Abstract
With an interest in identifying the variables that constrain arm choice when reaching, the authors had 11 right-handed participants perform free-choice and assigned-limb reaches at 9 object positions. The right arm was freely selected 100% of the time when reaching to positions at 30 degrees and 40 degrees into right hemispace. However, the left arm was freely selected to reach to positions at -30 degrees and -40 degrees in left hemispace 85% of the time. A comparison between free-and assigned-limb reaching kinematics revealed that free limb selection when reaching to the farthest positions was constrained by joint amplitude requirements and the time devoted to limb deceleration. Differences between free-and assigned-arm reaches were not evident when reaching to the midline and positions of +/- 10 degrees, even though the right arm was freely selected most often for these positions. Different factors contribute to limb selection as a function of distance into a specific hemispace.