Effect of physical fatigue on motor control at different skill levels

The purpose of this experiment was to explore the effect of fatigue on motor coordination, and of prospective adjustment strategies to compensate for fatigue in a multijoint movement. Two male groups (N = 8) participated in the experiment: Highly skilled table tennis players (M age = 27 yr., SD = 2.3, n = 4) and Recreational table tennis players (M age = 25.9 yr., SD = 0.04, n = 4). The task was an attacking forehand drive towards a scaled target on the opposite side of the net. The Highly skilled players adjusted their movement patterns and preserved the task requirements in terms of spatial accuracy under the condition of fatigue by using opportunistic movement coordination. The Recreational players did not adjust their forehand drive, and spatial accuracy deteriorated. The current results support the notion that expertise enhances potential to adjust motor coordination strategies as a reaction to induced physical fatigue.     

Bimanual interference in children performing a dual motor task

The present study addressed the development of bimanual interference in children performing a dual motor task, in which each hand executes a different task simultaneously. Forty right-handed children (aged 4, 5-6, 7-8 and 9-11years, ten in each age group) were asked to perform a bimanual task in which they had to tap with a pen using the non-preferred hand and simultaneously trace a circle or a square with a pen using the preferred hand as quickly as possible. Tapping and tracing were also performed unimanually. Differences between unimanual and bimanual performance were assessed for number of taps, length of tap trace and mean tracing velocity. It was assumed that with increasing age, better bimanual coordination would result in better performance on the dual task showing less intermanual interference. The results showed that tapping and tracing performance increased with age, unimanually as well as bimanually, consistent with developmental advancement. However, the percentage of intermanual interference due to bimanual performance was not significantly different in the four age groups. Although performing the dual task resulted in mutual intermanual interference, all groups showed a significant effect of tracing shape. More specifically, all age groups showed a larger percentage decrease in tracing velocity when performing the circle compared to the square in the dual task. The present study reveals that children as young as four years are able to coordinate both hands when tapping and tracing bimanually.     

Self-perception and motivational characteristics of tennis participants: The influence of age and skill

Abstract

An integrated approach to the study of psychosocial factors related to participation behavior was adopted by incorporating developmental, skill acquisition, and psychosocial variables. Specifically, the relationship of age and skill with self-perceptions and motivational characteristics of tennis participants was examined. Males and females (N = 240) ranged in age from 10 to 67 years. Professional tennis coaches verified the skill rating of each player using the National Tennis Rating Program introduced by the United States Tennis Association. Individuals completed self-report scales measuring perceived tennis competence, tennis salience, global self-worth, challenge motivational orientation, task and ego orientations, and competitive trait anxiety. Canonical correlation analyses revealed that age and skill were significantly related to psychosocial variables for both males and females. These findings suggest that an integrated research approach can extend our understanding of social-psychological variables in the physical activity setting.     

Effects of stimulus cueing on the acquisition of groundstrokes by beginning tennis players

A multiple baseline design was used to examine the effects of stimulus self-cueing on the acquisition of forehand and backhand returns by beginning tennis players (N = 24). A four-step verbal cueing program was introduced during intervention. Both the use of the technique and the successful number of returns were recorded. Each group showed an acceleration in skill acquisition during intervention, with both forehand and backhand returns improving over 45% from baseline conditions. Implications for the teaching of beginning tennis skills are discussed.     

Importance of head movements in gaze tracking during table tennis forehand stroke

The purpose of this study was to clarify the properties of gaze and head movements during forehand stroke in table tennis. Collegiate table tennis players (n = 12) conducted forehand strokes toward a ball launched by a skilled experimenter. A total of ten trials were conducted for the experimental task. Horizontal and vertical movements of the ball, gaze, head and eye were analyzed from the image recorded by an eye tracking device. The results showed that participants did not always keep their gaze and head position on the ball throughout the entire ball path. Our results indicate that table tennis players tend to gaze at the ball in the initial ball-tracking phase. Furthermore, there was a significant negative correlation between eye and head position especially in the vertical direction. This result suggests that horizontal VOR is suppressed more than vertical VOR in ball-tracking during table tennis forehand stroke. Finally, multiple regression analysis showed that the effect of head position to gaze position was significantly higher than that of eye position. This result indicates that gaze position during forehand stroke could be associated with head position rather than eye position. Taken together, head movements may play an important role in maintaining the ball in a constant egocentric direction in table tennis forehand stroke.     

How do children coordinate simultaneous upper and lower extremity tasks? The development of dual motor task coordination

When performing simultaneous clapping with walking or galloping, adults adopt coupled, consistent and stable dual motor task coordination; do developmental trends in this coordination exist? In this study, we measured and compared coupling characteristics, consistency across trials and variability of phasing in 4-, 6-, 8-, and 10-year-olds (n=44) as they also performed the same dual motor task. For walk/clap, children adopted specific coupling patterns like adults by 8 years and with the same consistency by 10 years. Across age, children became less variable in clap and step movements separately and as coupled together. In the gallop/clap, children did not resemble adults in coupling patterns by 10 years but all measures were becoming more consistent across age. We discuss dual motor task coordination as a function of age and task complexity using a "dynamic" perspective within a developmental context.     

Development of strategies for recalling letter sequences

Kindergarten, second-grade, and fourth-grade children (6, 8, and 10 years of age, respectively) were asked to recall letter sequences on a task that required the use of: (a) a verbal strategy; (b) a positional strategy; or (c) either strategy. Additional trials, allowing either strategy, were interspersed among those requiring a verbal or positional strategy; strategy use was determined from performance on these interspersed trials. The results show that children at all grade levels attempted to use a task-appropriate strategy. Performance on the verbal task showed a more marked developmental increase than did performance on the positional task. A second experiment replicated the first with the interspersed trials removed. A third experiment was designed to determine whether letter names interfered with older children's efficient use of a positional strategy. Even with this source of interference removed, the developmental pattern of Experiments 1 and 2 was replicated. There was a Sex by Condition interaction in Experiments 2 and 3 which showed that males do better in the condition requiring a positional strategy, and females do better in the condition requiring a verbal strategy.     

Children show limited movement repertoire when learning a novel motor skill

Examining age differences in motor learning using real‐world tasks is often problematic due to task novelty and biomechanical confounds. Here, we investigated how children and adults acquire a novel motor skill in a virtual environment. Participants of three different age groups (9‐year‐olds, 12‐year‐olds, and adults) learned to use their upper body movements to control a cursor on a computer screen. Results showed that 9‐year‐old and 12‐year‐old children showed poorer ability to control the cursor at the end of practice. Critically, when we investigated the movement coordination, we found that the lower task performance of children was associated with limited exploration of their movement repertoire. These results reveal the critical role of motor exploration in understanding developmental differences in motor learning.     

Table Tennis Experts Outperform Novices in a Demanding Cognitive-Motor Dual-Task Situation

Abstract

Theories on motor skill acquisition predict that earlier learning stages require more attention, which should lead to higher cognitive-motor dual-task interference in novices as compared to experts. Expert and novice table tennis players returned balls from a ball machine while concurrently performing an auditory 3-back task (working memory). The groups did not differ in 3-back performance in the single task. Cognitive dual-task performance reductions were more pronounced in novices. A similar pattern emerged for the number of missed balls in table tennis, except that experts outperformed novices already in the single task. Experts consistently showed costs of about 10%, while novices showed costs between 30% and 50%. The findings indicate that performances of novices suffer considerably in motor-cognitive dual-task situations.     

3~6岁儿童执行功能子成分发展的研究

执行功能是对目标指向活动进行信息整合和控制调节的一系列认知能力,在学前期发展迅速。研究使用执行功能任务组软件考察了210名3~6岁儿童（6组,组间年龄跨度6个月）执行功能各子成分（工作记忆、抑制控制和认知灵活性）的发展特征。结果表明：（1）随年龄增长,3~6岁儿童执行功能呈上升趋势发展,4岁左右为抑制控制与认知灵活性的高速发展期;（2）执行功能各子成分发展不同步,抑制控制最快,工作记忆最慢;（3）各子成分间呈中度正相关。结论：3~6岁执行功能能力发展迅速,但各子成分的发展进程并不一致;幼儿阶段执行功能测试的年龄分组最好精确到6个月。     

What colour is the car? Implicit memory for colour information in children

Three experiments were conducted to examine age-related differences in colour memory. In Experiment 1, preschool age and elementary school age children were given a conceptual test of implicit colour memory (a colour-choice task). They were presented with the names or achromatic versions of previously studied coloured line drawings and asked to select an appropriate colour. Significant priming could be demonstrated: The children chose the previously seen colours more often than was expected by chance. Equivalent priming was found for both versions (pictorial and verbal) suggesting that colour priming may be conceptually mediated. Moreover, colour priming proved to be age invariant. Experiment 2 replicated and extended this finding by using a wider age group (preschool, elementary school, and young adults) and by giving a perceptual implicit task (picture identification) in addition to a verbal colour-choice task. Colour did not affect priming in the perceptual task. Whereas priming showed no developmental change, agerelated improvements were observed on an explicit colour memory task that differed only in the test instructions from the implicit colour-choice task (Experiments 2 and 3). Taken together, the results suggest that implicit colour memory may be mediated by conceptual processes that are age invariant.     

Constrained action selection in children with developmental coordination disorder

The effect of advance ('precue') information on short aiming movements was explored in adults, high school children, and primary school children with and without developmental coordination disorder (n=10, 14, 16, 10, respectively). Reaction times in the DCD group were longer than in the other groups and were more influenced by the extent to which the precue constrained the possible action space. In contrast, reaction time did not alter as a function of precue condition in adults. Children with DCD showed greater inaccuracy of response (despite the increased RT). We suggest that the different precue effects reflect differences in the relative benefits of priming an action prior to definitive information about the movement goal. The benefits are an interacting function of the task and the skill level of the individual. Our experiment shows that children with DCD gain a benefit from advance preparation in simple aiming movements, highlighting their low skill levels. This result suggests that goal-directed RTs may have diagnostic potential within the clinic.     

Studying the effects of self-talk on thought content with male adult tennis players

The current study examined the effects of self-talk on thought content during a tennis forehand crosscourt exercise. 16 adult tennis players (M age = 37.3 yr., SD = 8.31) were randomly assigned to either an experimental or a control group. After completing three baseline assessments, the players of the intervention group developed and implemented self-determined instructional cue words throughout three intervention trials. The participants' thought content was divided into three categories, and repeated-measures analyses of variance indicated a significant group by time interaction for execution-related thoughts and outcome-related thoughts, but not for circumstance-related thoughts. Follow-up comparisons showed that the experimental group players' execution-related thoughts increased and outcome-related thoughts decreased significantly, whereas thought content did not change significantly in the control group. The results of this study provided evidence for the effects of self-talk on players' thought content and supported the idea that self-talk could help athletes to focus on task relevant information.     

Age differences in executive functioning across the lifespan: the role of verbalization in task preparation

Age-related changes in executive functioning across the lifespan were assessed in children (mean age=9.4 years), younger adults (mean age=21.5 years), and older adults (mean age=65.3 years). Executive functioning was investigated with a task-switching paradigm that permits the separation of two control components: to select and to switch between task sets. The specific aims of this study were (a) to determine developmental functions in both control components across the lifespan; and (b) to examine whether age-related changes in these components are influenced by verbal prompts during task preparation. The results revealed an inverted u-shaped developmental function for the ability to select between task sets but not for the ability to switch between task sets. In contrast to younger adults and children, older adults generally benefited from verbalizations during task preparation. Children, but not older adults, showed a facilitation of task execution when verbal prompts were task-compatible. Conversely, older adults, but not children, showed stronger interference when verbal prompts are task-incompatible. Our findings suggest that inner speech in an important modulator of developmental changes in executive functioning across the lifespan.     

Development of flexible visual recognition memory in human infants

Research using the visual paired comparison task has shown that visual recognition memory across changing contexts is dependent on the integrity of the hippocampal formation in human adults and in monkeys. The acquisition of contextual flexibility may contribute to the change in memory performance that occurs late in the first year of life. To assess this skill, the images are presented on a background of one colour during familiarization and on a different coloured background during the recognition test. Our research showed that recognition memory is impaired by a change in context at 6 and 12 months of age but is unaffected at 18 and 24 months of age. The findings are discussed in relation to hippocampal development and the proposed developmental step in memory at 9-10 months of age.     

A study of 60- to 89-mo.-old children's skill at writing numerals

The skill of writing numerals necessitates a certain developmental maturity. Studying the age at which children start to develop this skill and assessing problems they encounter while writing numerals should give direction to their training. From 8 schools a total of 267 children, ages 60 to 89 mo., were asked to write the numerals 1 to 9. Analysis showed that 80% of the children wrote most of the numerals correctly, 15% wrote inverted numerals, 2.0% wrote some numerals as letters, and 4% did not write certain numerals at all. In addition, 64% of children ages 60 to 65 mo. gave correct responses, and the perception of correct responses increased across age groups until 95% were correct in the group who were 84 to 89 mo. There was no significant difference between girls and boys in these writing skills.     

Cognitive Bias for the Distribution of Ball Landing Positions in Amateur Tennis Players (Cognitive Bias for the Motor Variance in Tennis)

This study aimed to investigate whether the isotropy bias (estimating one's own motor variance as an approximately circular distribution rather than a vertically elongated distribution) arises in tennis players for the estimation of the two-dimensional variance for forehand strokes in tennis (Experiment 1), as well as the process underlying the isotropy bias (Experiment 2). In Experiment 1, 31 tennis players were asked to estimate prospectively their distribution of ball landing positions. They were then instructed to hit 50 forehand strokes. We compared the eccentricity of the ellipse calculated from estimated and observed landing positions. Eccentricity was significantly smaller in the estimated ellipse than in the observed ellipse. We assumed that the isotropy bias for the estimated ellipse comes from the process of variance estimation. In Experiment 2, nine participants estimated the 95% confidence interval of 300 dots. Eccentricity was significantly smaller in their estimated ellipses than it was in the ellipses for the dots, though the magnitude of bias decreased for the estimation of dots. These results suggest that the isotropy bias in tennis ball landing position includes the bias of recognizing landing position and the bias of estimating the ellipse confidence interval from the recognized landing position.     

Application of Variability of Practice Hypothesis in Alzheimer Patients

This study examined the effects of constant versus variable practice on learning a simple motor task in eight patients diagnosed with Alzheimer's Disease (AD). According to the variability of practice hypothesis, variations in practice of a motor skill result in superior learning as evidenced by better ability to transfer the skill. Eight AD patients were matched for Mini-Mental State Exam and baseline scores and then randomly assigned to a constant or variable practice group. Then, the participants were trained in hitting a tennis ball with a small racquet against a horizontal target (practice task) over 12 sessions. Finally, they were asked to aim at a vertical target (transfer task). All participants showed improvement on the practice task. On the transfer task, three of four participants in the variable practice group outperformed their matched counterparts, suggesting learning benefits of variable practice.     

Testing predictive control of movement in children with developmental coordination disorder using converging operations

Recent systematic reviews (Wilson et al., 2013, Dev. Med. Child Neurol., 55, 217; Adams et al., 2014, Neurosci. Biobehav. Rev., 47C, 225) suggest that a common underlying problem in developmental coordination disorder (DCD) is the internal modelling deficit. The study presented here is the first to test this hypothesis using a within‐subject design, assessing motor imagery, action planning, and rapid online control (ROC) in a sample of children screened rigorously for DCD. Participants were 66 children; 33 children (26 boys and seven girls) aged 6–11 years in the DCD group and 33 controls (gender and age matched). Motor imagery was assessed with the hand rotation task (HRT), action planning with an end‐state comfort effect test, and ROC with the double‐step pointing task. Results showed that children with DCD were slower and less accurate than controls in the HRT. Reduced forward planning for comfortable end‐state was also shown in DCD. Finally, no group differences were found on the ROC task. Collectively, children with DCD manifest deficits in the internal modelling of movements, but this varies under different task constraints, particularly those related to movement complexity.     

Variable practice in learning the forehand drive in tennis

One of the most important factors that has occupied researchers in motor learning is the method of practicing motor skills. This study examined the effect of variable practice in learning the forehand drive in tennis by children and adolescents. Variability of practice was achieved by the alternation of targets and the distance between the point of execution and the target. 40 male children ages 9 to 10 years and 40 male students ages 18 to 19 years were divided into eight equal groups according to age and training group (No Specific target, 1 target, 4 targets, and 5 targets). After 18 practice sessions over 40 days and similar teaching, the participants performed 60 transfer trials after a rest of 72 hours. The experimental design used was a 2 (age) x 4 (practice group) x 6 (block of trials) with repeated measures on the last factor for absolute and constant error scores. The analysis of variance showed that the children performed more poorly than the adolescents, and variable practice yielded better performance than constant and specialized practice. The results support the variability of practice hypothesis and indicate that the effect of variable and specialized practic was related to age of the groups of trainees.