Premotor and Motor Reaction Time As a Function of Response Complexity

Abstract

Two experiments were conducted to identify the response elements responsible for the complexity effect found by Henry and Rogers (1960). An attempt was made to determine if these elements were affecting the premotor time component of simple reaction time (SRT). If they were, a strong case could be made for the argument that neuromotor programming time was affected because premotor time is a more exact estimate of it than SRT. The results revealed that premotor time was unaffected by a forward change in movement direction, but increased as the number of movement parts increased from one to two and as the demand for movement accuracy increased. Thus, increasing the (1) number of parts and (2) accuracy demands were identified as elements of response complexity which increase programming time and support Henry and Rogers (1960) hypothesis that the time to initiate a response becomes longer as the programming process become more complex.     

Fractionated Reaction Time Responses to Auditory and Electrocutaneous Stimuli

Abstract

It is well documented that simple reaction time (RT) varies inversely with stimulus intensity, but there is disagreement as to which stimulus modality produces the fastest simple RT. An investigation was conducted to equate two stimulus modalities, auditory (A) and electrocutaneous (EC), using varying stimulus intensities in a simple RT protocol. A second investigation was then conducted to examine neuromotor characteristics of stimulus-evoked responses using previously equated A and EC stimuli of varying intensity from the first investigation. Results showed that RT, premotor time (PMT), and motor time (MT) were all inversely related to stimulus intensity, while maximum displacement (MAXD) was directly related to stimulus intensity, and movement time was not affected by stimulus intensity. We conclude that: (a) both central and peripheral components of RT are altered by varying stimulus intensities, and (b) rapid movements are enhanced by increasing stimulus intensity.     

Properties of Isokinetic Fatigue at Various Movement Speeds in Adult Males

Abstract

Eighteen male subjects, ages 20–28 years, engaged in three fatigue bouts using an isokinetic dynamometer (Cybex II). Maximum knee extension contractions were given for 100 s at a rate of 30 per minute. The three contraction speeds chosen were 120° · s ^–1 160° · s ^–1 and 200° · s ^–1.Peak torque at 120° · s ^–1 was significantly greater (p <.05) than at 200° · s ^–1 for the first 60 s, and 160° · s ^–1 for the first 50 s. Thereafter, no significant differences existed among conditions. All three curves were found to follow two-component exponential functions as shown by the equation y_t =a ₂ e^k2^t – a ₁ e^k1^t + c. The three curves possessed similar rate constants for both components. Time to peak torque was achieved at similar times for testing at 160 and 200° · s ^–1 (p <.05). It is concluded that peak torque varies inversely with movement speed, and that the pattern of decrement is independent of movement speed. Time to peak torque does not appear to change significantly across trials in isokinetic fatigue.     

Motor variability in sports: A non-linear analysis of race walking

Abstract

This aim of this study was to analyse the nature of movement variability and to assess whether entropy measures may represent a valuable synthetic index of neuromuscular organization. The regularity of kinematic/kinetic time series during race walking, the changes in the structure of intra-individual variability over the test session, and the influence of athletic skill in (inter)national rank athletes were investigated. Motion analysis techniques were used. Sample entropy (SampEn) was adopted to examine fluctuations in lower limb angles and ground reaction forces. The regularity of both original and surrogate time series was assessed and compared, by estimating SampEn, to verify the presence of non-linear features in movement variability. SampEn was statistically lower in the original data than in surrogates. In contrast, the regularity of time series did not change significantly throughout the subsequent intra-individual repetitions. Hip and ankle joint angles and vertical ground reaction force manifested increased entropy for skilled athletes. Results suggest that race walking variability was not only the product of random noise but also contained information about the inherent propriety of the neuro-musculo-skeletal system. Furthermore, they provide some indications about neuromuscular control of the lower limb joints during race walking gait, and about the differences between more and less skilled individuals.     

Baumgartner's Modified Pull-Up Test For Male and Female Elementary School Aged Children

Abstract

Nineteen college men and women (aged 18–23 yrs, × = 21.1) were studied to ascertain the force-time components of a rapid maximal voluntary isometric contraction (MVC) for ankle dorsiflexors, knee extensors, elbow flexors, wrist flexors and hand grip. Standardized isometric strength testing protocol was used. After a practice period subjects were instructed to make an MVC without jerking and as quickly as possible, for each of the muscle actions noted above. Force readings were taken from a load cell assembly through an analogue-to-digital converter and analyzed to yield time values for MVC, 3/4 MVC, 1/2 MVC, and 1/4 MVC. The results indicated significant differences (p < .01) between the responses of the men and women, with the women reaching full MVC more rapidly than the men. Also, there were significant differences among the five muscle groups tested, with the wrist flexor muscle group developing MVC most quickly, while the knee extensors took the longest time to full MVC. Based upon these data it may be concluded that the time to full MVC differs between men and women, and also that the time to full MVC differs among the five muscle groups tested in this experiment.     

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.     

论时空变化与篮球运动的发展

时间和空间在篮球运动中有着明确的规定,二者的辩证关系广泛地存在于篮球比赛的技术和战术之中.篮球规则的修改是从时间和空间入手,逐渐细化和严格起来的,规则的修改促进了篮球技术和战术的不断发展.现代篮球的基本战术是基于对时空的不同侧重而建立起来的时空框架,从时空的视角审视篮球有利于加深对现代篮球战术的理解.     

网络环境下图情学与管理学老化规律及其比较研究

选择基于网络的引文数据库CSSCI 2006-2009年间管理学和图书情报与文献学学科领域的33 4689条引文数据,进行两学科的负指数老化模型分析、老化指标分析。研究发现,在网络环境下,这两个学科都符合负指数的老化规律,管理学的学科稳定性要比图书情报与文献学好,而图书情报与文献学的老化速度要比管理学快。本文近似地计算出了目前阶段这两个学科的半衰期分别为4.64年、5.29年;普莱斯指数分别为0.54、0.47;最大引文年限分别为2年、3年。     

航海类专业学生补考时间选择对补考通过率影响的相关研究

通过对某航海院校不同学期相同补考科目学生121人,不同补考时间对补考通过率影响进行分析,得出于开学后三周内完成补考学生的通过率低于假期补考学生。最终确定补考时间的选择可以影响补考通过率,于开学后三周内完成补考学生的通过率较低。建议将补考时间规定为假期结束前l周。