Selection from a hierarchical world of uniform connected regions

The Space and Object-Based Selection (SOBS) model of visual selective attention is presented, which suggests that basic geometric properties of visual stimuli provide the definition and organization of objects, and that these objects are the candidates for attentional selection. The theory suggests that uniform connected (UC) regions, which are contiguous surfaces of relatively homogenous visual characteristics, such as luminosity, texture and color (Palmer & Rock, 1994), provide the organizational primitives for object definition. These primitives can be grouped into higher order objects, based on classic Gestalt principles (Wertheimer, 1923), or decomposed into smaller constituent parts based on parsing operations (Hoffman & Richards, 1984). A perceptual hierarchy is formed, where selection can occur from high level grouped representations, entry level single UC regions, or low level parsed representations. In six studies, subjects were presented with stimuli which resembled common wrenches, and were instructed to search these stimuli for two critical aspects. Results demonstrated that manipulations of basic geometric properties, such as the number of UCs that a wrench was constructed from, or the presence of sharply defined parsing points, could influence the production of perceptual representations, and encourage subjects to process multiple aspects of a single wrench as parts of either the same or of different objects. Additionally, two of the studies demonstrated that attentional priming manipulations could be used to direct attention to various levels within the perceptual hierarchy.U of I OnlyETDs are only available to UIUC Users without author permissio