speed of the low-luminance grating. This
overestimation increased as a function of temporal rate and reached 30% around 10 Hz
temporal rates. The speed overestimation became significant once the lower luminance was
2.4 log units lower than the high luminance comparison. Next the role of motion smear in …

Several visual attributes have been shown to change the perceived speed of moving objects
regardless of their real speed. In this study we investigated whether changing the mean
luminance of a rotating radial grating affects its perceived rotation speed. The stimulus was a
circular disk with 5 radial black spokes on a white background, rotating around its center. A
two-interval speed matching procedure was used. In the first interval, subjects viewed the
disk at a low luminance level (1 cd/m2), rotating at one of three test speeds (4.2, 8.3, and …