Des particularités dans l’exploration visuelle des visages, notamment des yeux et/ou des lèvres, sont caractéristiques des personnes atteintes de troubles du spectre de l’autisme (TSA) et contribuent à expliquer leurs difficultés de communication sociale et/ou verbale. Elles pourraient être en partie liées à la vitesse excessive des informations véhiculées par les visages lors des interactions. Pour tester cette hypothèse, nous avons enregistré, à l’aide d’un oculomètre, chez 23 enfants avec TSA et 29 enfants typiques, les comportements d’exploration visuelle, i.e. le nombre, le temps total et la durée moyenne des fixations visuelles, sur une scène visuelle montrant le visage d’une narratrice racontant une histoire enfantine dans trois vitesses différentes : temps réel (TR), ralentie à 70 % (R70), ralentie à 50 % (R50). Nos principaux résultats indiquent que : les enfants avec TSA regardent moins le visage et la bouche de la narratrice, mais autant ses yeux, que les enfants typiques ; les enfants avec TSA font des fixations visuelles d’une durée moyenne significativement plus longue sur la scène visuelle et particulièrement sur la bouche de la narratrice, en condition R50 comparativement à la vitesse TR ; les enfants ayant un autisme léger passent d’autant plus de temps à explorer le visage de la narratrice, et notamment sa bouche et ses yeux, que la vitesse est ralentie. Ces résultats encourageants confirment que la dynamique faciale est trop rapide pour certains enfants autistes et démontrent que le ralentissement de la dynamique faciale peut stabiliser leur regard sur le visage d’autrui et ses traits internes, qui sont cruciaux pour le développement de la communication verbale et socio-émotionnelle.

Face and gaze avoidance are among the most characteristic and salient symptoms of autism spectrum disorders (ASD). Studies using eye tracking highlighted early and lifelong ASD-specific abnormalities in attention to face such as decreased attention to internal facial features. These specificities could be partly explained by disorders in the perception and integration of rapid and complex information such as that conveyed by facial movements and more broadly by biological and physical environment. Therefore, we wish to test whether slowing down facial dynamics may improve the way children with ASD attend to a face.

We used an eye tracking method to examine gaze patterns of children with ASD aged 3 to 8 (n=23) and TD controls (n=29) while viewing the face of a speaker telling a story. The story was divided into 6 sequences that were randomly displayed at 3 different speeds, i.e. a real-time speed (RT), a slow speed (S70=70% of RT speed), a very slow speed (S50=50% of RT speed). S70 and S50 were displayed thanks to software called Logiral™, aimed at slowing down visual and auditory stimuli simultaneously and without tone distortion. The visual scene was divided into four regions of interest (ROI): eyes region; mouth region; whole face region; outside the face region. The total time, number and mean duration of visual fixations on the whole visual scene and the four ROI were measured between and within the two groups.

Compared to TD children, children with ASD spent significantly less time attending to the visual scenes and, when they looked at the scene, they spent less time scanning the speaker's face in general and her mouth in particular, and more time looking outside facial area. Within the ASD group mean duration of fixation increased on the whole scene and particularly on the mouth area, in R50 compared to RT. Children with mild autism spent more time looking at the face than the two other groups of ASD children, and spent more time attending to the face and mouth as well as longer mean duration of visual fixation on mouth and eyes, at slow speeds (S50 and/or S70) than at RT one.

Slowing down facial dynamics enhances looking time on face, and particularly on mouth and/or eyes, in a group of 23 children with ASD and particularly in a small subgroup with mild autism. Given the crucial role of reading the eyes for emotional processing and that of lip-reading for language processing, our present result and other converging ones could pave the way for novel socio-emotional and verbal rehabilitation methods for autistic population. Further studies should investigate whether increased attention to face and particularly eyes and mouth is correlated to emotional/social and/or verbal/language improvements.