دقت ترسیم در کار دوگانه و مطالعه مقاوم به حواس پرتی :اختلال حرکتی و یا توجه؟

Abstract To determine whether manual incoordination is caused by attention deficit or not, we used an accuracy drawing task as a primary task in dual-task and resistance-to-distraction studies, and examined if thus measured attention could differentiate inattention (IA) and combined (CO) subtypes of ADHD. The secondary tasks and distractions failed to lower the primary task performance in IA, CO and control groups. We also compared the impairment scores of the accuracy drawing tasks from the Movement Assessment Battery for Children [Henderson, S. E., & Sugden, D. A. (1992). Movement assessment battery for children. London: Psychological Corporation.] between the groups with attention deficit hyperactivity disorder (ADHD) and/or developmental coordination disorder-inaccurate drawing type (DCD-ID). There were no group differences in the impairment score between the control and the ADHD groups, and between ADHD and ADHD plus DCD-ID groups. We concluded that inaccurate drawing is not caused by attention deficit, but that it is a manifestation of a motor deficit as a separate entity from attention deficit.

Introduction Attention deficit hyperactivity disorder (ADHD) hampers children’s academic achievement and activity of daily living. Children with ADHD have difficulty in attending to cognitive and motor tasks that demand attention for a length of time to complete them. In a classroom situation, they may have difficulty in sitting still and listening to teachers and other students, and react to any stimuli that trigger their attention. While engaged in academic activities, they may thus not be able to stay on a task until they complete it. At home, children with ADHD may have problems similar to those in the classroom. They may be restless and fidget while eating at the dining table or studying at a desk. As the contemporary diagnostic criteria of DSM-IV (American Psychiatric Association; APA, 1994) indicate, the core attributes that encompass these behavioural symptoms are inattention, impulsivity and hyperactivity. The DSM-IV (APA, 1994) distinguishes three sub-types of ADHD, the predominantly inattentive subtype (IA), the hyperactive–impulsive subtype (HI), and a combination of these symptoms (CO). Behavioural examples of inattention, impulsivity and hyperactivity are not difficult to describe. In fact, almost all individuals, children and adults alike, behave as such from time to time. To diagnose ADHD, therefore, it is important to judge whether the behavioural problems are in excess or not, compared to the age norms. The comparison of this sort has been left to subjective judgment by teachers, parents and clinicians. A number of questionnaires (e.g., Achenback and Edelbrock, 1983, Conners, 1997 and Levy and Hay, 1991) have been developed to standardise the process of the subjective judgment. The inheritant limitation of questionnaire assessment lies in the subjective nature of rating children’s behavioural characteristics. For example, school teachers who have Type A personality (Hunter, Parker, & Williamson, 1985) or mental health problems (Schachar, 1991) seem to rate children’s behaviours strictly. Different settings (e.g., mainstream class, segregated special class) also influence the way teachers rate children’s behaviours (Miyahara, Möbs, & Doll-Tepper, 2001). On one hand, it is important to tap into phenomenological realities of teachers and parents for holistic understanding of the problems. On the other hand, subjective diagnosis of ADHD can cause over diagnosis, over prescription and potential abuse of stimulant medication. To supplement subjective ratings of children’s behaviours, attempts have been made to measure inattention, impulsivity and hyperactivity objectively. For the objective measurement of sustained attention and motor inhibition, in particular, computerised choice reaction time tasks, such as the Continuous Performance Task (Conners, 1995) and the Stop Signal Test (Gordon, 1983) have been developed and clinically utilised at times. However, reaction time tasks are repetitive and tedious (Lezak, 1995), and attention measures and motor inhibition measures often do not correspond to attention and behaviour inhibition outside the laboratory (cf. Scheres, Oosterlaan, & Sergeant, 2001). In addition to choice reaction-time tasks, researchers have measured children’s attention by applying the dual-task paradigm (Kahneman, 1973 and Wickens, 1976) which posits that concurrent execution of two tasks interferes with the performance of one or both tasks as a result of dividing attention. Lawrence et al. (2002) distinguished children with ADHD from those without ADHD in their performance on a commercial videogame (primary task), while they were watching a TV animation program (secondary task). A significant group difference was found in the decreased performance on the primary task in the expected direction in such meaningful tasks for children. Although the tasks were not as meaningful as the ones used by Lawrence et al., 2002 and Karatekin, 2004 also assessed dual-task performance with a simple reaction time task as a primary task and either counting continuously from 1 to 9 out loud or repeating back digit span as a secondary task. No group difference existed in reaction times between a group of children with ADHD and their controls under the baseline condition without any secondary task and under the counting condition. However, a significant group difference emerged under the digit span condition. Thus, children with ADHD revealed difficulty in dividing attention when the secondary task was cognitively more demanding. In addition to the dual-task paradigm, Lawrence et al. (2002) examined behavioural inhibitions, or resistance to distractions in other meaningful contexts for children. In a zoo, children were instructed to go to see assigned animals where more attractive animals and sound effects were prepared to distract children, and come back to the starting points as soon as possible. Children with ADHD were distracted more and took longer time to complete the task than control children especially when working memory and distracter loads were high. Taken together with Karatekin’s (2004) findings, attentional problems in ADHD seem to be dependent on context and cognitive loads. Children with ADHD often have cooccurring motor deficits, and the comorbidity varies depending on the assessment tools and cutoffs (Miyahara et al., 2001). According to the DSM-IV (1994), the poor motor coordination associated with ADHD may be linked to the children’s lack of attention or distractibility when they are performing the motor tasks. Doyle, Wallen, and Whitmont (1995) suggested that ADHD may be associated with manual dexterity in particular. Piek, Pitcher, and Hay (1999) identified an association between manual incoordination and attention deficits. Moreover, Pitcher, Piek, and Hay (2003) found that poor manual dexterity in children with both DCD and ADHD was not linked to ADHD symptomatology, but appeared to be a distinct deficit of DCD. However, these foregoing studies assessed ADHD by questionnaires and DCD by a standardised movement assessment battery independently. To investigate the role that attention in situ plays in manual coordination, it is necessary to use a manual dexterity task as a primary task in dual-task or resistance-to-distraction studies. We used an accuracy drawing task as the primary manual task and examined effects of various secondary tasks and distractions between different diagnostic groups of children. To account for how secondary tasks and distractions interfere with the performance of primary tasks, Wickens (2002) proposed the four-dimensional multiple resource model that predicts greater degrees of interference if tasks share stages of information processing, sensory modalities, codes, and perceptual channels. The primary task of accuracy drawing mainly uses the visual modality for spatial coding in all stages of perception, cognition and responding. We aimed to manipulate the levels of attention to accuracy drawing by various secondary tasks and distractions, and examined the effects of decreased attention in different diagnostic groups in order to test the assertion by the DSM-IV that the poor fine motor skills of children with ADHD may be linked to inattention and distractibility rather than a specific motor deficit. If manual incoordination is associated with attention deficit in children with ADHD, the performance of the primary task should deteriorate with decreased attention to the task. If there is no direct association between attention and motor deficits, the effects of secondary tasks and distractions on the performance of the primary task should be equivalent between children with ADHD and those without. Moreover, we tested the same research question about the role that attention plays in drawing accuracy from a slightly different angle. The second purpose of this study was to examine the effect of additional ADHD diagnosis on the performance of accuracy drawing. If a group of children without ADHD who draw inaccurately perform significantly better than those with ADHD who draw inaccurately, or if a group of children without ADHD who draw accurately perform significantly better than those with ADHD who draw accurately, then additional diagnosis of ADHD, or attention deficit is considered to have an effect on the performance of drawing accuracy. Consistent with the statement in DSM-IV, we hypothesised that manual incoordination of children with ADHD should be associated with distraction and attention deficit.

Conclusion The dual-task or resistance-to-distraction studies failed to test the attention deficit hypothesis of poor manual coordination in children with ADHD because the primary task performance was not significantly affected by secondary tasks and distractions. However, the absence of significant group difference on drawing accuracy between the control and the ADHD groups, and between ADHD and ADHD plus DCD-ID groups lent support for the motor deficit rather than the attention deficit hypothesis of manual incoordination in ADHD. This findings need to be further verified by additional dual-task studies using secondary tasks of probed cognitive load in order to ensure that less attention is paid to the primary manual task. If the motor deficit hypothesis is further supported, the attention deficit hypothesis stated in DSM-IV will need to be revised, and intervention should focus on motor component rather than attention to manual tasks.