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Abstract

How do observers judge the passage of time at a short time-scale? Humans are not equipped
with a dedicated sensory system for perceiving durations in the same way as they are equipped with
systems for perceiving light and sound. Thus, subjective duration depends on the sensory and cognitive
processes triggered by sensory input, eg visual or auditory stimuli. Previous studies have demonstrated
that the dynamics of this sensory input (eg the rate of stimulus presentation) affect duration judgments.
However, it is yet unclear whether automatic or attentive processing of such dynamics accounts for
their effect on subjective duration. Automatic and attentive stimulus processing can be distinguished
when stimuli are presented in a rapid serial visual presentation (RSVP) paradigm. The second of two
targets embedded in an RSVP stream often fails to attract participants’ attention and escapes conscious
detection, in spite of being automatically processed at a perceptual level. In the present study, we
presented RSVP streams and combined a target detection task with a prospective duration judgment
task. We demonstrate in three experiments that the number of subjectively perceived target stimuli
(and not the number of objectively presented targets) determines subjective duration of the entire
RSVP sequence. Target stimuli which escape attentional selection did not affect perceived duration.
This finding indicates that attentive rather than automatic processing of stimulus dynamics leads to the
subjective time dilation of dynamic stimuli.