Jörges Björn, Bury Nils, McManus Meaghan, Bansal Ambika, Allison Robert S, Jenkin Michael, Harris Laurence R
Center for Vision Research, York University, Toronto, ON, Canada.
Institute of Visual Computing, Hochschule Bonn-Rhein-Sieg, St. Augustin, Germany.
NPJ Microgravity. 2024 Oct 4;10(1):95. doi: 10.1038/s41526-024-00430-3.
Altering posture relative to the direction of gravity, or exposure to microgravity has been shown to affect many aspects of perception, including size perception. Our aims in this study were to investigate whether changes in posture and long-term exposure to microgravity bias the visual perception of object height and to test whether any such biases are accompanied by changes in precision. We also explored the possibility of sex/gender differences. Two cohorts of participants (12 astronauts and 20 controls, 50% women) varied the size of a virtual square in a simulated corridor until it was perceived to match a reference stick held in their hands. Astronauts performed the task before, twice during, and twice after an extended stay onboard the International Space Station. On Earth, they performed the task of sitting upright and lying supine. Earth-bound controls also completed the task five times with test sessions spaced similarly to the astronauts; to simulate the microgravity sessions on the ISS they lay supine. In contrast to earlier studies, we found no immediate effect of microgravity exposure on perceived object height. However, astronauts robustly underestimated the height of the square relative to the haptic reference and these estimates were significantly smaller 60 days or more after their return to Earth. No differences were found in the precision of the astronauts' judgments. Controls underestimated the height of the square when supine relative to sitting in their first test session (simulating Pre-Flight) but not in later sessions. While these results are largely inconsistent with previous results in the literature, a posture-dependent effect of simulated eye height might provide a unifying explanation. We were unable to make any firm statements related to sex/gender differences. We conclude that no countermeasures are required to mitigate the acute effects of microgravity exposure on object height perception. However, space travelers should be warned about late-emerging and potentially long-lasting changes in this perceptual skill.
改变相对于重力方向的姿势，或暴露于微重力环境已被证明会影响感知的许多方面，包括大小感知。我们在本研究中的目的是调查姿势变化和长期暴露于微重力环境是否会使物体高度的视觉感知产生偏差，并测试是否有任何此类偏差伴随着精度的变化。我们还探讨了性别差异的可能性。两组参与者（12名宇航员和20名对照组人员，女性占50%）在模拟走廊中改变虚拟正方形的大小，直到他们认为其与手中拿着的参考棒相匹配。宇航员在国际空间站长期停留之前、期间两次以及之后两次执行该任务。在地球上，他们分别以直立坐姿和仰卧姿势执行任务。地面对照组也同样间隔进行了五次测试；为了模拟国际空间站上的微重力测试，他们采取仰卧姿势。与早期研究不同，我们发现微重力暴露对感知物体高度没有即时影响。然而，宇航员相对于触觉参考显著低估了正方形的高度，并且在他们返回地球60天或更长时间后，这些估计值明显更小。在宇航员判断的精度方面未发现差异。对照组在第一次测试（模拟飞行前）仰卧时相对于坐姿低估了正方形的高度，但在后续测试中没有。虽然这些结果在很大程度上与文献中的先前结果不一致，但模拟眼高的姿势依赖性效应可能提供一个统一的解释。我们无法就性别差异做出任何确凿的陈述。我们得出结论，无需采取任何对策来减轻微重力暴露对物体高度感知的急性影响。然而，应该提醒太空旅行者注意这种感知技能后期出现且可能持续很长时间的变化。
