Anticipating the terminal position of an observed action: Effect of kinematic, structural, and identity information

International audienc

Visual Perception of Elliptic movements in 7- to-11-year-old children : Influence of Motor Rules

Cette recherche porte sur la perception visuelle des mouvements humains chez l’enfant. Le but est de vérifier si le principe d’isochronie (tendance à maintenir le temps de mouvement constant quelle que soit son amplitude) que l’on observe sur le plan moteur est également présent sur le plan perceptif. On présentait sur un écran un point décrivant une trajectoire elliptique. La taille de l’ellipse variait de 2.94 à 53 cm. Des enfants âgés de 7 à 11 ans devaient ajuster selon leur préférence la vitesse (période) du mouvement. Les résultats montrent que la relation ente la période choisie et la taille de l’ellipse correspond à celle observée lors de la réalisation du mouvement (Viviani et Schneider, 1991) : dès 7 ans les ajustements perceptifs sont conformes au principe d’isochronie. Ces résultats permettent de discuter les liens motricité-perception.The aim of the present study is to analyse the visual perception of human movements in children. We evaluated whether the isochrony motor principle (that is the tendency to maintain constant the duration of movement across change of movement amplitude) is at work in a perceptive task. Children, aged 7 to 11 years, had to adjust the velocity (the period) of a dot depicting an elliptic motion. The size of the ellipse varied from 2.94 to 53 cm. Results showed that the relation between the chosen period and the size of the ellipse corresponded to that observed in motor production (Viviani & Schneider, 1991) : From 7-year-old perceptual adjustments were in agreement with the isochrony principle. The results are discussed in terms of motor-perception relationships

The Added Value of Point-Light Display Observation in Total Knee Arthroplasty Rehabilitation Program: A Prospective Randomized Controlled Pilot Study

Background and Objectives: The present study aimed to assess the potential benefit of the observation of rehabilitation-related point-light display in addition to a conventional 3-week rehabilitation program, the objective being to improve functional capacity in patients having undergone total knee arthroplasty. Materials and Methods: Patients randomized in the control group had conventional rehabilitation treatment with two sessions per day 5 days a week of physical therapy (90 min), whereas patients in the experimental group had a program of conventional rehabilitation combined with a point-light display observation two times per day (5 min) and 3 days a week. Results: The patients of both groups had improved their performances by the end of the program, and the pre- and post-test improvement were superior for the experimental group over the control group concerning the total WOMAC score (p = 0.04), the functional WOMAC score (p = 0.03), and correct recognition of point-light displays (p = 0.003). Conclusions: These findings provide new insight favoring systematic point-light display observation to improve functional recovery in patients with total knee arthroplasty

Développement des liens perception d’action-langage chez l’enfant

National audienc

Motricité et perception visuelle des mouvements humains : expériences chez l'adulte, l'enfant et le patient parkinsonien

This dissertation aims at analysing the role of motor-perceptual interactions in the visual perception of human movements. Most of studies showed that recognition of human movements was influenced by motor competences and then validated the motor theories of perception. The aim of our research was to demonstrate that visual perception of human movement does not necessarily depend on motor abilities and does not imply motorperceptual interactions. The experiments consisted in analysing 1) the visual preferences for human movements which does not conform to the motor rules (unnatural movements) and 2) the influence of the level of motor competences on visual performances, in children and in patients presenting motor impairments (Parkinson’s disease). Researches only focused on space-time relations which were observed in the morphocinetic (isochrony principle) and topocinetic (Fitts’ law) movements. The results indicate that the violation of the kinematics does not influence the visual judgement of elliptic or reaching movements. However, a significant disturbance of velocity profile modifies the visual preference in handwriting. Inaddition, we observed that the visual performances of children and those of patients with a Parkinson’s disease are not totally dependent of motor competence. Taken together, the findings suggest that the motor system is not systematically involved in the visual perception of human movements. Particularly, the type of the movement (handwriting vs reaching movement) or the properties of the handled object (glass vs cylinder) has an influence on the implication of the motor system in visual judgements of human motions.Cette thèse est consacrée à l’étude du rôle de la motricité dans la perception visuelle des mouvements humains. L’objectif est de montrer que les correspondances entre les performances motrices et les jugements perceptifs, contrairement à ce qui est postulé par les théories motrices de la perception, ne sont pas forcément dues à l’intervention du système moteur. Pour cela nous avons analysé d’une part les jugements perceptifs pour des stimuli dont la cinématique ne respecte plus les règles de production motrices et d’autre part les liens existant entre les capacités motrices et perceptives chez des populations présentant un niveau de développement moteur variable (enfants, patients atteints de la maladie de Parkinson). Ces travaux ont concerné uniquement les relations espace-temps telles qu’elles s’expriment dans les mouvements morphocinétiques (principe d’isochronie) et topocinétiques (loi de Fitts). Les résultats indiquent que la modification de la cinématique des mouvements n’empêche pas le respect des règles motrices lors du jugement perceptif de mouvements d’ellipse ou de pointage de cible. Par contre, une perturbation très importante de la cinématique entraîne une modification du jugement des mouvements d’écriture. D’autre part, on observe des décalages entre les compétences motrices et les compétences perceptives chez les enfants et les patients parkinsoniens. Ces résultats suggèrent que la perception visuelle des mouvements humains n’implique pas systématiquement une intervention du système moteur. On constate en particulier que le type de mouvement (écriture vs mouvement d’atteinte de cible) et les propriétés des objets manipulés (verre vscylindre) ont un effet très important sur le degré d’intervention du système moteur lors du jugement visuel de mouvements humains

Are judgments for action verbs and point-light human actions equivalent?

International audienceThe aim of the present study was to examine whether the ability to judge action words and the ability to judge human actions share common mechanisms. With this purpose in mind, we proposed both a lexical and an action decision task to twenty-four healthy participants. For both tasks, the participants had to judge whether the stimulus that was presented (a letter string or a point-light sequence) was valid or not (i.e. a word vs. a pseudo-word, an action vs. a pseudo-action). The data analysis showed that the action decision task has common characteristics with the lexical decision task. As for verbal material, judgements of pseudo-actions were slower than judgements for actions. Moreover, we demonstrated that the ability to judge an action verb was positively correlated with the ability to judge a point-light human action, whereas no significant correlation appeared between nouns and point-light judgements abilities. This dissociation supports the argument that the judgement of action words and the judgement of human actions share a common but specific basis through the involvement of motor representation

Motor Knowledge Modulates Attentional Processing during Action Judgment

International audienceSeveral studies have revealed the role of motor experience when humans have to judge human actions. However, the possible influence of motor knowledge on attentionprocesses has been neglected. This study used a flanker paradigm (Eriksen andEriksen1974) to analyze the attentionresponses of male and female participants during the judgment of running movements. Three running actions appeared simultaneously on a computer screen, with the target in the center and the flankers in the periphery. The target and flankers could be compatible or incompatible concerning both the direction of the movement and the sex of the runner. Moreover, flankers were presented upright or upside-down. The results indicate that the distracting effect of the flankers was different for male and female participants. Whereas direction-incompatible flankers systematically disturbed the female participants’ performance, regardless of the sex and the orientation of the flanker, male participants were only distracted when the flankers were upright males. This finding offers new directions to explain sex differences in the judgment of human action

Motor Representation and Language in Space, Object, and Movement Perception

International audienc