The continuous nature of timing reprogramming in an interceptive task

The time course of movement timing reprogramming was examined in a task requiring temporal coincidence of the conclusion of a forehand drive with the arrival of a moving luminous target at the end of an electronic trackway. The moving target departed from one end of the trackway at a constant velocity of 2?m ^. s^?1, and for a part of the trials its velocity was increased to 3?m ^. s^?1. Target velocity was modified at different moments during stimulus displacement, producing times-to-arrival after velocity increment (TAVIs) from 100 to 600?ms. The effect of specific practice on movement reprogramming was also examined. The results showed early adjustments to the action (TAVIs = 100?–?200?ms) that seemed to be stereotyped, while feedback-based corrections were implemented only at TAVIs of 300?ms or longer. Temporal accuracy was progressively increased as longer TAVIs were provided up to 600?ms. Skill training led to an overall increment of temporal accuracy, but no effect of specific practice was found. The results indicate that timing reprogramming in interceptive actions is a continuous process limited mainly by intrinsic factors: latency to initiate more effective adjustments to the action, and rate-of-movement timing reprogramming.     

Memory for Preselected and Constrained Short Movements

Abstract

The present experiment investigated the recall of terminal location and distance of both preselected and constrained short movements (12 cm ± 4 cm approximately) following 5 second and 30 second unfilled retention intervals. Systematic alteration of the magnitude and direction of the starting position for recall movements revealed that the distance moved markedly interfered with the recall of the terminal location, but distance was essentially recalled independently of terminal location. Recall of distance was superior to terminal location for both the unfilled retention intervals, and there was a decrease in location recall performances following the longer 30 second delay when compared to recall attempts after the shorter 5 second delay. The Findings are discussed in terms of recent proposals to account for the memory for, and control of, discrete limb movements.     

Assimilation Effects in Coincident Timing Responses

Abstract

The purpose of the study was to investigate ways in which gender-related perceptions and actions influenced students' construction of realities in curriculum-in-action in secondary school physical education. The participants were junior and senior secondary school students in a midwestern city in the United States. Data collection methods included observations and interviews. Data were analyzed with inductive analytical procedures. The findings of the study revealed that a majority of the female and male students reproduced traditionally dominant forms of femininity and masculinity. Female students patterned their behavior consistent with feminine ideology in selecting and participating in class activities, and male students chose and participated in class activities along masculine conceptions. The results were interpreted with reproduction and resistance theories. While femininity and masculinity cultures were reproduced through students' choice of activities and participation patterns, these cultures were resisted through students' construction of oppositional behavior.     

Two-Handed Movement Control

Abstract

The purpose of this study was to investigate the discrepancy between the finding that when two hands make movements to targets of different distances, they have the same movement time (Kelso, Southard & Goodman, 1979a, b) and the finding that they have different movement times (Marteniuk & MacKenzie, 1980). The present experiment shows that when the ratio of the distance traveled by the two hands is 4:1, they do not take the same time. The hand moving the shorter distance lakes less time, although it takes more lime than when moving alone or when moving the same distance as the other hand. This finding is highlighted when individual data are examined. It appears that there is no difference between using homologous or nonhomologous muscle groups.     

The Effects of Visual and Auditory Models on the Learning of a Rhythmical Synchronization Dance Skill

The purpose of this study was to investigate the effect of visual and auditory concurrent models on the acquisition of a rhythmical synchronization task. Subjects attempted to synchronize a series of dance steps to the beat of two auditory rhythms. Subjects performed five trial blocks in one of four practice conditions: (a) audio-visual (auditory rhythms combined with a visual model), (b) audio-auditory (auditory rhythms combined with an auditory model), (c) auditory only (auditory rhythms with no model), and (d) visual only (no auditory rhythms but exposure to a visual model). Rhythmical timing and synchronization accuracy served as the dependent variables. Results revealed no practice condition learning differences for rhythmical timing. For synchronization accuracy, the audio-auditory group produced significantly lower error scores at acquisition, but no differences were found at retention. Apparently, the availability of models created an information dependency that resulted in a decrease of performance and, consequently, no group differences in retention.     

Response Timing Accuracy of Long-Distance Movements

Abstract

The purpose of the study was to compare the effectiveness of the Red Cross and Silvia methods of teaching beginning swimming. College women (N = 76), who were beginners in swimming, served as subjects. Pretests indicated no differences among the four classes prior to instruction. Reliability coefficients of the post-tests for distance and survival time (test-retest method) ranged from .70 to .98. ANOVA procedures utilizing front crawl distance, back crawl distance, survival time, and length of time required to pass the Red Cross combined tests as dependent variables resulted in superiority of the Silvia method over the Red Cross method in each analysis.     

增益开关激光脉冲时基抖动的测量方法

分析了增益开关激光脉冲抖动产生的原因及其分类.系统介绍了取样示波器法、相位噪声法、谐波分析法和互相关法等测量脉冲抖动的方法,并总结了它们的优缺点及适用范围.     

The effects of explicit timing on middle‐school students’ writing production across 5‐ and 15‐min sessions

Enhancing rates of accurate, active, academic responding can enhance learning. Both temporal manipulations (i.e., reducing time to work on assignments) and providing multiple distributed temporal cues (MDTC), sometimes referred to as explicit timing, have been shown to enhance rates of accurate mathematics responding. The current study was designed to evaluate the effects of session length (i.e., 5 vs. 15 min to write) and temporal cues (i.e., a single initial temporal cue vs. MDTC) on seventh‐ and eighth‐grade students writing assignment rates and writing accuracy. Results showed that the 5 min writing sessions did result in significantly greater rates of accurate responding than the 15 min sessions; however, explicit timing did not significantly alter writing rates or accuracy. These findings suggest that educators can enhance rates of accurate writing by reducing writing session lengths. Discussion focuses on applied implications of providing briefer writing sessions and future research investigating the interaction between multiple temporal cues and assignments.     

基于模糊-遗传杂合算法对证券投资市场时机预测的研究

基于证券市场和国家经济数据密切相关的思想提出一种根据国家综合经济数据对证券投资市场时机进行指导预测的方法 .采用模糊逻辑和遗传算法相结合来描述综合经济数据和各种资产类之间的相关关系 ,模糊逻辑表征经济数据的上下波动在多大程度上影响这种相关关系预测的准确性 ,而遗传算法的全局搜索能力保证得到综合经济数据与证券投资之间在最小风险条件下的投资时机决策关系 .最后 ,用该方法对股市实例进行仿真实验 ,得到较为理想的结果     

基于粒子群优化的神经网络实时交通信号配时

由于人工神经网络具有表征复杂输入输出系统的强大功能,将其用于城市道路交叉口的实时信号配时,是极有应用前景的尝试。文章采用三层人工神经网络建立城市道路交叉口信号配时模型,并把粒子群优化算法作为神经网络的学习算法。该算法具有极高的全局优化形态与计算效率。这种方法建立的模型将有助于降低交叉口的总延误,提高通行能力,使神经网络发挥更好的控制效果。