Background: Eye-tracking has been used to investigate social perception in autism spectrum disorder (ASD) with variable results. This heterogeneity may be due to the types of stimuli used. In this study, we investigated whether the use of moving vs static stimuli or human actors vs cartoons characters would be more sensitive in detecting gaze abnormalities and discriminating children with ASD from typically developing children.
Methods: We studied 18 children with ASD (mean age = 12.9 ± 2.9) and 21 typically developing controls (mean age = 11.3 ± 2.5). Gazes were tracked using Tobii-T120 eye-tracker. Four different types of stimuli were presented: movie with human actors, cartoon movie, picture with human actors and cartoon picture. To identify the type of stimuli that best discriminate the ASD group from the control group, a two-way ANOVA was performed using ecological dimension [human-actors/cartoon] and presentation form [movie/picture] as factors.
Results: Children with ASD presented significantly less fixations to eyes and faces in the movie with human actors and in the picture with human actors. Children with ASD also presented significantly more fixations to non-social backgrounds in the movie with human actors and in the cartoon movie. A significant ecological effect was observed for the reduction in fixations to the eyes [human-actors > cartoon]. A significant presentation form effect was observed for the increased fixations to the non-social background [movie > picture].
Conclusions: The direct comparison of gaze behavior across four different types of stimuli demonstrates that gaze abnormalities in ASD depend on the type of stimuli that is used. Our results suggest that general gaze abnormalities in children with ASD are better detected when using dynamic stimuli, and finer details of these abnormalities, especially looking less to the eyes, are better detected in a more ecologically relevant situation presenting human characters.
Full PDF:click here