Interacting Constraints and the Emergence of Postural Behavior in ACL-Deficient Subjects

In this study, the authors examined how task, informational, and sensorimotor system constraints influence postural control. Postural behavior of subjects with (n = 15) and without (n = 15) a key sensorimotor system constraint, anterior cruciate ligaments (ACLs) in 1 knee, was examined during 1- and 2-legged stance with and without vision. Postural control was assessed on a commonly used postural sway meter and on a dynamic stabilometer. Data on postural sway characteristics were obtained for 30 s under 6 different conditions: standing, with eyes open and closed, on both legs, on the injured leg, and on the noninjured leg. The interaction of task, informational, and sensorimotor constraints was observed only on the dynamic stabilometer and not the postural sway meter. Vision was the most important informational constraint on postural control for subjects on the dynamic stabilometer, particularly for the ACL-deficient group standing on the injured leg. Under more static task constraints, ACL deficiency did not prove a significant disadvantage, because vision was confirmed as a significant source of exproprioceptive information. The results support the functionality of using dynamic tasks such as a stabilometer in assessing postural behavior of subjects with sensorimotor system constraints.     

Examining the Effects of Postural Constraints on Estimating Reach

The tendency to overestimate has consistently been reported in studies of reachability estimation. According to one of the more prominent explanations, the postural stability hypothesis, the perceived reaching limit depends on the individual's perceived postural constraints. To test that proposition, the authors compared estimates of reachability of 38 adults (a) in the seated posture (P1) and (b) in the more demanding posture of standing on one foot and leaning forward (P2). Although there was no difference between conditions for total error, results for the distribution and direction of error indicated that participants overestimated in the P1 condition and underestimated in the P2 condition. It therefore appears that perceived postural constraints could be a factor in judgments of reachability. When participants in the present study perceived greater postural demands, they may have elected to program a more conservative strategy that resulted in underestimation.     

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.     

Interaction Between the Development of Postural Control and the Executive Function of Attention

The authors examined the interaction between the development of postural control and the development of the executive function of attention in 13 children and 6 adults in dual-task conditions. Participants performed an attentionally demanding cognitive task and a postural task simultaneously. The authors equalized the attentional load of the cognitive task across age groups. Comparative changes in the center of pressure in dual- and single-task conditions indicated that dual tasks interfered with postural performance in the wide stance (WS) and the modified Romberg stance (RS). Children at 4-6 years of age (but not children at ages 7-12 years of age or adults) experienced postural control interference in both stance positions, but interference was greater in the RS (p = .018). For all participants, cognitive task performance in RS was unchanged from that in WS. The knowledge gained from the results of this study will contribute to the design and implementation of academic and preacademic programming for young children. Their performance of an intentionally demanding cognitive task would be enhanced by the provision of appropriately sized desks and chairs or their use of an alternate, less demanding position.     

Effects of Visual Information and Task Constraints on Intersegmental Coordination in Playground Swinging

The authors investigated how and to what extent visual information and associated task constraints are negotiated in the coordinative structure of playground swinging. Participants (N = 20) were invited to pump a swing from rest to a prescribed maximal amplitude under 4 conditions: normal vision, no vision, and 2 visual conditions involving explicit phasing constraints. In the latter conditions, participants were presented with a flow pattern consisting of a periodically expanding and contracting optical structure. They were instructed to phase the swing motion so that the forward turning point coincided with either the maximal size (enhanced optical flow) or the minimal size (reduced optical flow) of the presented flow pattern. Removal of visual information clearly influenced the swinging behavior, in that intersegmental coordination became more stereotyped, reflecting a general stiffening of the swinger. The conditions involving explicit phasing requirements also affected the coordination, but in an opposite way: The coordination became less stereotyped. The two phasing instructions had differential effects: The intersegmental coordination deviated more from normal swinging (i.e., without phasing constraints) when optical flow was enhanced than when it was reduced. Collectively, those findings show that visual information plays a formative role in the coordinative structure of swinging, in that variations of visual information and task constraints were accompanied by subtle yet noticeable changes in intersegmental coordination.     

Interstimulus Intervals and Sensory Modality Modulate the Impact of a Cognitive Task on Postural Control

The present literature not only reveals the use of a wide variety of cognitive tasks but variability in their interaction with postural control. The question then arises, as to, whether postural control is sensitive to specific features of a cognitive task. The present experiment assessed the impact of cognitive tasks with interstimulus intervals (ISI) of varied duration and sensory modality on postural control in young adults. Seventeen participants (23.71 ± 1.99 years old) were instructed to stand on a force platform while concurrently performing cognitive tasks with ISIs of two and 5 s. The tasks were presented both, auditorily and visually. The visual tasks consisted of counting the total occurrence of a single digit. The auditory tasks consisted of counting the total occurrence of a single letter. Performing the cognitive tasks with an ISI of 2 s resulted only in an increase in the anteroposterior mean power frequency. Presenting the tasks visually also significantly reduced area of 95% confidence ellipse and AP and mediolateral sway variability. These results may suggest that ISIs can modify postural performance by altering the allocation of attentional focus. Also, presenting tasks using a visual sensory modality appears to yield lower postural sway.     

Two Factors to be Considered in the Design of Experiments in Anxiety and Motor Behavior

The authors examined the influence that attentional focus on either a postural or a suprapostural task had on the performance of each task. Participants (N = 32) stood on an inflated rubber disk and held a pole horizontally. All participants performed under 4 attentional focus conditions: external (disk) or internal (feet) focus on the postural task, and external (pole) or internal (hands) focus on the suprapostural task. Compared with internal focuses, external focuses on either task resulted in similar and reduced postural sway. Response frequency on each task increased when participants focused on the respective task. Finally, an external focus on either task produced higher frequencies of responding on the suprapostural task. The authors conclude that suprapostural task goals have a stronger influence on postural control than vice versa, reflecting the propensity of the motor system to optimize control processes on the basis of the desired movement effect.     

Executive control of thought and action: in search of the wild homunculus

Executive control is studied in many areas of psychological research using a wide variety of procedures. This article focuses on studies of the executive processes involved in switching between tasks. The experiments discussed were designed to isolate and measure the duration of the executive processes required to switch from one task to another. However, the research is open to alternative interpretations that do not hypothesize executive processes, suggesting that task-switching procedures may not measure the duration of executive control. Further research is required to determine whether or not behavioral effects reflect the involvement of executive processes.     

Work and Rest Variables in the Acquisition of Psychomotor Tracking Skill

College students (75 men, 75 women) matched in preliminary performance of 100 sec on the rotary pursuit apparatus were randomly assigned to five experimental groups. Their work/rest ratios, measured in seconds, were: 20/20, 30/30, 60/60, 90/90,120/120. All subjects received 30 min of total practice time after the matching trial. There was a significant practice effect and a significant practice x conditions interaction, but no main effect due to the cycles’ length or number. The decay rate of reactive inhibition (lr) is probably independent of its prior growth level; hence postrest residual lr is proportional to prerest accumulation. Partly because they generated lr in hypothetically greater amounts, women were significantly less proficient on the average than men, and sex interacted with practice. Although males had higher initial and final levels of ability than females, the two sexes’ acquisition curves showed the same rate parameters in our mathematical model.     

Problem decomposability as a factor in complexity of the dimensional change card sort task

According to cognitive complexity and control (CCC) theory complexity depends on number of levels of a hierarchy of rules. According to relational complexity (RC) theory complexity is a function of the number of related variables in the task, and the most difficult tasks are those in which there is a constraint on decomposition into simpler subtasks. One hundred and twenty, 3–6-year old children were tested on the standard dimensional change card sort (DCCS) task, or a modified version, the DecompDCCS, in which the dimensions could be decomposed into subtasks. The standard version requires two levels of a hierarchy to be processed, and is ternary relational according to RC theory, whereas the subtasks of the DecompDCCS are binary relational. The DecompDCCS was easier than the DCCS for 3–4 year-olds, but all 5–6 year-olds succeeded on both. The results indicate that decomposability into simpler subtasks, as suggested by RC theory, is a factor in difficulty of DCCS. The role of decomposability in other tasks that are persistently difficult for young children is discussed.     

Temporal dynamics of interference in Simon and Eriksen tasks considered within the context of a dual-process model

Behavioral and brain potential measures were employed to compare interference in Eriksen and Simon tasks. Assuming a dual-process model of interference elicited in speeded response tasks, we hypothesized that only lateralized stimuli in the Simon task induce fast S–R priming via direct unconditional processes, while Eriksen interference effects are induced later via indirect conditional processes. Delays to responses for incongruent trials were indeed larger in the Eriksen than in the Simon task. Only lateralized stimuli in the Simon task elicited early S–R priming, maximal at parietal areas. Incongruent flankers in the Eriksen task elicited interference later, visible as a lateralized N2. Eriksen interference also elicited an additional component (N350), which accounted for the larger behavioral interference effects in the Eriksen task. The findings suggest that interference and its resolution involve different processes for Simon and Eriksen tasks.     

血液净化防治多器官功能障碍综合征的思考

血液净化防治多器官功能障碍综合征已在临床医疗中广泛应用。简要介绍血液净化及多器官功能障碍综合征的相关知识。重点运用科学思维分别从系统论方法、控制论方法、信息方法三方面阐述两者间的内在联系,为临床工作提供新的指导。     

时间、目的与行为特征对群体决策绩效的影响

96名大学生,4人一组,参加了评价警察行为的决策实验.研究采用2×2×2(时间×目的×行为特征)因子式设计,旨在分析时间、目的和行为特征如何对中国人群体决策行为产生影响.结果表明,决策群体在行为记忆上的准确性优于成员个体,但群体的决策标准比个体冒险;时间、目的及行为特征影响群体决策的绩效.结论支持了"互补性假设"及K R Murplhy对时间与目的之间交互作用的解释.     

An Introduction to the Special Issue on Advances in Process and Dynamic System Analysis of Social Interaction and the Development of Antisocial Behavior

A thorough understanding of how social relationships contribute to child and adolescent trajectories for antisocial behavior may be facilitated by: (a) ascertaining multiple relationship processes (e.g., warmth and reciprocity, coercion and deviancy training); (b) focusing on multiple relationships (e.g., with parents, peers, siblings, and teachers): and (c) assessing relationship processes using increasingly sophisticated measurement and theoretical models (e.g., global ratings and sequential and dynamical systems analyses) of observed microsocial interaction. The reports comprising this special issue, and how they build on and advance previous research efforts, are described from this frame of reference.     

基础医学研究进展的还原论与系统论

从分子生物学、基因组学、蛋白质组学到糖组学,以还原论为哲学指导的医学研究已经取得了辉煌成果,与此同时,以系统论为哲学指导的系统生物学也日益受到关注,更被誉为新世纪生物学、医学研究的核心驱动力。还原论是系统论的基础和条件,而系统论则是还原论的归宿和终点,整个基础医学的研究进展经历了一场由还原论到系统论、再实现还原论与系统论辩证统一的演化过程。医学科学的发展历程闪耀着人类哲学理性思考的光辉,同时哲学思维也对医学研究进展做出了巨大的指导作用。     

系统论方法在糖尿病性视网膜病变危险因素及治疗研究中的应用

全球糖尿病患者人数在不断的增多,大约10％的Ⅰ型糖尿病患者在10年后可出现糖尿病性视网膜病变,而大约95％的Ⅱ型糖尿病患者在20年后可出现糖尿病性视网膜病变。目前,糖尿病性视网膜病的发病机制尚不明确,影响其发生发展的因素也很复杂,因此,对糖尿病性视网膜病的发病危险因素及其诊治的研究,具有相当重要的意义。系统论,研究各种物质运动形态所共有的系统联系和关系,具有普遍的方法论意义,为现代医学的进步提供了全新的思维方式和科学方法论原则。本文试用系统论的整体性、优化原理阐述糖尿病性视网膜病变发病的危险因素与治疗进展,为对其深入研究提供方法论依据。     

Integrating the most unintuitive empirical observations of 2007 in the domain of personality and social psychology into a unified framework

Two obstacles impede the development of productive theories in personality, social, and organizational psychology. First, the distinct frameworks are seldom integrated; the various theories sometimes yield incompatible implications. Second, because many findings in these fields seem intuitive, these observations do not augment the validity of these theories. To override these issues, this paper integrates the 70 most unintuitive findings of 2007 into a unified framework, derived from personality systems interaction theory. Specifically, 10 participants extracted the most unintuitive observations from 17 scholarly journals. These findings were reconciled within a single framework that generates 41 testable propositions. The framework assumes that an associative self system, underpinned by a vast network of schemas, governs behavior as well as enhances intuition, engagement, creativity, and cooperation. When individuals experience a threat, this system is inhibited, unless the requisite defense mechanisms to accommodate potential hazards have been developed. Furthermore, individuals attempt to distance themselves from unassailable threats, which activate an analytical system that formulates plans that could accommodate future contingencies. These plans are retained in memory or executed if individuals have acquired sufficient confidence.     

LAW培养模式在医学教育中的建立

LAW模式的建立是要改变被动的、填鸭式学习方式为积极、主动及高效的学习,培养有能力、高素质、有知识的人才.LAW模式给出学习的目标、学习方式及自我检查的标准,基本特点:多层次、多角度学习潜力的调动;启发式、以问题为导向、以学生为中心的互动学习方法;逻辑性、批判性及创造性思维的培养与应用;重点与相关学科内容的整合方式;观察、思考、信息与实践的有机结合.     

Ultimate Questions of Science and the Theory of System Relations

Summary  Whenever an adequate theory is found in science, we will still be left with two questions: why this theory rather than some other theory, and how should this theory be interpreted? I argue that these questions can be answered by a theory of system relations. The basic idea is that fundamental characteristics of systems, viz. those arising from the general systemic nature of those systems, cannot be comprehended with the aid of discipline-specific methods. The systems theory required should commence with an analysis of the qualitatively different relations possible between systems, because it is precisely the nature of those relations that determines the basic structures of systems. That the theory of the fundamental system relations and their ontological and epistemological implications is indeed able to provide the answers sought is demonstrated in theoretical physics and Plessner’s analysis of the basic structures of plant, animal and human being.     

酒精性肝损伤的防治思考

酒精性肝损伤已成为继病毒性肝炎后的主要肝损伤病因,因此酒精性肝病的防治已经成为重要的医疗课题。其病因、发病机制、病理改变及治疗等有其独特的特点,用哲学的方法对其进行科学、全面的分析,可有助于对该病的认识和研究,指导我们从总体考虑,更为合理、有效地防治酒精性肝损害。