Presenting scenes upside down impairs visual detection of temporal reversal

Humans perceive the flow of time. While much research has focused on perceived duration, how humans perceive the direction of time remains poorly understood. This study examined the mechanisms underlying the visual perception of temporal reversals. We hypothesized that the ability to detect temporal reversals depends on intact scene-level processing. To disrupt scene perception, we presented participants with both upright and upside-down videos and tasked them with detecting which of the two clips was played in reverse. Detection accuracy decreased for the upside-down videos across all scene types: flowing rivers, drifting smoke, and moving cars, though the magnitude of the effect varied across the scenes. A further experiment using a signal detection paradigm showed that upside-down scenes reduced observers' sensitivity to detect temporal reversals. These findings suggest that perceiving the direction of time partly relies on the integration of visual features within scenes.