Abstract
A considerable body of research has shown that right-handed individuals exhibit a dominant hand advantage for the initial planning and control of goal-directed reaching movements. Interestingly, however, a dominant hand advantage has not been reliably shown for precision grasping. A possible basis for the equivocal finding is that previous research has relied, in large part, to contrasting hand differences at the time of peak grip aperture. Notably, peak grip aperture represents a late occurring kinematic metric (i.e., ~70% of grasping time) and therefore does not index putative hand differences that may arise during early aperture shaping. To that end, we had right-handed participants (N = 14) perform precision grasping movements with their left and right hands to differently sized targets. Results showed that the magnitude and timing of early (i.e., peak aperture acceleration, peak aperture velocity) and late (i.e., peak grip aperture) aperture shaping kinematics did not vary across hands. We did, however, observe that the left hand produced greater aperture shaping variability relative to the right hand during the early (i.e., 20 and 30% of grasping time) but not late (i.e., > 40% of grasping time) stages of grasping. Such results provide evidence that the initial kinematic parameterization of aperture shaping in the left hand is susceptible to greater neural noise than the right hand. Perhaps more importantly, our results evince a time-dependency in the expression of hand differences for precision grasping.
