Rhythmic ability in children with developmental coordination disorder: a pilot investigation

Introduction

Manifestations of Developmental Coordination Disorder (DCD), though easily recognizable among children due to the observed lack of coordination in daily life motor tasks, they seem to be very individualized and task dependent [1]. Although the exact mechanisms behind the manifested motor deficits are not known, it has been suggested that these may be related to the central organization and programming of movement [2][4]. The present study investigated rhythmic motor performance in children with DCD using a finger-tapping task in an attempt to identify possible differences in information processing associated with rhythm perception. The effect of external auditory cueing as well as movement speed on tapping performance was examined.
Methods
The sample consisted of six (6) children (mean age: 10.80.61) diagnosed with DCD using Movement Assessment Battery for Children [3] and six (6) age matched controls (mean age: 10.73  0.37). Children were asked to periodically press a response key with their index finger (Vienna Test System) under two task conditions: a) unilaterally (right index finger only) and b) bilaterally (both index fingers moving in synchrony). During the synchronization phase, tapping was externally paced by a computer generated auditory signal at two different pacing frequencies: a) every 833 ms (slow tempo) and b) every 417 ms (fast tempo). After a series of 18 taps in the synchronization phase, children were asked to maintain the same tapping rhythm for another 18 taps without the guidance of the external auditory signal (continuation phase). Temporal accuracy was assessed by the mean tap-target sound interval calculated over the series of 18 taps performed in each condition. Similarly, temporal variability was reflected in the standard deviation (SD) of the tap-target intervals. Differences across the two groups, tasks (unilateral, bilateral), tapping frequencies (417 ms, 833 ms) and phases (continuation, synchronization) were analyzed by means of repeated measures ANOVA.

Results

When temporal variability was examined, a significant speed x group interaction [F(1,10) = 6.56, p<.05] confirmed that children with DCD had significantly higher SDs of the tap-target interval than controls during bilateral tapping at the fast tempo [synchronization: t(10) = 2.46, p<.05, continuation: t(10) = 2.69, p<.05]. In addition, unilateral tapping was significantly more stable than bilateral performance [F(1,10) = 10.8, p<.01]. In temporal accuracy of finger tapping, no significant between-group differences were noted, associated by increased individual variations within the DCD group. Significantly smaller mean tap-target intervals were associated with unilateral compared to bilateral performance [F(1,10) = 8.87, p<.05] as well as with the synchronization compared to the continuation phase [F(1,10) = 12.98, p<.01].

Discussion / Conclusions

The results of the present study are in accordance with previous findings showing that DCD is associated with increased variability of finger tapping [1] suggesting a possible deficit in underlying cognitive processing [5]. On the other hand, the fact that children with DCD reproduced the externally imposed rhythms with similar temporal accuracy as controls and regardless of the presence of external auditory cueing indicates that the problem may be related to movement execution [2]. It should be noted however that the particularly large individual variations within the DCD group in association with the small sample size of the present study do not permit the generalization of the present findings. Several other studies have pointed to the individualized and task-dependant manifestations of DCD [6][7].

References

[1]. Volman J.M. & Geuze R.H. (1998). Human Movement Sci. 17, 541-572.
[2]. Williams H.G., Woolacott M.H., Ivry R.B. (1992). J. of Motor Behav.,, 24, 165-172
[3]. Henderson S.E. & Sugden D.A. (1992). The Psyc. Corporation, Kent.
[4]. Missiuna,C. (1994). A.P.A.Q., 11. 214-235.
[5]. Salman M.S. (2002). J. of Child Neurol., 17, 1-9.
[6]. Visser, J. (2003). Human Movement Sci., 22, 479-493.
[7]. Wright H.C. & Sugden D.A. (1996). A.P.A.Q., 13, 357-371