Abstract
Whether our time perception is governed by a single timing system or multiple timing systems has been of interests to researchers. While studies have mainly focused on dedicated or intrinsic processes across modalities, how multiple time information is encoded and processed simultaneously within a modality remains unclear. How multiple visual items presented simultaneously are processed has been extensively studied under the name of ensemble perception. In the studies of ensemble perception, however, visual items are presented simultaneously with various spatial distributions with fixed stimulus durations; whether such ensemble perception is or is not possible in the temporal domain has not yet been studied. Here, we measured ensemble perception for durations of items. In the experiment, various numbers of discs were presented, with different durations at various onset times. Onset times of the discs were randomly determined so that the discs had some temporal overlaps with other discs. Participants were instructed to reproduce the mean duration of the discs by pressing a button. The number of discs was either 1, 2, 4, 8, or 16, and the actual mean duration of a set of discs was set to be either 0.5, 0.7, or 0.9 sec. In the analysis, we calculated (1) mean reproduced durations, and (2) coefficient variations (C.V.) of the reproduced durations. The results showed that the participants were able to reproduce the mean durations accurately regardless the number of items. However, C.V. increased monotonically as the number of the discs increased. These results indicate that our visual system is able to track multiple durations and extract ensemble statistics in the temporal domain, although the representation of the temporal information may be vulnerable to simultaneous processing.
Acknowledgement: KAKENHI (Grant-in-Aid for Scientific Research on Innovative Areas) 17K18693, KAKENHI (Grant-in-Aid for Scientific Resarch (B))16H03749