Effects of colour environment on spaceflight cognitive abilities during short-term simulations of three gravity states

Colour is an important factor of the work environment and profoundly affects people's physical and psychological state. This study explored the effects of colour environments on spaceflight cognitive performance during three postures (normal sitting posture (SP) to reflect conditions on Earth; -12 ° head-down (HD) bed rest to simulate microgravity; and 9.6 ° head-up tilt (HU) bed rest to simulate lunar gravity) in order to simulate the impact of the colour of an environment on spaceflight cognitive ability in different gravity states. To achieve this goal, three psychophysical experiments were conducted to explore the impact of nine colour environments on three spaceflight cognitive tasks. The first experiment compared the task accuracy and visual strain of fifty-four participants performing a visual tracking task in nine colour environments during the three postures. The results showed that the -12 ° head-down bed rest posture significantly affected task accuracy and visual strain. The participants’ visual tracking accuracy in the cyan environment was significantly higher than that in other colour environments, and their visual strain was the lowest. The second experiment, which followed the paradigm of the previous study, compared sixty participants performing a consistency proofreading task during the three postures in nine colour environments to assess changes in task error rates and emotion. The results showed a significant increase in task error rates and negative emotion during the -12 ° head-down bed rest posture. Task performance in the cyan environment was the best and negative emotions were at the lowest level, while task performance in the grey environment was the worst. In the red environment, negative emotions increased significantly. Having found through the first two studies that colour environments can significantly impact subjective responses and task performance, a physiological-psychological experiment was designed to measure the performance of thirty participants in a mental load task in nine colour environments during the three postures. The results showed that the -12 ° head-down bed rest posture significantly increased prefrontal cortex activation and subjective load, and decreased task performance. The participants’ cerebral oxygenation and subjective load increased significantly when they performed tasks in the red environment, while the green environment caused the lowest activation of cerebral oxygenation and the lowest subjective load. The cyan environment also contributed to the improvement of task performance.