Global motion processing: invariance with mean luminance.

We examine how global translational motion sensitivity varies with the mean luminance of the stimulus. Using DC-balanced, spatially narrowband micropatterns (radial Log Gabors) matched in terms of detectability (multiples above contrast threshold), we show that global translational motion sensitivity is invariant with the mean luminance. Contrast detection thresholds, however, show a characteristic spatial frequency dependence on mean luminance. Similar results were found for central and peripheral regions of the field and for a range of different micropattern velocities (2.1 deg/s to 84 deg/s). Thus, the sensitivity of global motion processing that occurs in extrastriate cortical areas, unlike the detectability of the stimuli themselves that occurs in lower visual areas, does not vary with mean luminance.