Basic and supplementary sensory feedback in handwriting

International audienceThe mastering of handwriting is so essential in our society that it is important to try to find new methods for facilitating its learning and rehabilitation. The ability to control the graphic movements clearly impacts on the quality of the writing. This control allows both the programming of letter formation before movement execution and the online adjustments during execution, thanks to diverse sensory feedback (FB). New technologies improve existing techniques or enable new methods to supply the writer with real-time computer-assisted FB. The possibilities are numerous and various. Therefore, two main questions arise: (1) What aspect of the movement is concerned and (2) How can we best inform the writer to help them correct their handwriting? In a first step, we report studies on FB naturally used by the writer. The purpose is to determine which information is carried by each sensory modality, how it is used in handwriting control and how this control changes with practice and learning. In a second step, we report studies on supplementary FB provided to the writer to help them to better control and learn how to write. We suggest that, depending on their contents, certain sensory modalities will be more appropriate than others to assist handwriting motor control. We emphasize particularly the relevance of auditory modality as online supplementary FB on handwriting movements. Using real-time supplementary FB to assist in the handwriting process is probably destined for a brilliant future with the growing availability and rapid development of tablets

Dynamique de coordination dans la formation de la trace écrite chez l'adulte et l'enfant

L'écriture est un mouvement parmi les plus complexes et les plus rapides de notre répertoire moteur. Elle requiert l'activité coordonnée de nombreux muscles et articulations du membre supérieur pour produire une succession de formes conventionnelles, des lettres, de manière suffisamment précise pour être reconnues. Ce travail de thèse a pour objectif de comprendre 1) comment les individus arrivent à contrôler et à coordonner l'ensemble des éléments du système moteur (ici graphomoteur) pour accomplir une telle tâche et 2) comment s'acquiert cette habileté motrice. Les concepts et outils de l'approche dynamique de la coordination motrice permettent d'envisager la formation de la trace écrite comme un processus auto-organisé qui répond aux modèles d'oscillateurs couplés. A partir de la modélisation de l'écriture en termes de couplage non linéaire de deux oscillateurs orthogonaux abstraits, la phase relative entre ces deux oscillateurs permet d'observer, de comprendre et de prédire la formation, le maintien et la dégradation de la trace écrite. Dans notre première étude, centrée sur la coordination graphomotrice adulte dans la reproduction de formes géométriques simples, nous avons confirmé qu'une ellipse d'excentricité intermédiaire et un trait sont plus faciles à tracer que toutes les autres formes elliptiques. Nous avons de plus montré que la production préférentielle d'ellipses d'excentricité intermédiaire est biaisée en faveur de formes plus arrondies lorsque leur orientation devient contraignante. Dans notre deuxième étude, centrée sur la coordination graphomotrice chez l'enfant de 7 à 11 ans, nous avons révélé que les enfants sont plus précis et plus stables dans le tracé de cercles que dans le tracé d'ellipses, préférentiel chez l'adulte. Nos résultats confirment que, comme tout mouvement rythmique coordonné, la stabilité des modes de coordination (grapho)motrice détermine la manière d'écrire.Handwriting movement is through one of the fastest and the most complex known to human motor behaviors. This ability involves a sophisticated coordination of many muscles and joints recruited in order to produce a trace sufficiently consistent and precise to be recognized as letters. The aim of the present thesis is to understand 1) how we succeed in controlling and coordinating the motor (here graphomotor) system to realize this task and 2) how this motor behavior is acquired. Concepts and tools of the dynamical approach of the motor coordination permit to consider the written trajectory formation as a self-organized process resulting from the dynamics of non-linear coupled oscillators. From the modeling of handwriting movements in terms of the non-linear coupling of two abstract orthogonal oscillators, the relative phase between these oscillators make possible to observe, to understand and to predict the formation, the maintaining and the deterioration of the written trajectory. In a first study based on graphic coordination of adults in production of simple geometrical shapes, we confirmed that the ellipse with intermediate eccentricity and the line are easier to produce that all other shapes. Moreover, we demonstrated that the preferential production of intermediate ellipse is biased toward a more circular shape when orientation becomes a constraint. In a second study based on graphic coordination of 7 to 11 year-old children, we revealed that children are more precise and stable in circle drawing than in ellipse drawing, preferential in adults. Our results confirm that, as all cyclic coordinated movements, the stability of the motor coordination patterns determine the way of handwriting

Handwriting Movement Sonification for the Rehabilitation of Dysgraphia

International audienceSounds can be used to inform about the correctness of an ongoing movement, without directly interfering with the visual and proprioceptive feedback. Furthermore, the dynamic features of sounds make them particularly appropriate means of accessing the spatiotemporal characteristics of movements. Finally, because of their playful characteristics, sounds are potentially effective for motivating children in particular need of such assistance. Based on these theoretical considerations, the present work investigated the relevance of applying an online auditory feedback to spatiotemporal characteristics of handwriting for the rehabilitation of handwriting learning disabilities

Handwriting Movement Sonification: Why and How?

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Dynamique de coordination dans la formation de la trace écrite chez l'adulte et l'enfant

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

On the Auditory-Proprioception Substitution Hypothesis: Movement Sonification in Two Deafferented Subjects Learning to Write New Characters

International audienceThe aim of this study was to evaluate the compensatory effects of real-time auditory feedback on two proprioceptively deafferented subjects. The real-time auditory feedback was based on a movement sonification approach, consisting of translating some movement variables into synthetic sounds to make them audible. The two deafferented subjects and 16 age-matched control participants were asked to learn four new characters. The characters were learned under two different conditions, one without sonification and one with sonification, respecting a within-subject protocol. The results revealed that characters learned with sonification were reproduced more quickly and more fluently than characters learned without and that the effects of sonification were larger in deafferented than in control subjects. Secondly, whereas control subjects were able to learn the characters without sounds the deafferented subjects were able to learn them only when they were trained with sonification. Thirdly, although the improvement was still present in controls, the performance of deafferented subjects came back to the pre-test level 2 h after the training with sounds. Finally, the two deafferented subjects performed differently from each other, highlighting the importance of studying at least two subjects to better understand the loss of proprioception and its impact on motor control and learning. To conclude, movement sonification may compensate for a lack of proprioception, supporting the auditory-proprioception substitution hypothesis. However, sonification would act as a " sensory prosthesis " helping deafferented subjects to better feel their movements, without permanently modifying their motor performance once the prosthesis is removed. Potential clinical applications for motor rehabilitation are numerous: people with a limb prosthesis, with a stroke, or with some peripheral nerve injury may potentially be interested

Tools and Methods for Diagnosing Developmental Dysgraphia in the Digital Age: A State of the Art

Handwriting is a complex perceptual motor task that requires years of training and practice before complete mastery. Its acquisition is crucial, since handwriting is the basis, together with reading, of the acquisition of higher-level skills such as spelling, grammar, syntax, and text composition. Despite the correct learning and practice of handwriting, some children never master this skill to a sufficient level. These handwriting deficits, referred to as developmental dysgraphia, can seriously impact the acquisition of other skills and thus the academic success of the child if they are not diagnosed and handled early. In this review, we present a non-exhaustive listing of the tools that are the most reported in the literature for the analysis of handwriting and the diagnosis of dysgraphia. A variety of tools focusing on either the final handwriting product or the handwriting process are described here. On one hand, paper-and-pen tools are widely used throughout the world to assess handwriting quality and/or speed, but no universal gold-standard diagnostic test exists. On the other hand, several very promising computerized tools for the diagnosis of dysgraphia have been developed in the last decade, but some improvements are required before they can be available to clinicians. Based on these observations, we will discuss the pros and cons of the existing tools and the perspectives related to the development of a universal, standardized test of dysgraphia combining both paper-and-pen and computerized approaches and including different graphomotor and writing tasks

Tools and Methods for Diagnosing Developmental Dysgraphia in the Digital Age: A Brief State-of-Art

Handwriting is a complex perceptual-motor task that requires years of training and practice before complete mastering. Its acquisition is crucial since handwriting is the basis, together with reading, for the acquisition of higher-level skills such as spelling, grammar, syntax, and text composition. Despite correct learning and practice of handwriting, some children never master this skill to a sufficient level. These handwriting deficits, referred to as developmental dysgraphia, can seriously impact the acquisition of other skills and thus the academic success of the child if they are not diagnosed and handled early. In this review, we present a non-exhaustive listing of the tools which are the most reported in the literature for the analysis of handwriting and the diagnosis of dysgraphia. Tools focusing on both the final handwriting product and the handwriting process will be considered. We will then discuss the pros and cons of the existing tools, and the perspectives for the development of future tools

Self-Control of Task Difficulty During Training Enhances Motor Learning of a Complex Coincidence-Anticipation Task

International audienceThe aim of the present work was to analyze the influence of self-controlled task difficulty on motor learning. Participants had to intercept three targets falling at different velocities by displacing a stylus above a digitizer. Task difficulty corresponded to racquet width. Half the participants (self-control condition) could choose the racquet width at the beginning of each trial. Each was paired with a participant from the yoked group. The self-control condition resulted in better performances and accuracy during immediate and delayed retention tests. These results confirm the advantage of a self-control condition on motor learning. They are discussed with reference to the challenge point hypothesis (Guadagnoli & Lee, 2004)