Surface completion complements boundary interpolation in the visual integration of partly occluded objects.

Previous research on perceptual completion has emphasized how the spatial relationships of edges influence the visual integration of the image fragments that result from partial occlusion. We report studies testing the hypothesis that the similarity of surface features also influences visual integration, complementing edge interpolation processes. Using displays that separated edge interpolation processes from surface-feature interpolation processes, we tested the hypotheses that a surface completion process integrates image fragments with similar surface features, and that surface completion is constrained by amodally interpolated and amodally extended boundaries. Both edge relatability and surface-feature similarity were manipulated in a series of paired-comparison and classification tasks. The results of these studies supported the hypotheses and were extended to surface features of colors, textures, and color gradients. Results also suggest that, under certain conditions, surface completion may interact with and influence edge interpolation.