汉字表象加工中的心理位移研究

自谢帕德等首次进行心理旋转实验以来,表象加工方式的研究主要集中在心理旋转、心理扫描和认知地图等方面,而作为另一种加工方式的心理位移尚未有研究。本研究以人造汉字作为研究材料,试图证实在表象加工过程中存在心理位移加工方式,结果证实心理位移是表象的加工方式之一。在心理位移过程中,反应时间与构成新形象的两种刺激表象之间的呈现距离成正比;汉字构字过程中心理位移所需加工时间的临界点可能是0．5-1秒。     

调节模式理论：自我调节领域的新进展

作为Higgins自我调节理论体系的重要组成部分,调节模式理论认为自我调节包括运动和评估两种模式,两者分别关注状态的改变和最佳方案的获得。本文分析了两种调节模式的特点并介绍了其测量及诱导方法,概括了调节模式对基本心理现象的影响以及调节匹配效应有关的研究,并对新近进展进行了介绍。未来研究尚可针对调节模式的形成、多元化测量工具及诱发范式的开发、及其对反事实思维等特定心理现象的影响等问题作更深入探讨。     

Speed Modulation in Swimming Frogs

Swimming movements of 7 European green frogs (Rana esculenta) were studied, starting from the detailed analysis of the speed and timing of the propulsive, glide, and recovery phases of their intermittent swimming behavior. First, the authors identified the spatiotemporal factors used by the frogs to modulate their swimming behavior. None of the gait variables correlated strongly with average swimming speed, and no significant correlations were found between variables belonging to different phases. There did not seem to be an obvious control strategy. Instantaneous speeds at the transition of the different phases all increased significantly with average speed, however. The strong correlation between maximal speed at the end of propulsion and the speed averaged over a cycle might reflect the dominance of the propulsive phase in the determination of the overall swimming speed. The modulation of swimming speed thus seemed largely comparable with the regulation of jumping distance. That finding was confirmed in a mathematical model, in which the positive correlations between both glide and recovery speeds, on the one hand, and average speed, on the other, were shown to be only mathematical consequences of the strong impact of the propulsive phase on overall swimming performance. That finding suggests that the correlations did not result from an active control strategy.     

The Continuing Saga of the Nerve Compression Block Technique

In response to Bairstow and Laszlo (1976) the present paper points out the inconsistencies of their arguments relative to Laszlo’s previous work and that of Kelso, Stelmach, and Wanamaker (1974). Data are presented indicating that the nerve compression block, as a tool, fails to meet the stringent requirements necessary for examining motor performance in the absence of kinesthetic information. Some possibilities for the discrepancy between Laszlo’s performance data and those from Kelso et al. are discussed. These hinge on the availability of sensory information rather than any artifact in the Kelso et al. nerve conduction procedures as Bairstow and Laszlo (1976) suggest.     

Effects of Gradual Versus Sudden Training on the Cognitive Demand Required While Learning a Novel Locomotor Task

The cognitive demand required for a range of locomotor tasks has been described for a variety of populations. However, the effect of different training strategies on the cognitive demand required while learning novel locomotor tasks is not well understood and may inform physical rehabilitation. The authors examined whether two training strategies, gradual and sudden training, influenced the cognitive demand required while practicing a novel locomotor task, asymmetric split-belt treadmill walking. Simple reaction times and whole-body kinematics were recorded throughout practice. Gradual training resulted in significantly lower reaction times during much of training, suggesting that gradual training is less cognitively demanding than sudden training, possibly due to a reduction in error feedback or movement planning demands.     

Simulated Visual Field Loss Does Not Alter Turning Coordination in Healthy Young Adults

Turning, while walking, is an important component of adaptive locomotion. Current hypotheses regarding the motor control of body segment coordination during turning suggest heavy influence of visual information. The authors aimed to examine whether visual field impairment (central loss or peripheral loss) affects body segment coordination during walking turns in healthy young adults. No significant differences in the onset time of segments or intersegment coordination were observed because of visual field occlusion. These results suggest that healthy young adults can use visual information obtained from central and peripheral visual fields interchangeably, pointing to flexibility of visuomotor control in healthy young adults. Further study in populations with chronic visual impairment and those with turning difficulties are warranted.     

Vertical adaptation of the center of mass in human running on uneven ground

In running we are frequently confronted with different kinds of disturbances. Some require quick reactions and adaptations while others, like moderate changes in ground level, can be compensated passively. Monitoring the kinematics of the runner’s center of mass (CoM) in such situations can reveal what global locomotion control strategies humans use and can help to distinguish between active and passive compensation methods.In this study single and permanent upward steps of 10 cm as well as drops of the same height were used as mechanical disturbances and the adaptations in the vertical oscillation of the runners CoM were analyzed. We found that runners visually perceiving uneven ground ahead substantially adapted their CoM in preparation by lifting it about 50% of step height or lowering it by about 40% of drop height, respectively. After contact on the changed ground level different adaptations depending on the situation occur. For persisting changes the adaptation to the elevated ground is completed after the first step on the new level. For single steps part of the adaptation takes place while returning to the ground. The consistent adaptations for the different situations support the idea that controlling the CoM by adapting leg parameters is a general control principle in running.     

Mechanical work in shuttle running as a function of speed and distance: Implications for power and efficiency

Biomechanics (and energetics) of human locomotion are generally studied at constant, linear, speed whereas less is known about running mechanics when velocity changes (because of accelerations, decelerations or changes of direction). The aim of this study was to calculate mechanical work and power and to estimate mechanical efficiency in shuttle runs (as an example of non-steady locomotion) executed at different speeds and over different distances. A motion capture system was utilised to record the movements of the body segments while 20 athletes performed shuttle runs (with a 180° change of direction) at three paces (slow, moderate and maximal) and over four distances (5, 10, 15 and 20 m). Based on these data the internal, external and total work of shuttle running were calculated as well as mechanical power; mechanical efficiency was then estimated based on values of energy cost reported in the literature. Total mechanical work was larger the faster the velocity and the shorter the distance covered (range: 2.3–3.7 J m⁻¹ kg⁻¹) whereas mechanical efficiency showed an opposite trend (range: 0.20–0.50). At maximal speed, over all distances, braking/negative power (about 21 W kg⁻¹) was twice the positive power. Present results highlight that running humans can exert a larger negative than positive power, in agreement with the fundamental proprieties of skeletal muscles in vivo. A greater relative importance of the constant speed phase, associated to a better exploitation of the elastic energy saving mechanism, is likely responsible of the higher efficiency at the longer shuttle distances.     

Newborns modulate their crawling in response to their native language but not another language

Human newborns can propel themselves to their mother's breast when positioned skin to skin on her abdomen just after birth. For decades, researchers have considered this primitive crawling behavior a spinal reflex, immune to supra spinal control. However, recent research suggests that neonatal crawling is already responsive to visual and olfactory stimuli processed at a supra spinal level. Here we report that a few hours post birth, French newborns can also modulate their crawling in response to their native language – a source of information that is processed supra-spinally. The crawling patterns of 23 French-born newborns were recorded on video and via an infrared motion capture system during two randomly ordered 2-min trials. The newborns were secured on a mini skateboard to facilitate arm and leg movements during their crawling propulsion. They heard a repetitive sequence of the same sentences either in French, their native language, or in English, a rhythmically different and hence discriminable unfamiliar language, on each trial. In French, compared to English, crawling was enhanced, with significantly more arm and leg steps and significantly more and larger trunk rotations in the cephalo-caudal axis. Moreover, newborns rotated their heads and trunk toward the appropriate loud speaker when hearing French but not English. These preliminary findings suggest that newborn crawling is not a simple stereotyped reflex under spinal control, but a complex pattern that can be modulated in response to higher-order, supra-spinally processed stimuli. The findings open fascinating questions about the range of stimuli to which newborn crawling is responsive.     

Dynamic balance assessment during gait in children with Down and Prader-Willi syndromes using inertial sensors

Down (DS) and Prader-Willi (PWS) syndromes are chromosomal disorders both characterized by obesity, ligament laxity, and hypotonia, the latter associated with gait instability. Although these shared features may justify a common rehabilitation approach, evidence exists that adults with DS and PWS adopt different postural and walking strategies. The development of an instrumented protocol able to describe these strategies and quantify patients’ gait stability in the current clinical routine would be of great benefit for health professionals, allowing them to design personalized rehabilitation programs. This is particularly true for children with DS and PWS, where motor development is dramatically constrained by severe hypotonia and muscle weakness. The aim of this study was, thus, to propose an instrumented protocol, integrated with the clinical routine and based on the use of wearable inertial sensors, to assess gait stability in DS and PWS children.Fifteen children with DS, 11 children with PWS, and 12 typically developing children (CG) were involved in the study. Participants performed a 10-meter walking test while wearing four inertial sensors located at pelvis, sternum, and both distal tibiae levels. Spatiotemporal parameters (walking speed, stride frequency, and stride length) and a set of indices related to gait symmetry and upper-body stability (Root Mean Square, Attenuation Coefficient and Improved Harmonic Ratio) were estimated from pelvis and sternum accelerations. The Gross Motor Functional Measures (GMFM-88) and Intelligence Quotient (IQ Wechsler) were also assessed for each patient. A correlation analysis among the GMFM-88 and IQ scales and the estimated parameters was then performed.Children with DS and PWS exhibit reduced gait symmetry and higher accelerations at pelvis level than CG. While these accelerations are attenuated by about 40% at sternum level in CG and DS, PWS children display significant smaller attenuations, thus reporting reduced gait stability, most likely due to their typical “Trendelenburg gait”. Significant correlations were found between the estimated parameters and the GMFM-88 scale when considering the whole PWS and DS group and the PWS group alone.These results promote the adoption of wearable technology in clinical routines to monitor gait patterns in children with DS and PWS: the proposed protocol allows to markedly characterize patient-specific motor limitations even when clinical assessment scores provide similar results in terms of pathology severity. This protocol could be adopted to support health professionals in designing personalized treatments that, in turn, could help improving patients’ quality of life in terms of both physical and social perspectives.