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Speed-accuracy trade-off of grasping movements during microgravity
S Jüngling1, O Bock, M Girgenrath
1Department of Physiology, German Sport University, Köln. jungling@hrz.dshs-koeln.de
Background:
Earthbound studies have shown that for pointing movements there is a specific relationship between movement speed, amplitude, and accuracy that is known as Fitts' law. We investigated the validity of Fitts' law for grasping movements in normal and microgravity.
Method:
Subjects performed grasping movements toward virtual targets under three different time constraint conditions before and during exposure to microgravity in parabolic flights.
Results:
The "speed-accuracy trade-off" phenomenon was observed for the grasp component of prehension movements. The results were quantitatively similar in normal and microgravity such that increasing the speed resulted in a diminished accuracy.
Conclusions:
Fitts' law is partially valid for grasping movements toward virtual targets without visual feedback of the hand in normal gravity. In a microgravity environment, performance of grasping movements also follows some of the predictions of Fitts' law.