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Skilled adult movers plan for a comfortable end position even when this requires an uncomfortable start position (end-state-comfort effect). This ability declines in late adulthood and has been linked to age-related differences in cognitive functioning. Other factors, which may also drive difference in motor planning in later adulthood have not been systematically examined. These include perceptions of comfort and levels of motor imagery ability (one's ability to mentally simulate action/predict the outcome of action). Therefore, this study investigated the constraints on movement planning across the life span, including executive functions, general motor ability, physical constraints to movement and motor imagery ability. One hundred and twenty-two participants aged 20-81 years completed an end-state-comfort task with increasing levels of complexity. Individuals' executive functions, motor control, motor imagery ability, and perceived rotation span were also examined. Age-related decline was shown in planning for sequential movements but not in simple single-step movements. Motor planning demonstrated an age-related difference that was associated with an increasing number of constraints as age increased, and in older adults chronological age influenced the effect of each constraint on motor planning. Age-related difference in motor planning may reflect effective compensatory strategies in response to differing constraints in motor imagery ability, executive functions, perceived rotation span, and general speed and accuracy of movement as we age. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Emotional state, in particular anxiety, has been shown to constrain perceptual judgement of action capabilities. However, whether anxiety also constrains actual behaviour is unknown. The current study, therefore, aimed to determine whether state anxiety constrained firstly perceptual judgements of action capabilities and secondly actual behaviour. To do this, we asked participants to make perceptual judgements and perform action behaviours in relation to crossing ground-based apertures representing puddles. State anxiety was measured in 30 participants using the State-Trait Anxiety Inventory. The critical ratio of aperture size relative to leg length at which participants' behaviour choice would switch between a step and a spring was calculated. In a perceptual judgement task, participants judged the ratio at which they would choose to switch. In a subsequent executed action task, the ratio at which they actually switched was measured. Perceptual critical ratio could be predicted via state anxiety and age, while action critical ratio was not predicted by either. Therefore, this study has demonstrated that state anxiety and age both constrain perceptual judgement of action capabilities, as shown in previous studies. However, this does not seem to result in a change in emergent behaviour. This highlights the importance of measuring emergent behaviour rather than inferring it from perceptual judgements even when they are couched in terms of action.

The Adult Dyspraxia/DCD Checklist (ADC) is the only existing self-report questionnaire to screen adults for potential Developmental Coordination Disorder (DCD). It was developed in English and Hebrew, however, its factor structure has not yet been assessed.The goals of the current study were to (1) develop and refine a German translation, (2) explore the emerging factors in a new and restructured ADC in German and apply this structure to an English ADC, and (3) explore its potential for distinguishing DCD versus ADHD.In a series of three studies, we assessed comprehensibility of the translation and revisions to the questionnaire. We further examined subscale structure in a sample of N = 148 individuals with DCD or ADHD and retested it in an English-speaking sample (N = 134).Overall, we found decent reliability and construct validity for the German ADC. Three components emerged with themes of fine motor coordination, gross motor coordination, and executive functions which had strong psychometric properties in German and English.The studies collectively highlight the German translation is effective and has strong potential to differentiate DCD and ADHD. Most notably, there are unique symptom profiles in motor and executive functioning difficulties in adults with DCD or ADHD. WHAT THIS PAPER ADDS?: The translation and preliminary validation of the German ADC in this study has the potential to screen for probable DCD in German-speaking adults for the first time. In addition, the new subscale structure can be generalized to the English version as well and allows for the potential assessment of several key symptomatic patterns in the realms of gross motor, fine motor, and executive functioning skills that differ between adults with DCD and ADHD. These differences were fairly consistent between English- and German-speaking samples, indicating potential for more widespread assessment and differentiation of DCD and ADHD.

Second-order planning, planning that takes into account imminent and subsequent task demands, has been shown to be essential during everyday movement. For example, the kinematics of a "reach to an object" action have been shown to be linked to the intended goal for the object (the prior intention). However, it is unclear whether this type of second-order planning for prior intention is preserved during aging or indeed how this differs across the adult lifespan. Kinematics of a reach action preceding four prior intentions-place in a "tight" hole, place in a "loose" hole, throw, or lift-were measured in 122 people aged 20-81 years. The kinematics of the reach movement demonstrated that all participants tailored their reach movement to the prior intention, with the deceleration period of the reach discriminating across groups. The 20s and 30s group showed a different deceleration period during the reach for tight versus loose place prior intentions; this was not seen after 39 years of age, and the 70 + group showed no discrimination across the deceleration period for the four prior intentions. When considering movement efficiency of the place actions, we found it could be predicted by age and that this relationship was mediated by discrimination across the deceleration period. This study demonstrates that a clear difference is seen in the way in which second-order planning is used across the lifespan and that this has implications for movement efficiency. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Objective To explore factors that could explain why older adults are more at risk at the roadside. Background The physical and psychological health benefits of walking have been well-established, leading to the widespread promotion of walking amongst older adults. However, walking can result in an increased risk of injury as a pedestrian at the roadside, which is a greater risk for older adults who are overrepresented in pedestrian casualty figures. Method Relevant databases were searched up to January 2020. All peer-reviewed journals that presented data on healthy older adults and some aspect of road crossing or roadside behavior were included. A total of 142 papers were assessed and 60 met the inclusion criteria. Results Identified papers could be grouped into three areas: crossing at a designated crossing place; crossing with no designated crossing place; perceptions or behaviors. Conclusion Multiple individual (attitudes, perceived behavioral control, walking time, time-to-arrival judgments, waiting endurance, cognitive ability), task (vehicle size, vehicle speed, traffic volume), and environmental (road layout, time of day, weather) constraints influence road crossing in older adulthood. Application Accessibility of designated crossing areas needs to be addressed by ensuring sufficient time to cross and nonrestrictive waiting times. Signalized crossings need to be simplified and visibility increased. Where there is no designated crossing place, a reduction in speed limit alongside the provision of pedestrian islands to provide “pause” places are needed. Educational-based programs may also help ensure safety of older adults where there is no designated crossing place.

Pedestrians are one of the most vulnerable groups at the roadside, furthermore, previous research has demonstrated perceptual-motor limitations in individuals with DCD which may put these individuals at even more at risk in the context of road crossing. However, it is unclear whether this is the lived experience of these individuals at the roadside. Furthermore, difficulties with road crossing and safety have been found in other neurodevelopmental disorders but the impact this might have on an individual with co-occurring difficulties is unknown. Therefore, we utilised a questionnaire to survey the lived experience of adults with DCD and parents of children with DCD with the specific objectives of describing behaviours exhibited by adults and children with DCD (the latter reported by parents) at the roadside and to determine the how these individuals perceive road crossing actions. For each of these we compared different co-occurrence groups. We also had one final objective which was not focussed on road crossing but more on the general perception of accidents and unrealistic optimism. Individuals with co-occurrences which have previously been linked to unsafe crossing behaviours (i.e. ADHD, ASD and LD) reported a greater regularity of dangerous looking behaviour (forgetting to look, running without looking) and visibility (crossing between cars, crossing when you can’t see), these adults and the parents of these children were seemingly aware of the risky nature of these behaviours. When asked ‘why’ crossing ability might be different, perceptual and motor difficulties alongside heightened awareness of risk and lowered awareness of risk were all cited by participants. Unrealistic optimism was not an explanation for the risky behaviour in adults with DCD and in fact, these adults demonstrated a clear understanding of the likelihood of accidents. The findings of this study suggest that road crossing is perceived to be more challenging for both children and adults with DCD and this needs to be taken into account when considering remediation for this group.

Pedestrians represent one of the most vulnerable road user groups worldwide. Children and adult pedestrians with neurodevelopmental disorders may be at greater risk due to deficits in a range of domains, such as attention, social communication, motor control and executive function. According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (American Psychological Association, 2013), neurodevelopmental disorders include individuals with a diagnosis of Autism Spectrum Disorders, Attention Deficit Hyperactivity Disorder, Specific Learning Disorder, Motor Difficulties, Communication Disorders and Intellectual Disabilities. The purpose of this systematic review and meta-analysis was to explore existing literature relating to determine the nature of the risk faced by pedestrians with neurodevelopmental disorders. Relevant databases including Web of Science, PhysInfo and CINAHL were searched up to July 2019. All peer reviewed journals that presented data focusing on neurodevelopmental disorders and some aspect of road crossing or roadside behaviour that included a control or comparison group were included. A total of 149 abstracts were assessed and 17 met the inclusion criteria. The identified papers could be grouped into four areas: (1) rate of injury; (2) assessment of risk; (3) eye gaze and understanding of road layout and (4) gap choice. No papers exploring the risk factors at the roadside for individuals with Specific Learning Disorders or Communication Disorders were identified. Overall, the review provide evidence for an elevated risk of injury for individuals with ADHD at the roadside, potentially as a consequence of poor temporal gap choice, although there was evidence that this risk could be mediated by executive dysfunction rather than ADHD symptomology. Furthermore, poor temporal gap choice was found in children with DCD but it remains unclear as to whether this risk translates to the roadside. Finally, both children and adults with ASD and children with ID were found to demonstrate differences in behaviour / understanding at the roadside. In general, co-occurrence between neurodevelopmental disorders has been largely ignored in the current literature relating to pedestrian risk and future research could consider this along with executive functioning.

Background Previous research suggests that adults with Developmental Coordination Disorder (DCD) report lower general wellbeing and higher general anxiety levels than typically developing (TD) adults. Aims To examine and explore relationships between anxiety and confidence (self-efficacy and resilience) generally and in a movement-specific context, along with self-concept among adults with DCD and TD adults. Methods 74 adults with diagnosed DCD, 26 adults with suspected DCD and 79 TD adults (18−60 years) completed an online questionnaire composed of a mixture of existent psychometric measures and novel scales. Results General and movement-specific anxiety, self-efficacy and general resilience were all poorer in adults with diagnosed and suspected DCD compared to TD adults. Higher resilience was related to higher self-efficacy and lower anxiety in adults with DCD. Individuals with suspected DCD for whom motor skills difficulties were an important aspect of their self-concept had lower movement-specific self-efficacy. Conclusions Interventions to improve the psychosocial wellbeing of adults with DCD should include a focus on lowering anxiety and building self-efficacy and resilience, with particular attention to movement-related domains. Implications This would facilitate the effective development of strategies to manage motor skills difficulties and their impact on everyday life for adults with DCD.

Adjustments to locomotion to avoid an obstacle require a change to the usual pattern of foot placement, i.e. changes to step length and/or step width. Previous studies have demonstrated a difficulty in individuals with Developmental Coordination Disorder (DCD) in controlling stability while both stepping over and while circumventing an obstacle. In a previous study, we have considered the way in which individuals with DCD prepare for the possibility of an obstacle appearing (Wilmut and Barnett in Exp Brain Res 235:1531-1340, 2017). Using a parallel data set from this same task on the same individuals, the aim of the current study was to investigate the exact nature of changes in foot placement during obstacle avoidance, as this was not clear from previous work. Children and adults aged from 7 to 34 years of age took part in the study. Forty-four met the criteria for a diagnosis of DCD and there were 44 typically developing (TD) age and gender-matched controls. Participants walked at a comfortable pace down an 11 m walkway; on 6 out of 36 trials a 'gate' closed across their pathway which required circumvention. These 6 'gate close' trials were analysed for this study. The number and magnitude of step length and step width adjustments were similar across the DCD and TD groups, however, the younger children (7-11 years) made a greater number of early adjustments compared to the older children and adults (12-34 years of age). In contrast the adults made a greater number of adjustments later in the movement compared to the children. In terms of foot placement adjustments a clear preference was seen across all participants to use adjustments which resulted in reducing step length, stepping away from the obstacle and a combination of these. Apart from subtle differences, the individuals with DCD make step placements to circumvent an obstacle in line with their peers. It is suggested that the choice of foot placement strategy in individuals with DCD, although in line with their peers, may not be optimal for their level of motor ability.

Purpose of Review Developmental coordination disorder is by very nature a disorder of movement and coordination. The constraints-based approach to motor control advocates the idea that the environment, the task and the individual can all constrain and promote movement/coordination. The purpose of this review is to describe factors which have been shown to explain the movement patterns in developmental coordination disorder (DCD) and discuss these in light of the constraints-based approach.

Obstacles often appear unexpectedly in our pathway and these require us to make adjustments to avoid collision. Previous research has demonstrated that healthy adults will make anticipatory adjustments to gait where they have been told there is the possibility of an obstacle appearing. One population that may find this type of anticipatory movement difficult is individuals with Developmental Coordination Disorder (DCD). The current study considered how individuals with and without DCD adjust to the possibility of an obstacle appearing which would require circumvention. Fortyfour individuals with DCD and 44 age-matched controls (aged from 7 to 34 years of age) walked down an 11 m walkway under three conditions. Initially they were told this was a clear pathway and nothing in the environment would change (1, no possibility of an obstacle, no obstacle). They then performed a series of trials in which a gate may (2, possibility of an obstacle, obstacle) or may not (3, possibility of an obstacle, no obstacle) partially obstruct their pathway. We found that all participants increased medio-lateral trunk acceleration when there was the possibility of an obstacle but before the obstacle appeared, in addition the typical adults and older children also increased step width. When describing circumvention we found that the younger children showed an increase in trunk velocity and acceleration in all three directions compared to older children and adults. We also found that the individuals with DCD adjusted their path sooner and deviated more than their peers. The degree of adjustment to step width in anticipation of an obstacle was related to later medio-lateral velocity and timing of the deviation. Therefore, the lack of 'readying' the system where there is the possibility of an obstacle appearing seen in the individuals with DCD and the younger typical children may explain the increased medio-lateral velocity seen during circumvention.

Children with Developmental Coordination Disorder (DCD) demonstrate inefficient motor planning ability with a tendency to opt for non-optimal planning strategies. Motor imagery can provide an insight to this planning inefficiency, as it may be a strategy for improving motor planning and thereby motor performance for those with DCD. In this study, we investigated the prevalence of end-state-comfort (ESC) and the minimal rotation strategy using a grip selection task in children with DCD with and without motor imagery instructions. Boys with (n = 14) and without DCD (n = 18) aged 7–12 years completed one, two and three colour sequences of a grip selection (octagon) task. Two conditions were examined; a Motor Planning (MP) condition requiring only the performance of the task and a Motor Imagery and Planning (MIP) condition, which included an instruction to imagine performing the movement before execution. For the MP condition, children with DCD ended fewer trials in ESC for the one (p = 0.001) and two colour (p = 0.002) sequences and used a minimal rotation strategy more often than those without DCD. For the MIP condition, the DCD group significantly increased their use of the ESC strategy for the one colour sequences (p = 0.014) while those without DCD improved for the two colour (p = 0.008) sequences. ESC level of the DCD group on the MIP condition was similar to those without DCD at baseline for all colour sequences. Motor imagery shows potential as a strategy for improving motor planning in children with DCD. Implications and limitations are discussed.

DCD is commonly described as a motor learning disorder. However, surprisingly few studies have specifically examined motor skill learning in individuals with DCD. This chapter will begin by describing studies which have considered skill acquisition in a DCD population. The findings of these studies will then be discussed in light of the theoretical framework put forward in the previous chapter by Newell and Pacheco. Furthermore, we will address issues surrounding motor control in this population including the lack of research focusing on coordination in Developmental Coordination Disorder and we will discuss the issue of variability of movement within a DCD context.

Given the importance of walking in everyday life, understanding why this is challenging for some populations is particularly important. Studies focusing on gait patterns of individuals with Developmental Coordination Disorder (DCD) have shown that whilst increased variability is characteristic of walking patterns for this group, differences in spatio-temporal gait variables seem only to arise when task demands increase. However, these differences occur under rather artificial conditions, for example using a treadmill. The aim of this study, therefore was to examine the step characteristics of individuals with and without DCD whilst walking along an irregular terrain. Thirty-five individuals with DCD aged 8–32 years and 35 age and gender-matched controls participated in this study. Participants were divided into 3 age groups; 8–12 years (n = 12), 13–17 years (n = 12) and 18–32 years (n = 11). Participants walked up and down a 6 m walkway for two minutes on two terrains: level and irregular. VICON 3D motion analysis was used to extract measures of foot placement, velocity and angle of the head and trunk. Results showed that both groups adapted their gait to negotiate the irregular terrain, but the DCD group was more affected than their TD peers; walking significantly slower with shorter, wider steps and inclining their head more towards the ground. This suggests an adaptive approach used by individuals with DCD to preserve stability and increase visual sampling whilst negotiating an irregular terrain.

Several studies suggest that children with Developmental Coordination Disorder (DCD) may be able to plan simple movements as well as their peers, but experience increasing difficulties as the movements become complex. The present study aimed to clarify the nature of motor planning in DCD, including a putative deficit, by being the first to investigate motor planning using converging measures of simple and complex motor planning in a single sample of children with DCD. Boys aged between 8 and 12 years with (n = 10) and without DCD (n = 17) completed three commonly used ‘simple’ (bar grasping, sword, and bar transport tasks) measures and one ‘complex’ (octagon task) measure of end-state-comfort (ESC), a classic measurement of motor planning ability. To achieve ESC when manipulating an object, a person may choose to start with an uncomfortable grip in order to end the movement in a comfortable position. Results indicate that the participants with DCD planned for ESC as efficiently as their peers when performing the ‘simple’ measures of ESC but were significantly less likely to end their performances in ESC than those without DCD for the more ‘complex’ octagon task. Taken together, our data suggest that school-aged children with DCD may be able to plan simple movements as efficiently as their peers, but have more difficulty doing so for multi-movement or complex sequences. Based on the assumption that the efficiency of such motor planning is dependent on the integrity of internal modelling systems, we argue that our study provides indirect support for the internal modelling deficit hypothesis.

Obstacles often appear unexpectedly in our pathway and these require us to make immediate adjustments. Despite how regularly we encounter such situations only few studies have considered how we adjust to unexpected obstacles in the pathway that require us to walk around them. The authors considered how adults adjust to the possibility of an obstacle appearing and then also how foot placement is adjusted to circumvent an obstacle. Fifteen healthy adults walked down an 11-m walkway, initially they were told this was a clear pathway and nothing in the environment would change (no gate), they then performed a series of trials in which a gate may (gate close) or may not (gate open) partially obstruct their pathway. The authors found that mediolateral trunk velocity and acceleration was significantly increased when there was the possibility of an obstacle but before the obstacle appeared. This demonstrates an adaptive walking strategy that seems to enable healthy young adults to successfully circumvent obstacles. The authors also categorized foot placement adjustments and found that adults favored making shorter and wider steps away from the obstacle. They suggest this combination of adjustments allows participants to maintain stability while successfully circumventing the obstacle.

When generating a movement adults favor grasps which start the body in an uncomfortable position if they end in a comfortable position (the end-state-comfort effect). In contrast, children with Developmental Coordination Disorder (DCD) select grasps which require little initial hand rotation even though they result in an uncomfortable end position. The current study considered grip selection of individuals with DCD when asked to make simple one step movements and when making more complex multi-staged movements. Adults with DCD (N = 17, mean age 24:09, SD age = 52 months) and children with DCD (N = 20, mean age 9:00, SD age = 20 months) and age and gender matched controls rotated a disc so an arrow pointed toward a specific target(s). Task complexity was increased by increasing the number of targets from 1 to 3. Planning for end-state-comfort was seen in all groups albeit to a lesser extent in children versus adults. The children with DCD showed fewer grips for end-state-comfort compared to their peers and this was explained by a propensity to select minimal initial rotation grasps. This result was mirrored in adults with DCD but only for the longest movement sequence. These results suggest some changes in ability from childhood to adulthood in individuals with DCD.

Motor learning results from repeated exposure to the same movement and allows a mover to increase movement optimality. Typically, this has only been considered in single-step movements. In sequential movements, an initial reach movement is tailored to the demands of the onward movement. However, the exact role of motor practice in the tailoring to onward task demands is unknown. Eighteen adults performed blocks of 15 movements; each movement consisted of a reach phase and an onward phase (the object was placed in a tight-fitting hole, placed in a loose-fitting hole or thrown). Simple practice effects were seen; for the reach phase, the amount of time spent decelerating decreased over trials, and for the onward phase, the accuracy of the place/throw movements increased over trials. Furthermore, approximately 30 % of variance in the practice effect of the onward phase could be explained by the practice effect in the reach phase. Therefore, we suggest that the changes in the reach phase are directly linked to the changes in the efficiency of action and that this is necessary but not sufficient for explaining the calibration of the onward action.

Neurocomputational models of reaching indicate that efficient purposive correction of movement midflight (e.g., online control) depends on one's ability to generate and monitor an accurate internal (neural) movement representation. In the first study to test this empirically, the authors investigated the relationship between healthy young adults' implicit motor imagery performance and their capacity to correct their reaching trajectory. As expected, after controlling for general reaching speed, hierarchical regression demonstrated that imagery ability was a significant predictor of hand correction speed; that is, faster and more accurate imagery performance associated with faster corrections to reaching following target displacement at movement onset. They argue that these findings provide preliminary support for the view that a link exists between an individual's ability to represent movement mentally and correct movement online efficiently.

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

Background Symmetry between the left and right side of the body during locomotion is key in a coordinated gait cycle and is also thought to be important in terms of efficiency. Although previous studies have identified aspects of the gait cycle which are atypical in children and adults with Developmental Coordination Disorder (DCD), studies have not considered whether this could be explained by asymmetrical gait. Method and procedure The current study included 62 participants with and 62 without DCD (aged 7–34 years). Participants were asked to walk continuously for 1 min up and down a walkway while movement was captured using an optical tracking system. Measures of step length and step time were taken for both the right and the left leg and symmetry ratios were calculated. Results The DCD group showed significantly higher symmetry ratios for both measures compared to the typically developing (TD) group, with approximately a third of DCD participants falling outside the normative range for symmetry. Furthermore, a relationship was found between movement variability and degree of asymmetry. Conclusions These findings demonstrate an asymmetry in the gait of individuals with DCD which, despite improving with age, does not reach the same level as that shown by TD individuals.

We investigated the purported association between developmental changes in grip selection planning and improvements in an individual’s capacity to represent action at an internal level (i.e., motor imagery). Participants were groups of healthy children aged 6-7 years and 8-12 years respectively, while a group of adolescents (13-17 years) and adults (18-34 years) allowed for consideration of childhood development in the broader context of motor maturation. A group of children aged 8-12 years with probable DCD (pDCD) was included as a reference group for atypical motor development. Participants’ proficiency to generate and/or engage internal action representations was inferred from performance on the hand rotation task, a well-validated measure of motor imagery. A grip selection task designed to elicit the end-state comfort (ESC) effect provided a window into the integrity of grip selection planning. Consistent with earlier accounts, the efficiency of grip selection planning followed a non-linear developmental progression in neurotypical individuals. As expected, analysis confirmed that these developmental improvements were predicted by an increased capacity to generate and/or engage internal action representations. The profile of this association remained stable throughout the (typical) developmental spectrum. These findings are consistent with computational accounts of action planning that argue that internal action representations are associated with the expression and development of grip selection planning across typical development. However, no such association was found for our sample of children with pDCD, suggesting that individuals with atypical motor skill may adopt an alternative, sub-optimal strategy to plan their grip selection compared to their same-age control peers.

Introduction There is substantial evidence to support the relationship between transcription skills (handwriting and spelling) and compositional quality. For children with developmental coordination disorder, handwriting can be particularly challenging. While recent research has aimed to investigate their handwriting difficulties in more detail, the impact of transcription on their compositional quality has not previously been examined. The aim of this exploratory study was to examine compositional quality in children with developmental coordination disorder and to ascertain whether their transcription skills influence writing quality. Method Twenty-eight children with developmental coordination disorder participated in the study, with 28 typically developing age and gender matched controls. The children completed the ‘free-writing’ task from the detailed assessment of speed of handwriting tool, which was evaluated for compositional quality using the Wechsler objective language dimensions. Results The children with developmental coordination disorder performed significantly below their typically developing peers on five of the six Wechsler objective language dimensions items. They also had a higher percentage of misspelled words. Regression analyses indicated that the number of words produced per minute and the percentage of misspelled words explained 55% of the variance for compositional quality. Conclusion The handwriting difficulties so commonly reported in children with developmental coordination disorder have wider repercussions for the quality of written composition.

The ability to safely cross a road is a perceptual-motor skill that involves coordination between a pedestrian’s perception of the approaching vehicles and their locomotive capability to execute the road crossing action. Developmental Coordination Disorder (DCD) is a chronic disorder that is characterised by significant motor difficulties that impact on daily living, including a reduced ability to perform visually guided actions. A total of 25 typically developing primary school aged children and 25 age- and gender-matched children with DCD were presented with a virtual desktop task that required them to select suitable temporal crossing gaps between vehicles a stream of traffic approaching at either 20 mph, 30 mph or 40 mph from the near-side (one-lane) or both near + far-sides (two-lane). A best-PEST staircase procedure was used to measure the temporal gaps that children accepted and the maximum likelihood value was taken after nine reversals as each participant’s threshold. Typically developing children accepted temporal gaps that were sufficient to execute a safe crossing for vehicles approaching at 20 mph and 30 mph, but insufficient for vehicles approaching at 40 mph. In contrast, children with DCD selected insufficient temporal crossing gaps across all approach speeds, which if translated to the roadside would have resulted in collision. These findings add to our understanding of the difficulties that children with DCD appear to have with visually guided behaviour and suggest the potential impact on one aspect of daily functioning that could have significant consequences.

Perception and action are tightly coupled, and previous studies have demonstrated that action experience can improve perceptual judgment. We investigated whether this improvement in perceptual judgment could be attributed to knowledge regarding movement variability being gained during action experience. Fifteen adults made perceptual judgments regarding the passability of a series of aperture sizes. These judgments were made both before and after walking through the same set of apertures (action experience). When considering the group as a whole, perceptual judgment did not change after action experience. However, when splitting the group into those with low and high preaction perceptual judgments, only those with low perceptual judgments showed an improvement in perceptual judgment following action experience, which could be explained in part by movement variability during the approach. These data demonstrate that action informs perception and that this allows adults to account for movement variability when making perceptual judgments regarding action capabilities.

Objective: Children with Developmental Coordination Disorder demonstrate a lack of automaticity in handwriting as measured by pauses during writing. Deficits in visual perception have been proposed in the literature as underlying mechanisms of handwriting difficulties in children with DCD. The aim of this study was to examine whether correlations exist between measures of visual perception and visual motor integration with measures of the handwriting product and process in children with DCD. Method: The performance of twenty-eight 8-14 year-old children who met the DSM-5 criteria for DCD was compared with 28 typically developing (TD) age and gender-matched controls. The children completed the Developmental Test of Visual Motor Integration (VMI) and the Test of Visual Perceptual Skills (TVPS). Group comparisons were made, correlations were conducted between the visual perceptual measures and handwriting measures and the sensitivity and specificity examined. Results: The DCD group performed below the TD group on the VMI and TVPS. There were no significant correlations between the VMI or TVPS and any of the handwriting measures in the DCD group. In addition, both tests demonstrated low sensitivity. Conclusion: Clinicians should execute caution in using visual perceptual measures to inform them about handwriting skill in children with DCD. This study was funded by the Doctoral Training Programme for Children and Young People at Oxford Brookes University.

Background Despite their movement difficulties, youngsters with Developmental Co-ordination Disorder (DCD) generally have sufficient capability for physical activity. However, they tend to be less physically active and less physically fit than their well co-ordinated age peers. The aim of this study was to use qualitative research methods to understand which factors constrain and facilitate participation in physical activity in teenagers with DCD, in order to help inform future health promotion programmes. Method Semi-structured interviews were conducted with eight teenagers with DCD (aged 13-15) and their parents. The interviews focused on how much physical activity was typically undertaken by the child and the perceived constraints and facilitators to being physically active. Interviews were transcribed and subjected to categorical-content analysis. Results Half of the children and all but one of the parents reported that the children did little physical activity. Although most children disliked competitive team games, they reported many physical activities that they did enjoy and they reported wanting to be more physically active. Perceived internal constraints to participation included poor motor skill, lack of motivation and reports of fatiguing easily. Perceived external constraints included difficulty travelling to activities, negative comments from peers and teachers' lack of understanding of DCD. Conclusions Reports of low levels of physical activity support previous literature and are a cause for concern for this group. The teenagers expressed the desire to be more active, yet the interviews revealed both personal and environmental constraints to engagement in physical activity. It is clear that these factors interact in a dynamic way and that teachers, schools and communities play an important role in creating a motivational environment for youngsters with DCD to engage in physical activity and learn to maintain an active lifestyle as they move into adulthood. Language: en

Almost all locomotor animals are sensitive to optical expansion (visual looming) and for most animals this sensitivity is evident very early in their development. In humans there is evidence that responses to looming stimuli begin in the first 6 weeks of life, but here we demonstrate that as children become independent their perceptual acuity needs to be 50 to 100 times better than has been demonstrated in infants in order to be skilful at collision avoidance at a roadside. We have recently established that sensitivity to the detection of visual looming in 6- to 11-year-old children is significantly below that of adults (Wann, Poulter & Purcell, 2011). Here, using comparable methods, we explore looming detection sensitivity in children with Developmental Co-ordination Disorder (DCD), who show broad patterns of impairment in visuo-motor control. We presented visual simulations of approaching vehicles, scaled to represent different approach rates, to children with DCD aged between 6 and 11 years (n = 11) and typically developing age and gender matched controls (n = 11). Looming detection thresholds were measured under foveal and perifoveal viewing conditions, for isotropic expansion and isotropic expansion with simulated viewpoint motion. Our results show that there are situations in which children with DCD may fail to detect vehicles approaching at speeds in excess of 22 km/h, suggesting a developmental immaturity in looming sensitivity. This provides one of the first clear demonstrations of low-level motion processing deficits in children with DCD. The decrement observed may give rise to potential errors in the road crossing behaviour of these children, whereby approaching vehicles could be perceived as stationary. These findings further contribute towards understanding the adverse statistic that children under 9 years of age are four times more likely than adults to be involved in a road accident as a pedestrian.

As pedestrians, the perceptual ability to accurately judge the relative rate of approaching vehicles and select a suitable crossing gap requires sensitivity to looming. It also requires that crossing judgments are synchronized with motoric capabilities. Previous research has suggested that children with Developmental Co-ordination Disorder (DCD) may have deficits in visual processing, specifically in detecting visual motion. It is possible, therefore that this population are at greater risk at the roadside. In a series of motion prediction tasks, several component roadside skills were assessed in 15 children with DCD, or at risk of DCD, aged between 6 and 11 years along with 15 typically developing age and gender matched controls. First, threshold errors for relative approach rate judgments (looming) were measured when vehicle size (car or truck) varied. Second, thresholds for crossing gap selection were measured for vehicle approach speeds of 32, 48, 64 and 80 km/h (20-50 mph). These were related to the walking speeds of children of different ages and profiles. We found that children with DCD showed a deficit in making relative approach rate judgments, using looming, which suggests they may not discern that a vehicle is travelling faster than the urban speed limit. Children with DCD also left considerably longer temporal crossing gaps than controls perhaps reflecting a lack of confidence in their ability, these preferred gaps were over twice the average inter-car gaps that occurred on roads around their school. Our findings raise a number of issues concerning children with DCD and their competence and potential limitations as pedestrians.

The protracted maturation and development of speech articulation underlies the complexity of the skill, and suggests it may be an area susceptible to a general deficit in motor control. Recent research suggests a high co-occurrence between Developmental Coordination Disorder (DCD) and disordered speech production. Despite this there has been no systematic investigation of speech motor control in children with DCD. We conducted a pilot study which looked at speech motor control in a group of children with DCD (N=5) and a group typically developing (TD) children (N=5). Movements of the upper and lower lip were recorded during non-verbal movements, single words, syllable sequences, and sentence repetition. In the baseline conditions (normal talking speed or an isolated utterance) children with DCD demonstrated a typical pattern of movement, albeit a slower and shorter movement. In contrast, when task complexity was increased the children with DCD showed an atypical pattern of movement. It was concluded that children with DCD demonstrate inferior motor control for complex speech gestures, suggesting that the motor deficit in DCD may indeed be a more generalized phenomenon affecting the speech motor system.

During everyday locomotion we encounter a range of obstacles which require specific motor responses, for example a narrow aperture forces us to rotate the shoulders to pass through. Research has demonstrated that the decision to rotate the shoulders is body scaled (Warren & Whang, 1987) and that the visuo-motor system generates a rotation proportional to aperture size (Higuchi, Cinelli, Greig, & Patla, 2006). The current study considered how shoulder angle and movement speed are tailored to aperture size in nine adults. Aperture sizes were classified into shoulder/aperture ratios (SA ratio), including two for which participants had to rotate (0.9/1.1) and two for which participants could pass freely (1.5/1.7). During the initial approach phase (first 3s), shoulder rotation and movement speed were invariant across SA ratio. Later in the movement, angle of shoulder rotation and the magnitude and timing of the reduction in speed were proportional to SA ratio. The timing of the reduction in speed was progressively later in the movement as SA ratio increased, suggesting early adjustments of movement, such as the timing of the reduction in speed are tightly tuned to the ratio between aperture size and shoulder width, even when no later body adjustments are needed.

The accuracy of reaching movements improves when active gaze can be used to fixate on targets. The advantage of free gaze has been attributed to the use of ocular proprioception or efference signals for online control. The time course of this process, however, is not established, and it is unclear how far in advance gaze can move and still be used to parameterize subsequent movements. In this experiment, the authors considered the advantage of prescanning targets for both pointing and reaching movements. The authors manipulated the visual information and examined the extent to which prescanning of targets could compensate for a reduction in online visual feedback. In comparison with a conventional reaching/pointing condition, the error in pointing was reduced, the eye-hand lead decreased, and both the hand-closure time and the size of the maximum grip aperture in reaching were modulated when prescanning was allowed. These results indicate that briefly prescanning multiple targets just prior to the movement allows the refinement of subsequent hand movements that yields an improvement in accuracy. This study therefore provides additional evidence that the coordinate information arising from efference or ocular-proprioceptive signals can, for a limited period, be buffered and later used to generate a sequence of movements.

Williams syndrome (WS) is a developmental disorder in which visuo-spatial cognition is poor relative to verbal ability. At the level of visuo-spatial perception, individuals with WS can perceive both the local and global aspects of an image. However, the manner in which local elements are integrated into a global whole is atypical, with relative strengths in integration by luminance, closure, and alignment compared to shape, orientation and proximity. The present study investigated the manner in which global images are segmented into local parts. Segmentation by seven gestalt principles was investigated: proximity, shape, luminance, orientation, closure, size (and alignment: Experiment 1 only). Participants were presented with uniform texture squares and asked to detect the presence of a discrepant patch (Experiment 1) or to identify the form of a discrepant patch as a capital E or H (Experiment 2). In Experiment 1, the pattern and level of performance of the WS group did not differ from that of typically developing controls, and was commensurate with the general level of non-verbal ability observed in WS. These results were replicated in Experiment 2, with the exception of segmentation by proximity, where individuals with WS demonstrated superior performance relative to the remaining segmentation types. Overall, the results suggest that, despite some atypical aspects of visuo-spatial perception in WS, the ability to segment a global form into parts is broadly typical in this population. In turn, this informs predictions of brain function in WS, particularly areas V1 and V4.

Previous research has shown that children with Developmental Coordination Disorder (DCD) have poorly developed strategies for allocating attention. This study examines the allocation of attention and integration of visuo-spatial and motor systems in children with DCD in a motor (look+hit condition) and a motor-free (look condition) task.Three groups of control children were used to compare the performance of a group of children with DCD. Children were seated in front of a central fixation point and six peripheral targets, and were asked to look at or hit targets when illuminated. Saccade/hand movement latencies were measured on gap trials (gap between fixation offset and target onset) and overlap trials (fixation offset and target onset overlapped).DCD children were not slower than controls to disengage attention during the look condition. However, during the look+hit condition the DCD children showed a prolonged disengagement period, which was also seen in younger control children.The results suggest that DCD children may have deficits in the allocation of attention for action, in both the speed of onset of a movement and the accuracy of the movement. It is concluded that attention disengagement may contribute to problems of visuo-motor integration in DCD.

Previous research has shown that adults with Developmental Coordination Disorder (DCD) show increased variability of foot placement measures and movement of the centre of mass (CoM) while walking. The current study considered the gait patterns of young and older children with DCD. Fourteen young children with DCD (7-12 years), 15 older children with DCD (12-17 years) and 29 age and gender matched typically developing children took part. Children were asked to walk up and down a flat 10m long pathway for one minute while the movement of their feet and trunk was recorded using motion analysis. The gait pattern of children with DCD was characterised by wider steps, elevated variability in the time spent in double support and stride time and greater medio-lateral velocity and acceleration compared to their peers. An elevated variability in medio-lateral acceleration was also seen in the young but not the older children with DCD. In addition, the young children showed a greater variability in velocity and acceleration in all three directions compared to the older children. The data suggest that the high incidence of trips and falls seen in children with DCD may be due to differences in the control of the centre of mass.

Several studies have shown that Developmental Coordination Disorder (DCD) is a condition that continues beyond childhood. Although adults with DCD report difficulties with dynamic balance, as well as frequent tripping and bumping into objects, there have been no specific studies on walking in this population. Some previous work has focused on walking in children with DCD but variation in the tasks and measures used has led to inconsistent findings. The aim of the current study therefore was to examine the characteristics of level walking in adults with and without DCD. Fifteen adults with DCD and 15 typically developing (TD) controls walked barefoot at a natural pace up and down an 11m walkway for one minute. Foot placement measures and velocity and acceleration of the body were recorded, as well as measures of movement variability. The adults with DCD showed similar gait patterns to the TD group in terms of step length, step width, double support time and stride time. The DCD group also showed similar velocity and acceleration to the TD group in the medio-lateral, anterior-posterior and vertical direction. However, the DCD group exhibited greater variability in all foot placement and some body movement measures. The finding that adults with DCD have a reduced ability to produce consistent movement patterns is discussed in relation to postural control limitations and compared to variability of walking measures found in elderly populations. Language: en

Background: Shifting gaze and attention ahead of the hand is a natural component in the performance of skilled manual actions. Very few studies have examined the precise co-ordination between the eye and hand in children with Developmental Coordination Disorder (DCD). Methods This study directly assessed the maturity of eye-hand co-ordination in children with DCD. A double-step pointing task was used to investigate the coupling of the eye and hand in 7-year-old children with and without DCD. Sequential targets were presented on a computer screen, and eye and hand movements were recorded simultaneously. Results There were no differences between typically developing (TD) and DCD groups when completing fast single-target tasks. There were very few differences in the completion of the first movement in the double-step tasks, but differences did occur during the second sequential movement. One factor appeared to be the propensity for the DCD children to delay their hand movement until some period after the eye had landed on the target. This resulted in a marked increase in eye-hand lead during the second movement, disrupting the close coupling and leading to a slower and less accurate hand movement among children with DCD. Conclusions In contrast to skilled adults, both groups of children preferred to foveate the target prior to initiating a hand movement if time allowed. The TD children, however, were more able to reduce this foveation period and shift towards a feedforward mode of control for hand movements. The children with DCD persevered with a look-then-move strategy, which led to an increase in error. For the group of DCD children in this study, there was no evidence of a problem in speed or accuracy of simple movements, but there was a difficulty in concatenating the sequential shifts of gaze and hand required for the completion of everyday tasks or typical assessment items.

This article has been made available through the Brunel Open Access Publishing Fund. Difficulties with handwriting are reported as one of the main reasons for the referral of children with Developmental Coordination Disorder (DCD) to healthcare professionals. In a recent study we found that children with DCD produced less text than their typically developing (TD) peers and paused for 60% of a free-writing task. However, little is known about the nature of the pausing; whether they are long pauses possibly due to higher level processes of text generation or fatigue, or shorter pauses related to the movements between letters. This gap in the knowledge-base creates barriers to understanding the handwriting difficulties in children with DCD. The aim of this study was to characterise the pauses observed in the handwriting of English children with and without DCD. Twenty-eight 8-14 year-old children with a diagnosis of DCD participated in the study, with 28 TD age and gender matched controls. Participants completed the 10 min free-writing task from the Detailed Assessment of Speed of Handwriting (DASH) on a digitising writing tablet. The total overall percentage of pausing during the task was categorised into four pause time-frames, each derived from the literature on writing (250 ms to 2 s; 2-4 s; 4-10 s and >10 s). In addition, the location of the pauses was coded (within word/between word) to examine where the breakdown in the writing process occurred. The results indicated that the main group difference was driven by more pauses above 10 s in the DCD group. In addition, the DCD group paused more within words compared to TD peers, indicating a lack of automaticity in their handwriting. These findings may support the provision of additional time for children with DCD in written examinations. More importantly, they emphasise the need for intervention in children with DCD to promote the acquisition of efficient handwriting skill.