Effects of prolonged weightlessness on mental rotation of three-dimensional objects.

Previous experiments have suggested that the analysis of visual images could be a gravity-dependent process. We investigated this hypothesis using a mental rotation paradigm with pictures of three-dimensional objects during a 26-day orbital flight aboard the Soviet MIR station. The analysis of cosmonauts' response times showed that the mental rotation task is not greatly impaired in weightlessness. On the contrary, there are indications of a facilitation as: (1) the average rotation time per degree was shorter inflight than on the ground; (2) this difference seemed to be particularly marked for stimuli calling for roll axis rotations. However several factors may be responsible for this difference which was not obvious in one subject. Further experiments will have to test if this effect is really due to exposure to microgravity.