Visual perceptual deficits in clumsy children

The Effect of a Table Tennis Exercise Program With a Task-Oriented Approach on Visual Perception and Motor Performance of Adolescents With Developmental Coordination Disorder

In this study we investigated the effects of an 8-week table tennis exercise program with a task-oriented approach on visual perception and motor performance of 31 adolescents with developmental coordination disorder (DCD). The participants were identified by their teachers as having greater difficulty than their peers (450 students from three Korean middle schools) in physical education (PE) classes. On the Bruininks-Oseretsky Test of Motor Proficiency-2, these adolescents scored below the 15th percentile and showed difficulties in performing daily life activities due to motor performance problems; they did not have physical defects, intellectual or neurological impairments, or Attention Deficit Hyperactivity Disorder. Of 98 prospective adolescents with PE difficulties, we obtained personal assent and parents' informed consent from 54, and 31 of these met screening criteria for DCD through the Developmental Coordination Disorder Questionnaire-Korean. This final group was divided in non-random fashion (based on the proximal geographic grouping of the children's schools) between an experimental group (n = 16) and a control group (n = 15). The experimental group participated in the 8-week task-oriented table tennis training program with three 90-minute sessions per week, while the control group only participated in regular PE classes twice per week. We measured participants' visual perception and motor performance in the same environment before and after the intervention program. Participants' visual perception was significantly more improved in the experimental group than the control group, with specific improved skills in visual-motor search, visual-motor speed, figure-ground, and visual closure; copying and perceptual constancy skills did not improve significantly. In addition, total motor performance and motor sub-skills, including fine manual control, manual coordination, body coordination, strength, and agility were significantly more improved in the experimental group than in the control group. Thus, our task-oriented table tennis exercise program was of greater assistance than general PE classes for improving visual perception and motor performance in adolescents at risk of DCD.

Prevalence and Cognitive Profiles of Children With Comorbid Literacy and Motor Disorders

There is a high prevalence of comorbidity between neurodevelopmental disorders. Contemporary research of these comorbidities has led to the development of multifactorial theories of causation, including the multiple deficit model (MDM). While several combinations of disorders have been investigated, the nature of association between literacy and motor disorders remains poorly understood. Comorbid literacy and motor disorders were the focus of the two present studies. In Study 1, we examined the prevalence of comorbid literacy and motor difficulties relative to isolated literacy and motor difficulties in a community sample (N = 605). The prevalence of comorbidity was five times greater than expected by chance alone, implying some relationship between difficulties. In Study 2, we examined the cognitive profiles of children with literacy and motor disorders amongst a subsample of children from Study 1 (N = 153). Children with literacy disorder had deficits in phonological processing, selective attention, and memory whilst children with motor disorder had deficits in visuospatial processing and memory, suggesting the disorders should be considered to have both independent and shared (memory) cognitive risk factors. Children with comorbid literacy and motor disorder demonstrated an additive combination of these deficits. Together, these findings are consistent with predictions from the MDM.

Visual tracking behaviour of two-handed catching in boys with developmental coordination disorder

BACKGROUND

Developmental coordination disorder (DCD) is a motor learning disability that affects coordination resulting in an inability to perform movement skills at an age appropriate level. One area suspected to contribute to the movement difficulties experienced are deficits in visuomotor control.

AIMS

This study investigated visual tracking behaviour during catching in children with DCD.

METHODS AND PROCEDURES

Twenty-four boys completed the study: 11 with DCD (9.43 years ±0.73) and 13 controls (9.16 years ± 0.68). Participants performed 10 central catching trials, with the best five used to evaluate tracking behaviour and motor responses.

OUTCOMES AND RESULTS

Prior to ball release, the DCD group exhibited more fixations (p = 0.043) of lesser duration (p = 0.045). During flight, the DCD group took longer to initiate smooth pursuit (p = 0.003) however, once initiated, both groups were effectively able to maintain smooth pursuit. Despite initial delays, these had no impact on movement initiation time (p = 0.173), however, movement time was significantly slower in the DCD group (p = 0.031).

CONCLUSIONS AND IMPLICATIONS

The results of this study demonstrate that catching performance in children with DCD likely reflect a combination of errors in attending to visual information and movement organisation.

Navigating through apertures: perceptual judgements and actions of children with Developmental Coordination Disorder

Passing through a narrow gap/aperture involves a perceptual judgement regarding the size of the gap and an action to pass through. Children with DCD are known to have difficulties with perceptual judgements in near space but whether this extends to far space is unknown. Furthermore, in a recent study it was found that adults with DCD do not scale movements when walking through an aperture in the same way as their peers. The current study, therefore, considered perceptual judgements and motor behaviour of children with DCD while looking at or walking through apertures. Twenty‐nine children with DCD and 29 typically developing (TD) children took part. In Experiment 1, participants completed a perceptual task, where they made passability judgements. Children with DCD showed a significantly smaller critical ratio (aperture size at which a participant first rotates the shoulders to pass through) compared to their TD peers. In Experiment 2, participants completed an action task where they walked through the same apertures. Children with DCD showed a significantly larger critical ratio than TD peers when body size alone was accounted for. Taken together these results suggest that perception within a static context is different from that within a dynamic context for children with DCD. However, despite this difference we have demonstrated a clear relationship between perception and action in children with DCD. A video abstract of this article can be viewed at: https://youtu.be/SABXFrAJtF8

Visual and Motor Sequencing in Normal and Clumsy Children

An information-processing approach was used to investigate motor performance differences between normal children and children designated as clumsy. The focus of this study was on the planning stages of motor skill. Following a motor skills screening test, 38 children 6 to 9 years old were divided into a control group, consisting of children who had passed the screening and an experimental group consisting of children who had failed the screening. The children then performed three tasks involving visual and motor sequencing selected for this study: (a) visual sequencing and short-term recall of visual stimuli, (b) visual sequencing and long-term recall of skilled motor acts, and (c) visual sequencing and short-term recall with motor reproduction. Results of the study indicated that children who had failed the motor skills screening did significantly worse than the control group on the three tasks. Implications for occupational therapy are discussed in terms of the importance of perception in motor skill performance.

Aspects of Motor Performance and Preacademic Learning

This study examined preschool children's performance on a pursuit tracking task in relation to specific performance on motor and cognitive measures of preacademic skill development. Fifty children, ages 4.3 to 5.8 years were tested using the Miller Assessment for Preschoolers (MAP)and number/counting items. High and low performance groups were designated based on performance on the MAP, individual MAP spatial items as well as number/counting items. Groups were compared based on their performance on a pursuit tracking task. Results indicated that the low performance number/counting concept group demonstrated a significantly slower average response time, overshoot movement time and reaction time. These findings offer support for an underlying perceptual-motor difficulty in children exhibiting low scores on preacademic tasks of mathematical concepts. The low MAP and spatial groups demonstrated a significantly higher rate of overshoots, suggesting difficulty in processing visual spatial information.

Developmental coordination disorders: state of art

In the literature, descriptions of children with motor coordination difficulties and clumsy movements have been discussed since the early 1900s. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), it is a marked impairment in the development of fine or global motor coordination, affecting 6% of school-age children. All these children are characterized for developmental coordination disorder (DCD) in motor learning and new motor skill acquisition, in contrast to adult apraxia which is a disorder in the execution of already learned movements. No consensus has been established about etiology of DCD. Intragroup approach through factor and cluster analysis highlights that motor impairment in DCD children varies both in severity and nature. Indeed, most studies have used screening measures of performance on some developmental milestones derived from global motor tests. A few studies have investigated different functions together with standardized assessments, such as neuromuscular tone and soft signs, qualitative and quantitative measures related to gross and fine motor coordination and the specific difficulties -academic, language, gnosic, visual motor/visual-perceptual, and attentional/executive- n order to allow a better identification of DCD subtypes with diagnostic criteria and to provide an understanding of the mechanisms and of the cerebral involvement.

Are Motor-free Visual Perception Skill Constructs Predictive of Visual-motor Integration Skill Constructs?

Background

Theoretical perspectives vary in considering whether visual perceptual skills and visual-motor integration (VMI) skills are related, interdependent skill sets, or two discrete skill constructs.

Objective

This study investigated whether motor-reduced/free visual perceptual skill constructs were predictive of motor-enhanced VMI skill constructs.

Method

A total of 45 typically developing children aged 6–12 years completed the Developmental Test of Visual Perception-Second Edition (DTVP-2) and the Test of Visual Perceptual Skills-Third Edition (TVPS-3). Four multiple linear regression analyses were completed with the four DTVP-2 motor-enhanced VMI subscales being the dependent (criterion) variables and the seven TVPS-3 motor-reduced subscales being the independent variables.

Results

The total variance accounted for in the four DTVP-2 VMI skill constructs by all the seven TVPS-3 skill constructs ranged from 29.3% to 60.10%. In the first regression analysis, the TVPS-3 Visual Sequential Memory and TVPS-3 Visual FigureGround constructs explained 5.40% and 4.90%, respectively, of the variance in the DTVP-2 Eye Hand Coordination construct. In the second regression, the TVPS-3 Visual Sequential Memory and TVPS-3 Visual Figure–Ground constructs accounted for 5.60% and 3.10%, respectively, of the DTVP-2 Copying construct's variance. The third analysis revealed that the TVPS-3 Visual Memory and TVPS-3 Visual Form Constancy constructs represented 6.20% and 7.90%, respectively, of the DTVP-2 Spatial Relations construct's variance. In the fourth and final regression analysis, the TVPS-3 Visual Sequential Memory and TVPS-3 Visual Figure–Ground construct explained 14.60% and 4.90%, respectively, of the variance in the DTVP-2 Visual-Motor Speed construct.

Conclusion

In the four regression analyses, specific types of motor-reduced visual perception constructs were predictive of the four specific types of motor-enhanced VMI constructs. Visual Sequential Memory and Visual FigureGround, specific types of motor-reduced visual perceptual constructs, were frequent and significant predictors of VMI skill constructs in children. It would appear that motor-reduced visual perceptual skills and motor-enhanced VMI skills as theoretical constructs are related and dependent on one another.

Subtypes of developmental coordination disorder: research on their nature and etiology

Children with Developmental Coordination Disorder (DCD) are a group embracing clumsiness and developmental dyspraxia. Our study provides a better understanding of the nature of DCD and its etiology, and identifies subtypes of dyspraxia. Forty-three children with DCD (5-15 years) were enrolled on the Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV-TR]; American Psychiatric Association, 2000) criteria. Extensive standardized evaluations were conducted. We distinguished from two patterns of "pure" developmental dyspraxia: ideomotor and visual-spatial/visual-constructional, and mix dyspraxia with more co-morbidities. Our study provides a better understanding of the nature of DCD, and sheds light on its etiology and brain dysfunction, so as to identify subtypes of developmental DCD/dyspraxia with specific clinical criteria.

Relationship of Visual Perceptual Deficit and Motor Impairment in Children with Developmental Coordination Disorder

The study explored the relations of visual perceptual deficits and motor impairments in 60 children with Developmental Coordination Disorder (120.8 ± 4.0 mo.) and 60 controls (121.0 ± 5.3 mo.), who were matched by sex (29 boys and 31 girls) and age. They were separately assessed on fine and gross motor-dexterity tasks of the Movement Assessment Battery for Children, static balance and reaction time of lower extremities with eyes open or closed, and the Test of Visual-Perceptual Skills–Revised. Analysis showed the children with Developmental Coordination Disorder performed significantly worse than the control group, but only the visual perception and motor skills with timed responses were significantly correlated. When visual information was controlled, no significant correlation was noted, so motor-free visual perception appears to be significantly related to motor performance having a speed component in these children.

Impaired re-weighting of sensory feedback for maintenance of postural control in children with developmental coordination disorder

To further the understanding of postural control impairments seen in children with developmental coordination disorder (DCD) and the effect of these impairments on motor performance in these children, 30 children with and without DCD (mean age=9 years, 7 months +/- 1 year, 10 months) were administered the Movement Assessment Battery for Children (M-ABC), Wechsler Abbreviated Scale of Intelligence and the Sensory Organization Test. Analyses of covariance revealed that children with DCD had greater difficulty maintaining postural control when visual and somatosensory feedback were compromised in sensory conflict environments (p=.031). Group differences in postural control were independent of age. Additionally, no correlation was seen between motor performance on the M-ABC and postural control measures for the Sensory Organization Test. Our results demonstrate that impaired ability to utilize vestibular feedback while re-weighting somatosensory and visual feedback for orientation may be responsible, in part, for the postural control impairments observed in some children with DCD.

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).

Children with low motor ability have lower visual-motor integration ability but unaffected perceptual skills

The purpose of this study was to examine perceptual, visual-motor abilities and intellectual skills in children with low, average and above average motor abilities. The participants were 144 children (aged 6-10 years) attending elementary school. Three groups of children were identified on the basis of their performance at the TGMD (Test of Gross Motor Development; [Ulrich, D.A. (1985). TGMD, Test of Gross Motor Development. Austin, Texas: PRO-ED. Edizione Italiana a cura di D. Ianes, TEST TGM. Test di valutazione delle abilita grosso-motorie. 1994, Trento: Edizioni Centro Studi Erickson]). Each child received an intelligence test (K-BIT; [Kaufman, A.S., & Kaufman, N.L. (1990). K-BIT. Kaufman Brief Intelligence Test. Circle Pines, MN: American Guidance Service]) and was evaluated for perceptual and visual-motor integration abilities (DTVP; [Hammill, D.D., Pearson, N.A., & Voress, J.K. (1993). Developmental Test of Visual Perception (2nd ed.). Austin, Texas: PRO-ED. Edizione Italiana a cura di D. Ianes, TEST TPV. Test di percezione visiva e integrazione visuo-motoria. Trento: Edizioni Centro Studi Erickson]). Results highlight a significant difference in visual-motor integration between children with high and low gross-motor abilities, in the absence of significant differences in perceptual skills or intellectual ability. The findings are discussed with reference to the concept of atypical brain development [Gilger, J.W., & Kaplan, B.J. (2001). Atypical brain development: A conceptual framework for understanding developmental learning disabilities. Developmental Neuropsychology, 20, 465].

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.

Goal-directed upper limb movements by children with and without DCD: a window into perceptuo-motor dysfunction?

BACKGROUND AND PURPOSE

Developmental co-ordination disorder (DCD) occurs in at least 6% of school-aged children. Researchers agree that motor co-ordination problems evident in DCD are, in part, the result of perceptual and cognitive processes, but the limited research available remains inconclusive. The present study investigated perceptual-motor abilities, with regard to vision, kinaesthesia and cross-modal judgement, in children with and without DCD.

METHOD

A cross-sectional study design was used. Nine children, aged six years (+/- six months) with DCD, and nine children without DCD, matched for age and gender, participated in the study. The children were required to point with the preferred hand to a target in three different positions under four sensory conditions, either with or without vision. Three-dimensional motion analysis was used to investigate trajectory lengths, endpoint error and movement time. The results were analysed using a generalized linear mixed model to examine the systematic effects of group, target position and task.

RESULTS

Compared with children without DCD, the children with DCD produced larger endpoint errors, greater movement times and longer trajectories. Children in both groups produced larger endpoint errors, greater movement times and longer trajectories in non-visually guided aiming versus visually guided aiming tasks.

CONCLUSIONS

Children with DCD moved more slowly, with longer movement trajectories and were less accurate than children without DCD when aiming to all target positions under all sensory conditions. The greatest error and trajectory length occurred for both groups when aiming movements were performed in the absence of vision. As children in the DCD group had difficulties with movement executed under kinaesthetic or visual control, the results indicate that the normal advantage of vision displayed by children without DCD is not apparent, and visual and kinaesthetic problems may be present in children with DCD.

Developmental coordination impairments in adulthood

The aim of this study was to extend the understanding of Developmental Coordination Disorder (DCD) into adulthood. We recruited 19 adults aged between 18 and 65 who had received diagnoses of DCD or dyspraxia or who self-reported as having motor impairments consistent with a history of DCD, together with age- and gender-matched controls. Participants were given tests of manual dexterity, handwriting, construction, obstacle avoidance, dynamic balance, static balance, dual task performance, ball skills, reaction time, movement time and sequencing. As a group, adults with DCD performed more poorly than controls across all tasks. Slowness and variability of movement was a pervasive feature of their performance and many individuals had considerable problems with sequencing and with dual task performance. A discriminant function analysis conducted using six performance measures correctly classified participants as car drivers or non-drivers. Adults do retain motor difficulties and these can exclude them from important activities of daily living.

Developmental coordination disorder: a review of research on subtypes and comorbidities

The interest in Developmental Coordination Disorder (DCD) has grown considerably over the last decade. Nevertheless, its etiology and prognosis are still poorly understood. The idea is growing that DCD may not be a uniform disorder. This review summarizes research on DCD, with a particular focus on subtype and comorbidity studies. The main message of the paper is that, in order to understand the etiology and prognosis of DCD, we need to have a better understanding of its nature. This requires an awareness of the existence of subtypes and comorbidities. Current theories on comorbidity phenomena are discussed in terms of their possible merit for the development of the field. Particular attention is given to the Automatization Deficit Hypothesis, a theory based on research on dyslexia.

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.

Form and motion coherence processing in dyspraxia: evidence of a global spatial processing deficit

Form and motion coherence was tested in children with dyspraxia and matched controls to assess their global spatial and global motion processing abilities. Thresholds for detecting form coherence patterns were significantly higher in the dyspraxic group than in the control group. No corresponding difference was found on the motion coherence task. We tested eight children with dyspraxic disorder (mean age 8.2 years) and 50 verbal-mental-age matched controls (mean age 8.4 years) to test for a neural basis to the perceptual abnormalities observed in dyspraxia. The results provide evidence that children with dyspraxia have a specific impairment in the global processing of spatial information. This finding contrasts with other developmental disorders such as Williams syndrome, autism and dyslexia where deficits have been found in global motion processing and not global form processing. We conclude that children with dyspraxia may have a specific occipitotemporal deficit and we argue that testing form and motion coherence thresholds might be a useful diagnostic tool for the often coexistent disorders of dyspraxia and dyslexia.

Perceptual skills of children with developmental coordination disorder

The aim of this study was to investigate whether children with a Developmental Coordination Disorder (DCD) experience problems in the processing of visual, proprioceptive or tactile information. Different aspects of visual perception were tested with the Developmental Test of Visual Perception (DTVP-2), tactile perception was assessed with the Tactual Performance Test (TPT), and a manual pointing task was employed to measure the ability to use visual and proprioceptive information in goal-directed movements. Nineteen children with DCD and nineteen age and sex-matched controls participated in this study. Differences between groups were most pronounced in the subtests measuring visual-motor integration of the DTVP-2, and in two subtests measuring visual perception (visual closure and position in space). On average the children with DCD performed slightly below the norm for tactile perception, with only three children failing the norm. On the manual pointing task, children with DCD made inconsistent responses towards the targets in all three conditions (visual, visual-proprioceptive and proprioceptive condition). No significant differences between groups were found for absolute error. Inspection of the individual data revealed that only two children failed on the majority of perceptual tasks in the three modalities. Across tasks, no consistent pattern of deficits appeared, illustrating the heterogeneity of the problems of children with DCD.

Clinical and research diagnostic criteria for developmental coordination disorder: a review and discussion

The aim of this review was to investigate the selection criteria used in the past in studies of children with developmental motor problems (excluding those suffering from neurological dysfunctions such as cerebral palsy, muscular dystrophy, etc.). We therefore conducted an extensive analysis of 176 publications. First, an overview of the main characteristics of these studies (terminology, population, type and purpose) and the selection criteria that are reported in these publications are presented. Following this, the DSM-IV selection criteria for developmental coordination disorder (DCD) are contrasted with the selection criteria reported in 41 publications that have used this terminology to classify the children. The results of this comparison show that the inclusion criteria are largely followed, albeit with little consistency concerning selection instruments and quantitative cut-offs, while adherence to the exclusion criteria is not common practice. Strengths and weaknesses of the DSM-IV criteria, complementary to the previous discussion by Henderson and Barnett in the HMS special issue on DCD in 1998 on this same topic, are discussed. The results of the review also show that many studies have used additional selection criteria related to the specific research questions of the study concerned. In the broader context of clinical practice as well as basic research, the latter result suggests the usefulness of a distinction between Clinical Diagnostic Criteria and Research Diagnostic Criteria. This distinction helps to develop a unifying view on the use of diagnostic criteria for research and clinical practice. We conclude with a number of recommendations concerning the selection criteria for children with DCD.

Intervention approaches and children with developmental coordination disorder

Children with Developmental Coordination Disorder (DCD) have a marked impairment in the performance of functional motor skills required to succeed at school. Longitudinal studies show that without intervention children with DCD often do not improve with development and the poor motor behaviour appears to have a detrimental effect on other aspects of functioning such as school achievement, behaviour and self esteem. Outside of clinical situations, there are only a small number of controlled empirical investigations, and from this small number two types of approaches emerge. The first concentrates on processes underlying motor skills and purports to improve areas such as kinesthesis or sensory motor processes. The second concentrates on teaching functional tasks aiming to specifically intervene in the deficient areas. Evaluations of these approaches show that they both work, producing significant improvements over control groups but show no differences between other approaches. It is hypothesized that more general learning principles are producing the effect, such as accurate assessment and tailoring activities to meet the needs of any individual child. Further, it is suggested that work with non-specialists in the motor area, such as teachers and parents, is a way forward with all but the most severely affected children.

Fractioned reflex and reaction time in children with developmental coordination disorder

The patellar tendon reflex (PTR) and simple visual reaction time (RT) were fractionated and compared in 40 subjects with developmental coordination disorder (DCD) and normal coordination (NC) in two age groups. Four equal groups of subjects, 6 years DCD (6DCD), 6 years NC (6NC), 9 years DCD (9DCD), and 9 years NC (9NC) were compared using ANOVA for the main effects of coordination and age. PTR and its components of reflex latency and motor time were not significantly affected by the level of coordination; however, a significant coordination by age interaction (p < .05) revealed an increased motor time in the 6DCD group. RT, premotor time, and motor time were all significantly (p < .05) increased in children with DCD; the increased RT and premotor time support earlier findings, whereas the increased motor time has not previously been found. These findings suggest that the processing of reflexive and volitional responses by children with DCD differs from that of their NC peers.

Relation of visual perception and visual-motor integration for clumsy children

The purpose of this study was to examine the relationship between visual perception and visual-motor integration in 30 normal children compared to 30 clumsy children. Difficulty in visual perception, as assessed by the Test of Visual-Perceptual Skills, accounts for about half the variance in the clumsy children's performance in visual-motor integration, as assessed by the Developmental Test of Visual Motor Integration. In contrast, the correlation between scores on these tests for normal control children was low and not significant. These results suggest that visual perception and visual-motor integration may be separate functions in normally developing children. When considering clumsy children, however, these functions cannot be considered as two independent skills.

Inter- and intrasensory modality matching in children with hand-eye coordination problems: exploring the developmental lag hypothesis

This study set out to explore the suggestion that the problems experienced by 8-year-old children diagnosed as clumsy in the area of hand-eye coordination (HECP) might be attributed to a developmental lag. The performances of this group of HECP children were compared with those of groups of 5-year-old and 8-year-old controls without such deficits, when required to carry out a task involving pointing, without vision, to targets located, visually, visually/proprioceptively, or proprioceptively, the dependent variable being the distance error score from the centre of the target. The performances of the HECP children, when vision or vision/proprioception was used to locate the targets, were shown to be inferior to those of the two control groups of children thereby supporting a visual deficit hypothesis. When the targets had to be located proprioceptively, the performance of the HECP children was shown to be similar to that of the 5-year-olds, while both groups were inferior to the 8-year-olds, thereby supporting a developmental lag hypothesis in proprioceptive terms. However, when the scores for the preferred and non-preferred hands were analysed separately a marked deterioration in the performances of both the 5-year-old controls and the HECP children was observed while the 8-year-old controls were unaffected. While this finding supports a developmental lag explanation of the inferior performances of the HECP children, it was necessary to qualify such an explanation when the within-group performances using the preferred and non-preferred hands were compared. Only the HECP children, under the visual/proprioceptive or proprioceptive conditions, showed significant performance differences, in favour of the preferred hand. This finding was taken as a suggestion that the developmental lag exhibited by the HECP children might have pathological overtones possibly related to the development of the corpus callosum.

Covert orienting of visuospatial attention in children with developmental coordination disorder

It is still unclear whether impairments in visuospatial processing in children with developmental coordination disorder (DCD) are a consequence of their motor deficits or are independent of them. In two experiments, 20 children with DCD and 20 matched controls were tested on the covert orienting of a visuospatial attention task (COVAT). Experiment 1 used a COVAT with peripheral cues and an 80% probability that targets would appear at the cued location. While the results suggested a deficit in the disengage operation of orienting covert attention for the DCD group, they were difficult to reconcile with models of covert orienting and the results of past research. Experiment 2 tested subjects on two new versions of the COVAT: the first used peripheral cues and no probability information (exogenous mode), and the second used central cues and an 80% probability that targets would appear at the cued location (endogenous mode). The DCD group displayed attentional orienting deficits only for the endogenous mode. These results suggest that impairments in the endogenous control of visuospatial attention are independent of motor deficits in DCD.

Visual-perceptual and phonological factors in the acquisition of literacy among children with congenital developmental coordination disorder

Much research has shown that children with congenital developmental coordination disorder (CDCD) have marked impairments in the perception of visual-spatial information, a deficit which has been assumed to be causally related to difficulties that many CDCD children experience when learning to read and spell. However, current research in reading disability suggests that poor reading is mainly related to difficulties with the processing of phonological information or with metaphonological ability, not to visual-perceptual deficits. This study aimed to explore the relationship between reading achievement and the visual-perceptual, phonological and general cognitive ability of CDCD children. Twenty-eight children with a mean age of 8.3 years were tested on motor coordination, language, general ability, visual discrimination, visual-motor integration, phoneme awareness, phoneme discrimination, reading and spelling. Results showed that phoneme awareness was the most strongly related to reading and spelling performance, and that visual discrimination showed no relationship to reading ability, although it was related to spelling performance, phonological awareness, and motor coordination. These results suggest that CDCD children who have difficulty with the acquisition of literacy may suffer from visual-perceptual problems and metaphonological deficits, but these problems are differentially related to reading and spelling.

Visuospatial difficulties and clumsiness: on the interpretation of conjoined deficits

Sixteen children with motor difficulties and 16 controls, matched on age, gender and verbal I.Q., were assessed on the Test Of Motor Impairment, various graphic tasks and a measure of visuospatial discrimination. Poor perceptual and motor performance tended to co-occur but contrary to the visuospatial deficit account of clumsiness these abilities were uncorrelated even when attention was restricted to the less proficient children. There was no tendency for the control group's superiority in graphic reproduction to diminish when visual feedback was withheld. Some suggestions are offered concerning more appropriate methods for framing and testing causal deficit hypotheses.

Cross-modal transfer of sequential visual and haptic shape information by clumsy children

The ability of clumsy children aged 9 to 13 years to transfer sequential shape information between the haptic and visual modalities was examined in a matching-to-sample task. In both modalities, spatiotemporal integration of information relevant for shape was involved and transfer was examined between them by using intramodal transfer scores as covariates. The responses of clumsy children were not different from those of nonclumsy children of similar age, sex, and intelligence in the cross-modal condition involving matching of a haptic standard to a visual shape. However, when matching a visual standard to a haptic shape they were consistently both faster and less accurate. It was concluded that a specific visual-to-haptic translation process possibly involving poor visual memory for shape distinguishes clumsy children from their nonclumsy peers.

Impaired motor skill (clumsiness) in otherwise normal children: a review

Some children, who are otherwise normal, experience unusual difficulties with the acquisition and performance of motor skills. These children are commonly described as being clumsy. Impaired performance of motor skills, to the degree experienced by clumsy children, is unlikely to present a serious problem. However, a review of the literature suggests that significant associated and secondary emotional problems are common. In particular, such problems are likely to result in children not achieving their full potential. Therefore, it is important that the cause of affected children's impaired motor skills be recognized early so that these problems can be avoided, or at least minimized, by a sympathetic understanding of their difficulties. The problem is that, whilst severely affected children can be readily recognized, identification of mildly and moderately clumsy children is difficult.

Timing and Motor Control in Clumsy Children

The study examined timing control in clumsy children and employed the Wing-Kristofferson (1973) model of repetitive movements in an attempt to identify the locus of timing control difficulties in clumsy children. Two groups of children classified as normal and clumsy (ages 6-7 and 9-10) performed tapping and perception of duration and loudness tasks. Results indicated that clumsy children were significantly more variable than normal children in maintaining a set rate of tapping and in accurately judging time intervals. Evidence indicated that the source of timing control problems in clumsy children may be in a central timekeeping mechanism, possibly the cerebellum.

Patterns of rotary pursuit performance in clumsy and normal children

The present study is concerned with the development of motor programs in clumsy children. In order to investigate this, the performance of clumsy and normal children on a rotary pursuit tracking task was compared. The performance of the clumsy group was inferior to that of the control group in terms of time on target, but the pattern of performance across successive trials was broadly similar for the two groups, suggesting a progression from control by visual feedback to control by motor programs. It was concluded that the performance of clumsy children on the rotary pursuit task may be limited more by impaired visual feedback control than by an impairment in the ability to develop motor programs.

Perceptual judgments of normal and clumsy children

The performance of normal and clumsy children was compared on a range of measures of visuo-spatial perception. It was found that the clumsy children performed more poorly than the normal children on size-constancy judgements and area, slope, spatial position and linear length discriminations. The differences could not be explained by variations in visual acuity. These results are discussed in terms of information-processing models of motor control, and their possible implications for the assessment and treatment of clumsy children are briefly outlined.

Clumsy children--a review of recent research

Clumsy children have severe problems in developing adequate skills of movement in the absence of general sensory and intellectual impairments and without showing signs of overt neurological damage. Descriptive studies indicate a variety of characteristics which are typical of these children including difficulties with feeding and dressing, poor drawing and writing skills, and lower performance than verbal IQ. Studies which explore the underlying functional impairments in these children are reviewed, with an emphasis on the methodological problems inherent in demonstrating causal influences. It is concluded that attempts to relate clumsiness to impairments of visual and kinaesthetic perception, although as yet inconclusive, are worthy of further study.

Visual, kinaesthetic and cross-modal judgments of length by clumsy children: a comparison with young normal children

In a previous study, clumsy children, when compared to normal children of the same age, were found to be impaired in their ability to match the length of successively presented straight lines within and between the modalities of vision and kinaesthesis. The present study explores this finding further by comparing the clumsy children's performance with that of a group of younger normal children whose skills of movement are comparable to those of the clumsy children. It was found that the clumsy children's performance on the perceptual measures was equivalent to that of the younger normal children.