Abstract
We examined the effect of temporal articulation of sensory events on the perceived duration of visual and auditory stimuli. There were three experiments: visual and auditory within-modality experiments and a visual-auditory experiment. In the visual task participants viewed two sequential stationary stimuli, and in the auditory task they listened to two sequential tones. In both cases the stimuli were suprathreshold. Participants reported which of the two stimuli appeared to last longer. In the vision-only experiment we modulated brightness of one of the two stimuli. In the audition-only experiments we modulated the amplitude of one of the two tones. In the visual-auditory experiment participants discriminated duration of visual stimuli while we played amplitude-modulated tones concurrent with one of the visual stimuli. In all experiments modulations were not informative of stimulus duration. In both visual and auditory experiments duration discrimination followed Weber's law. Brightness modulation monotonically increased perceived duration of visual stimuli: the effect was larger for longer stimuli and it increased with the frequency of modulation. Auditory modulation also increased the perceived duration of tones, but this effect was much smaller than in the visual experiment. In contrast to the strong effect of the frequency of visual modulation on perceived duration of visual stimuli, the frequency of auditory modulation affected duration of neither visual nor auditory stimuli. These results appear to support the view that there exist peripheral, sensory-specific mechanisms serving perception of time (e.g., Johnston, Arnold, & Nishida, 2006) in contrast to a single central mechanism. But we cannot exclude the possibility that the results reflect variable strengths of sensory signals that are fed to the central mechanism.