Dynamic similarity promotes interpersonal coordination in joint-action

Human movement has been studied for decades and dynamic laws of motion that are common to all humans have been derived. Yet, every individual moves differently from everyone else (faster/slower, harder/smoother etc). We propose here an index of such variability, namely an individual motor signature (IMS) able to capture the subtle differences in the way each of us moves. We show that the IMS of a person is time-invariant and that it significantly differs from those of other individuals. This allows us to quantify the dynamic similarity, a measure of rapport between dynamics of different individuals' movements, and demonstrate that it facilitates coordination during interaction. We use our measure to confirm a key prediction of the theory of similarity that coordination between two individuals performing a joint-action task is higher if their motions share similar dynamic features. Furthermore, we use a virtual avatar driven by an interactive cognitive architecture based on feedback control theory to explore the effects of different kinematic features of the avatar motion on the coordination with human players

Unravelling socio-motor biomarkers in schizophrenia

We present novel, low-cost and non-invasive potential diagnostic biomarkers of schizophrenia. They are based on the ‘mirror-game’, a coordination task in which two partners are asked to mimic each other’s hand movements. In particular, we use the patient’s solo movement, recorded in the absence of a partner, and motion recorded during interaction with an artificial agent, a computer avatar or a humanoid robot. In order to discriminate between the patients and controls, we employ statistical learning techniques, which we apply to nonverbal synchrony and neuromotor features derived from the participants’ movement data. The proposed classifier has 93% accuracy and 100% specificity. Our results provide evidence that statistical learning techniques, nonverbal movement coordination and neuromotor characteristics could form the foundation of decision support tools aiding clinicians in cases of diagnostic uncertainty

Effects of Facial Emotions on Social-motor Coordination in Schizophrenia

Schizophrenia patients are known to be impaired in their ability to process social information and to engage in social interactions. To understand better social cognition in schizophrenia, we investigate the links between these impairments. In this paper, we focus primarily on the influence of social feedback, such as facial emotions, on motor coordination during joint action. To investigate and quantify this influence, we exploited systematically-controlled social and nonsocial feedback provided by a humanoid robot. Humanoid robotics technology offers interactive designs and can precisely control the properties of the feedback provided during the interaction. In this work, a joint-action task with a robot is performed to investigate how social cognition is affected by cognitive capabilities and symptomatology. Results show that positive social feedback has a facilitatory effect on social-motor coordination in the control participants compared to nonsocial positive feedback. This facilitation effect is not present in schizophrenia patients, whose social-motor coordination is similar in social and nonsocial feedback conditions. This result is strongly correlated with performances in the Trail Making Test (TMT), which highlights the link between cognitive deficits and social-motor coordination in schizophrenia

La dynamique des coordinations inter-segmentaires, résultat d'une coalition des contraintes neuromusculaires et spatiales

This Thesis presents the results of five experiments carried out to investigate the roleof neuromuscular constraints, spatial constraints, visual feedback and plane of motion, oninterlimb coordination dynamics (bimanual, hand-foot, handheld pendulum). In particular, weinvestigated the conditions under which these constraints influence pattern stability andchanges. Specifically, we assessed (1) the nature of the interaction between neuromuscularand directional constraints as a function of the plane of motion of the task are performed and(2) the role of visual perception as a support of the directional constraint.Pattern stability (phase transitions, time to transition, and relative phase variability)and accuracy of performance (absolute error of the relative phase) were analyzed.Results show that whatever the experimental task context, directional constraints playa dominant role in interlimb coordination dynamics. Indeed, symmetrical movements withrespect to the sagittal plane of the body exhibit the most stable and accurate patterns of coordination,irrespective of the plane of motion in which the tasks are performed. However, neuromuscularconstraints also play a secondary role. Manipulation of the visual informationabout the relative direction of movement shows that a “perceptual isodirectional principle” isat work during the production of interlimb coordination. However, the influence of this principledepends on the conditions in which the tasks are performed (plane of motion, neuromuscularcoupling).To sum up, the present work suggests that interlimb coordination dynamics is a resultof complex interaction, in cooperation or in competition, between constraints of various origins.Ce travail de thèse présente les résultats de cinq expériences qui ont porté sur l'étude des contraintes neuromusculaires, spatiales, visuelles et du plan de mouvement sur la dynamique des coordinations motrices inter-segmentaires (bimanuelles, poignet-cheville, pendules).Plus particulièrement il s'intéresse aux conditions dans lesquelles ces contraintes influencentla production des patrons de coordination. Plus spécifiquement, nous avons étudié (1) la naturede l'interaction entre les contraintes neuromusculaires et directionnelles en fonction duplan de mouvement dans lequel les tâches sont réalisées et (2) le support perceptif de lacontrainte directionnelle.Nous avons analysé la stabilité (nombre de transitions de phase, temps avant transition,variabilité de la phase relative) et la précision (erreur absolue de la phase relative) descoordinations.La manipulation systématique et différenciée des contraintes neuromusculaires et directionnellesa montré qu'indépendamment du type de coordination réalisé, la contrainte directionnellejouait un rôle dominant sur la dynamique des coordinations inter-segmentaires.En effet, quel que soit le plan de mouvement, les mouvements symétriques par rapport au plansagittal médian du corps sont toujours les plus stables et les plus précis. Toutefois, lacontrainte neuromusculaire joue également un rôle dans cette dynamique mais de moindreimportance. La manipulation de la perception visuelle du déplacement des membres a montréque le principe d'isodirectionnalité perceptive dépendait des conditions dans lesquelles lestâches sont réalisées (plan de mouvement et couplages neuromusculaires).L'ensemble de ce travail de thèse suggère que la dynamique des coordinations motricesrésulte de l'assemblage complexe en coopération ou en compétition des contraintes relativesau degré de symétrie des coordinations, aux couplages musculaires impliqués dans lemouvement et aux plans de mouvement dans lequel les tâches sont réalisées

A dynamical approach to the effects of aging on bimanual coordination

International audienceno abstrac

A Dynamic Systems Approach to the Effects of Aging on Bimanual Coordination

International audienceThe present study examined the effects of aging on the execution of a bimanual coordination task in a classical phase transition paradigm in which coordination patterns (in-phase and anti-phase) and movement frequency were manipulated. Two groups of adults, the so-called young (average age 26 years) and old (average age 71 years) participants, performed both in-phase and anti-phase patterns at different frequencies. As we expected variability of relative phase was larger for older participants than for younger ones for both the in-phase and the anti-phase coordination patterns. Moreover, phase transitions occurred at lower frequencies for older participants and more transitions were observed for older than for younger participants. Although no specific hypotheses were made about the prominent source(s) of age-related changes in coordination dynamics (i.e., an alteration in the coupling function and/or an increase of the magnitude of noise), our results suggest that these changes might result from increases in the (neural) noise to be found in the (bimanual) action system. Copyright (C) 2009 S. Karger AG, Base

A dynamic systems approach to the effects of aging on bimanual coordination

The present study examined the effects of aging on the execution of a bimanual coordination task in a classical phase transition paradigm in which coordination patterns (inphase and anti-phase) and movement frequency were manipulated. Two groups of adults, the so-called young (average age 26 years) and old (average age 71 years) participants, performed both in-phase and anti-phase patterns at different frequencies. As we expected variability of relative phase was larger for older participants than for younger ones for both the in-phase and the anti-phase coordination patterns. Moreover, phase transitions occurred at lower frequencies for older participants and more transitions were observed for older than for younger participants. Although no specific hypotheses were made about the prominent source(s) of age-related changes in coordination dynamics (i.e., an alteration in the coupling function and/or an increase of the magnitude of noise), our results suggest that these changes might result from increases in the (neural) noise to be found in the (bimanual) action system.status: publishe

A dynamical approach to the effects of aging on bimanual coordination

International audienceno abstrac

Testing promotes effector transfer.

International audienceThe retrieval of information from memory during testing has recently been shown to promote transfer in the verbal domain. Motor-related research, however, has ignored testing as a relevant method to enhance motor transfer. We thus investigated whether testing has the potential to induce generalised motor memories by favouring effector transfer. Participants were required to reproduce a spatial-temporal pattern of elbow extensions and flexions with their dominant right arm. We tested the ability of participants to transfer the original pattern (extrinsic transformation; i.e., goal-based configuration) or the mirrored pattern (intrinsic transformation; i.e., movement-based configuration) to the unpractised non-dominant left arm. To evaluate how testing affects motor transfer at 24-h testing, participants were either administered an initial testing session during early practice (early testing group) or shortly after the end of practice (late testing group; i.e., no alternation between practice and testing sessions). No initial testing session was completed for the control group. We found better effector transfer at 24-h testing for the early testing group for both extrinsic and intrinsic transformations of the movement pattern when compared with the control group, while no testing benefit was observed for the late testing group. This indicates that testing positively affects motor learning, yielding enhanced long-term transfer capabilities. We thus demonstrate the critical role of retrieval practice via testing during the process of motor memory encoding, and provide the conditions under which testing effectively contributes to the generalisation of motor memories