Bourrelly Aurore, McIntyre Joseph, Luyat Marion
SCALab CNRS UMR 9193, University of Lille, Lille, France,
Cogn Process. 2015 Sep;16 Suppl 1:171-4. doi: 10.1007/s10339-015-0692-y.
On Earth, visual eye height (VEH)--the distance from the observer's line of gaze to the ground in the visual scene--constitutes an effective cue in perceiving affordance such as the passability through apertures, based on the assumption that one's feet are on the ground. In the present study, we questioned whether an observer continues to use VEH to estimate the width of apertures during long-term exposure to weightlessness, where contact with the floor is not required. Ten astronauts were tested in preflight, inflight in the International Space Station, and postflight sessions. They were asked to adjust the opening of a virtual doorway displayed on a laptop device until it was perceived to be just wide enough to pass through (i.e., the critical aperture). We manipulated VEH by raising and lowering the level of the floor in the visual scene. We observed an effect of VEH manipulation on the critical aperture. When VEH decreased, the critical aperture decreased too, suggesting that widths relative to the body were perceived to be larger when VEH was smaller. There was no overall significant session effect, but the analysis of between-subjects variability revealed two participant profile groups. The effect of weightlessness was different for these two groups even though the VEH strategy remained operational during spaceflight. This study shows that the VEH strategy appears to be very robust and can be used, if necessary, in inappropriate circumstances such as free-floating, perhaps promoted by the nature of the visual scene.
在地球上，视觉眼高（VEH）——即观察者视线到视觉场景中地面的距离——基于人脚在地面的假设，构成了感知诸如通过孔洞的可通行性等可供性的有效线索。在本研究中，我们质疑观察者在长期处于失重状态（无需与地板接触）时是否仍会使用视觉眼高来估计孔洞的宽度。对10名宇航员进行了飞行前、国际空间站飞行中以及飞行后的测试。要求他们调整笔记本电脑设备上显示的虚拟门道的开口，直到他们认为其宽度刚好足以通过（即临界孔径）。我们通过升高和降低视觉场景中地板的高度来操纵视觉眼高。我们观察到视觉眼高操纵对临界孔径有影响。当视觉眼高降低时，临界孔径也会减小，这表明当视觉眼高较小时，相对于身体的宽度会被感知为更大。没有整体显著的测试阶段效应，但对个体间变异性的分析揭示了两个参与者特征组。尽管在太空飞行期间视觉眼高策略仍然有效，但这两组的失重效应有所不同。这项研究表明，视觉眼高策略似乎非常稳健，并且在必要时可以在诸如自由漂浮等不适当的情况下使用，这可能是由视觉场景的性质所促成的。
