VARIABILITY AND STABILITY IN SKILL ACQUISITION

描述（由申请人提供）：知觉运动的习得和适应是日常生活的基础。在技能获得和控制的研究中，稳定性和可变性的概念发挥了核心作用，尽管有不同的定义和严格程度。最常见的是，性能的提高与某些任务参数可变性的减少有关。这种减少的可变性反过来又被解释为稳定性的增加。这种反比关系掩盖了经验可变性可以表明许多不同的方面，从明显的“缺乏控制”，被视为目标导向任务中的错误或不稳定，到更有益的方面，如参数之间的补偿性变化，以及对新任务的探索。异常水平的变异性是功能失调行为的特征，如震颤、过度运动或缺乏波动的刻板印象。我们的方法的一个基本假设是，一定程度的不可减少的“噪音”是生物系统的基本表达。因此，稳定性也比某些性能参数的不变性更重要。具体来说，动态稳定性被定义为对扰动的抵抗力，它可以独立于变异性进行量化。该项目考察了两项任务中的技能获取，以区分我们对人类行为的可变性和稳定性的理解。在前馈控制下的以目标为导向的投掷动作中，我们开发了一种方法，将可变性分解为三个独立的组成部分：容忍度、协变和噪声，每个部分都捕获对成功行为的单独贡献。在6个实验中，我们测试了可变性的不同组成部分如何在不同的学习阶段做出贡献，以及随机噪声如何成为找到成功解决方案的一种手段。第二个任务是持续的有节奏地弹跳球的感知引导技能。先前的建模工作导出了动态稳定性能的标准，我们表明受试者使用这种“被动”稳定性。六个实验研究如何技能习得的特点是越来越依赖于动态稳定性。将分析性能可变性，以测试不同的组件对稳定性变化的影响。获得对习得和知觉运动任务控制的更深入的理解将促进对运动障碍诊断的认识，并开发康复方法。

DESCRIPTION (provided by applicant): The acquisition and adaptation of perceptual-motor is fundamental to everyday life. In the inquiry of skill acquisition and control the concepts of stability and variability have played a central role, albeit with different definitions and levels of rigor. Most commonly, improvement of performance has been associated with a decrease in variability of some task parameters. This reduced variability, in turn, has been interpreted as an increase in stability. This inverse relationship obscures that empirical variability can be indicative of many different facets, ranging from the obvious "lack of control", seen as errors or inconstancy in target-oriented tasks, to more beneficial aspects, such as compensatory variation between parameters, and exploration of new tasks. Abnormal levels of variability are characteristic for dysfunctional behavior, as evidenced in tremor, excessive movements, or stereotypy, the absence of fluctuations. A fundamental assumption in our approach is that a certain irreducible level of "noise" is a basic expression of biological systems. Hence, also stability is more than invariance of some performance parameter. Specifically, dynamical stability is defined as resistance to perturbations, which can be quantified independently from variability. The project examines skill acquisition in two tasks to differentiate our understanding of variability and stability in human action. In skittles, a target-oriented throwing action under feedforward control, we develop a method to decompose variability into three independent components: tolerance, covariation, and noise, each capturing a separate contribution to successful behavior. In 6 experiments we test how different components of variability contribute in different stages of learning, and how stochastic noise can be a means to find successful solutions. The second task is the continuous perceptually-guided skill of rhythmically bouncing a ball. Previous modeling work derived criteria for dynamically stable performance and we showed that subjects used this "passive" stability. Six experiments examine how skill acquisition is characterized by an increasing reliance on dynamical stability. Performance variability will be analyzed to test how different components contribute to this change in stability. Obtaining a deeper understanding of acquisition and the control of perceptual-motor tasks will advance knowledge for diagnosis of movement disorders as well as to develop methods of rehabilitation.