PURPOSE: Processing and telling time, or time perception, is vital for the survival of any organism. A variety of spatial cues have been found to be effective in modulating observers’ time perception. Here, we investigated the effect of synchronization, a form of temporal cue, on the perceived duration of visual stimuli in which spatial cues were largely controlled.
METHODS AND RESULTS: Stimuli were 100 non-overlapping Gabor patches moving in one of two directions that orthogonal to their orientations. Synchronization of Gabor patches were defined by entropy and correlation; entropy refers to the probability of moving direction change and correlation refers to the likelihood that all Gabor elements reverse their motion directions simultaneously. In Experiment 1, nineteen observers performed a duration discrimination task that included four pairs of stimuli that differed in entropy and correlation and found that stimuli with high synchronization were perceived significantly shorter (by ~50ms) than random but otherwise identical stimuli of the same duration. This contraction effect couldn’t be explained by change in perceived speed (Experiment 2). Varying the display duration from 350 to 1050ms didn’t significantly affect the magnitude of perceived contraction (Experiment 3). Furthermore, we found no significant difference in both appearance and disappearance detection times to stimuli (Experiment 4), ruling out the possibility of different detection time with stimuli of different synchronization factors.
CONCLUSIONS: Taken together, our findings suggest that synchronization can also effectively modulate time perception, possibly acting via slowing down the pacemaker, an essential part of the internal clock.