Relative phase stability of bimanual and visuomanual rhythmic coordination patterns in children with a Developmental Coordination Disorder

A dynamic pattern approach is used to examine the relative phase stability of rhythmic coordination in 24 children with a Developmental Coordination Disorder (DCD) and 24 matched controls in two functionally different tasks - a within-subject task (bimanual coordination) and a subject-environment task (visuomanual coordination). The stability of basic rhythmic coordination patterns tin-phase and antiphase patterns) was tested by applying perturbations, and by increasing the movement frequency towards the frequency where a loss of stability occurred. Coordination patterns of children with DCD were less stable than those of controls, both in the bimanual and the visuomanual task. According to the dynamic model (Haken, H., Kelso, J.A.S., Bunt, H., 1985. Biological Cybernetics 51, 347-356; Kelso, J.A.S., Delcolle, J.D., Schoner, G., 1990. In: Jeannerod, M. (Ed.), Attention and Performance XIII: Motor Representation and Control. Lawrence Erlbaum, Hillsdale, NJ, pp. 139-169), this reduced stability is due to a weaker coupling strength between the oscillators that represent the rhythmic units involved in the tasks. Further, within the DCD group three subtypes were found on the basis of particularly poor stability in bimanual rhythmic coordination (N = 2), visuomanual rhythmic coordination (N = 4), or both (N = 7). These data were related to the presence of neurological soft signs in the DCD group, which did not reveal specific patterns of minor neurological dysfunction in these children. Theoretical and practical implications of these findings were discussed. (C) 1998 Elsevier Science B.V. All rights reserved.