Extended pausing by humans on multiple fixed-ratio schedules with varied reinforcer magnitude and response requirements

We conducted three experiments to reproduce and extend Perone and Courtney's (1992) study of pausing at the beginning of fixed-ratio schedules. In a multiple schedule with unequal amounts of food across two components, they found that pigeons paused longest in the component associated with the smaller amount of food (the lean component), but only when it was preceded by the rich component. In our studies, adults with mild intellectual disabilities responded on a touch-sensitive computer monitor to produce money. In Experiment 1, the multiple-schedule components differed in both response requirement and reinforcer magnitude (i.e., the rich component required fewer responses and produced more money than the lean component). Effects shown with pigeons were reproduced in all 7 participants. In Experiment 2, we removed the stimuli that signaled the two schedule components, and participants' extended pausing was eliminated. In Experiment 3, to assess sensitivity to reinforcer magnitude versus fixed-ratio size, we presented conditions with equal ratio sizes but disparate magnitudes and conditions with equal magnitudes but disparate ratio sizes. Sensitivity to these manipulations was idiosyncratic. The present experiments obtained schedule control in verbally competent human participants and, despite procedural differences, we reproduced findings with animal participants. We showed that pausing is jointly determined by past conditions of reinforcement and stimuli correlated with upcoming conditions.     

Nonlinear Growth Models as Measurement Models: A Second-Order Growth Curve Model for Measuring Potential

Recent methodological work has highlighted the promise of nonlinear growth models for addressing substantive questions in the behavioral sciences. In this article, we outline a second-order nonlinear growth model in order to measure a critical notion in development and education: potential. Here, potential is conceptualized as having three components—ability, capacity, and availability—where ability is the amount of skill a student is estimated to have at a given timepoint, capacity is the maximum amount of ability a student is predicted to be able to develop asymptotically, and availability is the difference between capacity and ability at any particular timepoint. We argue that single timepoint measures are typically insufficient for discerning information about potential, and we therefore describe a general framework that incorporates a growth model into the measurement model to capture these three components. Then, we provide an illustrative example using the public-use Early Childhood Longitudinal Study–Kindergarten data set using a Michaelis-Menten growth function (reparameterized from its common application in biochemistry) to demonstrate our proposed model as applied to measuring potential within an educational context. The advantage of this approach compared to currently utilized methods is discussed as are future directions and limitations.     

Local dynamic stability of the spine and its coordinated lower joints during repetitive Lifting: Effects of fatigue and chronic low back pain

The nonlinear Lyapunov exponent (LyE) has been proven effective for evaluating the local stability of human movement and exploring the effects of load, speed and direction of individuals with and without nonspecific chronic low back pain (CLBP). The purpose of this study was to examine spinal and lower joint stability and response to fatigue of individuals with and without CLBP while performing lifting-lowering movements. Fourteen healthy individuals and 14 patients with nonspecific CLBP were recruited to perform lifting movement repeatedly while holding two equally-sized dumbbells in their hands. The participants continued lifting until they reported their highest level of fatigue. Kinematic data for the spine and its coordinated lower joints were recorded during the task (more than 40 lifting cycles on average). The first and last 20 cycles of each cyclic time series were defined as early- and late-fatigue conditions, respectively. The maximum LyE was estimated to quantify the local dynamic stability of the angular displacement time series of the spine, hip, knee and ankle on different anatomical planes in both the early- and late-fatigue conditions. The results revealed that local stability of the spine and hip was affected by fatigue. Spinal stability decreased as fatigue increased on the sagittal plane (p < 0.05). The hip exhibited a similar affectation (destabilization under fatigue) on all anatomical planes. Patients with CLBP showed more stable hip movement on the frontal and transverse planes (p < 0.05). These results suggested that lifting/progressive fatigue could increase the risk of injury to the spine and hip. These findings indicate that patients with CLBP applied different control strategies for the hip; thus, spinal control stability should be evaluated together with the stability of the lower joints.     

相对到达时间任务中飞行员对客体特征与运动特征的分离

相对到达时间任务(RAT)是判断两个运动客体哪个先到达指定目标, 可用来评估个体动态空间能力。采用RAT任务对飞行员与普通被试进行对照研究, 寻求发现两组在运动客体特征和视觉空间运动特征及其相互关系上的处理差异。设计了3个实验分别考察客体颜色、客体大小、运动方向、速率大小、视线方向以及背景特征对判断的影响。结果显示：(1)客体颜色不影响运动客体的相对时间判断, 客体大小、运动方向、速率大小、视线方向以及背景特征影响判断; (2)控制组对显示屏上从左到右的运动客体的相对时间判断好于从右到左任务, 大速率任务判断更好, 对大客体快速行驶而小客体低速行驶时的相对到达时间更易区分, 且与两眼视线方向不一致的运动方向会使控制组判断更难, 运动背景中的目标线特征改变使控制组判断绩效降低; (3)和控制组比, 飞行员反应快正确率高, 其快速判断优势集中体现在从右到左运动以及小速率任务上, 且在不同运动方向和不同速率上的反应时均无差异, 飞行员的处理优势还表现在不受客体大小、视线方向改变和目标线特征改变的影响。结论：飞行员能在变化的空间中准确处理相对速度、相对距离、相对时间等运动信息, 能分离客体大小、背景、运动方向等因素对相对到达时间判断的影响, 在运动空间中飞行员具有较高场独立性认知特征和动态空间处理能力。     

记忆再巩固的时间动态性及其生物学机制

记忆巩固需经觉醒状态下的信息编码和睡眠状态下的巩固阶段两个过程。记忆再巩固理论认为记忆巩固是一个需要多次反复巩固的过程,即使已巩固的记忆也会在提取激活后变得不稳定, 需经再巩固才能重返稳定状态, 此过程需要新的蛋白质的合成。记忆再巩固具有较强的时间特征, 发生在记忆巩固之后, 依赖于蛋白质降解的去稳定化阶段和依赖于蛋白质合成的记忆再稳定阶段, 所持续的时间窗为6 h。不同类型的记忆是否引发记忆再巩固或消退行为, 取决于提取试次暴露所持续时间的长短。     

句子加工中的语义P600效应

句子加工领域的研究中,一般认为,N400效应与语义加工有关,句法违反通常引发P600效应。然而近年来一些研究发现,句子语义违反时也引发了P600效应,即语义P600效应。对语义P600效应的诱发原因及其功能意义,目前有三种代表性的解释:监控说认为,P600效应是由语言理解过程中的认知冲突引发的,反映了认知监控系统对可能出现的加工错误的检测与解决;而非句法中心动态模型认为语义P600效应反映的是句子理解过程中两条通路之间出现冲突时的持续分析;扩展的论元依赖模型则用新的句子加工模型来解释语义P600效应,认为语义P600效应与句法违反引发的P600效应产生于句子加工的不同过程。     

癫痫预测方法的分析与研究

癫痫预测目的有两个从技术的层面去理解癫痫发作的机理,并对癫痫发作进行测量和改善,探索引发癫痫发作的周期性及先兆;开发出可靠的“癫痫发作前预警及治疗装置”。癫痫预测的主要研究方法有频域分析方法;时序分析方法;智能系统工程方法;非线性动力学方法。目前,越来越多的研究集中在非线性动力学的方法上,且来自多种方法的很多证据证明癫痫可以预测。