Abstract
It is generally understood that each hand is specialized for certain aspects of movement, the preferred hand for limb trajectory dynamics (i.e., mobilizing) and the non-preferred hand for positional control (i.e., stabilizing). In this study we questioned whether differences between the hands persist in motor planning, in particular, with respect to end-state comfort. Adults typically demonstrate uncomfortable start postures to facilitate comfortable end postures, with a recent study revealing more end-state comfort with the right-hand regardless of hand preference (Janssen et al., 2011). As well, the kinematics of a reach-to-grasp movement can be affected by task context; however, the kinematics of end-state comfort have yet to be examined. Therefore, right- and left-handed adults (Mean age= 25.1) were asked to pick up a cup (i.e., upright or overturned) as if to pour water in four conditions (i.e., pantomime, pantomime using image/cup as guide, grasp cup) with the preferred and non-preferred hand. Results revealed right-handers displayed end-state comfort in all conditions with both hands, whereas a subset of left-handers failed to demonstrate end-state comfort. These results contrast with those previously reported (right-hand advantage) in the literature. Although no kinematic differences were revealed according to hand preference or hand use, analyses indicated reaction time was fastest in the pantomime condition. As individuals received full set of instructions prior to ‘go’ signal, they did not need to adjust their movements based on object presented (i.e., cup or picture). Results will be discussed in light of the extant literature pertaining to handedness and end-state comfort.
