Individual differences in timing of discrete and continuous movements: a dimensional approach.

This study investigated aspects of individual differences in timing of continuous and discontinuous movements to different pacing signals (auditory or visual), pacing intervals (500, 650, 800, 950 ms), and across effectors (dominant versus non-dominant hand). Correlation and principal component analysis demonstrated that a single statistical dimension accounted for up to 60% of the explained variance in discontinuous tasks and 25% of the variance in continuous tasks, when applied to performance obtained from tasks conducted with different effectors and at different pacing rates. Correlation analysis of factor scores representing effector and rate independent task performances showed that timing of discrete or continuous movements can be associated with modality independent mechanisms. Timing variability from discrete and continuous trials was not significantly correlated. This study goes beyond previous correlational work on individual differences in discrete and continuous movements, demonstrating that individual differences in discrete (event-based) or continuous (emergent) motor timing tasks can be modeled as distinctive statistical components with dissimilar capability to capture effector, rate, and modality independent variance.

Exploring individual differences in children's mathematical skills: a correlational and dimensional approach.

Individual differences in mathematical skills are typically explained by an innate capability to solve mathematical tasks. At the behavioural level this implies a consistent level of mathematical achievement that can be captured by strong relationships between tasks, as well as by a single statistical dimension that underlies performance on all mathematical tasks. To investigate this general assumption, the present study explored interrelations and dimensions of mathematical skills. For this purpose, 68 ten-year-old children from two schools were tested using nine mathematics tasks from the Basic Knowledge in Mathematics Test. Relatively low-to-moderate correlations between the mathematics tasks indicated most tasks shared less than 25% of their variance. There were four principal components, accounting for 70% of the variance in mathematical skill across tasks and participants. The high specificity in mathematical skills was discussed in relation to the principle of task specificity of learning.

Timing continuous or discontinuous movements across effectors specified by different pacing modalities and intervals.

Sensorimotor synchronization is hypothesized to arise through two different processes, associated with continuous or discontinuous rhythmic movements. This study investigated synchronization of continuous and discontinuous movements to different pacing signals (auditory or visual), pacing interval (500, 650, 800, 950 ms) and across effectors (non-dominant vs. non-dominant hand). The results showed that mean and variability of asynchronization errors were consistently smaller for discontinuous movements compared to continuous movements. Furthermore, both movement types were timed more accurately with auditory pacing compared to visual pacing and were more accurate with the dominant hand. Shortening the pacing interval also improved sensorimotor synchronization accuracy in both continuous and discontinuous movements. These results show the dependency of temporal control of movements on the nature of the motor task, the type and rate of extrinsic sensory information as well as the efficiency of the motor actuators for sensory integration.

The relationship between motor competence, physical fitness and self-perception in children.

AIM: The aim of the current research was to explore the relationship between motor competence, physical fitness and self-perception, and to study to which extent this relationship may vary by gender. METHODS: A sample of 67 children (mean age 11.46 years, SD 0.27) completed Harter's Self-Perception Profile for Children (SPPC), the Movement Assessment Battery for Children (MABC) and the Test of Physical Fitness (TPF) to assess self-perception, motor competence and physical fitness. RESULTS: The SPPC was stronger related to total score on TPF than to total score on MABC. However, when looking at boys and girls separately, this result was found for the boys only. In the group in general, total scores on both TPF and MABC correlated significantly with three of the domains of SPPC (social acceptance, athletic competence and physical appearance) and general self-worth. This relationship varied by gender. Interestingly, TPF was highest correlated with perception of athletic competence in boys but with perception of social acceptance in girls. A high and significant correlation was found between physical fitness and motor competence for both genders. CONCLUSION: The results indicated a strong relationship between physical fitness, motor competence and self-perception in children that varied by gender. This implies that all these factors are essential contributions in order to facilitate participation in physical activity in children.

Research on children with developmental coordination disorder--some challenges! Commentary on C. L. Tsai and S. K. Wu (2008).

This commentary focuses on the need for proper inclusion criteria for research on children who have motor problems. Researchers must be aware of the large range of individual differences found in samples used in research on children with Developmental Coordination Disorder. New theoretical perspectives in development and learning are a basis for research and practice.

Are poor mathematics skills associated with visual deficits in temporal processing?

Developmental learning disabilities such as dyslexia and dyscalculia have a high rate of co-occurrence in pediatric populations, suggesting that they share underlying cognitive and neurophysiological mechanisms. Dyslexia and other developmental disorders with a strong heritable component have been associated with reduced sensitivity to coherent motion stimuli, an index of visual temporal processing on a millisecond time-scale. Here we examined whether deficits in sensitivity to visual motion are evident in children who have poor mathematics skills relative to other children of the same age. We obtained psychophysical thresholds for visual coherent motion and a control task from two groups of children who differed in their performance on a test of mathematics achievement. Children with math skills in the lowest 10% in their cohort were less sensitive than age-matched controls to coherent motion, but they had statistically equivalent thresholds to controls on a coherent form control measure. Children with mathematics difficulties therefore tend to present a similar pattern of visual processing deficit to those that have been reported previously in other developmental disorders. We speculate that reduced sensitivity to temporally defined stimuli such as coherent motion represents a common processing deficit apparent across a range of commonly co-occurring developmental disorders.

Baby swimming: exploring the effects of early intervention on subsequent motor abilities.

AIM: The aim of the study was to explore the effects of baby swimming on subsequent motor abilities. BACKGROUND: A range of motor abilities was examined in 4-year-old children who had previously participated in a programme of baby swimming (n= 19) and compared with a matched group of coevals who had not had this experience (n= 19). RESULTS: As predicted from the nature of the exercises that comprise the programme, the effects of baby swimming were restricted to abilities associated with prehension and balance. CONCLUSIONS: Suggestions are made as to how the theme of this hypothesis-generating, demonstration study can be pursued in the future with more rigorous experimental controls and applications to children with disabilities and impairments.

Interrelationship among selected measures of motor skills.

BACKGROUND: This study set out to explore the interrelationship among selected measures of motor skills. METHODS: Ninety-one 4-year-old children from 10 nursery schools were tested using eight motor tasks from the Movement Assessment Battery for Children test. RESULTS: The most striking finding was that there were very low correlations between the motor tasks. CONCLUSIONS: In relation to these findings, it is possible to argue that learning of particular motor skills is specific to that task. This is discussed in relation to the principle of task specificity of learning.

Disorders of motor development (clumsy child syndrome).

This presentation will focus on motor competence, the clumsy child, perceptual deficits in clumsy children and possible neurological dysfunction in this group of children. Motor competence not only allows children to carry out everyday practical tasks, but it is also an important determinant of their level of self-esteem and of their popularity and status in their peer group. Research has shown that about 6-10% of children have motor competences well below the norm. It is unusual for motor problems to simply disappear over time. In the absence of intervention the syndrome is likely to manifest itself. In the clinical literature attempts have been made to establish causal links between surface manifestations of clumsiness and underlying perceptual deficits. In this respect the attention is primarily directed towards the concept of inter- and intra-modal matching, particularly with respect to vision and proprioception, an ability deemed to underlie many real-life motor skills. Neurobehavioural model of inter- and intra-modal matching and deficit model is presented. Findings from studies using this paradigm are discussed and it is argued that clumsiness must be seen as a neurological dysfunction (insufficiency).

Do visual processing deficits cause problem on response time task for dyslexics?

This study was set out to explore the prediction that dyslexics would be likely to have particular problems compared to control group, on response time task when 'driving' a car simulator. The reason for doing so stems from the fact that there is considerable body of research on visual processing difficulties manifested by dyslexics. The task was to drive a car and at the same time, the driver had to use either signal button on the right side of the wheel (condition 1) or a voice-activated microphone (condition 2) immediately when a road sign appears. In condition 1, the sign appears only in the mid-field zone and in condition 2, it appears in one of six possible positions in relations to the car ahead. As predicted, it was found that the dyslexics had significantly higher response time in both conditions than their controls. Dyslexics may have visual processing deficit which not only cause reading problems but also problems perceiving rapid changes in their environment such as responding on a sign when driving.

Do 'clumsy' children have visual recognition problems?

OBJECTIVE: Visual recognition by 8-year-old children with hand-eye co-ordination problems (HECP), and by a control group of children without such problems was tested using a task of visual closure. DESIGN: The task required the children to identify common objects from an incomplete visual presentation. RESULT: As predicted, it was found that the HECP children, who were designated as such solely on the basis of their motor difficulties, identified significantly fewer correct objects than their control counterparts. CONCLUSIONS: This finding raises the possibility that the visual processing problems of clumsy children contribute to, or even strongly determine, not only their movement problems but also their learning difficulties.

Perceptual deficits in clumsy children: inter- and intra-modal matching approach--a window into clumsy behavior.

This article will focus on the underlying perceptual deficits that might lead to inadequacies in motor performance in children. Two lines of enquiry have dominated the literature: visual-perceptual deficit and/or visual-motor deficits and proprioceptive deficits. The theoretical and methodological shortcomings in these approaches are discussed. Then attention is primarily directed toward the concept of inter- and intra-modal matching (sensory integration), particularly with respect to vision and proprioception, an ability deemed to underlie many real-life motor skills. Such an approach allows parallels to be drawn between behavioral manifestations of motor impairment and potential underlying neurological information-processing disorders, particularly as these relate to hemispheric competence.

Static balance in children with hand-eye co-ordination problems.

OBJECTIVE: The aim of the present study was to examine static balance on one leg in 10-year-old children with and without hand-eye co-ordination problems (HECP) in an attempt to come closer to an understanding of developmental co-ordination disorder in children. METHOD: The children were compared on three different balance tasks with the right and/or left leg together with a systematic manipulation of vision. RESULTS: The results showed that when the scores for both legs were combined, the control group, in general, had superior performance in all conditions. Separate preferred and non-preferred leg analyses demonstrated that the differences between the HECP group and control group could be accounted for by lowered performances when the non-preferred leg was used in only one static balance task, stork stand with vision. In the two other balance tasks, balance on beam and one-board balance, the HECP group displayed significantly worse performance than the control group irrespective of the use of the preferred or non-preferred leg. CONCLUSIONS: Explanation related to the development of the hemispheres controlling the preferred and non-preferred leg is invoked to account for the poor performance in the HECP group.

Sex differences in lateralisation of fine manual skills in children.

One hundred and twelve children (55 boys and 57 girls) were tested using two tasks taken from the Movement Assessment Battery for Children. The girls had a larger between-hands asymmetry than boys on the threading nuts on bolt task, thus indicating they were more lateralised. On the other task, placing pegs, no such sex differences were found. We present our findings as a warning to others that even though two tasks are assumed to measure the same, in this case unimanual performance, differences in task constraints will exist. Such differences may constitute a confounding factor when trying to infer about lateralisation based on behavioural tasks.

Do 'clumsy' children have visual deficits.

Visual processing by 10-year-old children diagnosed on the basis of standardised tests as having developmental 'clumsiness' syndrome, and by a control group of children without motor difficulties, was tested using three different psychophysical tasks. The tasks comprised a measure of global motion processing using a dynamic random dot kinematogram, a measure of static global pattern processing where the position of the target was randomised, and a measure of static global pattern processing in which the target position was fixed. The most striking finding was that the group of clumsy children, who were diagnosed solely on the basis of their motor difficulties, were significantly less sensitive than the control group on all three tasks of visual sensitivity. Clumsy children may have impaired visual sensitivity in both the dorsal and ventral streams in addition to their obvious problems with motor control. These results support the existence of generalised visual anomalies associated with impairments of cerebellar function.

Hand preference in children with developmental coordination disorders: cause and effect?

Inter- and intra-modal matching by eight-year-old children diagnosed as having hand-eye coordination problems (HECP) and categorized as left-handed, together with a left-handed control group of children without such problems, were tested using a manual sensory matching task. The task required the children to locate target pins, visually (seen target), proprioceptively (felt target) or in combination (felt and seen target), while matching to the located target was always carried out without vision. Performance was superior when the target was located visually or visually/proprioceptively for both groups of children. These results question the conclusion that intra-modal will always be more accurate than inter-modal matching. When the combined scores for both hands were analyzed, the HECP children showed inferior performance to the control children in both inter- and intra-modal matching. Separate right and left hand analyses, demonstrated that the differences between the HECP group and control children could be accounted for by lowered performances when the right hand (nonpreferred) was used to match the located target position. Putative neurological disorders related to the development of the hemisphere controlling the nonpreferred hand (left hemisphere) are invoked to account for the poor performance with the nonpreferred hand of the HECP children.

Dynamics of hand preference in 4 year-old children.

Hand preference in groups of 4 year-old children towards either end of the skill continuum (as determined by the Movement ABC test) was explored by means of a catching task in which the 'direction of approach of the ball' was used as a control parameter within a dynamical systems framework. In Condition 1, the ball direction was systematically scaled in degrees from the right side of the subject to the left and vice versa. In Condition 2, the spatial location of the ball direction was varied randomly, rather than systematically, over the same range as for Condition 1. In both conditions, the two groups of children were shown to switch between hands (from left to right and vice versa) at well-defined positions on the scale. The different scale values obtained when ball direction was scaled from left to right compared with right to left were used to define hysteresis areas. These areas were more extensive and located more to the left of the midline for the group towards the less skilled end of the continuum than for those towards the more skilled end. Additionally, the less-skilled children were shown to use the right hand more to catch the balls delivered to the left side than did the more skilled children. In Condition 3, objects were placed on the table of the ball-delivery apparatus in order to make the catching action more complicated. The less skilled group were shown to use the right hand more than the left hand in all catching positions whereas the more skilled group showed an equal usage of both catching regimes.

[Children and motor competence]. / Barn og motorisk kompetanse.

Recently, the topic of motor competence has figured prominently in the media. The claims made are many, but the research that support the statements is seldom cited. The aim of this review article is to address that deficiency by documenting what is really known about the motor competence of children. Motor competence not only allows children to carry out everyday practical tasks, but it is also an important determinant of their level of self-esteem and of their popularity and status in their peer group. While many studies have shown a significant correlation between motor problems and other problems in the social sphere, it has been difficult to establish causal relationships with any degree of confidence, as there appear to be several interactions which need to be taken into account. Research has shown that 6-10% of Norwegian children in the 7 to 10 year age group have a motor competence well below the norm. It is unusual for motor problems to simply disappear over time. In the absence of intervention the syndrome is likely to continue to manifest itself. More recent research points to some of the circularity in this causal network, children with motor problems having been shown to be less physically active than their peers. In a larger health perspective this in itself can have very serious consequences for the child.

Differential contributions of the two hemispheres in intra-modal proprioceptive sensory matching in 7-10-year-old boys.

This study explores putative differential contributions of the two hemispheres when 7-10-year-old right-hand and left-hand preferent boys are required to carry out a 'foot-hand' target location and matching task. The task required subjects to locate a target pin with the big-toe (felt target), and match the located target position with the hand, without vision. Right-handed (n=25) and left-handed (n=22) boys were tested in a four-condition design. Two intra-hemispheric conditions (right foot locating-right hand matching, left foot locating-left hand matching), and two inter-hemispheric conditions (right foot locating-left hand matching, left foot locating-right hand matching) were used. When the criterion for handedness was writing hand only the results were found to be confounded by the large number of subjects with indeterminate handedness (isolated by use of the Edinburgh Handedness Inventory) originally assigned to the left-handed group. Reclassification of the handedness groups, on the basis of this inventory, showed the pure-left handers to be as good on those conditions mediated by the right hemisphere as pure right handers were with those conditions mediated by the left. These findings are discussed with respect to the contention that left handers are not just 'reversed' right handers.

Development of proprioceptive sensitivity.

The development of proprioceptive sensitivity was studied in 140 children between the ages of 5.8 and 11.8 years using a so-called foot-hand task. Ten boys and ten girls were included in each age group. The task required the children to locate a target pin with the "big toe" (felt target) and match the located target position with the hand, without vision. There were four conditions: location of targets by the right big toe: matching located target position with the right hand (RfRh) and left hand (RfLh); and location of targets by the left big toe: matching located target position with the left hand (LfLh) and right hand (LfRh). The results showed a significant developmental trend in proprioceptive sensitivity, when the absolute error scores for boys and girls were combined, with most of the improvement occurring between the ages of 5.8 and 7.8 years. The most interesting and novel finding seems to be the significant two-way interaction between age and sex--the clearest differences manifesting themselves in the age group 9.9 years. Separate within-sex group analyses showed the trend to be determined by the results for the girls, the trend being absent in the results for the boys. Furthermore only the boys showed a significant difference between the intra- and inter-hemispheric conditions. We propose that these differences may only manifest themselves in particular tasks, i.e. there may be a sex-task interaction. The implications of this proposal for theoretical interpretations of the phenomenon of inter-hemispheric processing as well as possible sources of the task differences are briefly discussed.