Cutting J E
Department of Psychology, Cornell University, Ithaca, New York 14853-7601.
J Exp Psychol Hum Percept Perform. 1987 Aug;13(3):323-34. doi: 10.1037//0096-1523.13.3.323.
Pictures and cinema seen at a slant present the optics of virtual objects that are distorted and inconsistent with their real counterparts. In particular, it should not be possible for moving objects on slanted film and television screens to be seen as rigid, at least according to rules of linear perspective. Previous approaches to this problem have suggested that some process (perhaps cognitive) rectifies the optics of objects in slanted pictures to derive true shape and preserve shape constancy. The means for this rectification is usually thought to be based on recovery of true screen slant. In three experiments I show that this account is unnecessary and insufficient to explain the perception of rotating, rectangular objects in slanted cinema. I present data in favor of an alternate view, one in which the information is sufficient for perceivers to determine rigidity in an object on slanted screens, at least for parallel projections. In the human visual system, local measurements of objects are apparently made according to projective geometry; in those measurements, small amounts of certain distortions in projection are tolerated. Stimuli that appear nonrigid are ones that violate certain local principles, known as Perkins's laws, of projections of rectangular solids.
倾斜观看的图片和电影呈现出虚拟物体的光学效果，这些物体是扭曲的，与它们的真实对应物不一致。特别是，倾斜的电影和电视屏幕上的移动物体至少根据线性透视规则不应被视为刚性的。以前解决这个问题的方法表明，某种过程（可能是认知过程）会纠正倾斜图片中物体的光学效果，以得出真实形状并保持形状恒常性。这种纠正的方式通常被认为是基于对屏幕真实倾斜度的恢复。在三个实验中，我表明这种解释对于解释倾斜电影中旋转矩形物体的感知是不必要且不充分的。我展示的数据支持另一种观点，即对于倾斜屏幕上的物体，至少对于平行投影而言，信息足以让感知者确定其刚性。在人类视觉系统中，物体的局部测量显然是根据射影几何进行的；在这些测量中，投影中的某些小程度的扭曲是可以容忍的。看起来非刚性的刺激是那些违反矩形实体投影的某些局部原则（称为珀金斯定律）的刺激。
