Exploration of core features of a human face by healthy and autistic adults analyzed by visual scanning.

Autism is a neurodevelopmental disorder characterized by disorders in social interaction and emotional reciprocity which can be explained by impairments of the ability to understand the mental states of others ("theory of mind") and recognition of facial expressions. These impairments may be related to the difficulties with face recognition characteristic of this disorder. Face perception plays a critical role in the development of social interaction and understanding of the internal emotional state of others. It depends on initial oculomotor exploration. The aim of this study was to quantify ocular behaviour in 11 adults with autism and 23 healthy subjects (15-35 years) while exploring neutral faces and faces expressing an emotion using an eye tracking method. The strategy used to explore faces was also studied. All subjects spent significantly more time on the eye region than on the rest of the face. However, subjects with autism spent less time on the eye region than healthy subjects. The latter used a strategy based on their own eye dominance when exploring faces. All healthy subjects significantly began their exploration of a face by looking at the eye in the contralateral visual field to their dominant eye. This strategy seemed to be impaired in patients with autism. To conclude, these results contrast with earlier reports regarding the lack of interest in the eye region in patients with autism, and demonstrate for the first time that perception of the face is dependent on eye dominance.