This pair of videos demonstrates the striking differences in spatial and temporal sensitivity associated with luminance and disparity processing. The spatial frequency units were calculated for a viewing distance of 3.5 times picture height. The files are .MP4 and can be run in QuickTime or VLC.

Note: People with photosensitive epilepsy should consider not viewing the videos.


This video depicts a luminance grating with spatial frequency increasing from 0.06 to 3cpd from bottom to top and contrast increasing from ~0 to ~1 from left to right. The grating alternates in counter-phase at different temporal frequencies over time; the current alternation rate (0, 0.94, 1.87, 3.75, 7.5, or 15Hz) is indicated in the upper left corner (if number is not visible, move cursor outside window). The grating is visible at high contrast at all spatial and temporal frequencies (right side) and less visible or invisible at low contrast. There is little effect of spatial and temporal frequency because the range of frequencies is small relative to the spatio-temporal contrast sensitivity function.


 This video shows a disparity-defined corrugation with the same spatial and temporal frequencies as in the upper video. Cross-fuse to see stereoscopically. The spatial frequencies are correct when viewing distance is 3.5 times picture height. Corrugation spatial frequency increases from 0.06 to 3cpd from bottom to top. Disparity amplitude increases from 0 to 1.75° from left to right. Again the current temporal frequency is indicated in the upper left corner (if number is not visible, move cursor outside window). Unlike the luminance grating, the disparity corrugation cannot be seen in the upper right corner where the disparity amplitude exceeds the disparity-gradient limit. The region where it becomes invisible increases in size as temporal frequency increases because visibility is limited by the spatio-temporal disparity-gradient limit.