More Pronounced Bimanual Interference in Proximal Compared to Distal Effectors of the Upper Extremities.

Bimanual performance depends on effective and modular bilateral communication between the two bodysides. Bilateral neural interactions between the bodysides could cause bimanual interference, and the neuromuscular system for proximal and distal muscles is differently organized, where proximal muscles have more bilateral interneurons at both cortical and spinal level compared to distal muscles. These differences might increase the potential for bimanual interference between proximal arm muscles, because of greater proportions of bilateral interneurons to proximal muscles. The purpose of the present experiment was to evaluate potential differences in bimanual interference between proximal versus distal effectors in the upper extremities. 14 participants first performed a unilateral primary motor task with dominant arm with (1) a proximal and (2) distal controlled joysticks (condition A). Performance in condition A, was compared with the same effector's performance when a bimanual interference task was performed simultaneously with the non-dominant arm (condition B). The results showed a significant bimanual interference for both the proximal and distal controlled joysticks. Most interestingly, the bimanual interference was larger for the proximal joystick compared to the distal controlled joystick. The increase in spatial accuracy error was higher for the proximal controlled joystick, compared with the distal controlled joystick. These results indicate that the proximal-distal distinction is an important organismic constraint on motor control, and especially for bilateral communication. There seem to be an undesired bilateral interference for both proximal and distal muscles. The interference is higher in the case of proximal effectors compared distal effectors, and the results seem to map the neuroanatomical and neurophysiological differences for these effectors.

Interpersonal and intrapersonal entrainment of self-paced tapping rate.

Entrainment is a ubiquitous property not only of interacting non-linear dynamical systems but also of human movements. In the study reported here, two premises of entrainment theory were investigated in a tapping task conducted in both interpersonal (i.e. between individuals) and intrapersonal (i.e. between effectors) conditions. Hypothesis 1 was that interacting oscillatory systems should demonstrate synchronisation, which was predicted to emerge as in-phase tapping behaviour in both inter- and intrapersonal conditions. Support for Hypothesis 1 was observed in the in-phase synchronisation of tapping in both individual bimanual trials and uni-manual and bimanual tapping in dyads. By contrast, Hypothesis 2 was that the oscillatory system with the faster initial rate would decelerate, whereas the one with the slower initial rate would accelerate, as manifest in increased self-paced tapping rates amongst participants with initially slower rates and decreased rates amongst ones who initially tapped at faster rates. However, that pattern predicted in Hypothesis 2 was not observed; on the contrary, all participants increased their tapping rates in interpersonal conditions, which occurred significantly amongst participants with the lowest preferred tapping rates. Such an outcome indicates a novel aspect of synchronised movement in humans that warrants further investigation.

Relative Age Effects and Gender Differences in the National Test of Numeracy: A Population Study of Norwegian Children.

Relative age effect (RAE) refers to the phenomenon by which children born early in their year of birth perform more highly than children born later in the same cohort. The purpose of this study was to evaluate whether an RAE exists in the Norwegian numeracy test for 5th, 8th, and 9th graders (National sample of 175,760). The results showed that the RAE is consistent across 5th, 8th, and 9th graders for both boys and girls. Mean scores decreased systematically with month of birth for both genders, and the mean scores for boys were higher compared with girls. The most interesting result and novelty is the gender difference in RAE observed analyzing high- vs. low scorers. Boys born early in the year were overrepresented as high scorers (RAE advantage), whereas girls born late in the year were overrepresented as low scorers (RAE disadvantage). It would be beneficial for researchers, teachers and education policymakers to be aware of RAE, both in terms of the practical use and implications of test results and to help identify strategies to adjust for relative age differences in national tests.

Transfer of Motor Learning Is More Pronounced in Proximal Compared to Distal Effectors in Upper Extremities.

The current experiment investigated generalizability of motor learning in proximal versus distal effectors in upper extremities. Twenty-eight participants were divided into three groups: training proximal effectors, training distal effectors, and no training control group (CG). Performance was tested pre- and post-training for specific learning and three learning transfer conditions: (1) bilateral learning transfer between homologous effectors, (2) lateral learning transfer between non-homologous effectors, and (3) bilateral learning transfer between non-homologous effectors. With respect to specific learning, both training groups showed significant, similar improvement for the trained proximal and distal effectors, respectively. In addition, there was significant learning transfer to all three transfer conditions, except for bilateral learning transfer between non-homologous effectors for the distal training group. Interestingly, the proximal training group showed significantly larger learning transfer to other effectors compared to the distal training group. The CG did not show significant improvements from pre- to post-test. These results show that learning is partly effector independent and generalizable to different effectors, even though transfer is suboptimal compared to specific learning. Furthermore, there is a proximal-distal gradient in generalizability, in that learning transfer from trained proximal effectors is larger than from trained distal effectors, which is consistent with neuroanatomical differences in activation of proximal and distal muscles.

The impact of physical growth and relative age effect on assessment in physical education.

Physical education (PE) is perhaps the school subject most likely to produce relative age effects (RAE). Like in sports, physical maturity gives students an advantage in PE, which might well be mistaken for superior ability. The aim of the present study is to investigate the extent to which physical growth, measured as height, and RAE reflect the assessment in Norwegian PE. Furthermore, we wanted to examine whether there is any gender differences in the assessment in PE as a function of physical growth and RAE. The participants (n = 2978) were pupils in the last three years of secondary school (13-16 years old). A custom-made questionnaire was designed to collect the necessary data. The correlations between height and mark in PE for boys in 8th, 9th, and 10th grades are respectively r = 0.14, r = 0.32, and r = 0.29. For girls, the correlations are r = 0.11, r = 0.33, and r = 0.21. All correlations are significant (p < .05). The number of pupils achieving top marks was 114 in the first half of the year, whereas it was 65 in the second half of the year. The present study showed that physical growth has an impact on the pupils' PE attainment. The physical growth is of course also mediated by the pupils' age. RAEs were found in PE attainments also in the Norwegian school system for both genders, despite all the intentions expressed in the PE curriculum.

Dominant paradigms in motor behavior research: the motor-action controversy revisited.

In 1992, Abernethy and Sparrow published an evaluation of the historical development of the field of motor behavior research as published from 1977 up to 1988 in the Journal of Motor Behavior. The present study extends their evaluation from 1988 through 2005 using content analyses of articles on motor control and learning in this journal. Papers were categorized into the two dominant and contrasting paradigms, the motor systems approach and the action systems approach. Analysis suggests that the field of motor behavior research has changed considerably over the last three decades. The action systems approach is now the leading approach, but the motor systems approach has, however, not perished. In a Kuhnian perspective, the results might be consistent with a more long-lasting crisis, and from the available data it is not possible to predict a future outcome of the dispute between the two approaches.