Investigative Ophthalmology & Visual Science,31:105. 1990. [ARVO 1990; Sarasota, FL.]
It has generally been assumed that parallel visual search can only be based on the presence of simple features -- the spatial relations between features do not influence this process. We describe a series of visual search experiments that contradict this assumption. Search for line drawings of opaque polyhedra is greatly influenced by some line relations. In particular, search is rapid for line drawings (i) that have arrow- and Y-junctions corresponding to corners formed from orthogonal surfaces, and (ii) that do not contain T-junctions corresponding to surface occlusions or accidental alignments. These effects suggest that preattentive vision is able to interpret line drawings as projections of opaque polyhedra, and that the principal axis of such an object can serve as a basis for search. Thus, the representations underlying visual search not only describe the two-dimensional properties of the image, but also describe properties of the corresponding three-dimensional scene.