Rapid processing of cast and attached shadows
Rapid processing of cast and attached shadows
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DOI：
10.1068/p5323
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发表时间：
2004-01-01
期刊：
影响因子：
1.7
通讯作者：
MacLean, D
中科院分区：
文献类型：
--
作者：
Elder, JH;Trithart, S;MacLean, D
我们使用了视觉搜索的方法来调查的作用，阴影的场景属性的快速歧视。目标和干扰物是浅或深的2-D新月，形状和大小相同，在中灰色背景上。从黑暗的刺激，虚幻的三维形状可以创建模糊的一个弧的新月。如果内弧模糊，则刺激被感知为带有阴影的曲面。如果外弧是模糊的，刺激被认为是一个平面投射阴影。在一系列的五个实验中，我们使用这个简单的刺激来绘制出人类视觉系统可以快速检测和区分的阴影特性。为了减去2-D图像的因素，我们比较了搜索性能的黑暗阴影的刺激与性能的光影刺激，一般不会引起强烈的3-D知觉。我们发现，人类视觉系统能够根据许多不同的阴影属性进行快速区分，包括阴影的类型（投射或附着），阴影的方向和阴影的位移。虽然很明显，在快速搜索中，阴影并没有被简单地忽略，但目前还不清楚快速辨别是作用于阴影本身，还是作用于由感知到的阴影引起的3-D物体形状和位置的表示。
We used a visual-search method to investigate the role of shadows in the rapid discrimination of scene properties. Targets and distractors were light or dark 2-D crescents of identical shape and size, on a mid-grey background. From the dark stimuli, illusory 3-D shapes can be created by blurring one arc of the crescent. If the inner arc is blurred, the stimulus is perceived as a curved surface with attached shadow. If the outer arc is blurred, the stimulus is perceived as a flat surface casting a shadow. In a series of five experiments, we used this simple stimulus to map out the shadow properties that the human visual system can rapidly detect and discriminate. To subtract out 2-D image factors, we compared search performance for dark-shadow stimuli with performance for light-shadow stimuli which generally do not elicit strong 3-D percepts. We found that the human visual system is capable of rapid discrimination based upon a number of different shadow properties, including the type of the shadow (cast or attached), the direction of the shadow, and the displacement of the shadow. While it is clear that shadows are not simply discounted in rapid search, it is unclear at this stage whether rapid discrimination is acting upon shadows per se or upon representations of 3-D object shape and position elicited by perceived shadows.