ANGULAR OVERESTIMATION ENHANCES CODING PRECISION: SCALE EXPANSION THEORY IN SLANT PERCEPTION

  • Frank H. Durgin
  • Zhi Li

Abstract

Why do hills appear so much steeper than their physical orientation? We review recent evidence for three distinct theories of slant overestimation including effort theory, depth foreshortening theory, and a new proposal, scale expansion theory. Scale expansion theory can account for a variety of errors in the perception of orientation across visual and haptic modalities, as well as the proprioception of gaze declination – an important variable in the perception of both slant and distance. Scale expansion theory proposes that angular scaling exaggerates deviations from defaults (such as horizontal) for the sake of precise coding. The theory is supported by explicit measures (including numeric measures and angle bisection tasks) as well as by implicit measures of perceived optical slant based on judging the aspect ratio of an L presented on a slanted surface. The misperception of hills can be understood as resulting from a combination of expansion of angular scales in near space and an increase of perceived optical slant with log viewing distance.

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