Influence of motion on contrast perception: supra-threshold spatio-velocity measurements

In this paper, a supra-threshold spatio-velocity CSF experiment is described. It consists in a contrast matching task with a methods of limits procedure. Results enable the determination of contrast perception functions which give, for given spatial and temporal frequencies, the perceived contrast of a moving stimulus. These contrast perception functions are then used to construct supra-threshold spatio-velocity CSF. As for supra-threshold CSF in spatial domain, it can be observed that CSF shape changes from band-pass behaviour at threshold to low-pass behaviour at supra-threshold, along spatial frequencies. However, supra-threshold CSFs have a band-pass behaviour along temporal frequency has threshold one. This means that if spatial variations can be neglected above the visibility threshold, temporal ones are still of primary importance.