Astronauts on long space missions can experience cognitive decline that makes them slower to read the emotions on other people’s faces and more likely to perceive facial expressions as angry. That’s according to a new study by scientists from the University of Pennsylvania and the German Aerospace Center (DLR), published on March 17, 2021, in the peer-reviewed journal. Frontiers in Physiology.
In their study, the scientists subjected people to simulated weightlessness for two months and tested their cognitive abilities, such as finding the item that does not belong in a group of objects or memorizing 10 shapes. In these cognitive tests, the participants showed an initial decrease in speed, but then it remained unchanged over time. The exception was emotion recognition, or being able to describe the emotion on someone’s face in a photo, which continued to deteriorate. The decline in these types of skills, the researchers say, could have serious consequences for the well-being of a crew on a long mission to Mars, due to the essential need for teamwork and harmony on such a precarious mission.
The study details experiments conducted to test cognitive functioning on a long mission to Mars. The study had 24 subjects spend 60 days confined to bed with their heads tilted down 6 degrees to simulate a weightless environment. Some of the participants also underwent 30 minutes a day in a centrifuge to simulate short periods of gravity, a method that could be used in space to help counteract the effects of weightlessness.
Participants completed cognitive tests along with a brief survey on alertness and mood before, during and after periods of head-down bed rest. At first, the subjects showed signs of slowing cognitive function, but only one factor that the experimenters assessed, performance in recognizing emotions, continued to decline during the study period. The longer the participants spent in the head-down tilted bed rest position, the longer it took for them to recognize facial emotions. They also reported seeing more negative emotions on faces during and after the study than before the antigravity simulations began.
the Emotion recognition task measures how well the participant recognizes emotions from facial expressions. Study participants would look at photographs of professional actors that displayed a variety of emotions on their faces. The participants then labeled the expressions as happy, sad, angry, fearful, or neutral. An in-depth analysis showed that participants were significantly less likely to rate faces as happy or neutral and more likely to rate faces as angry with increased time spent on antigravity simulation.
Being able to work together in space will be key to the success of any mission. The misinterpretation of emotional cues has all the hallmarks of a dramatic space opera. But the threat is real. As Mathias Basner of the University of Pennsylvania, lead author of the cognition and antigravity study, put it:
The ability of astronauts to correctly “read” the emotional expressions of others will be of the utmost importance to effective teamwork and mission success. Our findings suggest that your ability to do this may be affected over time.
For astronauts in space to feel the effects of gravity and perhaps combat some of the cognitive decline that might be associated, the spacecraft or the astronauts themselves would have to be rotated to induce artificial gravity. Neither method has yet been used in practice in space. But 30 minutes a day in a centrifuge to simulate artificial gravity had no positive effect on the participants in this test.
The results of the study on the harmful effects on the cognition of astronauts in weightless conditions raise questions about astronauts already in space for long periods of time. EarthSky asked Basner, “Is this an effect space station astronauts currently have to deal with?” He answered:
We do not know this. Astronauts spend more time on the International Space Station (ISS) than subjects were exposed to on bed rest in our study. However, the ISS is currently the size of a 4-bedroom house and there are many ways that astronauts can connect with loved ones on the ground. We have some data from emotion recognition tests on a very limited number of ISS astronauts, but we will need to increase the number of astronauts in the coming years.
EarthSky also asked Basner about the difference between an extended mission to Mars and astronauts who have spent a year or two in space on the International Space Station. He said:
There are only 4 astronauts who have spent more than one year in a row on the ISS! The mission to Mars will be much longer (~ 3 years), the spacecraft much smaller, the crew smaller (probably 3 or 4), no possibility of rescue, radiation exposure is a much bigger problem and delays in the comunications. So the mission to Mars will be much more stressful.
The effects of microgravity environments on astronauts’ emotional cognitive responses is an area that still needs further study. Alexander Stahn of the University of Pennsylvania was one of the scientists on the study. Stahn said:
We cannot say whether the effects observed in the emotion recognition test were induced by simulated microgravity or by the confinement and isolation inherent in the study, with separate bedrooms and sporadic contact with the study team. Future studies will need to unravel these effects.
But the possible connection between weightlessness and decreased ability to read someone’s emotions is an important one that still needs to be addressed. The study stated:
The relevance of spaceflight to impaired emotional processing with increasing time on the mission cannot be underestimated, especially for space exploration missions, where astronauts will be confined to a small space with a small group of companions for a period of up to 3 years.
Bottom line: a study has shown that people subjected to 60 days of simulated weightlessness had a slower ability to read the emotions on people’s faces, and they often saw anger there compared to before the tests began.
Source: Continuous and intermittent artificial gravity as a countermeasure to the cognitive effects of 60 days of head-down bed rest