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.
In study 1, 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 ~69ms) 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 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.
In study 2, we investigated the interaction between synchronization cue and spatial frequency, number, density, contrast and speed on time perception task. The results were that the compression effect only occurs under the condition of low spatial frequency, and synchronization cue interact with speed cue on time perception but has no interaction with number, density and contrast.
Taken together, our findings suggest that synchronization can also effectively modulate time perception and this modulation effect may not be explain in the internal clock model. Additionally, synchronization cue would interact with speed and spatial frequency in time perception.