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This study aims to test the hypothesis that handwriting is governed by the dynamics of non

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Niveau: Supérieur, Doctorat, Bac+8
This study aims to test the hypothesis that handwriting is governed by the dynamics of non- * Corresponding author. Tel.: . E-mail address: (S. Athenes). Human Movement Science 23 (2004) 621–641 0167-9457/$ - see front matter 2004 Elsevier B.V. All rights reserved. linear coupled oscillators. Accordingly, its first goal is to identify preferred, basic graphic shapes corresponding to spontaneously stable combinations of the two frequency-locked oscil- latory x–y components of the trajectories. Six participants were required to produce 26 ellip- soids of varying eccentricities and orientations presented consecutively on a graphic tablet. These shapes corresponded to a systematic manipulation of the relative phase and the relative amplitude of the oscillators by a constant step. Results showed that among those, only eight ellipsoids were produced in a spontaneous and stable fashion. They were characterized by attraction of nearby shapes, and by a higher accuracy and velocity. Alike all periodic motion, graphic skills, hence handwriting, exhibit preferred coordination patterns, which can be ascribed to the non-linear coupling of two oscillators. 2004 Elsevier B.V. All rights reserved. Keywords: Dynamical system; Self-organization; Dynamic pattern theory; Graphonomics Evaluating the coordination dynamics of handwriting Sylvie Athenes a,*, Isabelle Sallagoıty b, Pier-Giorgio Zanone b, Jean-Michel Albaret b a Centre d'Etudes de la Navigation Aerienne, 7

  • coordination pattern

  • finger movements

  • equilibrium between

  • stable pattern

  • alike all periodic

  • handwriting

  • shapes easily

  • nearby shapes


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HumanMovementScience23(2004)621–641www.elsevier.com/locate/humovEvaluatingthecoordinationdynamicsofhandwritingbb,aSylvieAthe`nes*,IsabelleSallagoı¨ty,Pier-GiorgioZanone,bJean-MichelAlbaretaCentredEtudesdelaNavigationAe´rienne,7AvenueEdouardBelin,BP4005,31005ToulouseCedex,FrancebEA3691‘‘LaboratoireAdaptation,Perceptivo-MotriceetApprentissage’’,UFRSTAPS,Universit´ePaulSabatier,118routedeNarbonne,31062ToulouseCedex4,FranceAbstractThisstudyaimstotestthehypothesisthathandwritingisgovernedbythedynamicsofnon-linearcoupledoscillators.Accordingly,itsfirstgoalistoidentifypreferred,basicgraphicshapescorrespondingtospontaneouslystablecombinationsofthetwofrequency-lockedoscil-latoryxycomponentsofthetrajectories.Sixparticipantswererequiredtoproduce26ellip-soidsofvaryingeccentricitiesandorientationspresentedconsecutivelyonagraphictablet.Theseshapescorrespondedtoasystematicmanipulationoftherelativephaseandtherelativeamplitudeoftheoscillatorsbyaconstantstep.Resultsshowedthatamongthose,onlyeightellipsoidswereproducedinaspontaneousandstablefashion.Theywerecharacterizedbyattractionofnearbyshapes,andbyahigheraccuracyandvelocity.Alikeallperiodicmotion,graphicskills,hencehandwriting,exhibitpreferredcoordinationpatterns,whichcanbeascribedtothenon-linearcouplingoftwooscillators.2004ElsevierB.V.Allrightsreserved.Keywords:Dynamicalsystem;Self-organization;Dynamicpatterntheory;Graphonomics*Correspondingauthor.Tel.:+33562259591.E-mailaddress:athenes@cena.fr(S.Ath`enes).0167-9457/$-seefrontmatter2004ElsevierB.V.Allrightsreserved.doi:10.1016/j.humov.2004.10.004
622S.Ath`enesetal./HumanMovementScience23(2004)6216411.IntroductionHandwritingcanbedefinedasthevisibletraceofaspokenlanguage.Therela-tionshipbetweenthevisiblesignsandtheaudiblesignscanbequitedifferentfromonelanguagetoanother,goingfromsystemswhereonesigncanencodeawholewordtoalphabeticalsystemswhereeachsignencodesabasicsound.Theappearanceofthesignsthemselvesvariesgreatly,withlanguagebeingwritteneitherfromlefttoright,orrighttoleft,oreventoptobottom.Inspiteofthisstaggeringdiversity,therearesomecommonalitiessharedbyallhandwritingsystems.Forexample,theircom-municationfunctionimposesthat,withineachlanguage,some–presumablyimpor-tant–featuresvarysystematicallylessthanothers,lestthereaderspendstoomuchtimeandeffortdecipheringthehandwrittentrace.Furthermore,regardlessofthelanguage,thesignsaresemanticallymeaningfulshapesthatarealwaystracedbythe–usuallyright–handofahumanbeing.Actingtogether,thesetwoconstraints,tracelegibilityandhumanmotorproperties,effectivelyreducethe‘‘creativity’’ofthewriter.Ourtenetisthathandwritingsystems,havingevolvedovermanycenturies,areaworkingcompromisebetweenasmallnumberoffastandcomfortablehumanarm/wrist/fingermovementsproducingstableshapesandthenecessitytohavealargeenoughvarietyofshapeseasilyrecognizableanddifferentiable.Indeed,shapesdolookdifferentacrossdifferentlanguages.Yet,theunderlyingmovementscannotbequiteasdifferentinspiteofthevariabilityinducedbythemedium,whetheritbeapencilorabrush,forexample.Comparingdifferenthandwritingsystems(Arabic,Hebrew,Chinese,andEnglishamongothers),VanSommers(1984)showedthatbasicstrokedirectionsarefairlysimilar:strokestowardsthebottom-rightandthebottom-left(andright,andtop-righttoacertainextent)aremostfrequent,whereasstrokestowardsthetopandtopleftarevirtuallynon-existent.Furtherargumentscomefromstudiesbylanguagehistoriansreportingsimilarevolutionoftheshapesfordifferentlanguages.Forexample,Irigoin(1990)describestheevolutionofAncientGreekfromcapitalletterstocursivehandwriting:anglesbecomecurves,lettersaresimplifiedandlinked,anddifferencesbetweensimilarshapesareenhanced(e.g.,RbecameCandnoteasex-pected,becauseitwouldhavebeentooclosetothealreadyexistinge).Summinguphisobservations,thisauthorcontendsthateverywritingsystemisastructurethatreachesamoreorlessstableequilibriumbetweentwoconflictingtendencies:aten-dencytosimplificationwithareducednumberofbasicstrokes,easytoexecute,com-binedtoformletters,andatendencytodifferentiationinordertoavoidsimilarlookingletters,whichwoulddecreaselegibilityandslowdownthereading.Ifrelativestabilityisanimportantnotiontounderstandbasicshapesinhandwriting,carefulmanipulationofoneortheothertendency(simplificationversusdifferentiation)shouldthenresultinlawfulchangesintherelativefrequencyofthedifferentshapescomposinghandwriting.Thepresentpaper,afirstattemptatasystematicexplora-tionofthehandwritingrelativestabilityinthefaceofconstraintsactingonmove-mentexecution,addressesexclusivelythebasisforthetendencytosimplification.Handwritingisacomplexmotorskillthatrequiresthecoordinationofnumerousstructuresandcomponentsinordertoproduceasuccessionofgraphicshapesof