Convexity has long been considered a potent cue as to which of two regions on opposite sides of an edge is the shaped figure. Experiment 1 shows that for a single edge, there is only a weak bias toward seeing the figure on the convex side. Experiments 1-3 show that the bias toward seeing the convex side as figure increases as the number of edges delimiting alternating convex and concave regions increases, provided that the concave regions are homogeneous in color. The results of Experiments 2 and 3 rule out a probability summation explanation for these context effects. Taken together, the results of Experiments 1-3 show that the homogeneity versus heterogeneity of the convex regions is irrelevant. Experiment 4 shows that homogeneity of alternating regions is not sufficient for context effects; a cue that favors the perception of the intervening regions as figures is necessary. Thus homogeneity alone does not alone operate as a background cue. We interpret our results within a model of figure-ground perception in which shape properties on opposite sides of an edge compete for representation and the competitive strength of weak competitors is further reduced when they are homogeneous.

Figure-ground segregation is modeled as inhibitory competition between objects that might be perceived on opposite sides of borders. The winner is the figure; the loser is suppressed, and its location is perceived as shapeless ground. Evidence of ground suppression would support inhibitory competition models and would contribute to explaining why grounds are shapeless near borders shared with figures, yet such evidence is scarce. We manipulated whether competition from potential objects on the ground side of figures was high (i.e., portions of familiar objects were potentially present there) or low (novel objects were potentially present). We predicted that greater competition would produce more ground suppression. The results of two experiments in which suppression was assessed via judgments of the orientation of target bars confirmed this prediction; a third experiment showed that ground suppression is short-lived. Our findings support inhibitory competition models of figure assignment, in particular, and models of visual perception entailing feedback, in general.Keywords Figure- The visual world contains an overwhelming amount of information, yet it seems immediately and effortlessly organized into differentiable objects. Perceptual organization is essential for interacting with the world, but relatively little is known about how it is accomplished. Vital to perceptual organization is the determination of which of two contiguous regions is the object (or figure) at the shared border, and which simply appears as a shapeless background to the object-what has been called figure-ground perception (Rubin, 1915(Rubin, /1958. Critically, shape is attributed to the figure, whereas no shape is attributed to the ground near the border that it shares with the figure.Numerous computational models of figure-ground perception have employed competition between figure attributes on opposite sides of borders in the visual input to resolve figure-ground perception (e.g

Nelson and Palmer (2007) concluded that figures/figural properties automatically attract attention after finding that participants were faster to detect/discriminate targets appearing where a portion of a familiar object was suggested in an otherwise ambiguous display. We investigated whether these effects are truly automatic and whether they generalize to another figural propertyconvexity. We found that Nelson and Palmer's results do generalize to convexity but only when participants are uncertain regarding when and where the target will appear. Dependence on uncertainty regarding target location/timing was also observed for familiarity. Thus, although we can replicate and extend Nelson and Palmer's results, our experiments show that figures do not automatically draw attention. In addition, our research went beyond Nelson and Palmer's in that we were able to separate figural properties from perceived figures. Because figural properties are regularities that predict where objects lie in the visual field, our results join other evidence that regularities in the environment can attract attention. More generally, our results are consistent with Bayesian theories in which priors are given more weight under conditions of uncertainty.

No abstract

No abstract