title: Perceptual grouping in shape from shading.
abstract: We report on the reversal of asymmetry in visual-search tasks with shaded items. Previous studies have suggested that the target of a bottom-lit disk among distractors of top-lit disks is detected in a rapid and parallel manner, but not vice versa. However, in this study, we have shown that the compound items of top-lit disks were searched more quickly than those composed of bottom-lit disks where the items had to be segregated from their background. By modulating the inter-element distances, we confirmed that the reversal of search asymmetry cannot be due to the grouping of items. Further, we showed that the regions of the top-lit disks were perceived as figure more consistently than those of bottom-lit disks. The results indicate that the boundary assignment to the compound items of the top-lit disks enhances the segregation of search items from the background, and that the search mechanism may access the relatively higher representation that includes figure-ground relations.
authors.affiliation: Behavioral and Health Sciences, Graduate School of Human-Environmental Studies, Kyushu University, 6-19-1, Hakozaki, Higashi-ku, Fukuoka-city, 8128581 Japan. kawabe@psycho.hes.kyushu-u.ac.jp
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kawabe
authors.forename: Kayo
authors.initials: K
authors.lastname: Miura
mesh_terms: D003867:Depth Perception; D005260:Female; D006801:Humans; D008029:Lighting / Q000379:methods; D008297:Male; D009903:Optical Illusions; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time