Professor Kate Wilmut

Pedestrians are a vulnerable group at the roadside and previous research has identified that children with DCD and ADHD are at a heightened risk of pedestrian injuries. Despite this, limited research has explored parental perspectives of the pedestrian risks faced by children with DCD and/or ADHD. Understanding parents’ perspectives provides a unique insight into the challenges children face every day and the concerns that parents perceive regarding their children’s safety as pedestrians. Therefore, the aim of this study was to explore parents’ perspectives of the pedestrian risks faced by their children with DCD and/or ADHD.

Semi-structured interviews were conducted with 14 parents of primary school and early secondary school aged children with age range 7- 17 (3 DCD, 5 ADHD and 6 both). All parents confirmed an existing diagnosis and completed the SNAP-IV and DCDQ as screening tools. The interviews explored parents’ perspectives regarding their children’s pedestrian behaviours, parents’ concerns and preventative measures taken to improve the pedestrian safety of their children with DCD and/or ADHD. Reflexive thematic analysis was undertaken to analyse the interviews, from which three themes were developed.

The first theme related to the challenges experienced by children at the roadside; parents emphasised the significance of structured and controlled pedestrian crossing sites, underlining their preference for designated crossings as safer options due to their heightened perceptions of risk associated with other road-crossing locations. The second theme: parental concerns and influences on children’s road safety referred to their children’s performance and safety at the roadside, leading to increased monitoring and a more protective approach to road crossing. The third theme: road safety education related to various strategies parents implemented to mitigate risks, whilst balancing independence and prioritising their safety. While there were commonalities in the challenges faced by children with DCD and/or ADHD at the roadside, there were also notable differences. Parents of children with DCD discussed challenges with spatial awareness and motor skills, whereas parents of children with ADHD discussed challenges with impulsivity and inattention. Parents of children with co-occurring DCD and ADHD described a complex interplay of these challenges.

It is evident from the interviews that children with DCD and/or ADHD require a distinct approach to develop their pedestrian skills effectively and parents reported specific strategies they used to address the risks associated with their children’s roadside behaviour. Promoting pedestrian safety for children with DCD and/or ADHD necessitates collaboration among parents, schools and local authorities to implement comprehensive measures ensuring their safety. These findings contribute to understanding parental experiences and needs, providing valuable guidance for targeted interventions and policies to enhance the road safety of children with DCD and/or ADHD.

When we complete sequential movements with different intentions, we plan our movements and
adjust ahead. Such a phenomenon is called anticipatory planning for prior intentions and is known to
decline with age. In daily life activities, we often need to consider and plan for multiple demands in
one movement sequence. However, previous studies only considered one dimension of prior
intentions, either different types of onward actions or different precisions of fit or placement.
Therefore, in this study, we investigated anticipatory planning for both extrinsic (movement
direction) and intrinsic (fit precision) target-related properties in a computer-based movement task
and analysed the computer cursor movement kinematics of both young and older adults. We found
that older people consider and adjust for different properties step-by-step, with movement direction
being considered as a prior intention during reach movement and fit precision as a motor constraint
during drop movement. The age-related changes in the completion of onward actions are constrained
by one’s general cognitive ability, sensorimotor performance and effective motor planning for prior
intentions.

Developmental coordination disorder (DCD) and attention-deficit/hyperactivity disorder (ADHD) overlap in symptoms and often co-occur. Differentiation of DCD and ADHD is crucial for a better understanding of the conditions and targeted support. Measuring electrical brain activity with EEG may help to discern and better understand the conditions given that it can objectively capture changes and potential differences in brain activity related to externally measurable symptoms beneficial for targeted interventions. Therefore, a pilot study was conducted to exploratorily examine neurophysiological differences between adults with DCD and/or ADHD at rest. A total of N = 46 adults with DCD (n = 12), ADHD (n = 9), both DCD+ADHD (n = 8), or typical development (n = 17) completed two minutes of rest with eyes-closed and eyes-open while their EEG was recorded. Spectral power was calculated for frequency bands: delta (0.5-3 Hz), theta (3.5-7 Hz), alpha (7.5-12.5 Hz), beta (13-25 Hz), mu (8-13 Hz), gamma (low: 30-40 Hz; high: 40-50 Hz). Within-participants, spectral power in a majority of waveforms significantly increased from eyes-open to eyes-closed conditions. Groups differed significantly in occipital beta power during the eyes-open condition, driven by the DCD versus typically developing group comparison. However, other group comparisons reached only marginal significance, including whole brain alpha and mu power with eyes-open, and frontal beta and occipital high gamma power during eyes-closed. While no strong markers could be determined to differentiate DCD versus ADHD, we theorize that several patterns in beta activity were indicative of potential motor maintenance differences in DCD at rest. Therefore, larger studies comparing EEG spectral power may be useful to identify neurological mechanisms of DCD and continued differentiation of DCD and ADHD.

This systematic review synthesizes the literature on physical activity amongst people with DCD using the COM-B framework. The review questions were: (1) what is the Capability (C), Opportunity (O) and Motivation (M) for physical activity and (2) what does physical activity behavior (B) look like? A mixed-methods systematic review was conducted by searching eight databases (PubMed, APA PsycINFO, EMBASE, Scopus, Child Development and Adolescent Studies, Cochrane Library, Web of Science, CINAHL) up to July 2023. Data were extracted, thematically analyzed, and mapped to the COM-B model. The quality of studies was assessed with the Joanna Briggs Institute (JBI) critical appraisal tool. The protocol was registered with PROSPERO (CRD42022319127). Forty-three papers, 42 of which related to children, were included. Fifteen aligned with physical activity behavior, nine with physical capability, thirteen with psychological capability, one with social opportunity, one with physical opportunity, one with reflective motivation and three with automatic motivation. Pre-school-aged children with DCD engage in comparable levels of physical activity behavior, but differences emerge from 6 years of age. Characteristics of DCD result in reduced physical capability and less varied participation in physical activity. This impacts psychological capability, whereby lower self-perceptions result in a negative feedback loop and reduce the
motivation to participate. Barriers relating to social opportunities may result in poor reflective and
automatic motivation, although there is evidence that interventions can enhance enjoyment in the
short term.

Background: Young people with Special Educational Needs and Disabilities (SEND) are especially vulnerable to physical inactivity. Research has demonstrated the effectiveness of tailored cycle training for children with SEND, however, it is unclear whether this then results in a greater uptake of cycling.

Aims: To determine parent based perceptions of a SEND cycle training programme, factors which predict intention to cycle more and ongoing barriers to cycling.

Methods: A tailored questionnaire was distributed to parents of children who took part in the cycle training.

Results: Parents reported increased confidence in their child's ability to cycle independently with many also highlighting improvements in confidence and resilience. The outcome of the cycle training (level of enjoyment and change in cycling ability) had a positive influence on intention to cycle more while cycling frequency prior to training had a negative influence. Continuing barriers to cycling were identified which included difficulties accessing specialised equipment and a need for additional on-road cycle training.

Conclusions and implications: This study demonstrates the success of a specialised cycle training programme for children with SEND in terms of improvement to cycling and influences on the intention to cycle more.

Background.

In everyday life, tasks are often performed simultaneously, which may be more difficult for children with developmental coordination disorder (DCD) than their peers.

Aims.

To examine (1) the effects of task complexity and type of concurrent task on dual-task performance in children with and without DCD; and (2) if the amount of effort that children put into the task performance differs between the groups.

Methods.

Participants were 64 children with and without DCD (aged 7–14 years). The dual-task paradigm consisted of a manual dexterity task of relatively low complexity (box and block test) or relatively high complexity (pegboard task), and a concurrent motor task (cycling task) or a concurrent cognitive task (word-listening task). To assess mental effort, children were asked how tired they felt before and after the experiment.

Results.

Dual-task interference was highest when the manual dexterity task of relatively high complexity was combined with the concurrent motor task. There were no group differences in dual-task interference, but children with DCD reported a larger increase in the level of tiredness after the experiment indicative of greater mental effort.

Conclusions.

Depending on task demands, children with DCD are able to perform dual-tasks at the same level as their peers, but performance may take children with DCD more mental effort.

Purpose of review: It is well-established that anxiety levels are higher among people with Developmental Coordination Disorder (DCD) compared to their peers. However, it is unclear whether this anxiety influences movement and behaviour. The purpose of this paper is to review studies demonstrating the influence of anxiety on movement and/or behaviour in non-DCD and DCD populations.

Recent findings: When considering non-DCD literature, many studies have illustrated the influence of anxiety on movement. Only two papers were found which explicitly aimed to consider the influence of anxiety on movement in a DCD population. These findings are described and explored against a backdrop of the wider research field.

Summary: This paper has highlighted the potential role of anxiety in constraining movement patterns in DCD. While a great deal more evidence is needed before definitive conclusions there is emerging evidence that motor behaviour may be related to task-specific anxiety in children with DCD. 

Background: 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.

Aims: 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.

Method: 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).

Results: 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.

Conclusions: 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.

Children with Developmental Coordination Disorder (DCD) have been shown to have different coordination patterns on some tasks compared to their typically developing peers. However, it is unclear whether these differences are driven by the fact that typically developing children tend to be more practiced at the task on which coordination is being measured. The current study used a novel pedalo task to measure coordination in order to eliminate any practice differences. Thirty children (8 years -16 years), 15 with DCD and 15 without were recruited for this study. Children pedalled along an 8m line 20 times. Movement of the 7th Cervical Vertebra, shoulders, elbows, wrists, hips, knees, ankles and toes was recorded. In terms of outcome measures, pedalling speed was not different between the groups but the coefficient of variation of speed was higher in the children with DCD indicating a less smooth movement. Coordination was measured by calculating angles at the shoulder, elbow, hip, knee and ankle. A higher correlation coefficient (more tightly coupled movement) and a greater variation in joint angle was seen in the typically developing children for specific joint segments. The relationship between group and movement outcome (smoothness of movement) was mediated by inter-limb coordination variability. Therefore, the poor coordination and slower learning generally reported in children with DCD could be due to a slower or less optimal exploration of motor solutions.

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.

Developmental Coordination Disorder and Attention-Deficit/Hyperactivity Disorder are unique neurodevelopmental disorders with overlaps in executive functions and motor control. The conditions co-occur in up to 50% of cases, raising questions of the pathological mechanisms of DCD versus ADHD. Few studies have examined these overlaps in adults with DCD and/or ADHD. Therefore, to provide insights about executive functions and motor control between adults with DCD, ADHD, both conditions (DCD+ADHD), or typically developed controls, this study used a stop-signal task and parallel EEG measurement. We assessed executive performance via go accuracy and go reaction time, as well as motor response inhibition via stop signal reaction time. This was complemented with analysis of event-related potentials (ERPs). Based on existing investigations of adults with DCD or ADHD, we expected groups would (1) not differ in behavioral performance on stop and go trials, but (2) differences in ERPs, particularly in components N200 (index of cognitive control) and P300 (index of attention and inhibition) would be evident. The sample included N=50 adults with DCD (n=12), ADHD (n=9), DCD+ADHD (n=7), and control participants (n=22). We replicated that there were no between-group differences for behavioral-level executive performance and motor response inhibition. However, on a physiological level, ERP components N200 and P300 differed between groups, particularly during successful response inhibition. These ERPs reflect potential endophenotypic differences not evident in overt behavior of participants with ADHD and/or DCD. This suggests a disorder specific employment of inhibition or general executive functions in groups of adults with DCD, DCD+ADHD, ADHD, or control participants.

Objective: To explore factors which 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 over-represented 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 behaviour 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 behaviours.

Conclusion: Multiple individual (attitudes, perceived behavioural control, walking time, time-to-arrival judgements, 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 non-restrictive waiting times. Signalised 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 programmes may also help ensure safety of older adults where there is no designated crossing place. 

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.

Emotional state and 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 (STAI). 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 judgment 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.

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.

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. 

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.

Second-order planning, planning which 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 aged from 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. 

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, 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 11m 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 (7-11yrs) 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. 

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 minute 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. 

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.

Method: Twenty eight children with DCD participated in the study, with 28 typically developing (TD) age and gender matched controls. The children completed the ‘free writing’ task from the Detailed Assessment of Speed of Handwriting (DASH), which was evaluated for compositional quality using the Wechsler Objective Language Dimensions (WOLD). 
 

Results: The children with DCD performed significantly below their TD peers on 5 of the 6 WOLD 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 DCD have wider repercussions for the quality of written composition.

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.

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.

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 11 m 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.

During everyday life we move around busy environments and encounter a range of obstacles,

such as a narrow aperture forcing us to rotate our shoulders in order to pass through.

In typically developing individuals the decision to rotate the shoulders is body scaled and

this movement adaptation is temporally and spatially tailored to the size of the aperture.

This is done effortlessly although it actually involves many complex skills. For individuals

with Developmental Coordination Disorder (DCD) moving in a busy environment and negotiating

obstacles presents a real challenge which can negatively impact on safety and participation

in motor activities in everyday life. However, we have a limited understanding of the

nature of the difficulties encountered. Therefore, this current study considered how adults

with DCD make action judgements and movement adaptations while navigating apertures.

Fifteen adults with DCD and 15 typically developing (TD) controls passed through a series

of aperture sizes which were scaled to body size (0.9-2.1 times shoulder width). Spatial and

temporal characteristics of movement were collected over the approach phase and while

crossing the aperture. The decision to rotate the shoulders was not scaled in the same way

for the two groups, with the adults with DCD showing a greater propensity to turn for larger

apertures compared to the TD adults when body size alone was accounted for. However,

when accounting for degree of lateral trunk movement and variability on the approach, we

no longer saw differences between the two groups. In terms of the movement adaptations,

the adults with DCD approached an aperture differently when a shoulder rotation was required

and then adapted their movement sooner compared to their typical peers. These results

point towards an adaptive strategy in adults with DCD which allows them to account

for their movement difficulties and avoid collision.

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.

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.

When reaching towards an object, adults favour grasps which, following the intended action, end in a comfortable position even when this requires them to start in an uncomfortable position (the end-state-comfort effect). However, this strategy is not consistently used by children who instead seem to favour a minimal pre-contact rotation of the hand, even when this results in an uncomfortable end position. In terms of multiple movements, the strategies used for grip selection are unclear; adults may still grasp for end-state-comfort given their propensity to plan to the end of a movement; however, children who are less able to concatenate movement may tend to start-state-comfort movements. The current study considered grip selection in children ranging from 4 to 12 years and in a group of adults. Participants were asked to rotate a disc so that an arrow pointed towards a specific target(s), the number of sequences in a movement was increased from one to three. Planning for end-state-comfort was seen in all participants and a clear developmental trajectory was identified whereby the relative comfort of an end position could be directly predicted by age in months. Adults and 10–12-year-olds favoured an end-state-comfort strategy whereas the younger children gave equal weighting to end-state-comfort, start-state-comfort and no initial rotation strategies. All groups were able to end a movement comfortably when it was composed of three steps; however, the proportion of movements relying on an end-state-comfort strategy decreased as sequence length increase whereas the proportion of start-state-comfort and no initial rotation strategies increased. The current data support the concept that a mechanism for planning grasps may be based on motor experience.

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.

When picking up an object, adults show a longer deceleration phase when the onward action has a greater precision requirement. Tailoring action in this way is thought to need forward modelling in order to predict the consequences of movement. Some evidence suggests that young children also tailor reaching in this way; however, how this skill develops in children with Developmental Coordination Disorder (DCD) is unknown. The current study compared the kinematics of reaching to an object when the onward intention was: to place the object on a target (either with high or low precision requirements), to throw the object or to lift the object vertically. Movements of both adults (N=18) and children (N=24) with DCD and their age-matched controls were recorded. The typically developing adults discriminated across all action types, the adults with DCD and the typically developing children only across the actions to place and throw and the children with DCD only between the actions to lift and throw. The results demonstrate developmental progression towards fine tuning the planning of reaching in relation to onward intentions. Both adults and children with DCD are able to plan movement using inverse models but this skill is not yet fully developed in early adulthood.

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.

During everyday locomotion, we encounter a range of obstacles requiring specific motor responses; a narrow aperture which forces us to rotate our shoulders in order to pass through is one example. In adults, the decision to rotate their shoulders is body scaled (Warren and Whang in J Exp Psychol Hum Percept Perform 13:371-383, 1987), and the movement through is temporally and spatially tailored to the aperture size (Higuchi et al. in Exp Brain Res 175:50-59, 2006; Wilmut and Barnett in Hum Mov Sci 29:289-298, 2010). The aim of the current study was to determine how 8-to 10-year-old children make action judgements and movement adaptations while passing through a series of five aperture sizes which were scaled to body size (0.9, 1.1, 1.3, 1.5 and 1.7 times shoulder width). Spatial and temporal characteristics of movement speed and shoulder rotation were collected over the initial approach phase and while crossing the doorway threshold. In terms of making action judgements, results suggest that the decision to rotate the shoulders is not scaled in the same way as adults, with children showing a critical ratio of 1.61. Shoulder angle at the door could be predicted, for larger aperture ratios, by both shoulder angle variability and lateral trunk variability. This finding supports the dynamical scaling model (Snapp-Childs and Bingham in Exp Brain Res 198:527-533, 2009). In terms of movement adaptations, we have shown that children, like adults, spatially and temporally tailor their movements to aperture size.

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 80km/h (20-50mph). 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.

The need for a movement response may often be preceded by some advance information regarding direction or extent. We examined the ability of individuals with Developmental Coordination Disorder (DCD) to organise a movement in response to advance information. Pre-cues were presented and varied in the extent to which they indicated the response target. Both eye movement latencies and hand movements were measured. In the absence of pre-cues, individuals with DCD were as fast in initial hand movements as the typically developing (TD) participants, but were less efficient at correcting initial directional errors. A major difference was seen in the degree to which each group could use advance pre-cue information. TD participants were able to use pre-cue information to refine their actions. For the individuals with DCD this was only effective if there was no ambiguity in the advance cue and they had particular difficulty in using predictive motion cues. There were no differences in the speed of gaze responses which excluded an explanation relating to the dynamic allocation of attention. Individuals with DCD continued to rely on the slower strategy of fixating the target prior to initiating a hand movement, rather than using advance information to set initial movement parameters.

PURPOSE:

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.

METHOD:

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).

RESULTS:

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.

CONCLUSIONS:

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.

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.

Visual information is vital for fast and accurate hand movements. It has been demonstrated that allowing free eye movements results in greater accuracy than when the eyes maintain centrally fixed. Three explanations as to why free gaze improves accuracy are: shifting gaze to a target allows visual feedback in guiding the hand to the target (feedback loop), shifting gaze generates ocular-proprioception which can be used to update a movement (feedback-feedforward), or efference copy could be used to direct hand movements (feedforward). In this experiment we used a double-step task and manipulated the utility of ocular-proprioceptive feedback from eye to head position by removing the second target during the saccade. We confirm the advantage of free gaze for sequential movements with a double-step pointing task and document eye-hand lead times of approximately 200 ms for both initial movements and secondary movements. The observation that participants move gaze well ahead of the current hand target dismisses foveal feedback as a major contribution. We argue for a feedforward model based on eye movement efference as the major factor in enabling accurate hand movements. The results with the double-step target task also suggest the need for some buffering of efference and ocular-proprioceptive signals to cope with the situation where the eye has moved to a location ahead of the current target for the hand movement. We estimate that this buffer period may range between 120 and 200 ms without significant impact on hand movement accuracy.

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.