The perception of emotional facial expressions by children with autism using hybrid multiple factorial design and eye-tracking

Abstract

Children with autism spectrum disorder (ASD) have the deficits in emotional facial expression recognition and understanding, which is considered as the core source of their social communication disorder and stereotype behaviour. Previous studies have suggested that individuals with ASD have the deficits in the perception of static emotional facial expressions, but results are inconclusive. The use of 3D or dynamic facial stimuli that express emotions at different levels of intensities may produce more robust results, since these resemble the expression of emotions in daily life to a greater extent. In this study, 30 children (aged 2–7 years) with ASD and 51 age-matched children with typical development (TD) performed an emotion recognition (ER) task, in which morphs, presented on a computer screen, depicted facial expressions associated with two basic emotions (happiness and fear) at four levels of emotional intensity(25%–100%). Using a hybrid-design experiment and eye-tracking technology, we explored the influencing factors of ER in children with ASD and their interaction. In addition, we analyzed the gaze characteristics and processing patterns of children with ASD during the ER, and their impact on ER. The results showed that the type of subject, expression category, and intensity of expression had the main effect on recognition accuracy, and there was interaction among the factors that affected the emotional face recognition ability of the children with ASD. Moreover, children with ASD and TD both had an advantage when recognizing dynamic expressions rather than static expressions in 2D or 3D. The recognition accuracy of 3D expressions of children with TD was higher than that of 2D expressions, but children with ASD had the opposite result. The recognition accuracy of fearful expression for both ASD and TD groups was significantly better than that of happy expression. There was an interaction effect between gender and expression category, but age was not significant. In particular, girls’ facial expression recognition ability was superior to that of boys. The eye-tracking results showed that children with ASD have face-specific processing mechanisms: avoidance of eye contact, increased focus on the mouth and background information, and a preference for local feature processing. In conclusion, this study suggests that the material, category, and intensity of facial expression combines with the age and gender of subjects to affect the emotional expression recognition ability of children with ASD. Children with autism have the advantage of dynamic processing and mouth-directed gaze. In addition, dynamic facial expressions may be used as effective training and intervention materials for ER. Abnormal face processing and eye-tracking characteristics can help to understand the social disorders of ASD and provide behavioral characteristic indicators for early identification of ASD.