Abstract
In a hierarchical stage account of vision, figure-ground assignment is thought to be completed before the operation of focal spatial attention. Previous results support this account by showing that unpredictive, exogenous spatial precues do not influence figure-ground assignment, although voluntary attention can influence figure-ground assignment. However, in these studies, attention was not summoned directly to a region in a figure-ground display. In three experiments, we address the relationship between figure-ground assignment and visuospatial attention using a visual short-term memory matching task. In Experiment 1, subjects saw figure-ground displays and an unpredictive peripheral precue that appeared outside the figure-ground stimulus; we replicated the finding that exogenous precues do not influence figure-ground assignment when they direct attention outside of a figure-ground stimulus. In Experiment 2, unpredictive peripheral precues were placed inside figure-ground display so that attention was directed to one of the possible figural regions. Exogenous attention influenced figure-ground assignment: Subjects were faster to match the precued region from memory than the uncued region. Finally, in Experiment 3, we asked if unpredictive peripheral precues could modulate figure-ground assignment in displays containing a gestalt figure-ground cue (convexity). We found that exogenous attention interacted with the convexity cue in this experiment. When attention was directed to the convex region, subjects were faster to match this region than the uncued, concave region. When attention was directed to the concave region, the figural advantage produced by the convex region was reduced significantly. These results suggest that figure-ground processes are not entirely completed prior to the operation of spatial attention. Exogenous spatial attention acts as a cue for figure-ground assignment and can affect the outcome of figure-ground processes.