When lifting or moving a novel object, humans are routinely able to quickly characterize the nature of the unknown load and swiftly achieve the desired movement trajectory. It appears that both tactile and proprioceptive feedback systems help humans develop an accurate prediction of load properties and determine how associated limb segments behave during voluntary movements. While various types of limb movement information, such as position, velocity, acceleration, and manipulating forces, can be detected using human tactile and proprioceptive systems, we know little about how the central nervous system decodes these various types of movement data, and in which order or priority they are used when developing predictions of joint motion during novel object manipulation. In this study, we tested whether the ability to predict motion is different between position- (elastic), velocity- (viscous), and acceleration-dependent (inertial) loads imposed using a multiaxial haptic robot. Using this protocol, we can learn if the prediction of the motion model is optimized for one or more of these types of mechanical load. We examined ten neurologically intact subjects. Our key findings indicated that inertial and viscous loads showed the fastest adaptation speed, whereas elastic loads showed the slowest adaptation speed. Different speeds of adaptation were observed across different magnitudes of the load, suggesting that human capabilities for predicting joint motion and manipulating loads may vary systematically with different load types and load magnitudes. Our results imply that human capabilities for load manipulation seems to be most sensitive to and potentially optimized for inertial loads.

在提升或移动新物体时，人类通常能够快速表征未知负载的性质，并迅速实现所需的运动轨迹。触觉和本体感觉反馈系统似乎都有助于人类对负荷特性进行准确预测，并确定相关肢体节段在随意运动期间的行为方式。虽然可以使用人类触觉和本体感觉系统检测各种类型的肢体运动信息，例如位置、速度、加速度和操纵力，但我们对中枢神经系统如何解码这些不同类型的运动数据知之甚少，其中包括在新的对象操作期间开发关节运动预测时使用它们的顺序或优先级。在这项研究中，我们测试了使用多轴触觉机器人施加的位置（弹性）、速度（粘性）和加速度相关（惯性）载荷之间预测运动的能力是否不同。使用此协议，我们可以了解运动模型的预测是否针对这些类型的机械负载中的一种或多种进行了优化。我们检查了十个神经系统完好的受试者。我们的主要研究结果表明，惯性和粘性载荷表现出最快的适应速度，而弹性载荷表现出最慢的适应速度。在不同的负载量级上观察到了不同的适应速度，这表明人类预测关节运动和操纵负载的能力可能会随着不同的负载类型和负载量级而系统地变化。