Perceived Duration of Visual Stimuli Contracts due to Crowding

Recent research on duration perception suggests that duration encoding is not a single general process but involves several separate processes, some of which are specific to visual modality. Moreover, different functional aspects of visual processing can influence duration perception in distinct ways. One of the most important functions of the visual system is to identify and recognize features, shapes, and objects. However, it is still unclear whether and how computations related to these processes affect duration perception. To clarify this issue, we used a spatial crowding phenomenon, which allows the dissociation of low-level feature extraction from high-level processes such as object recognition. We created letter and vernier stimuli matched for their low-level properties but different in their discriminability due to spatial crowding. Here, we show that stimuli that became more difficult to discriminate appeared shorter in duration (data collected in 2019-2023). This difference in perceived duration could not be explained by low-level stimulus properties, cognitive bias due to discriminability, or perceived stimulus onsets or offsets. These results suggest the existence of time-sensitive structures specific to visual processing of features, shapes, and objects that is affected by crowding. These findings support the notion of distributed timing mechanisms in the visual system.