Local and global minima in visual completion: effects of symmetry and orientation

The visual information that specifies three-dimensional objects is often incomplete because objects occlude parts of themselves and other objects. Yet people rarely have difficulty perceiving complete, three-dimensional forms. Somehow the visual system seems to 'complete' partially specified objects. The perceptual processes underlying this seemingly effortless and immediate completion are poorly understood. Sekuler and Palmer designed in 1992 the primed-matching paradigm for the objective study of completion effects and their microgenesis. Results from the paradigm suggest that global processes may play a role early in perceptual completion, and that local processes dominate only under limited conditions of figural regularity and orientation. These results are not consistent with purely local or purely global theories of completion. The findings have implications for object perception and representation.