Time perception in astronauts on board the International Space Station

Abstract

We perceive the environment through an elaborate mental representation based on a constant integration of sensory inputs, knowledge, and expectations. Previous studies of astronauts on board the International Space Station have shown that the mental representation of space, such as the perception of object size, distance, and depth, is altered in orbit. Because the mental representations of space and time have some overlap in neural networks, we hypothesized that perception of time would also be affected by spaceflight. Ten astronauts were tested before, during, and after a 6–8-month spaceflight. Temporal tasks included judging when one minute had passed and how long it had been since the start of the workday, lunch, docking of a vehicle, and a spacewalk. Compared to pre-flight estimates, there is a relative overestimation for the 1-min interval during the flight and a relative underestimation of intervals of hours in duration. However, the astronauts quite accurately estimated the number of days since vehicle dockings and spacewalks. Prolonged isolation in confined areas, stress related to workload, and high-performance expectations are potential factors contributing to altered time perception of daily events. However, reduced vestibular stimulations and slower motions in weightlessness, as well as constant references to their timeline and work schedule could also account for the change in the estimation of time by the astronauts in space.

Spaceflight alters reaction time and duration judgment of astronauts

“…During the test, subjects wore a head-mounted display (Oculus Rift, Oculus VR, Menlo Park, CA), external noisecancelling earphones, and used a finger trackball connected to a laptop to report their responses (Navarro Morales et al, 2023). On the ground, this test was performed in the seated upright position; on the ISS, astronauts were in the free-floating conditions.…”

“…When astronauts were asked to perform periodic arms movements with the same rhythm as a metronome and continue after the metronome had been switched off, the variability of inter-response intervals significantly increased during spaceflight (Semjen et al, 1998a;1998b). During time production tasks, some astronauts overestimated a 2-s interval during a short-duration space flight (Ratino et al, 1988), whereas other astronauts underproduced a 1min interval, and underestimated intervals in the range of hours during long-duration spaceflight compared to preflight baseline (Navarro Morales et al, 2023).…”

Cognitive and balance functions of astronauts after spaceflight are comparable to those of individuals with bilateral vestibulopathy

“…Table 2 shows the number of subjects in each group who performed each test. The astronauts performed the tests ~3 months before launch (Astro Pre), monthly during the spaceflight (duration judgment and reaction time test only) ( 12 , 19 ), and ~2 h after they returned to Earth (R + 0) and 24 h later (R + 1). Tests were performed on R + 0 and R + 1 because previous studies have shown significant changes in spatial orientation, eye movements, postural control, and gait during this period compared to preflight ( 23 ).…”

“…Only the “go” and “stop” buttons were displayed during the test. Subjects were not allowed to count the seconds passing by Navarro Morales et al ( 12 ).…”

“…After long-duration spaceflight, astronauts experience symptoms of vestibular dysfunction that are similar to those faced by patients with certain types of vestibular disorders, such as motion sickness ( 1 , 2 ), dizziness or vertigo ( 3 , 4 ), decreased ocular torsion ( 5 , 6 ), delayed target acquisition during gaze shift ( 7 ), decreased stability during standing and walking ( 8 , 9 ), inaccurate perceptions of self-orientation and motion ( 10 , 11 ), and altered cognitive processing ( 12 , 13 ). In addition, these challenges can cause increased weighting of or reliance on visual inputs ( 14 , 15 ).…”