title: Foreshortening produces errors in the perception of angles pictured as on the ground.
abstract: Observers viewed pictures of a simulated ground plane and judged the orientation of lines pictured as lying on the ground. We presented three lines at a time and manipulated three factors: (1) the declination of the lines below the horizon (depicting distance to the target angles), (2) their length, and (3) whether or not they converged to a point on the horizon. Only the first factor had a substantial effect on these errors. We conclude that perspective foreshortening in pictures produces errors in perceived 3-D orientation. Our explanation is based on the different rates of change of elevation and azimuth with distance.
authors.affiliation: University of Toronto, 1265 Military Trail, Toronto, Ontario, M1C1A4, Canada.
authors.forename: Marta
authors.initials: M
authors.lastname: Wnuczko
authors.affiliation: University of Toronto, 1265 Military Trail, Toronto, Ontario, M1C1A4, Canada.
authors.forename: Karan
authors.initials: K
authors.lastname: Singh
authors.affiliation: University of Toronto, 1265 Military Trail, Toronto, Ontario, M1C1A4, Canada. kennedy@utsc.utoronto.ca.
authors.forename: John M
authors.initials: JM
authors.lastname: Kennedy
mesh_terms: D000328:Adult; D003867:Depth Perception; D004215:Distance Perception; D005260:Female; D005556:Form Perception; D006801:Humans; D008297:Male; D009903:Optical Illusions; D009949:Orientation; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation / Q000379:methods*
keywords: 2-D shape and form; 3-D perception; Depth and shape perception; Space perception