Abstract
Several cues influence figure-ground assignment, including area (Rubin, 1958) and convexity (Metzger, 1953). In addition, top-down input such as attention (Vecera et al., 2004) or familiarity (Peterson, 1994) also influence figure-ground assignment. Although much is known about the factors that affect, or control, figure-ground assignment, little attention has been given to possible consequences, or effects, of this process. The subjective salience enjoyed by figural regions could be caused by at least two effects, either a perceptual enhancement of figures or to figures being given processing priority over grounds. We attempted to distinguish these effects of figure-ground assignment by using a perceptually demanding spatial resolution task. In Experiment 1, observers viewed figure-ground displays in which two features appeared in the figure or ground region; features appearing on figures were discriminated more accurately than those on grounds, consistent with an enhancement effect. In Experiments 2 and 3, the regions were presented separately to rule out stimulus effects on target discrimination. No differences in target discrimination were found between the regions, supporting the enhancement effect seen in Experiment 1. Experiment 4 tested a strong prediction made by an enhancement process, namely that targets on figural regions would be discriminated more accurately than targets on figurally neutral regions. As predicted, targets appearing on figures were discriminated more accurately than those appearing on either ground regions or on neutral stimuli. Taken together, these results suggest that figures are perceptually enhanced compared to grounds.
NSF grant BCS 03-39171 awarded to Shaun P. Vecera