title: Concave and convex phases in ambiguous figures showing colour shifts. Mach's figure and the AMBEGUJAS phenomenon.
abstract: Two ambiguous figures (Mach's book-figure and the AMBEGUJAS phenomenon) have been studied. They show colour shifts synchronised with the shifts of their alternative phases. The perceived concave phase appeared to have chromatic surface colour, but the perceived convex phase can appear to be in coloured illumination and shadow (film colour). The two perceived reversible shapes of the Mach figure (the book and the tent) and the three perceived alternative shapes of the Mondrians used in the AMBEGUJAS phenomenon (a roof, a ceiling, and a tile) all can appear to have chromatic surface colours in their concave phases but appear to have coloured illumination and shadow in their convex phases.
authors.affiliation: Department of Psychology, University of Umeå, SE 901 87 Umeå, Sweden. sten-sture.bergstrom@psy.umu.se
authors.forename: Sten Sture
authors.initials: SS
authors.lastname: Bergström
authors.forename: Karl-Arne
authors.initials: KA
authors.lastname: Gustafsson
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003118:Color Perception / Q000502:physiology*; D015350:Contrast Sensitivity; D003867:Depth Perception / Q000502:physiology*; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009903:Optical Illusions / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D055815:Young Adult