The Effects of Bilateral Symmetry, Viewing Distance, and Scene Context on Apparent 3D Shape
The Effects of Bilateral Symmetry, Viewing Distance, and Scene Context on Apparent 3D Shape
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双边对称性、观看距离和场景上下文对表观 3D 形状的影响
DOI：
10.1167/19.10.197c
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发表时间：
2019
影响因子：
1.8
通讯作者：
Petrov, Alexander A
中科院分区：
文献类型：
--
作者：
Yu, Ying;Todd, James T;Petrov, Alexander A
Pizlo等人（2014）认为，对称在3D形状的感知中起着关键作用，但令人惊讶的是，对这一假设的直接实证检验很少。本实验比较了对称和非对称物体在形状匹配任务中的调整精度。方法：利用计算机生成的三维多面体立体图像，通过百叶窗眼镜双眼观察。在每次试验中，可调节和参考两个物体并排呈现，参与者调整前者的z尺度以匹配后者的表观形状。刺激集包括10个类似Li et al.（2011）刺激的镜像对称多面体及其30个不对称变形。畸变明显是不对称的，是由多面体的每个顶点在三维中随机位移产生的。对称物体的四边形面都是平面的，而非对称物体的四边形面则不是平面的，而是弯曲的。这些刺激要么是在黑色背景下呈现的，要么是在一个走廊里呈现的，走廊里有纹理的墙壁立体地向纵深退去。对称和语境在2× 2因子设计中被操纵，在四个90个试验中，每个条件一个。到参考物体的距离在试验中被操纵（0.7 m， 1.5 m或2.3 m）；可调对象始终放置在1.5 m处，并且物理上大于参考对象。结果：所有七名观察员都产生了相似的定性模式。虽然统计能力很高，但对称和不对称条件之间没有显著差异，也没有显著的相互作用。观察距离对参考物体的视深度有显著的影响，随着观察距离的增加，所有刺激类型的参考物体的视深度都被系统地压缩。场景环境也有显著的影响——相对于调整对象，参考对象在走廊中比在黑色背景下看起来更有深度。
Pizlo et al.(2014) argue that symmetry plays a critical role in the perception of 3D shape, but there are surprisingly few direct empirical tests of this hypothesis. The present experiment compares the adjustment accuracy for symmetric and asymmetric objects in a shape-matching task. Method: Computer-generated stereoscopic images of 3D polyhedra were viewed binocularly through shutter glasses. On each trial, two objects–adjustable and reference–were presented side by side and the participant adjusted the Z-scaling of the former to match the apparent shape of the latter. The stimulus set included 10 mirror-symmetric polyhedra similar to the stimuli of Li et al.(2011), and 30 asymmetric distortions thereof. The distortions were obviously asymmetric and were produced by randomly displacing in 3D every vertex of the polyhedron. Whereas the quadrilateral faces of the symmetric objects were all planar, those of the asymmetric objects were not, and appeared curved. The stimuli were rendered either against a black background or inside a corridor with textured walls receding stereoscopically in depth. Symmetry and context were manipulated in a 2× 2 factorial design in four 90-trial sessions, one per condition. The distance to the reference object was manipulated across trials (0.7 m, 1.5 m, or 2.3 m); the adjustable object was always placed at 1.5 m and was physically larger than the reference. Results: All seven observers produced similar qualitative patterns. Although statistical power was high, there were no significant differences between the symmetric and asymmetric conditions and no significant interactions. Viewing distance had a large significant effect–the apparent depths of the reference objects became systematically compressed with increased viewing distance for all stimulus types. Scene context had a significant effect too–the reference objects appeared to have more depth when viewed in the corridor than against a black background, relative to the adjustment object.