Gravity is one of the most fundamental physical forces in the Earth’s environment. A recent research, led by Assoc. Prof. Ying Wang and Prof. Yi Jiang at the Institute of Psychology, Chinese Academy of Sciences (IPCAS), has provided new evidence that gravity not only determines how objects move but also profoundly affects how the human brain perceives and processes motion. 

By introducing implied gravitational acceleration cues into the classic coherent motion perception paradigms, the team conducted five experiments comparing participants’ perceptual thresholds for detecting coherent motion conveying natural (1g) and reversed (−1g) gravitational acceleration cues. Across diverse visual conditions—whether background noise contained acceleration or not, whether dot lifetimes were fixed or varied, and whether stimuli were presented in virtual- or real-world coordinates—participants consistently showed higher sensitivity to motion signals that conformed to natural gravity.

This work suggests that the human visual system has an advantage in processing and integrating local motion signals that imply the effect of natural gravitational force, thereby facilitating the visual perception of complex motion patterns in natural environments. It highlights that the effect of Earth’s gravity is deeply embedded in the brain’s internal models as a stable processing reference for visual motion perception. The findings deepen our understanding of how human perception is adapted to Earth’s physical environment and provide a scientific foundation for future studies on visual motion perception in altered gravity. Such research may contribute to better preparation for long-term human space exploration.

This research was supported by grants from the Space Medical Experiment Project of CMSP, the Ministry of Science and Technology of China, the National Natural Science Foundation of China, the Interdisciplinary Innovation Team, the Youth Innovation Promotion Association of the Chinese Academy of Sciences, and the Fundamental Research Funds for the Central Universities.

The full paper, titled "Implied gravity promotes coherent motion perception", was published in npj Microgravity.

A-E Motion coherence thresholds for Experiments 1–5.  Image by Dr. WANG Ying.