Visual attention and objects: one versus two or convex versus concave?

According to object-based theories of visual attention, attention can be divided within a single object more efficiently than between separate objects (J. Duncan, 1984). Recently, G. C. Baylis and J. Driver (1993) provided a theoretical framework for interpreting this single-object advantage within the domain of spatial organization. Using their hierarchical coding of location hypothesis, they showed that the latency to compare the location of 2 vertices was significantly faster for vertices that were seen as part of a single (convex) object than for vertices that were seen as parts of separate (concave) objects. This article reports the replication of this finding, as well as new evidence that shows that latency is affected by the convexity of the contour, and not by the number of objects.