Gravity, or lack of it, may affect decision-making

The countdown to Mars is on. According to current timelines, astronauts could be heading to the Red Planet as soon as the 2030s, and the race is on to fill the many gaps in our knowledge about how the journey is likely to affect them, both physically and mentally. 

Despite being perhaps the biggest physical difference between Earth and space environments, the impact that microgravity might have on their decision-making is one area that has received relatively little investigation. New research in Scientific Reports reveals that in microgravity, decision-making does indeed change, with potential implications for the success of future space missions.  

In the first of two studies, Leyla Loued-Khenissi at the University of Geneva and colleagues recruited 22 participants for an experiment on the ground. Wearing VR goggles, they got a first person view of a drone navigating through a cave. The brief videos stopped just before the drone reached the exit. Across a total of 420 trials, the participants had to decide whether the drone would go on to crash into the ceiling or floor of the cave, or successfully make it out, then rate their level of confidence in their decision. In total, the researchers had created 21 slightly different flight trajectories. Sometimes it was easy to judge whether the drone would safely exit the cave, while other times it was less obvious.

In these trickier scenarios the participants were, as the team had expected, less confident in their answers, and they also took longer to reach a decision. These results then functioned as performance baselines for use in a second experiment, in which two of the participants took to the skies in a small plane for a series of parabolic flights, which allow passengers to briefly float in a similar way to spaceflight. During these flights, the two participants did the VR drone task while experiencing higher than normal gravity — around 2.5G — and also 0G. 

Although the results showed that microgravity itself didn't affect their judgements, it did affect their confidence in those judgements. In microgravity, they were more confident in their responses, and this difference in confidence was greater when it was less obvious whether the drone would go on to crash or not.  

The researchers suggest a few possible reasons for this finding. The first relates to feelings of euphoria. Both of the participants in the plane experiment reported feeling euphoric while they were weightless and, as the team notes, astronauts have previously reported euphoria while adjusting to microgravity. Earlier work has also shown that positive feelings can boost confidence, so over-confidence driven by euphoria might help to explain the results. Repeating this study (or conducting a similar one) with astronauts on long-term missions to the International Space Station could potentially avoid this issue. Another potential reason is that microgravity may make people feel that their body is expanding — and this might have affected the participants' perceptual judgements. 

In the real world, greater confidence in more uncertain situations could translate into more risky — and more dangerous — decisions, which could potentially cause problems for Mars-bound missions. 

Of course, this was a study of only two people, so the results should be considered preliminary. "However, if replicated, these findings have real world consequences on human spaceflight, and highlight a potential gap to be solved with automated systems," the team concludes. 

Read the paper in full: https://doi.org/10.1038/s41598-023-36775-0