Will future explorers on Mars be able to overcome the cognitive difficulties associated with the long journey in weightless conditions? Image via Nicolas Lobos / Unsplash.
Astronauts on long space missions may experience cognitive decline that makes them more likely to read the emotions on other people’s faces and make facial expressions more likely to be angry. That’s according to a new study by scientists at the University of Pennsylvania and the German Aerospace Center (DLR), published 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 one item that doesn’t belong in a group of objects, or memorizing 10 shapes. In these cognitive tests, the participants showed an initial decrease in speed, but it remained unchanged over time. The exception was emotion recognition, or being able to describe the emotion on someone’s face in a photo that was getting worse. The decline in skills of this kind, the researchers say, could have serious consequences for the wellbeing of a crew on a long mission to Mars, because of the essential need for teamwork and harmony on such a precarious mission.
The study describes experiments conducted to test for cognitive functioning during a long mission to Mars. The study had 24 subjects who spent 60 days bedridden with their heads tilted 6 degrees down to simulate a weightless environment. Some 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 counteract the effects of weightlessness.
Head bed rest at a small angle of 6 degrees is the standard way to simulate the effects of microgravity on Earth. Image via DLR.
Subjects in the centrifuge are rotated to experience artificial gravity. Image via DLR.
In this long exposure photo, the stripes show the movement of the spinning centrifuge. Image via DLR.
The participants completed cognitive tests along with a short alertness and mood exam before, during, and after the periods of head-down bed rest. Early on, the subjects showed signs of slowing cognitive function, but only one factor that they experimented on – the performance of emotion recognition – continued to decline over the study period. The longer the participants spent in the head-down 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 anti-gravity simulations started.
The Emotion recognition task measures how well the participant recognizes emotions from facial expressions. The study participants looked at photos of professional actors portraying a variety of emotions on their faces. The participants then labeled the utterances as happy, sad, angry, anxious or neutral. An in-depth analysis showed that participants were significantly less likely to rate faces as happy or neutral and more likely to be angry because they spent more time on the anti-gravity simulation.
Collaboration in space is key to the success of any mission. Misinterpreting 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 anti-gravity study, said:
The ability of astronauts to correctly “read” each other’s emotional expressions will be paramount to effective teamwork and mission success. Our findings suggest that their ability to do this may be compromised over time.
Mathias Basner of the University of Pennsylvania was a lead author of the study who analyzed the cognitive effects astronauts might experience on a mission to Mars. Image via University of Pennsylvania.
In order for astronauts in space to feel the effects of gravity and perhaps combat some of the cognitive decline that can accompany it, either the spacecraft or the astronauts themselves would have to be rotated to generate artificial gravity . None of these methods have been practiced in space so far. But the 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 of deleterious effects on astronauts’ cognition in weightless conditions raise questions about astronauts who have been in space for a long time. EarthSky asked Basner, “Is this an effect that astronauts on the space station are currently dealing with?” He replied:
We don’t know this. Astronauts spend longer on the International Space Station (ISS) than the subjects in our study were exposed to bed rest. However, the ISS is currently the size of a 4-bedroom house, and there are many ways astronauts can connect with loved ones on the ground. We do have some emotion recognition test data from a very limited number of ISS astronauts, but the number of astronauts will have to increase in the coming years.
EarthSky also asked Basner about the difference between a long-term mission to Mars and the astronauts who spent a year or two in space on the International Space Station. He said:
There are only 4 astronauts who have spent more than a consecutive year on the ISS! The mission to Mars will take much longer (~ 3 years), the spacecraft much smaller, the crew smaller (probably 3 or 4), no rescue option, radiation exposure is a much bigger problem and communication delays. So the Mars mission will be much more stressful.
The effects of microgravity environments on astronauts’ cognitive emotional responses is an area that needs to be studied even more. Alexander Stahn of the University of Pennsylvania was one of the scientists in the study. Stahn said:
We cannot say whether the effects observed on the emotion recognition test were caused by simulated microgravity or by the confinement and isolation inherent in the study, with separate bedrooms and sporadic contact with the research team. Future studies will have to untangle these effects.
But the possible link between weightlessness and diminishing ability to read a person’s emotions is an important link that has yet to be addressed. The study stated:
Spaceflight’s relevance of a deterioration in emotional processing as time increases in mission cannot be overemphasized, especially for space exploration missions, where astronauts will spend up to 3 years with a small group of peers in a small space locked up.
Bottom Line: One study found that people subjected to simulated weightlessness for 60 days had a delayed ability to read the emotions on people’s faces, often seeing anger there compared to before testing began.
Source: Continuous and intermittent artificial gravity as a countermeasure to the cognitive effects of 60 days head-down bed rest
