The effect of external perturbations on variability in joint coupling and single joint variability

This paper explores the effect of goal-oriented external perturbations created by elastic tubes attached to the hip and ankles on lower limb joint variability and hip–knee and knee–ankle coordination variability during running. Kinematics of ten healthy male runners were analysed prior to and following a 7-week tube running intervention while running with and one without this constraint. The training intervention was based on variable training aspects to increase within-movement variability and adaptability of the running pattern. To analyse the effects of the tubes on the running pattern, the phase plot vector length deviation (i.e., the standard deviation of the phase plot vector length) for the within-joint variability and the continuous relative phase variability for the joint coupling variability were calculated. Results revealed acute increases of variability in both parameters. However, after the intervention, variability of the tube running situation returned to normal for all couplings and joints except the knee. No transfer effects to normal running were observed. This suggests very rapid adaptations to such perturbations. In the long-term, it may ask for more or different variations.     

Change in intraindividual variability over time as a key metric for defining performance-based cognitive fatigability

Cognitive fatigability is conventionally quantified as the increase over time in either mean reaction time (RT) or error rate from two or more time periods during sustained performance of a prolonged cognitive task. There is evidence indicating that these mean performance measures may not sufficiently reflect the response characteristics of cognitive fatigue. We hypothesized that changes in intraindividual variability over time would be a more sensitive and ecologically meaningful metric for investigations of fatigability of cognitive performance. To test the hypothesis fifteen young adults were recruited. Trait fatigue perceptions in various domains were assessed with the Multidimensional Fatigue Index (MFI). Behavioral data were then recorded during performance of a three-hour continuous cued Stroop task. Results showed that intraindividual variability, as quantified by the coefficient of variation of RT, increased linearly over the course of three hours and demonstrated a significantly greater effect size than mean RT or accuracy. Change in intraindividual RT variability over time was significantly correlated with relevant subscores of the MFI including reduced activity, reduced motivation and mental fatigue. While change in mean RT over time was also correlated with reduced motivation and mental fatigue, these correlations were significantly smaller than those associated with intraindividual RT variability. RT distribution analysis using an ex-Gaussian model further revealed that change in intraindividual variability over time reflects an increase in the exponential component of variance and may reflect attentional lapses or other breakdowns in cognitive control. These results suggest that intraindividual variability and its change over time provide important metrics for measuring cognitive fatigability and may prove useful for inferring the underlying neuronal mechanisms of both perceptions of fatigue and objective changes in performance.     

理性行动-社会认同整合性集体行动模型

为探究理性行动理论和社会认同理论两大社会心理学宏论对于个体集体行动参与倾向的共同解释力,以“中日撞船事件”为考察蓝本向天津市431名大学生被试进行调查研究,结果发现：效能和社会规范作为态度和行动倾向的中介变量,在不同情境下对行动倾向的作用不同,符合理性行动原则;内部动机作为态度和效能、社会规范之间的中介变量,并受到学校认同和国家认同的直接或间接影响,支持了社会认同理论对遵从规范行为的解释;回归分析验证了不同水平认同对行动倾向作用程度的差异,整合模型则揭示了其具体的作用路径和影响机制.结论：理性行动理论与社会认同理论可彼此互补成为集体行动参与的整合性解释框架.     

An investigation of intra-individual variability in children with fetal alcohol spectrum disorder (FASD)

Intra-individual variability (IIV) is defined as systematic within-person variation in performance either across test sessions (e.g., test/retest performance on the same task) or in one session (e.g., variations in performance on multiple trials of a single task). Higher levels of IIV have been noted as a characteristic of neurodevelopmental disorders such as attention deficit/hyperactivity disorder? (ADHD), but IIV is yet to be investigated in fetal alcohol spectrum disorder (FASD). FASD is a term used to describe a range of conditions resulting from prenatal exposure to alcohol. As part of a comprehensive neuropsychological battery, four study groups (1. fetal alcohol syndrome/partial fetal alcohol syndrome; 2. static encephalopathy/alcohol exposed; 3. neurobehavioral disorder/alcohol exposed as diagnosed using the University of Washington FASD 4-Digit Code; 4. typically-developing (TD) age-matched children with no prenatal alcohol exposure) were administered measures of motor response and inhibitory control, attention, and adaptive behavior. The results indicate increased levels of IIV in those with FASD compared to the TD controls. It was found that IIV uniquely contributes to predicting adaptive behavior above and beyond attention, while attention partially mediates the relationship between IIV and adaptive behavior. This is the first study to the authors’ knowledge to show the presence of increased IIV in children with FASD. It additionally provides evidence that IIV measures some inherent variability in performance independent of poor attention in children with FASD.     

Extreme Response Style and the Measurement of Intra-Individual Variability in Affect

Extreme response style (ERS) has the potential to bias the measurement of intra-individual variability in psychological constructs. This paper explores such bias through a multilevel extension of a latent trait model for modeling response styles applied to repeated measures rating scale data. Modeling responses to multi-item scales of positive and negative affect collected from smokers at clinic visits following a smoking cessation attempt revealed considerable ERS bias in the intra-individual sum score variances. In addition, simulation studies suggest the magnitude and direction of bias due to ERS is heavily dependent on the mean affect level, supporting a model-based approach to the study and control of ERS effects. Application of the proposed model-based adjustment is found to improve intra-individual variability as a predictor of smoking cessation.     

职业生涯背景行动理论及其方法的述评

背景行动理论是职业生涯研究中的新理论。此理论以人类职业行动为基本研究单位,认为:(1)人类的职业行动在本质上都是意向性和目标指向的;(2)应在日常生活中了解人们的职业观念、解释和选择;(3)职业是社会建构的。行动-项目质性方法基于此理论产生,从外显行为、内在过程和社会意义三方面收集职业行动的完整信息。背景行动理论对职业行动、发展过程及社会意义的认识为职业生涯研究提供了新的理论视角。     

Deactivation in the sensorimotor area during observation of a human agent performing robotic actions

It is well established that several motor areas, called the mirror-neuron system (MNS), are activated when an individual observes other’s actions. However, whether the MNS responds similarly to robotic actions compared with human actions is still controversial. The present study investigated whether and how the motor area activity is influenced by appearance (human vs. robot) and/or kinematics (human vs. robot) of the observed action using near-infrared spectroscopy. The results showed that there was a strong interaction between these factors, revealing strong deactivations in sensorimotor areas when the subject saw a human agent performing robotic actions, which was significantly different from responses when observing the human agent acting in a human way and the robot agent performing robotic actions. These results indicate that MNS activity is sensitive to congruency between the appearance and kinematics of the agent, especially when the agent has a human appearance. We discuss the experience-dependent characteristics of MNS sensitivity to observed actions.     

Incongruent imagery interferes with action initiation

It has been suggested that representing an action through observation and imagery share neural processes with action execution. In support of this view, motor-priming research has shown that observing an action can influence action initiation. However, there is little motor-priming research showing that imagining an action can modulate action initiation. The current study examined whether action imagery could prime subsequent execution of a reach and grasp action. Across two motion analysis tracking experiments, 40 participants grasped an object following congruent or incongruent action imagery. In Experiment 1, movement initiation was faster following congruent compared to incongruent imagery, demonstrating that imagery can prime the initiation of grasping. In Experiment 2, incongruent imagery resulted in slower movement initiation compared to a no-imagery control. These data show that imagining a different action to that which is performed can interfere with action production. We propose that the most likely neural correlates of this interference effect are brain regions that code imagined and executed actions. Further, we outline a plausible mechanistic account of how priming in these brain regions through imagery could play a role in action cognition.