Stoner G R, Albright T D, Ramachandran V S
Salk Institute for Biological Studies, La Jolla, California 92037.
Nature. 1990 Mar 8;344(6262):153-5. doi: 10.1038/344153a0.
When confronted with moving images, the visual system often must decide whether the motion signals arise from a single object or from multiple objects. A special case of this problem arises when two independently moving gratings are superimposed. The gratings tend to cohere and move unambiguously in a single direction (pattern motion) instead of moving independently (component motion). Here we report that the tendency to see pattern motion depends very strongly on the luminance of the intersections (that is, to regions where the gratings overlap) relative to that of the gratings in a way that closely parallels the physics of transparency. When the luminance of these regions is chosen appropriately, pattern motion is destroyed and replaced by the appearance of two transparent gratings moving independently. The observations imply that motion detecting mechanisms in the visual system must have access to tacit 'knowledge' of the physics of transparency and that this knowledge can be used to segment the scene into different objects. The same knowledge could, in principle, be used to avoid confusing shadows with real object boundaries.
当面对动态图像时，视觉系统常常必须判断运动信号是来自单个物体还是多个物体。当两个独立运动的光栅叠加时，就会出现这个问题的一种特殊情况。光栅往往会连贯起来，并朝着单一方向明确地移动（图案运动），而不是独立移动（成分运动）。在此我们报告，看到图案运动的倾向在很大程度上取决于交叉点（即光栅重叠的区域）相对于光栅的亮度，其方式与透明度的物理原理密切相似。当这些区域的亮度被适当地选取时，图案运动就会被破坏，并被两个独立移动的透明光栅的外观所取代。这些观察结果表明，视觉系统中的运动检测机制必定能够获取有关透明度物理原理的隐性“知识”，并且这种知识可用于将场景分割为不同的物体。原则上，同样的知识也可用于避免将阴影与真实物体边界混淆。
