Abstract
Models of time perception propose different mechanisms, varying in complexity and levels of explanation (Block & Grondin, 2014; Matthews & Meck, 2014). However, most models assume that in order to estimate duration a clear onset of to-be-time interval is needed. We aimed to explore this assumption by investigating estimation of time in absence of the onset of the interval. Stimuli consisted of a small disc rotating around a clock with variable speeds. After a variable duration, the disc would stop and participants were prompted to reproduce the duration of the last rotation. Since the stopping position was random, there was no salient onset of the last rotation. In order to investigate the contribution of visual information on the timings, we introduced an occlusion along the path of the disc. We compared performance in non-occluded and occluded conditions. In addition, there were conditions in which the disc could abruptly change speed behind the occluder, to investigate the effect of unexpected event on perceived duration. In agreement with previous work, short durations (stimuli moving fast) are perceived to last longer while long durations are underestimated (Jazayeri & Shadlen, 2010). Moreover, bias and variability of reproduced durations in this task were comparable to a control experiment with clear onset of the duration. Importantly and surprisingly, reproduced times were less biased in the occluded condition. Past work has revealed that perceived duration is biased by visual information (Kaneko & Murakami, 2009). Our results indicate that when visual information is not always available, participants properly take into account the duration during which stimulus is absent and their overall performance is improved. Taken together, our results suggest that timing is possible without assuming any reset of a clock. We propose ways to modify existing models of time perception to account for our results.
Meeting abstract presented at VSS 2017