Interindividual Variability in Use-Dependent Plasticity Following Visuomotor Learning: The Effect of Handedness and Muscle Trained

Motor learning has been linked with increases in corticospinal excitability (CSE). However, the robustness of this link is unclear. In this study, changes in CSE associated with learning a visuomotor tracking task were mapped using transcranial magnetic stimulation (TMS). TMS maps were obtained before and after training with the first dorsal interosseous (FDI) of the dominant and nondominant hand, and for a distal (FDI) and proximal (biceps brachii) muscle. Tracking performance improved following 20 min of visuomotor training, while map area was unaffected. Large individual differences were observed with 18%–36% of the participants revealing an increase in TMS map area. This result highlights the complex relationship between motor learning and use-dependent plasticity of the motor cortex.     

Costs and Benefits of Autonomy When Learning a Task: An Experimental Approach

ABSTRACT

Previous findings suggested that the positive relationship between autonomy and learning outcomes (such as improved task performance) only holds up until a certain optimum level of autonomy has been reached. This assumption was investigated in an experimental study where 95 participants had to learn a computer task. During the learning phase, we manipulated autonomy, distinguishing among no, moderate, and full autonomy. The results revealed that, when learning a task, having autonomy is preferred to having no autonomy. However, increases in autonomy beyond a certain level (i.e., full versus moderate autonomy) will not yield additional advantages regarding the motivation to learn and learning outcomes, and may have disadvantages in terms of learning efficiency.     

Generation of Bimanual Trajectories of Disparate Eccentricity: Levels of Interference and Spontaneous Changes Over Practice

The authors examined intermanual interactions of 2 hands that were required to concurrently follow trajectories that differed in eccentricity. Ten healthy participants attempted to learn to trace 2 figures, a circle and an ellipse, with bilaterally isochronous (1:1) timing demands. Initial unimanual trials were followed by bilateral practice comprising 750 movement cycles. Two objectives were addressed: The authors' primary aim was to determine if kinematic interlimb interference is evident independent of spatial and temporal interference and to observe the potential practice-related changes in the nature of that interference. That test was afforded by participants' natural tendency to draw a circle with a relatively constant tangential velocity and an ellipse with a systematically varying velocity. A second aim was to observe the nature of spontaneous changes in the performance of each individual effector, and in the relationship between effectors, across practice. Those objectives were specifically addressed in a context in which augmented feedback was not available to direct the learners' attention to a particular feature of performance. The results suggested that interlimb assimilation of spatial features is the primary source of interference for that task and that apparent effects at the kinematic level are the secondary, indirect product of spatial coupling. Those results were found across blocks of practice. With respect to nondirected performance changes, substantially less improvement was evident in the performance of each individual effector than in the reduction of interlimb interference. Specifically, no practice-related changes in temporal variability or velocity bias, and minimal changes in trajectory smoothness, were evident in individual limbs. Conversely, significant reductions were observed in the variability of relative phase between limbs and in the magnitude of interlimb phase lag.     

Motor Learning through Induced Variability at the Task Goal and Execution Redundancy Levels

The authors examined the influence of introducing variability at two different levels in the learning of a striking task. Variability at the task goal level was introduced by changing target location, whereas variability at the execution redundancy level was introduced by using an intermediate target that constrained participants to use different paths from trial to trial to strike the same target. After practice, participants were transferred to 2 test conditions: (a) a fixed-target test, where the position of the target was unchanged; and (b) a variable-target test, where the position of the target was varied from trial to trial. The results from the manipulation at the task goal level were consistent with predictions from the specificity of practice hypothesis. In both the fixed- and variable-target tests, the best performance was achieved by the group that had practiced in the condition matching the test condition. At the execution-redundancy level, practicing multiple solutions to achieve the task goal did not improve performance in either the fixed- or variable-target tests. These results show that introducing variability at the task goal and execution redundancy levels has different effects on learning and generalization and that practice schedules that constrain the participant to use redundant solutions may not facilitate learning.     

Specificity of Learning in a Video-Aiming Task: Modifying the Salience of Dynamic Visual Cues

The authors investigated whether the salience of dynamic visual information in a video-aiming task mediates the specificity of practice. Thirty participants practiced video-aiming movements in a full-vision, a weak-vision, or a target-only condition before being transferred to the target-only condition without knowledge of results. The full- and weak-vision conditions resulted in less endpoint bias and variability in acquisition than did the target-only condition. Going from acquisition to transfer resulted in a large increase in endpoint variability for the full-vision group but not for the weak-vision or target-only groups. Kinematic analysis revealed that weak dynamic visual cues do not mask the processing of other sources of afferent information; unlike strong visual cues, weak visual cues help individuals calibrate less salient sources of afferent information, such as proprioception.     

意义程度不同的对偶材料迁移效果的实验研究

通过两个对偶学习实验探讨了对偶材料的意义性对两种类型的迁移效果的影响 ,即刺激相同、反应不同的迁移类型和刺激不同、反应相同的迁移类型。从广州华南师范大学低年级随机选出 5 6名大学生 ,采取组内设计 ,自变量分无意义词对、抽象词对、具体词对三种水平 ;要求每名被试依次完成三种水平全部学习。依据前后学习成绩之差 ,考察三种水平下迁移效果的变化。结果表明 :当对偶材料意义性逐渐增大时 ,在刺激相同、反应不同的条件下 ,产生负迁移的程度逐渐增大 ;在刺激不同、反应相同的条件下 ,产生迁移的效果不受影响。     

Effects of A Dual-Task Intervention in Postural Control and Cognitive Performance in Adolescents

Abstract

The aim was to assess dual- versus single-task training for motor performance and cognitive performance in adolescents. Two experiments were performed. In the first, 30 adolescents were randomized to three groups to determine the effect of dual-task difficulty on postural control: α-scaling and root mean square (RMS). In the second, 20 adolescents were randomized to two groups to determine the effect of dual-task practice to improve working memory. RMS in the post-test was lower than the pre-test in both dual-task groups, while α-scaling was lower in post-test than pre-test only in the high-difficulty dual-task group. A practice effect was observed on the percentage of correct answers only in the dual-task group (p?=?0.035). Thus, dual-task training could enhance motor and cognitive performance more than single-task training.     

准备时间和预先信息对任务切换的影响

两个实验采用任务线索范式,考察了准备时间和预先信息对任务切换的影响。实验1的准备时间为可预测,实验2的为不可预测,以考察准备时间的可预测性对任务切换的影响。以被试执行重复任务、切到任务和切离任务的正确反应时为主要指标,结果：（1）在准备时间可预测和不可预测两种条件下,准备时间和预先信息之间存在显著交互作用。在可预测条件中,重复和切到任务的反应时随着准备时间的增加而减少,但切到代价无显著变化,切离任务的反应时不受准备时间的影响,切离代价表现出反准备效应;不可预测条件下,三种任务的反应时都随着准备时间的增加而减少,但是切到和切离代价表现出反准备效应;（2）切离任务的反应时和代价显著高于切到任务的反应时和代价;（3）在这两种条件下,都没有出现切换代价的准备效应     

Task Difficulty and the Time Scales of Warm-Up and Motor Learning

The authors investigated the influence of task difficulty on warm-up decrement and learning across practice sessions. Three groups of participants practiced a star-tracing task over 3 consecutive days with different levels (e.g., easy, medium, hard) of task difficulty. The performance data were modeled with a 2 time scale function that represented the transient, fast time scale process of warm-up decrement superimposed with the persistent, slow time scale process of learning. Movement time decreased as a function of practice with the most difficult condition exhibiting the greatest reduction though still the longest movement time. The 2 time scale model provided a better fit to the data than an exponential or power law function and showed that the 3 difficulty conditions exhibited similar rates of change for the respective slow (i.e., learning) and fast (i.e., warm-up decrement) time scale processes that varied by an order of magnitude. Task difficulty was inversely related to the initial level of warm-up decrement but not the rate of performance recovery early in a practice session. The findings support the postulation that there is a persistent learned component to the initial conditions in subsequent practice sessions but that there is a common time scale of accommodating the transient process of warm-up decrement.     

The Effect of Fatigue on Learning and Performance of a Gross Motor Task

40 college males were sequentially assigned to 1 of 2 groups to examine the effects of induced physical fatigue upon the performance and learning of a gross motor task, the stabilometer. All Ss were given 32 practice trials over 3 practice sessions, with 48 hr. rest interpolated between sessions. Trials 1 and 2 were performed under control conditions (no fatigue) for both groups. The Experimental Group was then required to perform under conditions of physical fatigue during Trials 3-26. Trials 27-32 (Session 3) were performed under control conditions. The condition of fatigue was achieved on Trials 3-26 by having Ss pedal a bicycle ergometer until a heart rate of 180 beats/min was attained prior to each trial. The Control Group cancelled vowels. The results indicated that physical fatigue was detrimental to the performance and learning of the Experimental Group.     

外显知识对运动技能内隐学习的影响

总结了近年来关于外显知识对运动技能内隐学习影响的研究。提出外显知识对内隐学习存在影响,但其作用的大小及其性质取决于外显知识的呈现时间、内容、内隐规则的可觉察程度、认知负荷以及压力等因素。提供外显知识既可能有利于任务的完成,也可能激发与任务规则无关的注意过程,阻碍内隐学习。外显知识可影响行为,却不一定能被有意识地提取。外显知识对学习者的认知过程和动作模式均会产生影响。     

延迟时间与预先信息对任务切换的作用

对切换代价的本质存在任务设置惯性和任务设置重构两种观点。为揭示二者在切换代价中的关系, 研究了不同延迟时间条件下预先信息对任务切换的作用, 结果发现：(1)延迟时间对切换代价有显著影响, 100 ms的切换代价显著高于1000 ms的切换代价, 而600 ms分别与100 ms、1000 ms之间的切换代价无显著差异; (2)预先信息对切换代价的影响显著, 全部信息的切换代价显著低于无信息和部分信息的切换代价, 而后二者之间无显著差异; (3)延迟时间与预先信息无交互作用。这表明, 延迟时间与预先信息分别作用于任务设置惯性和任务设置重构, 切换代价反映了这两种具有相加效应的加工过程。     

多媒体环境下图文的具体程度对学习效果的影响

让70名小学生在多媒体环境中学习概念材料与原理材料,以探讨文本和图画材料的具体程度对学习迁移效果的影响。结果表明,在概念材料上,文本与图画的具体性程度之间存在显著的交互作用,即在具体图水平上,具体文的迁移成绩显著高于抽象文;在抽象图水平上,具体文的迁移成绩低于抽象文,但没有达到显著性水平。在原理材料上,文本与图画的具体性程度之间也存在显著的交互作用,但交互作用的方式与概念材料相反,即在具体图水平上,具体文的迁移成绩显著低于抽象文;在抽象图水平上,具体文的迁移成绩高于抽象文,但没有达到显著水平。     

学习材料的背景颜色对认知负荷及学习的影响

本研究采用2×2的多因素混合实验设计,探讨了物理学习环境之一的学习材料背景颜色对认知负荷及学习的影响。结果发现：（1）背景颜色在对认知负荷的影响上与任务类型产生交互作用,在解决创造性问题时,暖色调（如红色）背景下的认知负荷显著高于冷色调（如蓝色）。（2）从学习成绩上看,暖色调（如红色）更有利于记忆测试问题的解决,冷色调（如蓝色）更有利于创造性问题的解决。（3）认知负荷与任务绩效呈一定程度相关。     

任务难度和反馈学习对儿童类比推理能力的影响

该研究采用情景类比任务,通过两个实验对180名小学生进行纸笔测验,探讨了任务难度对儿童类比推理能力的影响.结果发现:进行反馈学习以降低任务难度时,7～8岁儿童能完成更高年龄段儿童才能完成的任务;但增加任务难度,11岁以上儿童也表现出类比推理能力的弱化.结果提示,儿童是否能在类比推理任务中表现出相应的能力可能取决于任务难度,反馈学习可促进一定年龄段内儿童的类比推理能力发展.本结果为有机融合皮亚杰和Goswami等人的观点提供了有效的实验依据.     

A Note on the Conscious Controls of Motor Units by Children Under Six

A simple form of training the conscious control of motor units in skeletal muscle has been demonstrated in a series of children under age 6. Easy boredom is the chief deterrent in the very young. So long as a child understands and cooperates, he can learn to isolate single units in a period of about 30 min.     

合作学习情境下监控者监控发音任务中的定向遗忘效应

在以构建留学生的汉字语音库为共同目标的合作学习情境下,考察了合作学习中的监控者是否会表现出定向遗忘效应。实验一中,协助者朗读两字表的单字并接受定向遗忘或记忆字表中单字的指令;监控者监控发音的流畅性或准确性,并单独接受再认测验;实验二在协助者重新朗读单字的条件下监控者接受再认测验。结果发现:(1)实验一中,监控者只在深层监控发音准确性的任务时,再认成绩表现出定向遗忘效应,浅层监控发音流畅性的任务中未表现出定向遗忘效应;(2)实验二中在测验阶段复原学习情境后,深浅监控任务下的再认成绩虽存在显著差异,但定向遗忘效应也消失了。综合两个实验表明,合作学习情境下,非有意遗忘的监控者的定向遗忘效应与监控任务深度和学习情境复原与否存在密切联系。     

Challenge Point: A Framework for Conceptualizing the Effects of Various Practice Conditions in Motor Learning

The authors describe the effects of practice conditions in motor learning (e.g., contextual interference, knowledge of results) within the constraints of 2 experimental variables: skill level and task difficulty. They use a research framework to conceptualize the interaction of those variables on the basis of concepts from information theory and information processing. The fundamental idea is that motor tasks represent different challenges for performers of different abilities. The authors propose that learning is related to the information arising from performance, which should be optimized along functions relating the difficulty of the task to the skill level of the performer. Specific testable hypotheses arising from the framework are also described.     

Biomechanical Study of Tandem Stance in Healthy Young Adults: Effects of Weight-Bearing and Limb Dominance

Postural strategies of healthy young adults to control tandem stance were investigated through the calculation of the relative contribution of the two loading-unloading (LU) and pressure-distribution (PD) mechanisms and the two legs for controlling the resultant center-of-pressure (CP_Res) displacements. Weight-bearing asymmetry and limb dominance were also studied. For antero-posterior and medio-lateral CP_Res displacements, LU and PD mechanisms mainly contribute, respectively. A significant LU contribution is nonetheless observed for medio-lateral control, due to a lateral gap between the CP positions under each foot despite a strict sagittal alignment for the two feet. Moreover, for medio-lateral control, the respective involvement of the two legs is related to the level of weight-bearing asymmetry, whereas the front leg mainly controls the antero-posterior sway. By specifying potential effects of body-weight asymmetry and limb dominance, to a better testing of patients with deficiencies in lateral sway control.     

A Bayesian Theory of Sequential Causal Learning and Abstract Transfer

Two key research issues in the field of causal learning are how people acquire causal knowledge when observing data that are presented sequentially, and the level of abstraction at which learning takes place. Does sequential causal learning solely involve the acquisition of specific cause‐effect links, or do learners also acquire knowledge about abstract causal constraints? Recent empirical studies have revealed that experience with one set of causal cues can dramatically alter subsequent learning and performance with entirely different cues, suggesting that learning involves abstract transfer, and such transfer effects involve sequential presentation of distinct sets of causal cues. It has been demonstrated that pre‐training (or even post‐training) can modulate classic causal learning phenomena such as forward and backward blocking. To account for these effects, we propose a Bayesian theory of sequential causal learning. The theory assumes that humans are able to consider and use several alternative causal generative models, each instantiating a different causal integration rule. Model selection is used to decide which integration rule to use in a given learning environment in order to infer causal knowledge from sequential data. Detailed computer simulations demonstrate that humans rely on the abstract characteristics of outcome variables (e.g., binary vs. continuous) to select a causal integration rule, which in turn alters causal learning in a variety of blocking and overshadowing paradigms. When the nature of the outcome variable is ambiguous, humans select the model that yields the best fit with the recent environment, and then apply it to subsequent learning tasks. Based on sequential patterns of cue‐outcome co‐occurrence, the theory can account for a range of phenomena in sequential causal learning, including various blocking effects, primacy effects in some experimental conditions, and apparently abstract transfer of causal knowledge.