Dipartimento di Psicologia Generale, Università di Padova, Padova, Italy.
PLoS One. 2011;6(9):e25203. doi: 10.1371/journal.pone.0025203. Epub 2011 Sep 28.
Substantial literature has demonstrated that how the hand approaches an object depends on the manipulative action that will follow object contact. Little is known about how the placement of individual fingers on objects is affected by the end-goal of the action.
METHODOLOGY/PRINCIPAL FINDINGS: Hand movement kinematics were measured during reaching for and grasping movements towards two objects (stimuli): a bottle with an ordinary cylindrical shape and a bottle with a concave constriction. The effects of the stimuli's weight (half full or completely full of water) and the end-goals (pouring, moving) of the action were also assessed. Analysis of key kinematic landmarks measured during reaching movements indicate that object affordance facilitates the end-goal of the action regardless of accuracy constraints. Furthermore, the placement of individual digits at contact is modulated by the shape of the object and the end-goal of the action.
CONCLUSIONS/SIGNIFICANCE: These findings offer a substantial contribution to the current debate about the role played by affordances and end-goals in determining the structure of reach-to-grasp movements.
大量文献表明，手接近物体的方式取决于紧随物体接触之后的操作动作。对于操作的最终目标如何影响手指放置在物体上的位置，我们知之甚少。
方法/主要发现：在伸手去抓两个物体（刺激物）的过程中，测量了手部运动的运动学：一个普通圆柱形的瓶子和一个有凹缩部的瓶子。还评估了刺激物重量（半满或全满水）和动作最终目标（倾倒、移动）的影响。对伸手运动过程中测量的关键运动学地标进行的分析表明，无论准确性约束如何，物体的可及性都有助于动作的最终目标。此外，手指在接触时的位置会受到物体形状和动作最终目标的调节。
结论/意义：这些发现为当前关于可供性和最终目标在确定伸手抓握动作结构中所起作用的争论提供了重要贡献。
