Autism, Aspergers syndrome and atypical autism belong to the Autism Spectrum Disorders (ASD) which are early neurodevelopmental disorders.The communicative function of body is underused by patients with ASD: they do not initiate communicative and expressive gestures in order to interact with others and seem to be unable to answer to them.Moreover, patients with ASD are less able than healthy people to identify emotion and interaction displayed by human motion.What influence do social meaning and emotion have on visual exploration of human motion in ASD and during healthy development? With an infrared eye-tracker, ocular movements and pupil size of healthy participants (3-47 years) and of patients with autism, Aspergers syndrome or atypical autism (4-47 years) have been recorded.Videos of human motion (Johansson, 1973) were presented and displayed simultaneously scenes of social (SMo with and without emotional load) and non social human motion (NSMo, motor activities).Percentages of looking time on each scene related to total looking time on the screen and pupil diameter were measured and compared between emotional SMo, non emotional SMo and NSMo in healthy participants and patients.Patients with ASD looked significantly less to SMo (emotional and non-emotional) than healthy participants.Among ASD population, patients with autism looked specifically less to social motion than atypical autism patients.The mean pupil size for the ASD group was clearly smaller than for healthy participants and the pupil responses to emotional stimuli discriminated patients with ASD from control subjects.These potential biomarkers may advance our understanding of neurodevelopmental differences in autism.