Intraindividual Variability as an Indicator of Cognitive Function: Contrasting Operationalizations and Exploring Mechanisms

大多数研究关注的是平均表现（A组相对于B组完成任务的速度或效果）。不幸的是，这种以平均为中心的关注掩盖了对个人表现变异性（IIV）的研究，比如在一系列反应延迟试验中，特定个体反应的快慢波动，或者在执行任务时皮质血流动力学反应功能（即神经复杂性）的变化。包括认知神经科学、神经心理学和数学建模在内的各个科学学科越来越多的共识表明，从理论上讲，认知功能的有趣方面并不仅仅是由平均数捕获的。为了进一步了解iv的特征模式、潜在机制和相关性，本研究项目将：(1)采用并改进测量可变性的新方法和先进的定量方法，包括使用测量突发研究设计来促进对认知功能iv的短期（试验对试验）波动和长期（年对年）变化进行索引，推导和对比认知可变性的竞争性操作，并探索同时建模平均值和可变性的方法；(2)研究神经和生理功能变异性的新定义（例如，由近红外光谱索引的神经活动信号的多尺度熵及其优越的时间采样特性；跨时空步态指标的变异性），并研究这些变异性指标与认知功能的关系；(3)通过计算变异性跨域估计之间的关联，利用测量突发设计的优势，研究不同变异性信号的动态时变协变及其对认知表现的相应影响，表征变异性个体差异的潜在机制和过程（例如，神经iv是否与认知系统相关？）并通过评估或操纵关键调节因素，包括双重任务（增加认知负荷）的影响，探索IIV的可塑性。******该计划的主要优点包括采用密集的测量突发设计，以及使用我的研究实验室已经安装的新型仪器，包括GAITRite计算机化走道，以及功能近红外光谱（NIRS）系统。本研究计划对认知科学领域的预期意义在于提高对测量和计算变异性估计的最佳方法的理解，确定变异性和认知的系统变化是否相关，并进一步了解变异性潜在的机制。

Most research focuses on average performance (how much faster or better does group A perform a task relative to Group B). Unfortunately, this mean-centric focus has overshadowed research on intraindividual variability (IIV) in performance, such as the fluctuations in how fast or slow a given individual responds across a series of response latency trials, or the variation in the cortical haemodynamic response function (i.e., neural complexity) when performing a task. Growing consensus from various scientific disciplines, including cognitive neuroscience, neuropsychology, and mathematical modeling, suggests that theoretically interesting aspects of cognitive function are not captured by the mean alone. To further our understanding of the characteristic patterns, underlying mechanisms, and correlates of IIV, this research program will: (1) employ and refine novel methodological and advanced quantitative approaches for measuring variability including the use of measurement burst research designs to facilitate indexing short-term (trial-to-trial) fluctuations and long-term (year-to-year) change for IIV in cognitive function, derive and contrast competing operationalizations of cognitive variability, and explore approaches for simultaneous modeling of mean and variability; (2) investigate novel definitions of variability in neural and physiological function (e.g., multiscale entropy for the neural activity signal indexed by NIRS and its superior temporal sampling properties; variability across temporal and spatial gait indicators), and examine these variability indices in relation to cognitive function; and (3) characterize potential mechanisms and processes underlying individual differences in variability by computing associations among cross-domain estimates of variability, by capitalizing on the strengths of the measurement burst design to examine the dynamic time-varying covariation for distinct variability signals and their corresponding impact on cognitive performance (e.g., is neural IIV systematically associated with cognition?), and to explore the malleability of IIV by assessing or manipulating key moderating factors including the impact of dual tasking (increasing cognitive load).******Key advantages of this program include the adoption of an intensive measurement burst design, as well as the use of novel instrumentation already installed in my research laboratory including a GAITRite computerized walkway, as well as a functional near infrared spectroscopy (NIRS) system. The expected significance of this research program to the field of cognitive science lies in the improved understanding of optimal ways to measure and compute estimates of variability, ascertaining whether systematic changes in variability and cognition are associated, and furthering our understanding of the potential mechanisms underlying variability.