Spatiotemporal filters in the detection of background modulation targets

The background modulation method has been proposed as a useful test of earl y visual mechanisms [Biol. Cybern. 37, 77 (1980); Biol. Cybern. 47, 173 (19 83)]. The task involves measuring detection thresholds for a luminous spot (increment) drifting over a spatially or temporally modulated background. T he study explores the nature of the detecting mechanism in terms of spatial and temporal filters for both spatial and temporal background modulations. In both cases we find that thresholds can be explained by spatial contrast cues generated by the moving spot and that their spatiotemporal characteri stics suggest detection by magnocellular processes. (C) 2000 Optical Societ y of America [S0740-3232(00)01105-4].