Whole-body angular momentum in a complex dance sequence: Differences across skill levels

Due to the redundant degrees of freedom (DOF) and nonlinearity of reactional kinetic elements within the human motor apparatus, controlling the complex dynamics of the human musculoskeletal system presents considerable difficulties. Based on this challenge, Bernstein (1967) viewed skill development as the process whereby the central nervous system (CNS) gains mastery of kinematic DOF and kinetic reactional elements (passive forces, moments etc.), with the highest level of skill characterised by optimal exploitation of reactional elements in the achievement of movement goals. A previous kinematic investigation into coordination differences in a complex multidirectional dance sequence demonstrated that general unfreezing of kinematic DOF occurred as dance skill progressed (Chang et al., submitted for publication). To gain insight into the role of angular reactional elements in skill, the present kinetic study investigated angular momentum and associated variables across three skill levels (beginners, intermediates, experts) within this same complex dance sequence. The results showed that the angular momenta of segments and accompanying angular reactional elements generally increased with skill level. More specifically, the findings suggested that while improvements in movement economy from cancellation of angular momentum between body segments occur early in skill progression, later in skill progression, experts utilise increased whole-body angular momentum. Although this is energetically expensive, it may enhance the aesthetic value of dance movements, and/or have mechanical advantages. Overall, the findings here provide support for Bernstein’s (1967) model of skill development. Future research should quantify the relations between energy expenditure, key biomechanical variables that reflect skill and dance aesthetics as perceived by audiences.     

Central neuronal motor behaviour in skilled and less skilled novices – Approaching sports-specific movement techniques

Research on motor behavioural processes preceding voluntary movements often refers to analysing the readiness potential (RP). For this, decades of studies used laboratory setups with controlled sports-related actions. Further, recent applied approaches focus on athlete-non-athlete comparisons, omitting possible effects of training history on RP. However, RP preceding real sport-specific movements in accordance to skill acquisition remains to be elucidated.Therefore, after familiarization 16 right-handed males with no experience in archery volunteered to perform repeated sports-specific movements, i.e. 40 arrow-releasing shots at 60 s rest on a 15 m distant standard target. Continuous, synchronised EEG and right limb EMG recordings during arrow-releasing served to detect movement onsets for RP analyses over distinct cortical motor areas. Based on attained scores on target, archery novices were, a posteriori, subdivided into a skilled and less skilled group. EMG results for mean values revealed no significant changes (all p > 0.05), whereas RP amplitudes and onsets differed between groups but not between motor areas. Arrow-releasing preceded larger RP amplitudes (p < 0.05) and later RP onsets (p < 0.05) in skilled compared to less skilled novices. We suggest this to reflect attentional orienting and greater effort that accompanies central neuronal preparatory states of a sports-specific movement.     

工作记忆成分的年龄相关差异对算术策略运用的预测效应

采用选择/无选范式,借助工作记忆成套测验,在两位数乘法估算问题中探讨了工作记忆系统各成分对不同年龄段个体算术策略运用的预测效应。结果显示:(1)工作记忆的不同成分与年龄之间存在明显的相关。表现为,除视空模板成分外,其他各成分得分随着年龄增长而呈现上升趋势;(2)估算策略运用中,年龄与策略选择显著相关,表现为随着年龄增长,策略选择表现明显提高;(3)估算策略运用中,不同年龄个体的工作记忆不同成分和策略选择表现出不同的联系,中央执行均显示出显著的预测效应,语音环路和视空模板的预测效应均不显著。不同年龄个体的工作记忆不同成分对策略执行的预测效应均不显著。上述发现对于深刻理解工作记忆系统在算术认知策略运用中的作用机制具有重要理论含义。     

Mirror-drawing skill in children with specific language impairment: Improving generalization by incorporating variability into the practice session

This study aimed to investigate the procedural deficit hypothesis (PDH) in children with specific language impairment (SLI) by using a mirror-drawing task, a sensorimotor adaptation paradigm that does not involve sequence learning and has never before been used in SLI. A total of 30 school-aged children with SLI matched to 30 typically developing (TD) control children had to trace several figures seen only in mirror-reversed view in two practice sessions separated by a one-week interval. Two practice conditions were compared: a constant condition in which children had to trace the same figure throughout the learning trials, and a variable one in which they had to trace different figures in each trial. The results revealed a similar learning pattern between SLI and TD children in both practice conditions, suggesting that initial learning for a non-sequential procedural task is preserved in SLI. However, the children with SLI generalized the mirror-drawing skill in the same way as the TD children only if there was variability in the way the material was trained (variable practice). No significant schedule effects were observed in the control group.     

Do we reflect while performing skillful actions? Automaticity,control, and the perils of distraction

From our everyday commuting to the gold medalist’s world-class performance, skillful actions are characterized by fine-grained, online agentive control. What is the proper explanation of such control? There are two traditional candidates: intellectualism explains skillful agentive control by reference to the agent’s propositional mental states; anti-intellectualism holds that propositional mental states or reflective processes are unnecessary since skillful action is fully accounted for by automatic coping processes. I examine the evidence for three psychological phenomena recently held to support anti-intellectualism (choking under pressure, expertise-induced amnesia, and expert confabulation) and argue that it supports neither traditional candidate, but an intermediate attention-control account, according to which the top-down, intention-directed control of attention is a necessary component of skillful action. Only this account recognizes both the role of automatic control in skilled action and the need for higher-order cognition to thread automatic processes together into a unified, skillful performance. This applies to bodily skillful action in general, from the world-class performance of experts to mundane, habitual action. The attention-control account stresses that, for intentions to play their role as top-down modulators of attention, agents must sustain the intention’s activation; hence, the need for reflecting throughout performance.     

不同沟通方式下群体决策信息利用分析

以180名被试组成45个四人群体．完成模拟人事选拔的问题解决型任务,通过对群体决策过程的信息提取数量和提取次序的分析,考察不同的沟通方式和信息分享程度对群体决策信息利用的影响。结果表明。（1）在不同沟通方式下,决策成员的讨论前偏好对最终决策的影响很大。（2）在不同的沟通方式下,分享程度不同的信息在决策过程中的提取具有差异,体现了不同的规律。     

Investigating the relationship between meaningful time use and health in 18‐ to 25‐year‐old unemployed people in New South Wales,Australia

A vast body of literature has reported on the association between unemployment and poor psychological health. Nonetheless, there remains limited understanding of the influence of meaningfulness of time use, suggested by some to be the key mediator between time use and health. This project set out to explore the association between meaningful time use and health in 18‐ to 25‐year‐old unemployed people. In April 2007, 150 unemployed 18‐ to 25‐year‐old Australians (56% female) completed an online survey package exploring meaningfulness of time use and health. Hierarchical stepwise regression equations were developed to analyse the relationship between psychological health and measures of meaningful time use. Results provided partial support for the hypothesis that measures of meaningful time use would contribute to the prediction of psychological health. The addition of the person measure for the combined construct of ‘meaningful time use’ failed to make a significant contribution towards the prediction of psychological health. However, ‘reason for doing the activity’ emerged as a significant predictor. Findings provide preliminary evidence for the establishment of activity‐based programs to support young unemployed people. Further research is required to evaluate the outcomes of such programs and to replicate this study with other groups of unemployed individuals. Copyright © 2010 John Wiley & Sons, Ltd.     

Psychoticism and attentional flexibility

In three separate experiments, we tested the hypothesis that a systematic relationship between psychoticism (P) and visual selective attention is infrequently observed because the tasks typically used to test individual differences in efficiency of attentional mechanisms do not entail attentional flexibility. We manipulated the selection rule of the computerized divided visual attention (DIVA) task to be either (a) a predictable, or (b) a random manner, and a secondary task was added to check the quality of high P scorers’ performance in an interference condition; and we also introduced breaks between DIVA tasks to allow for cue utilization. Results revealed that low P scorers outperformed high P scorers in the regular selection rule alternation condition (cue utilization possible), whereas high P scorers performed better in random alternation condition – high P scorers also showed performance superiority in the dual task condition unless stimuli presentation was speeded up. Thus, P does not necessarily impair attentional performance; indeed, our data point to performance advantages of high P, especially attentional efficiency in tasks requiring small demands of attentional control.     

Overconfidence and underconfidence: When and why people underestimate (and overestimate) the competition

It is commonly held that people believe themselves to be better than others, especially for outcomes under their control. However, such overconfidence is not universal. This paper presents evidence showing that people believe that they are below average on skill-based tasks that are difficult. A simple Bayesian explanation can account for these effects and for their robustness: On skill-based tasks, people generally have better information about themselves than about others, so their beliefs about others’ performances tend to be more regressive (thus less extreme) than their beliefs about their own performances. This explanation is tested in two experiments that examine these effects’ robustness to experience, feedback, and market forces. The discussion explores the implications for strategic planning in general and entrepreneurial entry in particular.