In a previous study on hand selection in a sequential reaching task, the authors showed a shift of the point-of-change (POC) to the left of the midline. This implies that participants conducted a number of contralateral reaches with their dominant, right hand. Contralateral movements have longer planning and execution times and a lower precision. In the current study, we asked whether lower mechanical costs of motor execution or lower cognitive costs of motor planning compensated for these disadvantages. Theories on hemispheric differences postulate lower mechanical costs in the dominant hemisphere and lower cognitive costs in the left hemisphere (independent of handedness). In right-handed participants, both factors act agonistically to reduce the total cost of right-handed reaches. To distinguish between the cost factors, we had left- and right-hand-dominant participants execute a sequential, unimanual reaching task. Results showed a left-shift of the POC in the right-handed and a right-shift in the left-handed group. Both shifts were similar in magnitude. These findings indicate that only the mechanical cost of motor execution compensates for the disadvantages of the contralateral reaches, while the cognitive cost of motor planning is irrelevant for the POC shift.

中文翻译：

---

改变点的变化可以归因于较低的电机执行机械成本。

在先前关于顺序到达任务中选手的研究中，作者显示了变化点（POC）向中线左侧移动。这意味着参与者用其占优势的右手进行了许多对侧活动。对侧运动的规划和执行时间较长，精度较低。在当前的研究中，我们询问较低的运动执行机械成本或较低的运动计划认知成本是否可以弥补这些缺点。关于半球差异的理论假定优势半球的机械成本较低，而左半球的认知成本较低（与惯性无关）。在惯用右手的参与者中，这两个因素都激动地减少了惯用右手触及范围的总成本。为了区分成本因素，我们让左手和右手的参与者执行顺序的，单手的到达任务。结果显示，右手用POC左移，左手用POC右移。两种变化幅度相似。这些发现表明，只有运动执行的机械成本能够弥补对侧伸手的缺点，而运动计划的认知成本与POC转换无关。