Les troubles du spectre de l’autisme (TSA) se caractérisent par des altérations qualitatives dans les relations sociales et dans la communication tant verbale que non verbale. Dans cette étude, nous avons évalué si les enfants atteints de TSA utilisent les informations relatives au corps en mouvement pour catégoriser des scènes avec ou sans interactions sociales. Les performances des enfants avec TSA ont été comparées à celles d’enfants de développement typique appariés en âge mental non verbal et en âge chronologique. Le modèle minimaliste de Johansson a été utilisé afin d’isoler les indices sociaux issus de la cinématique du corps. Ces animations illustrant deux acteurs, engagés ou non dans une interaction sociale, ont été proposées aux participants. Nos résultats soulignent les compétences des enfants avec TSA à extraire de l’information sociale à partir de mouvements corporels bien qu’ils soient moins performants que des enfants de développement typique appariés. Cette différence ne s’explique ni par un déficit du traitement configural, ni par leur niveau intellectuel, ni même par les aspects émotionnels des scènes observées. L’interprétation de ces résultats s’appuie sur un déficit de la construction des représentations de l’action et du développement du mécanisme miroir dans l’autisme. En conclusion, le modèle de Johansson se révèle être un outil pertinent et prometteur à développer dans une perspective de remédiation cognitive.

Autism spectrum disorders (ASD) are characterized by difficulties in social interaction and verbal and non verbal reciprocal communication. Face and gaze direction, which participate in non verbal communication, are described as atypical in ASD. Also body movements carry multiple social cues. Under certain circumstances, for instance when seeing two persons from far, they constitute the only support that allows the grasping of a social content. Here, we investigated the contribution of whole-body motion processing in social understanding.

The aim of the study was to evaluate whether children with ASD make use of information carried by body motion to categorize dynamic visual scenes that portrayed social interactions.

In 1973, Johansson devised a technique for studying the perception of biological motion that minimizes static form information from the stimulus, but retains motion information. In these point-light displays, the movement figure, such as a body, is represented by a small number of illuminated dots positioned to highlight the motion of the body parts. We used Johansson’s model to explore the ability of children with ASD to understand social interactions based on human movement analysis. Three-second silent point-light displays were created by videotaping two actors. The two actors were either interacting together or moving side by side without interacting. A large range of social interaction displays were used to cover social scenes depicting social norms (conventional gestures and courteous attitudes), emotional situations (carrying positive or negative valences) and scenes from games (sports, dance, etc.). Children were asked to carefully watch the stimuli and to classify them according to the question “Are the two persons communicating or not?”. Four sessions of 3minutes were performed by each child. Children with ASD were compared with typically developing control children matched with either non verbal mental age or chronological age. Response and reaction time were recorded in this force-choice categorization task.

The performance of children with ASD suggested that they were able to extract a social content from body motion. However, they were significantly less efficient than typically developing control children, either matched for non verbal mental age or chronological age. This was especially the case for the social interaction displays. Neither impaired global perceptual processing, nor cognitive development, nor emotional content could explain these lower performances.

The results are discussed in the context of an action representation deficit and a dysfunction of the mirror mechanism in ASD. In conclusion, this behavioural study highlights the potential of point-light displays as a rehabilitation tool in ASD.