title: 17,000 years of depicting the junction of two smooth shapes.
abstract: Competent realistic drawings preserve viewpoint-invariant shape characteristics of simple parts, such that a contour in the object that is straight or curved, for example, is depicted that way in the drawing. A more subtle invariant--a V-shaped singularity of the occluding boundary, containing a T-junction and a contour termination--is produced at the junction between articulated smooth surfaces, as with the leg joining the body of a horse. 45% of the drawings made in 2007 by individuals with only minimal art education correctly depicted such junctions, a proportion that is not reliably different from the incidence (42%) of correct depictions in a large sample of cave art made 17000 years ago. Whether a person did or did not include the invariant in their drawing, all agreed that it made for a better depiction.
authors.affiliation: University of Southern California, Department of Psychology, 3641 Watt Way, Hedco Neurosciences Building, Room 316, Los Angeles, CA 90089-2520, USA. bieder@usc.edu
authors.forename: Irving
authors.initials: I
authors.lastname: Biederman
authors.forename: Jiye G
authors.initials: JG
authors.lastname: Kim
mesh_terms: D001154:Art; D005556:Form Perception / Q000502:physiology; D006801:Humans; D009903:Optical Illusions / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*