Selective facilitation of egocentric mental transformations under short-term microgravity

Understanding the impact of microgravity on human cognitive performance is crucial to guarantee the safety and success of future long-term manned missions. The effects of weightlessness on key mental processes such as spatial abilities are in particular not fully characterized. In this study, we examine the influence of microgravity on perspective-taking abilities--a type of mental operation especially relevant in the context of collaborative teamwork between free-floating astronauts. Twelve subjects performed a cooperative task in virtual-reality under both normal and short-term microgravity conditions during a parabolic flight. The task involved various degrees of mental transformations, and required subjects to perform actions instructed by a fellow astronaut aboard a virtual spacecraft. The experimental design allowed us to control for nuisance variables, training effects, and non-gravity related factors of parabolic flights. Overall, our results indicated that microgravity has a facilitatory effect on perspective-taking abilities. Notably, this facilitation was selective to conditions requiring subjects to rotate their perspective around their line of sight, i.e., for mental rotations in the frontal plane. Moreover, microgravity affected subjects differently depending on their visual field dependence, as determined via a classic rod-and-frame test. Specifically, improvement in performance was more pronounced in field-independent subjects. Together, these results shed light on a long standing debate about the impact of microgravity on egocentric mental imagery, and have direct operational consequences for future long-term missions.