Developmental coordination disorder (DCD) is characterised by deficits in the acquisition and execution of motor skills that can be identified at a young age and which has a negative impact on academic achievement and everyday activities (American Psychiatric Association [APA], 2013). DCD can only be diagnosed in the absence of any other neurological or intellectual disabilities (APA 2013). DCD is reported in 5% – 6% of 5- to 11-year-old children (APA 2013), with boys more likely than girls to have this condition (Asonitou et al. 2012; Lingam et al. 2009).

Several researchers report a link between motor problems and academic skills (Alloway & Temple 2007; Schoemaker et al. 2001; Sortor & Kulp 2003; Westendorp et al. 2011). Some explanations for this occurrence are given from a neuropsychological perspective. Motor and cognitive functions are coupled, because they use the same brain structures (Diamond 2000; Westendorp et al. 2011). Furthermore, Diamond (2000:49) reports that the cerebellum is involved in both motor and cognitive functions, while the prefrontal cortex plays an important role in motor and cognitive functioning as well as through the strong neural connections between these two brain areas. Dysfunction in any of these brain structures or neural pathways may therefore express itself in motor problems as well as in cognitive problems. A second argument is that motor and cognitive development follows the same timetable with an accelerated development between 5 and 10 years. If any dysfunction may occur in these brain structures, it could possibly lead to motor and cognitive problems. Furthermore, motor and cognitive functions share several common underlining processes, for example sequencing (Hartman et al. 2010; Westendorp et al. 2011), and monitoring and planning (Roebers & Kauer 2009; Westendorp et al. 2011) which might also account for the co-occurrence of these problems.

Academic problems in children with DCD are associated with visual integration skills (Bonifacci 2004), visual functioning (Coetzee & Pienaar 2011; Goldstand, Koslowe & Parush 2005), visual processing skills (Goldstand et al. 2005) and convergence skills (Morad et al. 2002). Pienaar, Barhorst and Twisk (2013:377) report that the mastering of mathematics in South African Grade 1 learners depends on visual-perceptual skills where good visual-motor skills, visuospatial orientation and visual discrimination are required for the successful mastering of the foundational mathematical concepts. Movement execution depends on the ability to detect and analyse visual information (vision) received from the eyes (Botha 2013). Visual perception and motor coordination are part of an umbrella term, namely visual-motor integration skills (Beery & Buktenica 1997) which is described as the ability to integrate visual-perceptual skills with fine motor coordination (Beery & Buktenica 1997; Cheatum & Hammond 2000). Motor coordination influences the effective co-operation of body parts to produce smooth body movement, while visual perception (Schoemaker et al. 2001) is an acquired process by which useful visual information is obtained through effective conversion of images (Bezrukikh & Terebova 2009; Cheatum & Hammond 2000).

Children with DCD’s visual-motor perception and spatial orientation are described as inhibited and their ability to make quick motor adjustments are hence affected (APA 2013). Purcell et al. (2012:304) are of the opinion that the ability of children with DCD to process movement demands is influenced by poor visual-motor integration skills. Well-planned, coordinated and conscious movement can only take place when strength control is applied correctly, when motor planning occurs in fine detail and when continuous adjustments are made correctly by the neurological feedback system (Botha 2013). Clarification of different subsystems, including sensory and perceptual systems that contribute to general coordination, development of motor coordination and motor coordination difficulties is therefore of importance when assessing DCD (Cermak & Larkin 2002). A variety of test components can be required to approach the general construct of coordination, including tasks measuring neurodevelopmental function, tasks classified on the basis of interaction with the environment and fine and gross motor tasks (Cermak & Larkin 2002). Researchers (Dwyer, Baur & Hardy 2009; Riethmuller, Jones & Okely 2009) highlight in this regard that many body systems, including sensory, musculoskeletal and neurological systems are being incorporated during a child’s motor skill development and are therefore different but important underlying constructs of coordinated performance in children.

Gross motor skills are highlighted by various researchers as an important contributor to later cognitive achievement (Lopes et al. 2013; Piek et al. 2008; Son & Meisels 2006). Skills, generally executed in the classroom such as copying activities and skills that must be performed at speed, appear to be weaker in children with poor motor coordination because of slower inhibition of dominant responses (Michel et al. 2011). Proper muscle functioning also influences writing tasks such as quality of handwriting and writing speed (Malloy-Miller, Polatajko & Anstett 1995; Schwellnus et al. 2012). Perceptual-motor skills also have an influence on various scholastic tasks where spatial orientation, for example, is important for a clear understanding of number lines (Gunderson et al. 2012) and plays an important role in general mathematical abilities (Van Lill 2011). Perceptual skills are reported to have the greatest impact in the earlier school years or more importantly contribute to the earlier stages of mathematics (Geary, Hamson & Hoard 2000).

Relationships between DCD and visual-motor integration skills (Bonifacci 2004; Cheng et al. 2014; Tsai, Wilson & Wu 2008), and between academic achievement and visual-motor integration skills are also reported (Goldstand et al. 2005; Kulp 1999; Pieters et al. 2012; Van Hartingsveldt et al. 2014). The findings reported by Alloway and Temple (2007:483) indicate that children with DCD display deficiencies with regard to working memory; thus implying that these children’s literacy and numeracy skills will be influenced negatively. Children with DCD have poor executive functioning abilities (Zhu, Tang & Shi 2012) which can negatively impact their motor development (Leonard et al. 2015; Schurink et al. 2012) and academic achievement (Thorell et al. 2013). Handwriting speed depends on the maturity of visual-motor integration as well as visual information processing and memory (Tseng & Chow 2000). The mastering of visual-motor abilities (Memisevic & Sinanovic 2013), visual working memory (Lepach, Pauls & Petermann 2015) and motor skills (Schurink et al. 2012:730) relies on effective executive functioning.

Thus, it appears from research findings that motor deficits in children with DCD based on different subsystems such as sensory, perceptual and neurodevelopmental function that contribute to the construct of general coordination, would impact negatively on their academic achievement. Research by Carlson, Rowe and Curby (2013:527) also indicates that visual-spatial integration keeps on developing and plays an important role in academic achievement. A lack of knowledge was identified from the literature, as no South African studies were found regarding this possible relationship which necessitates further research in this regard, especially on South African children. The objective of this study is therefore to determine whether an association exists between visual perception, motor coordination and visual-motor integration skills and academic achievement in 10-year-old children with DCD, and which of these perceptual and motor coordination skills have the largest contribution to academic performance.

Descriptive and demographic information of the group can be found in Tables 1 and 2. DCD was identified in 47 (21.27%; 23 boys and 24 girls) of the 221 participants of which 14 (6.33%; seven boys and seven girls) were classified with severe-DCD (at or below the 5th percentile). One hundred and seventy-four participants (78.73%) fell above the 16th percentile, showing no signs of DCD and will serve as the reference group referred to as a group without-DCD or typical children. Table 2 reports the number of participants per learning area as well as their academic achievements during the June mid-year school assessment and the September ANA.

Table 3 reports descriptive values of the group as well as significant differences between the DCD group (< 16th percentile) and the without-DCD group as obtained in each of the outcome variables which included all the subsections of the VMI-4 and the MABC-2. The mean values in the DCD group were poorer in each of these subsections of both the VMI-4 and the MABC-2, compared to those in the without-DCD group. Statistical (p ≤ 0.05) and medium to large practical (d ≥ 0.8) significant differences are found for all the VMI-4 and MABC-2 variables. The visual perception mean standard score (79.17) of the DCD group is also categorised as below average (68–82), compared to the visual perception of the without-DCD group (84.57) that fell in the average category (83–117) (Beery & Buktenica 1997) which have clinical relevance.

Relationships were further analysed with Spearman Rank order correlations (Table 4) between the three VMI-4 variables (VMI, visual perception and motor coordination), the three MABC-2 variables (manual dexterity, object manipulation and balance) as well as the academic achievements obtained in the mid-year school assessment and the National assessment (ANA) in the without-DCD group (n = 174). Visual perception showed the strongest correlations with all the learning areas during the mid-year school assessments and also correlated the highest with the ANA results for Afrikaans, English and mathematics in the group. Motor coordination also reflected correlations, but showed only a small strength of association with most of the learning areas, while a relationship indicating moderate practical significance was established with Afrikaans (r = 0.32). Visual-motor integration reflected the smallest number of correlations with the different academic learning areas all of which indicated a small practical significance.

Table 5 displays a similar analysis for children with DCD (n = 47). Manual dexterity and visual perception, and the total MABC score showed clear relationships with most of the learning areas, indicating medium to strong effect sizes. The strongest correlations were found between manual dexterity and most of the learning areas. The highest relationships in both the june school (r = 0.42) and ANA (r = 0.39) assessments were found between maths and manual dexterity.

As these correlations indicated that the outcome variables are all related to academic performance in children with and without-DCD, a forward step-by-step regression analysis was performed to determine the unique percentage variance explained contribution (ΔR²) of best predictors for academic achievement in the group (Table 6). This analysis determined which of the three perceptual-motor constructs and the three motor coordination constructs had the biggest contribution to the variance that are explained in academic performance by these variables. The results obtained for the six compulsory learning areas and the grade point average of these six learning areas in the mid-year June school assessment as well as the National assessment (ANA), which only assess mathematics, home language and first additional language, are both displayed in Table 6. Visual perception explained the largest unique contribution of the total variance of all six perceptual-motor and coordination predictor variables in both regression analyses (Table 6) with the exception in Afrikaans (June) and English (ANA) where motor coordination showed a higher contribution to the total variance. Visual perception had the highest unique contribution to the total variance in all the other learning areas as well as in the grade point average. A total percentage variance of 18.17% was explained by these predictor variables in the grade point average where 16.36% was contributed by visual perception, while motor coordination (0.42%) and manual dexterity (0.95%) made additional small contributions. The ANA results, which were based on standardised papers drawn up nationally where teachers’ subjective influence could hence not play a role, are also displayed in Table 6. The contribution of visual perception was even higher in two of the learning areas that were assessed. In Mathematics, visual perception explained 22.04% of the total percentage variance of 23.11%, while in Afrikaans visual perception contributed to 15.93% of the 23.65%. Manual dexterity and balance also proved to be contributors, although very small percentages of the total percentage variance were explained by these predictor variables. It appeared from these results that visual perception rather than visual-motor integration served as a significant contributor to academic achievement.

This study examined the association between DCD, perceptual and motor coordination skills and academic achievement in 10-year-old children, The results firstly confirmed an overall relationship between visual perception and academic achievement of children, irrespective of whether they had coordination problems (DCD) (Table 4), while moderate to strong correlations were also established between DCD, manual dexterity, visual perception and academic achievement (Table 5). The study also verified that of all the different perceptual and coordination constructs that were measured, visual perception had the highest correlation with mathematical achievement in typical children, emphasising the importance of this relationship in practice (Table 4). Kulp et al. (2004:161) confirmed similar relationships between visual perception and mathematical skills, specifically in activities that involved visual memory. Pienaar et al. (2013:377) also reported a stronger relationship between basic mathematics, reading and writing literacy, VMI and visual perception abilities compared to the relationship that they found between these basic literacy skills, motor proficiency and motor coordination skills in school beginners. Skills that are assessed in the Grade 3 and 4 National Mathematical exam paper of South African children include, among others, calculation ability, knowledge of monetary and measurement units, figure patterns, factors, rounding off, fractions and identification of two- and three-dimensional shapes (ANA 2013). Various perceptual-motor skills serve as the underlying foundation for the successful execution of these skills. Perceptual-motor skills also underlie a variety of abilities like balance, laterality, spatial relationships, ocular motor control, cross-lateral integration and body awareness (Auxter, Pyfer & Huettig 2010). Cheatum and Hammond (2000:210) report that body awareness, laterality and direction play a significant role in the effective development of a body scheme which, furthermore, overflows into the development of spatial orientation. Furthermore, Gunderson et al. (2012:1238) and Van Lill (2011:22) report that good spatial orientation contributes to a better understanding of the number line because of improved knowledge of the linear spatial representation of figures. Richardson, Hunt and Richardson (2014:754) support the above opinions by indicating that spatial orientation is a significant predictor of mathematical achievement and that visual-spatial function serves as an additional predictor. Pieters et al. (2012:503) highlight that fine motor activities like sorting and visual-perceptual activities are needed to form an adequate mental representation of numerical concepts. Problems with VMI such as copying a figure can be affected by problems with visual perception for instance perceiving a circle or motor skills such as drawing lines or by integrating both (Sortor & Kulp 2003). Furthermore, the study of Pieters et al. (2012:499, 503), on 7- to 9-year-old children with mathematical learning problems confirmed a relationship between visual perception and procedural calculation such as borrowing and transferring skills in maths. These findings confirm that visual perception and motor performance are closely linked (Gibson 1979) which, again, can influence performance in academic areas such as maths.

The results in Table 3 confirmed significantly poorer VMI, visual perception, motor coordination, manual dexterity, aiming-and-catching and balance skills in children with DCD which is also confirmed by other studies. The findings of Tsai et al. (2008:662) suggest a general immaturity of brain networks that support complex visual-spatial processing in children with DCD. A South African study on children with DCD confirmed relationships between ocular muscle control and moderate to serious DCD in 6- to 7-year-old children (Coetzee & Pienaar 2011). Furthermore, Tsai et al. (2008:663) and Cheng et al. (2014:2177) reported poorer visual-perceptual skills, while Schoemaker et al. (2001:130) reported distinctive poorer visual closure and position in space perception skills in children with DCD compared to their typically developing peers. Our findings confirmed statistical as well as practically significant lower visual-perceptual skills in children with DCD which partially agree with the findings of Bonifacci (2004:164) who reported significant VMI differences (p < 0.014).

Our overall results are further confirmed by other studies that have reported that children with DCD display poorer academic abilities (Asonitou et al. 2012; Missiuna, Rivard & Pollock 2004). Visual-motor integration and visual perception skills are indicated as role players in academic performance of children with DCD (Goldstand et al. 2005; Kulp 1999; Pieters et al. 2012; Van Hartingsveldt et al. 2014). Son and Meisels (2006:763) confirmed a relationship between visual-motor skills, gross motor skills and later reading, and especially mathematical achievement. Alloway and Temple (2007:483) states that learners with DCD have a poorer working memory which impacts directly on performance of literacy and numeracy skills. The child with DCD might also struggle with alignment and spacing of columns and numbers in mathematical questions which contribute to slower copying of figures or calculations from the board (Missiuna et al. 2004). Alloway and Temple (2007:483) reported that children with DCD performed poorly in literacy and numeracy assessments, while Sortor and Kulp (2003:761) found that motor coordination had a positive correlation with academic achievements. Morad et al. (2002:119) highlighted convergence skills, while Goldstand et al. (2005:383) add visual processing and visual functioning skills as role players in their academic achievement. Tsai et al. (2008:663) report clinically significant deficits in different but interrelated visual-perceptual abilities in children with severe-DCD. Therefore, the present study confirms the above findings and confirms that visual perception correlates with DCD and academic achievement. A possible reason for this could be that there is a close link between VMI and motor skills. Problems with VMI, as seen in manual dexterity, could be affected by delays in visual perception and motor skills (Sortor & Kulp 2003).

Impaired manual function is also reported in children with DCD (Bieber et al. 2016) and linked to poorer academic skills among them which also confirmed our findings regarding poorer manual dexterity in the DCD group. Luo et al. (2007) report significant relationships between fine motor skills and mathematics, stating that this relationship can be used to determine mathematical performance over time. In addition, Morales et al. (2011:411) report that fine motor skills have a stronger relationship with academic achievement than gross motor skills, and together with age, serves as a significant predictor of academic performance. Carlson et al. (2013:527) is of the opinion that the correlation between fine motor skills and academic achievement can also be ascribed to visual-spatial integration and not necessarily to poor visual-motor coordination.

Furthermore, our results established that visual perception was the largest unique contributor of all the different perceptual and coordination predictor variables that were analysed in explaining academic achievement in children, irrespective of motor difficulties (Table 6). Shin, Park and Park (2009:622) report a close interplay between 9- and 13-year-old children’s visual skills (especially accommodation) and their academic achievement, and state that binocular dysfunction has a negative effect on reading, mathematics, science and social science (Shin et al. 2009). However, motor coordination or hand control served to a lesser degree as contributors, especially in language-related learning areas (Table 6). Motor coordination and manual dexterity might reflect on the fine muscle control abilities of the group, as well-functioning fine motor muscles and control can influence the quality of handwriting tasks and writing speed (Malloy-Miller et al. 1995; Schwellnus et al. 2012). Tseng and Chow (2000:87) also confirmed a significant relationship between VMI skills and writing skills. It was also interesting to note that motor coordination (especially hand skills as assessed in the VMI-4) had a significant and bigger role to play in especially language learning areas. It may be that some similarities in underlying processes are shared, as handwriting skills are considered to be an integral part of language-expressive skills.

This research had limitations that need to be acknowledged. The DCD group (n = 47), which were identified from the overall group, was too small to be able to explore the differences and relationships that was investigated as extensive as what was intended. This group also included participants with moderate- and severe-DCD which could have influenced the strength of the associations that were established with academic performance. The participants also represent only one of nine regions in South Africa, influencing the generalisation of the results. Further studies, using a larger group and also representative of other parts of South Africa, is therefore recommended to confirm the above results. A fuller understanding of the contribution of the individual functional constructs of visual perception to academic performance is also still needed, as this relationship between academic achievement and underlying visual-perceptual-motor factors was only superficially investigated in this study. However, the strong link that was established between visual perceptual abilities and academic performance, necessitates more in-depth research into the role of different but interrelated visual-perceptual abilities in academic performance of children, especially those with DCD. The influences of factors such as poor socio-economic environments in this relationship should also be taken into account, as earlier studies indicated that it might account for or mediate relationships. The development and testing of interventions for young children with DCD with these deficits are also recommended.

Inferior VMI, visual perception, motor coordination, manual dexterity, aiming-and-catching and balance were found in children with DCD which showed statistical, practical and even clinical relevance. Visual perception made a significant contribution to academic performance of Grade 4 learners, irrespective of whether children had coordination problems such as DCD. Visual perception also correlated highly with mathematical achievement in children with DCD as well as in children without-DCD and therefore seems to play a significant role in the child’s ability to understand the perceptual concepts that are needed to execute mathematical tasks effectively at the age of 10 years. However, coordination problems as a predictor of academic performance in typical children did not increase this difficulty, while manual dexterity did not only show a higher association to academic performance in children with DCD compared to typical children, but also in comparison with visual perception. It is assumed that if a young child’s motor skills are atomised, they will need less energy to concentrate on performing these skills, especially fine motor tasks during the early school years and can instead concentrate on the academic tasks at hand. Gross motor control and visual perception develops during early childhood and both should be well developed by 10 years. As motor proficiency and visual perception are both developmental processes, exposure to relevant learning environments are thus necessary and educators and policymakers should hence provide adequate resources and opportunities to improve development of these skills. Intervention strategies should also be in place for those children who are at risk for academic failure based on these developmental deficits. Children should therefore be exposed to stimulating environments from a very young age where age-appropriate development of perceptual-motor skills can establish a firm foundation for later academic skills and especially mathematical achievement. Activities that can contribute to the improvement of visual perception abilities and mathematical achievement may include obstacle courses (spatial orientation), different animal walks (motor planning) and activities that include different colours, shapes and dimensions. Sufficient training and empowerment of teachers in the development of these skills are also essential. Our results highlight that all children, irrespective of whether they have motor coordination problems, need to participate in such development programs at a young age. Visual-motor integration, visual perception, motor coordination, manual dexterity, aiming-and-catching and balance skills of children with motor difficulties such as DCD should also receive remedial attention from an early age.

This study increased our understanding of the level of the relationship between perceptual and coordination factors in academic performance of children with DCD and also in typically developing children. Furthermore, it increases our understanding of the importance of these factors in academic performance of children.