Positive emotional valence in spontaneous facial expressions of autistic adolescents.

Facial expressions produced by autistic individuals are often perceived as difficult to interpret. Most data on facial expression production rely on posed or mimicked facial expressions, which may not be representative of spontaneous expressiveness. In this paper, we analyze facial expressions produced spontaneously in response to brief video clips. We presented a pseudo-randomized sequence of humorous and disgusting YouTube clips to autistic and non-autistic adolescents and videotaped their spontaneous facial reactions to the videos. Facial feature movements were coded for the duration (in milliseconds) and valence (positive or negative) of the expression. All coders were naïve to diagnosis and all videos were independently double coded. Autistic participants produced longer emotional facial expression durations (positive and negative) in response to video stimuli compared to non-autistic participants. Autistic adolescents specifically produced longer positive facial expressions, including in response to negative videos, a pattern not seen in non-autistic adolescents. These data provide important information regarding spontaneous facial expression production of autistic and non-autistic adolescents. Results indicate that social miscommunication between autistic and non-autistic adolescents may in part be based on autistic facial feature movements that are perceived as positive, even when they are prompted by stimuli with negative content.