Two hypotheses have been invoked so far to explain performance decrements in space: the microgravity hypothesis and the multiple stressors hypothesis. Furthermore, previous investigations of cognitive performance did not specifically target executive functions. The aim of this study was to investigate the impact of operational stress on cognitive control, towards both neutral and emotionally loaded material, using both psychometric and physiological indicators (autonomic nervous system activity computed through cardio-respiratory recordings). We applied the same design in a study on student pilots (N=12) in baseline conditions and right before a major evaluation flight and on astronauts (N=3) before, during and after a short-duration spaceflight. To address the problem of scarcity of subjects, we applied analytical methods derived from neuropsychology: comparing each astronaut treated as a single subject to a group of carefully matched controls (N=13). Results from both student pilots and astronauts showed that operational stress resulted in failing cognitive control, especially on emotionally loaded material that was relevant to the subjects' current concern. This impaired cognitive control was associated with a decreased physiological reactivity during mental tasks. Furthermore, for astronauts, this performance decrement appeared on the last data-collection before launch and lasted for the two in-flight measurements. These results thus allow us to conclude that: (i) performance testing including an emotional dimension seems more sensitive to operational stress, (ii) decreased heart rate reactivity was associated with impaired cognitive control and (iii) microgravity is not the sole causal factor of potential performance decrements in space, which are more likely due to the combination of multiple stressors.
|Number of pages||5|
|Publication status||Published - 2009|
- performance decrements in space