Is there manual asymmetry in movement preparation?

Manual asymmetry in response preparation was investigated in simple and complex movements by using simple reaction-time tasks. The simple movement consisted of lifting the index finger, while in the complex one subjects reversed direction of movement to hit a switch after reaching for and grasping a tennis ball. Analysis showed that performance with either the right or the left hand was equivalent, with longer latencies for reacting on the complex task in comparison to the simple one. These findings indicate similar capabilities of the right and the left cerebral hemispheres to prepare the motor system for action independently of the spatial requirements of movement.