Des troubles moteurs et de coordination sensorimotrice sont décrits depuis longtemps dans la schizophrénie. Les patients schizophrènes présentent notamment des troubles de la perception des mouvements que l’on qualifie de biologiques (c’est-à-dire issus d’un organisme vivant). Chez le sujet sain, depuis plus de 30 ans, l’étude de la dynamique des coordinations sensorimotrices et ses applications récentes à la cognition sociale (dynamique des coordinations sociales) ont permis de mieux comprendre et quantifier le rôle du corps et de ses mouvements dans nos relations à l’autre. Cette approche théorique et expérimentale permet de mesurer avec précision les performances sensorimotrices dans l’espace et dans le temps. Toutefois, elle n’a, jusqu’à présent, jamais été appliquée aux patients schizophrènes ni à l’étude de leurs troubles. Nous proposons un paradigme expérimental nouveau dans l’étude de la schizophrénie dont l’objectif principal est de tenter de mesurer, au-delà des troubles de coordination visuo-motrice généralement observés chez les patients, si le « caractère humain » du mouvement d’un stimulus avec lequel ils interagissent module ses capacités à effectuer des tâches sensori-motrices de poursuite de cible. Nos résultats préliminaires indiquent que, contrairement aux sujets sains, la capacité de synchronisation visuo-motrice des sujets schizophrènes est perturbée par le caractère biologique du mouvement de la cible. Notre paradigme expérimental, par son approche fonctionnelle, quantitative et dynamique (des troubles) de la coordination sensorimotrice dans la schizophrénie offre de nouvelles perspectives quant à l’étude de l’origine des troubles des interactions sociales identifiés chez ces patients. Il permet de fait d’aborder indirectement le vaste domaine de la cognition sociale par le biais de la cognition motrice.

Compared to healthy individuals, schizophrenic patients suffer from sensorimotor disorders including problems when tracking moving targets and perceiving biological motion. Recent advances in embodied cognition and social coordination dynamics have emphasized the important role played by bodily information exchange (e.g. facial expressions, posture, and movements) in the way people interact with and mutually influence each other. These experimental studies on healthy participants provide data on sensorimotor performances of a patient that are recorded at high temporal and spatial resolutions. They should therefore be considered in studies on schizophrenic patients. These functional, quantitive and dynamic aspects of sensorimotor coordination abilities, may offer promising perspectives and could lead to a better understanding of sensorimotor disorders in schizophrenia. The purpose of this article is to introduce a new experimental paradigm in schizophrenia inspired by the field of coordination dynamics, a theoretical and experimental approach born more than 30 years ago that has recently expanded to interpersonal interactions, the so-called social coordination dynamics. In our study, we hypothesize that the sensorimotor deficits associated with schizophrenia in social interaction may be, at least partially, due to a failure to properly pick up information about the movements of other people.

We therefore designed a study where healthy individuals and schizophrenic patients were asked to intentionally track the oscillations of visual targets of various social relevance using hand movements. Four different rhythmic visual stimuli varying in degree of biological relevance (form and motion) are used : [1] an oscillating dot; [2] a computer generated hand moving up and down continuously driven by a sine function; [3] pre-recorded oscillatory movements of a real hand; and [4] the hand of a real individual (behind a curtain that occluded vision of the rest of the body). Two distinct dependent variables are computed to quantify the coordination between the movements of the participants and the visual stimuli : the relative phase and the power spectrum overlap between their own movements. In this preliminary study, analyses of kinematic data revealed that schizophrenic patients had trouble synchronizing to (the more) “biological” target unlike control healthy individuals. These results suggest that patients with schizophrenia may suffer from sensorimotor coordination disabilities with socially relevant visual stimuli. The novel paradigm we introduce in research on schizophrenia should allow for a better understanding of the troubles these patients encounter when interacting with other people thanks to an approach rooted and building on social coordination dynamics as well as motor and social cognition.