Elsevier

Human Movement Science

Volume 27, Issue 5, October 2008, Pages 705-713
Human Movement Science

Effect of postural instability on drawing errors in children: A synchronized kinematic analysis of hand drawing and body motion

https://doi.org/10.1016/j.humov.2008.03.001Get rights and content

Abstract

To investigate the role that postural stability plays in fine motor control, we assessed kinematics of the head, shoulder, elbow, and the pen during an accuracy drawing task in 24 children. Twelve children were classified into an accurate drawing (AD) group and 12 children into an inaccurate drawing (ID) group based on a manual dexterity task from the movement assessment battery for children [Henderson, S. E., & Sugden, D. A. (1992). Movement assessment battery for children. London: Psychological Corporation.]. Their parents completed a questionnaire to assess children’s inattention, hyperactivity, and impulsivity. An electromagnetic tracking system was used to monitor 3-D kinematic data of the body parts, while 2-D kinematic data of pen movement was simultaneously collected from a computer digitizer tablet. If a sudden body motion (1 cm/s) occurred within a time window from one second prior to the onset of the drawing error to the end of the error, we considered that the error coincided with the extraneous body movement. For each drawing trial, the coincidence rate was computed as (number of coincidences)/(number of errors). The ID group had a significantly higher coincidence rate of head and shoulder movements compared with elbow movements, whereas coincidence rates did not differ between the three body parts in the AD group. Parental ratings of children’s behavioral ratings of inattention, hyperactivity, and impulsivity were not correlated with the coincidence rates. The results indicated that inaccurate drawing was a result of postural instability rather than fidgeting caused by inattention or hyperactivity/impulsivity.

Introduction

Fine motor skills, such as drawing a line through a narrow path, require not only manual dexterity, but also demand sustained attention and stable posture. A drawer needs to continuously focus on the task at hand, while filtering out irrelevant information from within themselves and from the external environment. Small-muscle and hand–eye coordination must be supported by large muscles that maintain and adjust posture and balance. Given the crucial roles that attention and posture play, how can we determine the extent to which attention and posture contribute to the execution of fine motor skills? Do those who have difficulties in fine motor skills have problems in attention, or postural control?

The relationship between attention and postural control has been studied in children with attention deficit hyperactivity disorder (ADHD). These children are typically restless and fidget while engaged in lengthy choice reaction time tasks like the continuous performance test (CPT). Tripp and Luk (1997) counted the number of movements at the wrist and the ankle using actometers which recorded swings of pendulums as the respective body parts moved. The children who pervasively exhibited the symptoms of ADHD in clinic, school, and home moved their wrists and ankles more than children with situational ADHD (exhibited only at school or home), and the control children without ADHD. Teicher, Ito, Glod, and Barber (1996) measured body motion more objectively with 3-D kinematic analysis, and found that a group of boys with ADHD moved their head, shoulder, and wrist more, and covered greater areas with linear and less complex patterns than a control group of boys without ADHD. Both studies confirmed poor sustained attention in children with ADHD as reflected in high error rates on the CPT, and hyperactivity based on objectively measured body movements.

The CPT demanded attention to stimulus identification and response selection. On the other hand the attention and motor skills required for the motor component of the response to press a computer key were minimal. While engaged in the CPT, only a finger is used to press the computer key, and therefore it is reasonable to interpret the movements of body parts distant from the hand (e.g., the ankles’ motion) as “fidgeting” because the movements of the body parts do not interfere with the manual responses. However, the hands are mechanically linked with and perturbed by the movements of the wrists and shoulders. Further, the head movements not only affect the vestibular, proprioceptive, and visual functions (Crowell, Banks, Shenoy, & Andersen, 1998), but are also functionally coupled with the eye and the hand movements (Pelz et al., 2001, Werner et al., 2000). While perturbation in the coordinative structure, or synergy of the head, eye, and hand may not affect the execution of such a simple ballistic motor task as pressing a key with a finger, it could nevertheless impact on the performance of more complex and enduring fine motor tasks. How do attention, posture, and motor skill interact given that both postural stability and attention are requisite for a fine motor skill?

The relationships between postural stability and fine motor skills have been investigated by examining the effect of postural support on fine motor performance, the effect of postural tremor on the steadiness of the hand, and the effect of postural muscle activity on arm movement. Infants improved their reaching behaviors when their posture was stabilized either with a seating device (Hopkins & Rönnqvist, 2004) or with therapeutic seating (Redstone & West, 2004). Johnson and Williams (1988) found that increased postural support improved pegboard performance in children with delayed gross motor development, but did not affect the performance of typically developing children. The researchers emphasized the need for postural support when children with gross motor delay perform fine motor skills. Birnbaum, Majnemer, Shevell, Limperopoulos, and Wood-Dauphinee (1999) demonstrated that children with postural tremor had difficulties holding their upper extremity steady while holding a stylus still with the end point placed in designated openings. These results suggest that postural instability is related to poor fine motor performance, such as handwriting. Finally, Johnston, Burns, Brauer, and Richardson (2002) conducted an EMG investigation of postural muscle activity before the arm starts reaching to a target, and revealed that the trunk of children with developmental coordination disorder (DCD) was not as well stabilized as children without DCD. All these studies provided evidence that alteration in posture stability affects fine motor performance, and that gross motor problems of posture instability is mechanically linked with the execution of fine motor skills.

Miyahara, Piek, and Barrett (2006) investigated the direct effect of obligatory attention in a fine motor skill, using a dual-task combined with a resistance-to-distraction paradigm. For the primary fine motor task they examined a standardized visual-motor control subtest (Bruininks, 1978) in which children with ADHD and without ADHD drew a line along a designated path. They performed this concurrently with a secondary task or distraction. No significant group difference was found, and we concluded that the errors in the primary fine motor task were caused by poor manual dexterity, and not by a lack of attention.

In this study we consider the analysis of 3-D kinematic data from the head, shoulder, and the elbow that were not reported by Miyahara et al. (2006). We use a method for data collection similar to that employed by Teicher et al. (1996). The present study examines specifically whether movements of the head, shoulder, and elbow, which are mechanically linked with the hand, occur prior to the performer committing an error in accuracy drawing. We intentionally avoid the notion of closed kinematic chain, or a linkage of rigid bodies, because the elbow or the forearm or the hand was often used as the anchor which could serve as error compensation. It is also difficult to determine if the end segment of the fingers and the thumb holding the pen on the tablet should be considered free in space or not. Accordingly, we refer instead to a postural instability which might be somehow, if not directly, linked as a cause of drawing errors. This postural instability may result from movement of the head, shoulder, or elbow. We examine drawing errors and postural stability in groups of children assessed for being accurate drawers and inaccurate drawers. Symptoms of inattention and hyperactivity/impulsivity were also assessed to rule out the possibility that the errors were a result of these behavioral problems, as fine motor problems are often linked to attention deficit hyperactivity disorder (e.g., Pitcher, Piek, & Hay, 2003).

Section snippets

Participants

A total of 24 children (9 girls, 15 boys), whose ages ranged from 5 to 11 years (M = 7.79, SD = 2.11), were recruited from schools, support groups, and clinics in Dunedin, New Zealand for a study on “children’s attention and coordination”. Except for the age range of primary school children, no inclusion and exclusion criteria, such as the presence or absence of difficulties in attention and coordination, were specified in the information sheet for the study. In fact, we had expected the

Bivariate correlations

Coincident rates were not significantly correlated with the variables of age, inattention, and hyperactivitiy/impulsivity at the head, shoulder, or elbow (see Table 2). None of these variables were used as covariates in subsequent analyses.

Postural instability of accurate and inaccurate drawers

We first examined coincidence rates of the three body parts between accurate drawers (AD) and inaccurate drawers (ID). In the ID group all participants produced coincidental movements for all three body parts. For the AD group all participants but three

Discussion

The present study revealed that the inaccurate drawers (ID) produced more movements in body parts adjacent to the drawing hand immediately prior to the commission of a drawing error compared to accurate drawers (AD). The result that the proximal body parts of the head and shoulder committed more coincident errors than the elbow, suggests that postural instability is important in fine motor control.

The increase in coincidence rates could not be attributed to inattention or

Acknowledgments

We wish to thank the participants, their parents, the schools and support groups for their participation in this research. Also thanks to Gavin Kennedy, Nigel Barrett, and Ian Case for their technical support, and Jenny Clarkson and Annelies Inghelbrecht for assisting data collection.

References (23)

  • G. Keppel

    Design and analysis: A researcher’s handbook

    (1991)
  • Cited by (16)

    • Innovation & evaluation of tangible direct manipulation digital drawing pens for children

      2017, Applied Ergonomics
      Citation Excerpt :

      Therefore, systems that can respond to the users' two hands or hand movements (Hinckley and Sinclair, 1999; Hinckley et al., 2016) and incorporate touch-based functions is suggested to potentially enable users to engage in superior and simpler manipulations (Buur et al., 2004). The stability of a child's posture can affect their muscles' performance, when they were drawing (Miyahara et al., 2008). Children aged between 4 and 7 are drawing development occurs later in the post-schematic stage; the drawing becomes the most direct method to communicate (Siegler and Alibali, 2005).

    • Do children with autism and Asperger's disorder have difficulty controlling handwriting size? A kinematic evaluation

      2015, Research in Autism Spectrum Disorders
      Citation Excerpt :

      We were also limited by the methods of this study to determine whether children with ASD wrote significantly faster and more fluently in the 40 mm condition because they used additional joints, such as the shoulder and elbow, to perform the task. Use of additional joints may also account for the significantly faster movements in the ASD group, and this may contribute to poorer handwriting legibility in a more complex handwriting task because the arm and wrist are less stable (Miyahara, Piek, & Barrett, 2008); however, we were unable to determine this in the present study. This is an important consideration for future research in handwriting research in children with ASD.

    • Understanding macrographia in children with autism spectrum disorders

      2013, Research in Developmental Disabilities
      Citation Excerpt :

      Macrographic handwriting in children with ASD, along with its associated increase in neuromotor noise, may also represent a preference for using proximal over distal musculature, or greater postural instability. Studies in typically developing children have revealed that greater postural and proximal limb instability, but not distal musculature instability, are associated with more inaccurate and extraneous movements, and thicker lines while drawing (Miyahara, Piek, & Barrett, 2008). Postural training, in the context of writing, may help to improve handwriting control and stability, and reduce neuromotor noise.

    • A validation study of the Keyboard Personal Computer Style instrument (K-PeCS) for use with children

      2012, Applied Ergonomics
      Citation Excerpt :

      Furthermore, teachers and therapists are increasingly recognising the importance of keyboarding for students to promote school achievement and/or as a tool for those who struggle with handwriting (Freeman et al., 2005; Goldberg et al., 2003; Gulek and Demirtas, 2005; Rogers and Case-Smith, 2002). In view of the substantial amount of time students are already spending on computers, there would be some concern in increasing overall computer usage as a therapeutic or educational or therapeutic recommendation, particularly for children who may also be at risk for atypical postures (Miyahara et al., 2008; Preminger et al., 2004). These changes require a preventive attitude for children who will need to gain appropriate computer-use habits to take into adulthood (Straker et al., 2010).

    View all citing articles on Scopus
    View full text