Schlüter Nick, Faul Franz
Institut für Psychologie, Christian-Albrechts-Universität zu Kiel, Germany.
Iperception. 2016 Sep 12;7(5):2041669516669616. doi: 10.1177/2041669516669616. eCollection 2016 Sep-Oct.
It has been proposed that the visual system is able to estimate the refractive index of thick transparent objects from background distortions caused by them. More specifically, it was hypothesized that this is done based on a mid-level cue, the distortion field, whose computation from the input requires comparing the part of the background seen through the object with the part visible in plain view. We test two predictions derived from this hypothesis: (a) scene variables that do not change the distortion field, for instance, the density of the background texture, should not systematically influence the subjects' settings in a material matching task. (b) The uncertainty of the estimates should increase sharply, if the part of the background texture in plain view is removed. Our results are not compatible with these two predictions but are completely in line with the alternative interpretation that the subjects maximized the similarity of the distorted background textures on the image level. Additional results indicate that subjects can take relations between the distorted and the undistorted background into account if this is encouraged by the experimental design, but they do this in a simplistic way that is inappropriate to estimate the refractive index.
有人提出，视觉系统能够根据厚透明物体造成的背景扭曲来估计其折射率。更具体地说，有人假设这是基于一种中级线索——扭曲场来完成的，从输入中计算该线索需要将透过物体看到的背景部分与直接可见的部分进行比较。我们检验了从该假设得出的两个预测：(a) 不改变扭曲场的场景变量，例如背景纹理的密度，在材料匹配任务中不应系统地影响受试者的设置。(b) 如果去除直接可见的背景纹理部分，估计的不确定性应急剧增加。我们的结果与这两个预测不相符，但完全符合另一种解释，即受试者在图像层面上最大化了扭曲背景纹理的相似性。其他结果表明，如果实验设计鼓励，受试者可以考虑扭曲背景和未扭曲背景之间的关系，但他们以一种简单的方式这样做，这种方式不适用于估计折射率。
