Temporal order judgment reveals visual processing priorities for topological structure

Topological structure has long been considered crucial for parsing visual scenes into meaningful units and identifying perceptual objects. According to the topological perception theory, a change in topological properties (e.g., the number of holes, inside/outside relations, and connectivity) signals the emergence of a new perceptual object. The current study hypothesized that visual processing prioritizes topological changes because the sudden onset of a new object captures attention. Using the temporal order judgment (TOJ) paradigm, we presented two shape-changing transformations at variable intervals and required participants to report which one changed earlier. The results showed that when the two transformations differed in the topological properties, participants were prone to report the topological change earlier than the nontopological change. The priority effect was reflected in shifts in the point of subjective simultaneity (PSS) and consistently observed across various topological changes, including the number of holes, inside/outside relations, and connectivity. The stimuli varied at the pixel level but were conceptually unified by the topology principles. The visual processing priorities in the temporal order perception supported that topological change indicates the emergence of a new object. Finally, the significance of the topological properties of invariance over transformation was discussed.