Background: It has been shown that pointing movements are slowed during microgravity, however there is a paucity of corresponding data for other movement types.
Methods: In our study, subjects pointed at visual targets without seeing their hand, and tracked targets moving around a circular path with and without hand vision, with and without a secondary reaction-time task.
Results: Pointing responses were slowed distinctly in microgravity, but the speed of tracking movements was not affected. The secondary task had comparable effects on tracking performance in space and on Earth.
Conclusions: Response slowing in space is not due to an increased dependence on visual feedback, since it persists without hand vision. Differential effects of microgravity on pointing and tracking could be due to subjects' strategic decisions.