Biederman Irving, Kim Jiye G
University of Southern California, Department of Psychology, 3641 Watt Way, Hedco Neurosciences Building, Room 316, Los Angeles, CA 90089-2520, USA.
Perception. 2008;37(1):161-4. doi: 10.1068/p5907.
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.
合格的写实绘画保留了简单物体的视角不变形状特征，例如，物体中笔直或弯曲的轮廓在绘画中也会如此描绘。一种更微妙的不变特征——遮挡边界的V形奇点，包含一个T形交叉点和一个轮廓端点——出现在关节光滑表面的交界处，比如马腿与身体相连的部位。2007年，仅有极少艺术教育背景的人所绘制的画中，有45%正确描绘了此类交界处，这一比例与17000年前大量洞穴壁画中正确描绘的发生率（42%）并无显著差异。无论一个人在绘画中是否包含了这种不变特征，所有人都认为这样的描绘更好。
