The relationships between figure-ground organization, objectness, and symmetry

Symmetry and objectness both play a supporting role in figure-ground organization. Previous work predominantly assessed their interplay using simple black and white stimuli. In this study, we examine the interaction between figure-ground organization and objectness in symmetry detection by analyzing data from a preregistered experiment where participants identified regions of symmetry in natural scenes using a bounding-box method. Objectness was assessed using state-of-the-art object detection and segmentation algorithms. Our findings revealed that most participants did not identify the largest possible symmetric region but rather relied on figures and objects as perceptual anchors. In this analysis, we also included a particular focus on the iterative process of nested symmetry identification. Participants who identified nested symmetries usually began with the largest symmetry and subsequently annotated smaller nested symmetries.