Three-dimensional symmetric shapes are discriminated more efficiently than asymmetric ones
Three-dimensional symmetric shapes are discriminated more efficiently than asymmetric ones
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DOI：
10.1364/josaa.20.001331
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发表时间：
2003-07-01
影响因子：
1.9
通讯作者：
Kersten, D
中科院分区：
文献类型：
--
作者：
Liu, ZL;Kersten, D
具有双侧对称性的物体，如人脸、动物形状和许多人造物体，在日常视觉中起着重要作用。因为它们经常出现，所以我们有理由推测大脑可能专门处理对称物体。我们研究了人类视觉系统处理三维（3D）对称对象是否比非对称对象更有效。人类受试者，学会了一个对称的金属线对象，辨别哪两个扭曲的副本的学习对象是更相似的学习。通过在导线对象的顶点处添加3D高斯位置扰动来实现失真。在非对称条件下，扰动从一个顶点到下一个顶点是独立的。在对称条件下，独立的扰动只加在物体的一半上;另一半上的扰动保持了物体的对称性。我们发现，在对称条件下，受试者的阈值较高。然而，由于在对称条件下的扰动是相关的，在对称条件下刺激图像提供较少的信息。考虑到这一点，理想观察者分析显示，受试者实际上更有效地区分对称物体。这种解释上的逆转强调了理想观察者分析的重要性。如果只分析人类的辨别阈值，就会得出一个完全相反的错误结论。在相同的信息量下，视觉系统实际上能够更好地区分对称物体而不是不对称物体。(C)2003年美国光学学会。
Objects with bilateral symmetry, such as faces, animal shapes, and many man-made objects, play an important role in everyday vision. Because they occur frequently, it is reasonable to conjecture that the brain may be specialized for symmetric objects. We investigated whether the human visual system processes three-dimensional (3D) symmetric objects more efficiently than asymmetric ones. Human subjects, having learned a symmetric wire object, discriminated which of two distorted copies of the learned object was more similar to the learned one. The distortion was achieved by adding 3D Gaussian positional perturbations at the vertices of the wire object. In the asymmetric condition, the perturbation was independent from one vertex to the next. In the symmetric condition, independent perturbations were added to only half of the object; perturbations on the other half retained the symmetry of the object. We found that subjects' thresholds were higher in the symmetric condition. However, since the perturbation in the symmetric condition was correlated, a stimulus image provided less information in the symmetric condition. Taking this into consideration, an ideal-observer analysis revealed that subjects were actually more efficient at discriminating symmetric objects. This reversal in interpretation underscores the importance of ideal-observer analysis. A completely opposite, and wrong, conclusion would have been drawn from analyzing only human discrimination thresholds. Given the same amount of information, the visual system is actually better able to discriminate symmetric objects than asymmetric ones. (C) 2003 Optical Society of America.