A single experiment is reported that measured the apparent stereoscopic shapes of symmetric and asymmetric objects at different viewing distances. The symmetric stimuli were specifically designed to satisfy the minimal conditions for computing veridical shape from symmetry. That is to say, they depicted complex, bilaterally symmetric, plane-faced polyhedra whose symmetry planes were oriented at an angle of 45° relative to the line of sight. The asymmetric stimuli were distorted versions of the symmetric ones in which the 3D position of each vertex was randomly displaced. Prior theoretical analyses have shown that it is mathematically possible to compute the 3D shapes of symmetric stimuli under these conditions, but those algorithms are useless for asymmetric objects. The results revealed that the apparent shapes of both types of objects were expanded or compressed in depth as a function of viewing distance, in exactly the same way as has been reported in many other studies, and that the presence or absence of symmetry had no detectable effect on performance.

报告了一个单独的实验，该实验测量了不同观看距离下对称和非对称物体的表观立体形状。对称刺激是专门为满足从对称计算真实形状的最小条件而设计的。也就是说，他们描绘了复杂的、双边对称的、平面的多面体，其对称平面相对于视线方向成 45°。非对称刺激是对称刺激的扭曲版本，其中每个顶点的 3D 位置随机移位。先前的理论分析表明，在这些条件下计算对称刺激的 3D 形状在数学上是可能的，但这些算法对于非对称对象是无用的。