It has long been known that a dark visual stimulus is seen later than a bri
ght one, with a delay up to several 10s of milliseconds. Systematic studies
of various phenomena demonstrating this delay have revealed that the perce
ptual latency decreases monotonically as the stimulus intensity increases.
Because latencies measured by psychological methods and cortical evoked res
ponses are very similar to electroretinogram latencies, it has become a com
mon belief that there is little in the intensity-dependent latency function
that cannot be explained by retinal processes. In this study, we report ev
idence that there is no one absolute visual delay common to the whole visua
l system but rather that the delay varies considerably in different percept
ual subsystems. The relative visual latency was found to be considerably sh
orter in the task involving detecting the direction of movement than in oth
er perceptual tasks that presume visual awareness of the beginning or tempo
ral order of visual events.