Competition-strength-dependent ground suppression in figure–ground perception

Abstract

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

Neural evidence for competition-mediated suppression in the perception of a single object

“…We take these data as neural evidence that suppressive competition underlies the perception of a single object. The results show that greater competition for object status from regions ultimately perceived as grounds produces greater suppression of the ground, supporting previous behavioral data (Salvagio et al, 2012). The same pattern was evident across V1, V2, and V4.…”

“…If it is, that will be consistent with the hypothesis that feedback from suppressive competition at higher levels modulates responses in lower-level brain regions. Consistent with this feedback hypothesis, Salvagio et al (2012) reported behavioral evidence of competitionmediated suppression for targets shown on grounds but not for targets shown on figures, even though the distance between targets on figures vs. grounds was less than 1 o of visual angle.…”

“…The stimuli were 80 enclosed, symmetric, silhouettes (cf., Peterson & Kim 2001;Peterson & Skow, 2008;Salvagio et al, 2012;Trujillo, Allen, Schnyer, & Peterson, 2010) that were smaller in area than the backdrops on which they were presented. These properties favored that percept that the inside was the object.…”

“…Peterson and Skow (2008;Salvagio et al, 2012) hypothesized that such suppression may be partially responsible for the fact that the groundside of a border is perceived as shapeless. Based on these results, models that implement suppressive competition in figure-ground perception should be amended to include competition-mediated ground suppression.…”

“…Moreover, Salvagio, Cacciamani, and Peterson (2012) showed that orientation discrimination performance was worse for targets presented on the on the groundside of high-competition than low-competition stimuli. These findings go beyond the models of suppressive competition in showing that the location of the losing competitor for object status is suppressed, and that greater suppression is applied to grounds that compete more for object status-a phenomenon we refer to as competition-mediated ground suppression.…”