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Role of Visual Cues in Spatial Orientation (VISO)

Principal Investigators

The Role of Visual Cues in Spatial Orientation (VISO) experiment is a collaboration between the Canadian Space Agency and the National Aeronautics and Space Administration (NASA).The experiment is carried out by Dr. Charles Oman, director of the Man Vehicle Laboratory from Massachusetts Institute of Technology (MIT) and Dr. Ian Howard, co-director of the Human Performance Laboratory at the Centre for Research in Earth and Space Technology (CRESTech) of York University, in Toronto.

Experiment description

The VISO experiment is designed to investigate how astronauts orient themselves during work in space.

In our daily lives, gravity provides a constant anchor for us to use as a reference for orientation. But in space, astronauts lose this reference. They lose sense of what is objectively "up" and "down", and often become motion sick while subconsciously trying to figure it out. This "space motion sickness" affects nearly half of astronauts. A contributing factor to space sickness may be a conflict between astronauts' visual cues and the absence of inner ear and somatic sensations (pressure on your feet or seat). Space motion sickness is a significant cost in terms of astronaut "down time", reduced work quality, and danger due to impaired co-ordination.

The Visual Cues experiment will attempt to discover how quickly astronauts switch from using the balance organs in their inner ears (vestibular system) and vision to using strictly visual cues. It will also investigate whether "fake gravity" (like putting pressure on the bottom of their feet) can override these visual cues and how long it takes to re-adapt on their return to Earth.

Will vision become more important in determining body position, since cues from the inner ear are no longer present?

Previous space flights have shown that crewmembers can experience visual illusions in space--particularly with determining what is "up" and what is "down". Is "down" always where the feet are pointed, or is it where the brain determines the "floor" to be? Without gravity as a guide, the brain can interpret a floor as a ceiling or vice versa. This team will use a variety of novel techniques to answer these questions and reveal how the sensory adaptation to microgravity takes place.

Experiment procedure

The experiment was performed using NASA's Virtual Environment Generator (VEG), a head-mounted display that shows computer generated virtual reality scenes rendered by a three-dimensional graphics computer. The VEG also tracks the motion of the head, so scenes that are displayed appear stable when the head moves.

The astronauts were tested in the real rooms before and after flight and in the "virtual reality" version of the rooms while on the Space Shuttle.

Astronauts performed three experiments:

• They investigated how visual scene content and symmetry influence their perception of up or down (spherical room with no "up" or "down" cues and a cubic room, furnished and unfurnished);
• They determined how quickly a moving visual scene produces the illusion of self-motion;
• They explored how the direction of perceived "down" alters their ability to recognize shapes and interpret curvature from shading.

In space, many tests were performed with the astronaut free floating, and alternately wearing a constant force spring harness that provides artificial "down" cues to the shoulders and hips.

Benefits

The VISO experiment will help improve our understanding of the human orientation system and the information obtained can be applied to situations on Earth. Pilots, especially trainees, can experience sensory conflict and become disoriented, which can be fatal. People using virtual reality devices for training purposes (firefighting, surgery) have experienced discomfort and this research will contribute to understanding and solving this problem.

In clinical medicine, the development of new methods for evaluating a patient's ability to use visual and pressure cues for maintaining balance and orientation could be useful.

Portable head-mounted virtual reality displays such as the one developed for this experiment may prove useful for patients, perhaps someday providing visual prostheses for individuals with vestibular impairment. The results from the studies could also be applicable to the design of flight simulator and virtual reality vision systems.

It was hoped that this experiment also help to determine if virtual reality pre-training for astronauts is more effective than current training practices.

A Quote from Dr. Oman before the mission:

"On Neurolab, we will be using immersive Virtual Reality (VR) techniques in space for the first time. The VR helmet gives us complete control of the visual stimulus. The sustained weightless environment of Neurolab provides a truly unique opportunity to understand the interaction between visual and gravireceptive cues in human spatial orientation."