Touch down: the effect of artificial touch cues on orientation in microgravity.

Orienting oneself in space is not an easy task. On Earth, we combine visual, vestibular and pressure cues into a coherent concept of up and down. Since there are no cues from gravity in space, astronauts have to adjust the way they determine up from down, with the possible risk of space motion sickness. In three tasks performed by one astronaut in the International Space Station (ISS), we examined the effect of artificial touch cues presented to the torso. The role of "natural" touch cues on spatial orientation in microgravity, such as pressure presented to the sole of the feet, has already been shown, but it is not trivial whether the brain can also integrate artificial orientation information that has no real life equivalent. We find that artificial touch information in the form of a localised vibration on the torso that indicates down can make orienting in microgravity faster, better and easier. The importance of the artificial touch information seems to increase over the initial 7 days of staying in microgravity while the weight of visual information decreases over the same period. The results underline the capacity of the brain to adapt to unusual environments and to use and integrate artificial cues. Besides astronauts, pilots, divers and people with a vestibular dysfunction may benefit from this technology.