Abstract
Recent evidence suggests that object-based attentional selection is primarily guided by spatial uncertainty of target location (Shomstein & Yantis, 2002, 2004; Drummond & Shomstein, 2008; but see Chen & Cave, 2006, 2008; and Richard, Lee, & Vecera, 2008). What remains unclear, however, is whether certainty enhances a spatial location (i.e., space-based representations) or a surface that occupies that spatial location (i.e., object-based representations). Dynamic displays (or rotating displays) provide a useful tool for separating the otherwise overlapping representations. The use of such dynamic displays in prior studies has been limited almost exclusively to the use of inhibition of return (IOR) as a measure (Becker & Egeth, 2000). The current study, however, aimed to examine the contribution of each representation while measuring attentional facilitation. In our paradigm, the two rectangle outlines rotated 90° or 180° clockwise or counter-clockwise, resulting in non-matching space and object locations, which separated the spatial and object-based reference frames. Results suggest that in dynamic displays, both space-based and object-based representations are abandoned under conditions of target location certainty, which provides further evidence for the prioritization account of object-based attention. Under conditions of uncertainty, space-based attention is inefficient for guiding attention, while the object-based reference frame becomes more stable and dominant, thus guiding attentional selection (i.e., attention tracks rotated objects). In addition, the same dynamic display paradigm was adopted for use with an IOR approach in order to investigate the extent to which certainty affects IOR.