Does gravity affect decision-making? This question comes into sharp focus as plans for interplanetary human space missions solidify. In the framework of Bayesian brain theories, gravity encapsulates a strong prior, anchoring agents to a reference frame via the vestibular system, informing their decisions and possibly their integration of uncertainty. What happens when such a strong prior is altered? We address this question using a self-motion estimation task in a space analog environment under conditions of altered gravity. Two participants were cast as remote drone operators orbiting Mars in a virtual reality environment on board a parabolic flight, where both hyper- and microgravity conditions were induced. From a first-person perspective, participants viewed a drone exiting a cave and had to first predict a collision and then provide a confidence estimate of their response. We evoked uncertainty in the task by manipulating the motion's trajectory angle. Post-decision subjective confidence reports were negatively predicted by stimulus uncertainty, as expected. Uncertainty alone did not impact overt behavioral responses (performance, choice) differentially across gravity conditions. However microgravity predicted higher subjective confidence, especially in interaction with stimulus uncertainty. These results suggest that variables relating to uncertainty affect decision-making distinctly in microgravity, highlighting the possible need for automatized, compensatory mechanisms when considering human factors in space research.

翻译：重力是否影响决策？随着星际载人航天计划的推进，这一问题日益受到关注。在贝叶斯大脑理论框架下，重力构成了一种强先验知识，通过前庭系统将个体锚定于参考框架，影响其决策及对不确定性的整合。当这种强先验被改变时会发生什么？我们利用空间模拟环境中的自我运动估计任务，在重力改变条件下探究这一问题。两名参与者被设定为火星轨道飞行的远程无人机操作员，在抛物线飞行器搭载的虚拟现实环境中，分别经历超重与微重力条件。参与者以第一人称视角观察无人机从洞穴飞出，需先预测碰撞，再对其判断进行置信度评估。我们通过改变运动轨迹角度来引发任务中的不确定性。结果显示，主观置信度报告随刺激不确定性增加而降低（与预期相符），但不确定性本身对重力条件下的外显行为反应（表现、选择）无差异性影响。然而，微重力环境可预测更高水平的主观置信度，尤其在与刺激不确定性的交互作用中更为显著。这些结果表明，与不确定性相关的变量在微重力条件下对决策的影响具有独特性，凸显了在太空研究中考虑自动化补偿机制的必要性。