GEOMETRIC REPRESENTATION OF THE MECHANISMS UNDERLYING HUMAN CURVATUREDETECTION

Combined manipulation of blur, line length and contrast reveal two dis tinct processes involved in curvature detection. When line length is s mall relative to blur, thresholds are almost directly proportional to blur and independent of line length. When line length is large relativ e to blur thresholds are directly proportional to line length and inde pendent of blur. The aspect ratio (line length/blur) of curved contour s represents a scale-invariant metric which forms the decisive factor in determining curvature performance. (C) 1998 Elsevier Science Ltd. A ll rights reserved.