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Dynamique de coordination spontanée de l'écriture

Abstract : Handwriting is considered as a sequence of cyclic movement and results from the coordination of two orthogonal coupled oscillators. We bear on the assumption that handwriting results from the dynamics of non-linear coupled oscillators. Our main concern was to draw dynamical phenomena that govern the formation of graphic patterns, their co-articulation as well as their destabilization under diverse constraints. In this way, three experiments had been conduced. In order to identify the underlying dynamics, right-handers produced 26 shapes corresponding to fixed values of relative phase and amplitude between the two orthogonal oscillators. Results revealed that among all shapes, only a few were spontaneously stable for each task (0°, 45°/53°, 135°/127° and 180°), which corresponded to ellipses and strokes in various orientations. Those preferred coordination patterns were characterized by attraction of nearby shapes, and by a higher accuracy and stability: hallmark of attractors. Moreover, there was a differential degree of stability among the preferred patterns. Based on this differential stability, the second experiment confirmed that under a high movement velocity or with the non dominant hand, the least stable pattern degraded steeper whereas the most stable preferred patterns kept a highly accurate and stable performance. Finally, our last experiment confirmed that the rules of transition between those preferred patterns come from their properties of stability: the time to switch from a most stable pattern to a least stable pattern took more time than on the other way. Alike all periodic motion, graphic skills exhibit preferred coordination patterns, nonlinear transition and predictable deterioration which corroborate the existence of dynamics underlying handwriting. This underlying dynamics comes from the dynamics of non linear coupled oscillator and might be described by the dynamic of a few variable(s). Our results open a new window to understand the production of handwriting and get robust predictions about its acquisition and degradation that had never explained by the traditional models of handwriting.
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https://tel.archives-ouvertes.fr/tel-00008545
Contributor : Isabelle Sallagoïty <>
Submitted on : Monday, February 21, 2005 - 1:46:10 PM
Last modification on : Friday, October 23, 2020 - 4:52:02 PM
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Isabelle Sallagoïty. Dynamique de coordination spontanée de l'écriture. Neurosciences [q-bio.NC]. Université Paul Sabatier - Toulouse III, 2004. Français. ⟨tel-00008545⟩

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