Institut für Neuroinformatik, Ruhr University Bochum, Bochum, Germany.
Exp Brain Res. 2012 Oct;222(3):185-200. doi: 10.1007/s00221-012-3205-6. Epub 2012 Aug 23.
By studying human movement in the laboratory, a number of regularities and invariants such as planarity and the principle of isochrony have been discovered. The theoretical idea has gained traction that movement may be generated from a limited set of movement primitives that would encode these invariants. In this study, we ask if invariants and movement primitives capture naturalistic human movement. Participants moved objects to target locations while avoiding obstacles using unconstrained arm movements in three dimensions. Two experiments manipulated the spatial layout of targets, obstacles, and the locations in the transport movement where an obstacle was encountered. We found that all movement trajectories were planar, with the inclination of the movement plane reflecting the obstacle constraint. The timing of the movement was consistent with both global isochrony (same movement time for variable path lengths) and local isochrony (same movement time for two components of the obstacle avoidance movement). The identified movement primitives of transport (movement from start to target position) and lift (movement perpendicular to transport within the movement plane) varied independently with obstacle conditions. Their scaling accounted for the observed double peak structure of movement speed. Overall, the observed naturalistic movement was astoundingly regular. Its decomposition into primitives suggests simple mechanisms for movement generation.
通过在实验室中研究人类运动，人们发现了一些规律性和不变性，例如平面性和等时性原则。理论上的观点已经得到了支持，即运动可能是由一组有限的运动基元产生的，这些基元将编码这些不变性。在这项研究中，我们询问不变性和运动基元是否可以捕捉到自然的人类运动。参与者在三维空间中使用不受限制的手臂运动来将物体移动到目标位置，同时避开障碍物。两个实验操纵了目标、障碍物和在运输运动中遇到障碍物的位置的空间布局。我们发现，所有运动轨迹都是平面的，运动平面的倾斜反映了障碍物的约束。运动的时间与全局等时性（不同路径长度的相同运动时间）和局部等时性（障碍物回避运动的两个分量的相同运动时间）一致。识别出的运输（从起点到目标位置的运动）和提升（在运动平面内垂直于运输的运动）运动基元独立于障碍物条件而变化。它们的缩放解释了观察到的运动速度的双峰结构。总的来说，观察到的自然运动非常规则。将其分解为基元表明了运动生成的简单机制。
