Shaping of Reach-to-Grasp Kinematics by Intentions: A Meta-Analysis

When we reach to grasp something, we need to take into account both the properties of the object we are grasping and the intention we have in mind. Previous research has found these constraints to be visible in the reach-to-grasp kinematics, but there is no consensus on which kinematic parameters are the most sensitive. To examine this, a systematic literature search and meta-analyses were performed. The search identified studies assessing how changes in either an object property or a prior intention affect reach-to-grasp kinematics in healthy participants. Hereafter, meta-analyses were conducted using a restricted maximum likelihood random effect model. The meta-analyses showed that changes in both object properties and prior intentions affected reach-to-grasp kinematics. Based on these results, the authors argue for a tripartition of the reach-to-grasp movement in which the accelerating part of the reach is primarily associated with transporting the hand to the object (i.e., extrinsic object properties), the decelerating part of the reach is used as a preparation for object manipulation (i.e., prepare the grasp or the subsequent action), and the grasp is associated with manipulating the object's intrinsic properties, especially object size.

当执行伸手抓握动作时，个体需要同时兼顾所抓握物体的属性与自身的行动意图。既往研究表明，上述约束条件会体现在伸手抓握运动学（reach-to-grasp kinematics）特征中，但目前学界尚未就哪些运动学参数最具敏感性达成共识。为探究这一问题，本研究开展了系统性文献检索与元分析。本次检索共筛选出评估健康受试者中，物体属性变化或预先行动意图如何影响伸手抓握运动学特征的相关研究。随后，本研究采用受限极大似然随机效应模型开展元分析。结果显示，物体属性与预先行动意图的变化均会对伸手抓握运动学特征产生显著影响。基于上述发现，研究者提出将伸手抓握运动划分为三个阶段：伸手动作的加速阶段主要负责将手部运送至目标物体处（主要匹配物体的外在属性）；伸手动作的减速阶段用于开展物体操作的前置筹备（即完成抓握动作或后续动作的准备工作）；而抓握动作本身则与操控物体的内在属性（尤其是物体尺寸）密切相关。