Department of Psychology and Centre for Vision Research, York University, Toronto, Ontario, Canada.
J Vis. 2022 Mar 2;22(4):9. doi: 10.1167/jov.22.4.9.
Stereopsis plays an important role in depth perception; if so, disparity-defined depth should not vary with distance. However, studies of stereoscopic depth constancy often report systematic distortions in depth judgments over distance, particularly for virtual stimuli. Our aim was to understand how depth estimation is impacted by viewing distance and display-based cue conflicts by replicating physical objects in virtual counterparts. To this end, we measured perceived depth using virtual textured half-cylinders and identical three-dimensional (3D) printed versions at two viewing distances under monocular and binocular conditions. Virtual stimuli were viewed using a mirror stereoscope and an Oculus Rift head-mounted display (HMD), while physical stimuli were viewed in a controlled test environment. Depth judgments were similar in both virtual apparatuses, which suggests that variations in the viewing geometry and optics of the HMD have little impact on perceived depth. When viewing physical stimuli binocularly, judgments were accurate and exhibited stereoscopic depth constancy. However, in all cases, depth was underestimated for virtual stimuli and failed to achieve depth constancy. It is clear that depth constancy is only complete for cue-rich physical stimuli and that the failure of constancy in virtual stimuli is due to the presence of the vergence-accommodation conflict. Further, our post hoc analysis revealed that prior experience with virtual and physical environments had a strong effect on depth judgments. That is, performance in virtual environments was enhanced by limited exposure to a related task using physical objects.
立体视在深度感知中起着重要作用；如果是这样，视差定义的深度不应随距离而变化。然而，立体深度恒常性的研究经常报告深度判断在距离上的系统扭曲，特别是对于虚拟刺激。我们的目的是通过复制虚拟对象中的物理对象来了解距离和基于显示的线索冲突对视差估计的影响。为此，我们在单眼和双眼条件下，使用虚拟纹理半圆柱和相同的三维（3D）打印版本在两个观察距离下测量感知深度。虚拟刺激使用镜像立体镜和 Oculus Rift 头戴式显示器（HMD）观看，而物理刺激在受控测试环境中观看。两种虚拟设备中的深度判断相似，这表明 HMD 的观察几何形状和光学变化对感知深度的影响很小。当双眼观察物理刺激时，判断是准确的，并表现出立体深度恒常性。然而，在所有情况下，虚拟刺激的深度都被低估，并且无法实现深度恒常性。显然，深度恒常性仅适用于线索丰富的物理刺激，而虚拟刺激中恒常性的失败是由于会聚调节冲突的存在。此外，我们的事后分析表明，对虚拟和物理环境的先验经验对深度判断有很大影响。也就是说，通过使用物理对象进行有限的相关任务暴露，在虚拟环境中的表现得到了增强。
