title: Helmholtz's principle.
authors: Richard L
authors: RL
authors: Gregory
mesh_terms: D000360:Afterimage; D003867:Depth Perception / Q000502:physiology; D006801:Humans; D008954:Models, Biological; D009903:Optical Illusions; D014785:Vision, Ocular / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*