Asymmetries in the Preparation and Control of Manual Aiming Movements

Two experiments were conducted to determine if typical right hand target aiming advantages could be reduced or eliminated by increasing the spatial demands of the aiming task. In Experiment 1, we found right hand advantages for both movement time and error regardless of spatial characteristics of the task. When we introduced a greater degree of spatial uncertainty in Experiment 2, subjects exhibited a left hand reaction time advantage. Taken together our results suggest that the right cerebral hemisphere may have a special role to play in preparing the spatial aspects of an aiming movement, while the left hemisphere is more important for movement execution.