Jean-Luc Velay | Aix-Marseille University (original) (raw)
Papers by Jean-Luc Velay
Éditions de la Maison des sciences de l’homme eBooks, Jul 3, 2017
Recognizing the letters encountered when reading is generally assumed to be a purely visual proce... more Recognizing the letters encountered when reading is generally assumed to be a purely visual process, yet a large body of data supports the view that movement plays a crucial role in letter representation and suggests that handwriting contributes to the visual recognition of letters. We established that simply viewing letters activated a part of the left premotor cortex that was also activated when the letters were being written by the subjects. These results, which were confirmed in left-hander subjects, indicate that writing motor processes are implicitly evoked when passively observing letters. The cerebral representation of letters is therefore presumably not strictly visual, but based on a multicomponent neural network built up while learning concomitantly to read and write. If so, changing the motor conditions while children are learning to write by using a method based on typing instead of handwriting should affect their subsequent letter recognition performances. In order to test this hypothesis, we trained two groups of 38 children to copy letters of the alphabet either by hand or by typing them. After three weeks of learning, in the older children, the handwriting training gave rise to a better letter recognition than the typing training. These findings show the existence of close functional relations between the reading and writing processes, and suggests that our reading abilities might be somehow dependent on the way we write
Vision Research, Sep 1, 1997
HAL (Le Centre pour la Communication Scientifique Directe), 2012
Psychologie Francaise, Jun 1, 2010
Human Movement Science, Aug 1, 2015
HAL (Le Centre pour la Communication Scientifique Directe), 2003
Journal of forensic document examination, 2011
During their career, forensic document examiners will inevitably be confronted with handwriting c... more During their career, forensic document examiners will inevitably be confronted with handwriting carried out under unusual conditions (UnC). A questioned document signed on top of a car or on a vertical surface like a wall are two examples. These atypical circumstances may give rise to more variability of the signatures or written words, in particular if the body was in non-traditional writing position without the traditional support. Few studies were devoted to handwriting variability under unusual writing conditions. The current study investigates whether individual variability changes with special writing conditions. In a previous study (Sciacca & al, 2009), we found that eight repetitions were sufficient to obtain a correct estimation of the variance. In the present study, twelve subjects were asked to write two word sets eight times in upper and eight times in lower case, under different conditions : sitting and writing on a horizontal (usual condition UC) or vertical support; and standing, kneeling or laying while writing on a horizontal or vertical support (unusual conditions UnC). Words were written on a pen tablet, normalized in space and time and then averaged. The variance of the eight words was measured under all conditions. Results showed only an increase in variability under the laying and kneeling / vertical UnC. Within the five other postural conditions tested, handwriting was shown to be very stable.
Abstract 1. put forward some experimental arguments supporting the assumption that whole-body, sp... more Abstract 1. put forward some experimental arguments supporting the assumption that whole-body, spatially oriented behaviour might be based on a body reference frame which results mainly from the common processing of various sensory feedbacks arising in the muscles ...
Experimental Brain Research, Aug 1, 1996
... a comparison between memory-guided and visually guided saccades ... Here we attempted to chan... more ... a comparison between memory-guided and visually guided saccades ... Here we attempted to change the initial eye position signal supplied to the oculomotor system before a memory-or visuo-guided saccade to a 10 left target by applying mechanical vibration to the IR muscle. ...
Human Movement Science, Apr 1, 1989
Experimental Brain Research, Jun 1, 1991
The egocentric localization of objects in extrapersonal space requires that the retinal and extra... more The egocentric localization of objects in extrapersonal space requires that the retinal and extraretinal signals specifying the gaze direction be simultaneously processed. The question as to whether the extraretinal signal is of central or peripheral origin is still a matter of controversy, however. Three experiments were carried out to investigate the following hypotheses: 1) that the proprioceptive feedback originating in eye and neck muscles might provide the CNS with some indication about the gaze direction; and 2) that the retinal and proprioceptive extraretinal inputs might be jointly processed depending on whether they are of monocular or binocular origin. Application of low amplitude mechanical vibrations to either the extraocular or neck muscles (or both) of a subject looking monocularly at a small luminous target in darkness resulted in an illusory movement of the target, the direction of which depended on which muscle was stimulated. A slow upward target displacement occurred on vibrating the eye inferior rectus or the neck sterno-cleido-mastoidus muscles, whereas a downward shift was induced when the dorsal neck muscles (trapezius and splenius) were vibrated. The extent of the perceptual effects reported by subjects was measured in an open-loop pointing task in which they were asked to point at the perceived position of the target. These results extend to visually-oriented behavior the role of extraocular and neck proprioceptive inputs previously described in the case of postural regulation, since they clearly show that these messages contribute to specifying the gaze direction. This suggests that the extraretinal signal might include a proprioceptive component.(ABSTRACT TRUNCATED AT 250 WORDS)
Éducation et socialisation, Sep 10, 2018
Pour faire progresser les recherches en education centrees tout particulierement sur les thematiq... more Pour faire progresser les recherches en education centrees tout particulierement sur les thematiques complexes telles que l’influence des emotions sur les apprentissages en classe, la collaboration entre les Sciences de l’Education et les Neurosciences se revele la demarche la plus pertinente. Cependant de telles recherches interdisciplinaires sont semees d’embuches et d’obstacles divers. Cela est du en partie aux interactions des approches theoriques et methodologiques des deux disciplines, mais egalement au caractere multidimensionnel de la situation experimentale en milieu scolaire ainsi qu’au phenomene complexe qu’est l’emotion elle-meme. Nous revenons ici sur les difficultes d’une etude experimentale en milieu scolaire et proposons des reflexions pour surmonter ces obstacles afin de faire progresser les connaissances sur l’apprentissage scolaire, et par consequent les pratiques educatives.
Neuropsychologia, Jul 1, 1999
Journal of Motor Behavior, Jun 1, 1991
The purpose of this study was to investigate the role of propriomuscular feedback in the control ... more The purpose of this study was to investigate the role of propriomuscular feedback in the control of pluriarticular pointing movements, performed without visual feedback toward visual targets. The proprioceptive inputs were distorted during movements by applying vibration to the distal tendon of the biceps muscle. Various movement and vibration durations were imposed. The results show that vibration affects the spatial outcome of the movements. The effects of vibration were movement time-independent when the durations were shorter than 450 ms and became movement time-dependent with longer durations. Moreover, the effects of vibration became more marked when a short vibration was applied at the end rather than at the beginning of a slow movement. These studies suggest that at least two types of proprioceptive control loops may be involved in correcting this kind of movement, depending on the execution time. In slow movements, the final phase might be a privileged period for on-line, propriomuscular-based corrections. Lastly, it emerged that the regulation of a goal-directed movement on the basis of proprioceptive feedback processing can take place within at most 200 ms.
Développements, Apr 1, 2013
Trends in Neuroscience and Education, Sep 1, 2016
Éditions de la Maison des sciences de l’homme eBooks, Jul 3, 2017
Recognizing the letters encountered when reading is generally assumed to be a purely visual proce... more Recognizing the letters encountered when reading is generally assumed to be a purely visual process, yet a large body of data supports the view that movement plays a crucial role in letter representation and suggests that handwriting contributes to the visual recognition of letters. We established that simply viewing letters activated a part of the left premotor cortex that was also activated when the letters were being written by the subjects. These results, which were confirmed in left-hander subjects, indicate that writing motor processes are implicitly evoked when passively observing letters. The cerebral representation of letters is therefore presumably not strictly visual, but based on a multicomponent neural network built up while learning concomitantly to read and write. If so, changing the motor conditions while children are learning to write by using a method based on typing instead of handwriting should affect their subsequent letter recognition performances. In order to test this hypothesis, we trained two groups of 38 children to copy letters of the alphabet either by hand or by typing them. After three weeks of learning, in the older children, the handwriting training gave rise to a better letter recognition than the typing training. These findings show the existence of close functional relations between the reading and writing processes, and suggests that our reading abilities might be somehow dependent on the way we write
Vision Research, Sep 1, 1997
HAL (Le Centre pour la Communication Scientifique Directe), 2012
Psychologie Francaise, Jun 1, 2010
Human Movement Science, Aug 1, 2015
HAL (Le Centre pour la Communication Scientifique Directe), 2003
Journal of forensic document examination, 2011
During their career, forensic document examiners will inevitably be confronted with handwriting c... more During their career, forensic document examiners will inevitably be confronted with handwriting carried out under unusual conditions (UnC). A questioned document signed on top of a car or on a vertical surface like a wall are two examples. These atypical circumstances may give rise to more variability of the signatures or written words, in particular if the body was in non-traditional writing position without the traditional support. Few studies were devoted to handwriting variability under unusual writing conditions. The current study investigates whether individual variability changes with special writing conditions. In a previous study (Sciacca & al, 2009), we found that eight repetitions were sufficient to obtain a correct estimation of the variance. In the present study, twelve subjects were asked to write two word sets eight times in upper and eight times in lower case, under different conditions : sitting and writing on a horizontal (usual condition UC) or vertical support; and standing, kneeling or laying while writing on a horizontal or vertical support (unusual conditions UnC). Words were written on a pen tablet, normalized in space and time and then averaged. The variance of the eight words was measured under all conditions. Results showed only an increase in variability under the laying and kneeling / vertical UnC. Within the five other postural conditions tested, handwriting was shown to be very stable.
Abstract 1. put forward some experimental arguments supporting the assumption that whole-body, sp... more Abstract 1. put forward some experimental arguments supporting the assumption that whole-body, spatially oriented behaviour might be based on a body reference frame which results mainly from the common processing of various sensory feedbacks arising in the muscles ...
Experimental Brain Research, Aug 1, 1996
... a comparison between memory-guided and visually guided saccades ... Here we attempted to chan... more ... a comparison between memory-guided and visually guided saccades ... Here we attempted to change the initial eye position signal supplied to the oculomotor system before a memory-or visuo-guided saccade to a 10 left target by applying mechanical vibration to the IR muscle. ...
Human Movement Science, Apr 1, 1989
Experimental Brain Research, Jun 1, 1991
The egocentric localization of objects in extrapersonal space requires that the retinal and extra... more The egocentric localization of objects in extrapersonal space requires that the retinal and extraretinal signals specifying the gaze direction be simultaneously processed. The question as to whether the extraretinal signal is of central or peripheral origin is still a matter of controversy, however. Three experiments were carried out to investigate the following hypotheses: 1) that the proprioceptive feedback originating in eye and neck muscles might provide the CNS with some indication about the gaze direction; and 2) that the retinal and proprioceptive extraretinal inputs might be jointly processed depending on whether they are of monocular or binocular origin. Application of low amplitude mechanical vibrations to either the extraocular or neck muscles (or both) of a subject looking monocularly at a small luminous target in darkness resulted in an illusory movement of the target, the direction of which depended on which muscle was stimulated. A slow upward target displacement occurred on vibrating the eye inferior rectus or the neck sterno-cleido-mastoidus muscles, whereas a downward shift was induced when the dorsal neck muscles (trapezius and splenius) were vibrated. The extent of the perceptual effects reported by subjects was measured in an open-loop pointing task in which they were asked to point at the perceived position of the target. These results extend to visually-oriented behavior the role of extraocular and neck proprioceptive inputs previously described in the case of postural regulation, since they clearly show that these messages contribute to specifying the gaze direction. This suggests that the extraretinal signal might include a proprioceptive component.(ABSTRACT TRUNCATED AT 250 WORDS)
Éducation et socialisation, Sep 10, 2018
Pour faire progresser les recherches en education centrees tout particulierement sur les thematiq... more Pour faire progresser les recherches en education centrees tout particulierement sur les thematiques complexes telles que l’influence des emotions sur les apprentissages en classe, la collaboration entre les Sciences de l’Education et les Neurosciences se revele la demarche la plus pertinente. Cependant de telles recherches interdisciplinaires sont semees d’embuches et d’obstacles divers. Cela est du en partie aux interactions des approches theoriques et methodologiques des deux disciplines, mais egalement au caractere multidimensionnel de la situation experimentale en milieu scolaire ainsi qu’au phenomene complexe qu’est l’emotion elle-meme. Nous revenons ici sur les difficultes d’une etude experimentale en milieu scolaire et proposons des reflexions pour surmonter ces obstacles afin de faire progresser les connaissances sur l’apprentissage scolaire, et par consequent les pratiques educatives.
Neuropsychologia, Jul 1, 1999
Journal of Motor Behavior, Jun 1, 1991
The purpose of this study was to investigate the role of propriomuscular feedback in the control ... more The purpose of this study was to investigate the role of propriomuscular feedback in the control of pluriarticular pointing movements, performed without visual feedback toward visual targets. The proprioceptive inputs were distorted during movements by applying vibration to the distal tendon of the biceps muscle. Various movement and vibration durations were imposed. The results show that vibration affects the spatial outcome of the movements. The effects of vibration were movement time-independent when the durations were shorter than 450 ms and became movement time-dependent with longer durations. Moreover, the effects of vibration became more marked when a short vibration was applied at the end rather than at the beginning of a slow movement. These studies suggest that at least two types of proprioceptive control loops may be involved in correcting this kind of movement, depending on the execution time. In slow movements, the final phase might be a privileged period for on-line, propriomuscular-based corrections. Lastly, it emerged that the regulation of a goal-directed movement on the basis of proprioceptive feedback processing can take place within at most 200 ms.
Développements, Apr 1, 2013
Trends in Neuroscience and Education, Sep 1, 2016