Stability of coordination patterns in handwriting: effects of speed and hand.

Previous studies have shown the existence of preferred stroke directions and shapes in handwriting. Assuming that such a two-dimensional trajectory formation process relies on the nonlinear coordination between two abstract orthogonal oscillators, a recent study (Athenes et al., in press) investigated the relative stability and the temporal accuracy of such coordination patterns in performing various ellipsoids corresponding to different phase and amplitude relationships between the oscillators. Results showed that only a small subset of the patterns was stable and accurate. The present study tested and verified the assumption that more stable coordination patterns deteriorate less under a speed constraint. In addition, differences between the dominant and nondominant hands gave insights into various effects modulating the stability and accuracy of such preferred patterns. Evidence of preferred coordination patterns and the predictability of their deterioration corroborate the existence of dynamics underlying handwriting in terms of nonlinearly coupled oscillators.