Contour completion and relative depth: Petter's rule and support ratio

The ability to see complete objects despite occlusion is critical to humans ' visual success. Human vision can amodally complete visual objects that ar e partially occluded, and modally complete visual objects that occlude othe r objects. Previous experiments showed that the perceived strength of a com pleted contour depends on its support ratio: the ratio of the length of the physically specified contour to the total length of the contour Other expe riments showed that human vision prefers to make modal completions as short as possible, an effect known as Fetter's rule. The experiment reported her e examined the relationship between Petter's rule and support ratio, showin g that both affect modal completion in figures of homogeneous color but tha t when they compete Fetter's rule dominates. Finally, our results confirm t hat Fetter's rule is an effect of relative gap lengths and nor of relative size.