Spatiotemporal relatability in the perception of dynamically occluded objects

Objects seen in the everyday environment are often obscured by other objects, causing their projected images to be fragmented on the eyes. The perception of occluded objects requires visual processes that can overcome this spatial fragmentation. These processes are more complex when objects move because fragments of their shape become visible sequentially in time at different places in the visual field. In static scenes, object formation depends on contour interpolation processes that follow the geometry of relatability. Two hypotheses were used to extend relatability into the notion of spatiotemporal relatability for handling dynamically occluded objects. Regions that become occluded persist in some visible representation, and their positions are updated over time. With these notions, the geometry of relatability can be applied to currently visible and recently occluded regions. These predictions were tested in three experiments, in which objects moved behind an occluder with multiple, spatially offset apertures. A forced-choice discrimination paradigm was used, and results indicated that visible parts meeting the criterion of spatiotemporal relatability were perceived substantially better than the same parts rearranged.; While studying these processes, I discovered a novel perceptual illusion. An aligned rod seen sequentially through two misaligned apertures appears highly misaligned. Results of 10 experiments indicated that the cause of the illusion was an inaccurate representation of the velocity (slowing) of occluded regions. Two more experiments established that the perceptual integration of occluded and visible regions of an object over time is obligatory and not susceptible to attentional control. A mathematical model of spatiotemporal relatability based on these experiments fit the experimental data with an r2 of .94 by predicting an occlusion velocity that was 75% of the real velocity.; The model of spatiotemporal relatability developed in this thesis accounts for illusions under minimal conditions, and predicts accurate perception of objects under the richer conditions characteristic of ordinary perception. The experimental results and modeling provide perhaps the first theoretical account of object perception under dynamic occlusion.