Brief report: Temporal distribution of visual attention between the eyes and mouth in young autistic children

Background: Face scanning studies in autistic children report mixed results as to attention allocated to the eyes and mouth regions. While face scanning is a dynamic process, the way autistic children distribute their attention between the eyes and mouth of their interlocutor is usually analyzed by averaging the proportion of time spent looking either on the eyes or the mouth over the whole duration of stimulus presentation.Method: In this study, instead, we focused on the temporal distribution of visual attention between the eyes and mouth of adult faces in 58 autistic and 61 typically developing (TD) children. Participants' eye movements were recorded as they were freely watching videos of faces of silent and speaking adults. We explored attention to the eyes and mouth with fine-grained analyses of the temporal trajectory of fixations on the two regions using generalized additive mixed effects models.Results: These analyses revealed that both groups started their observation of speaking faces on the eyes and shifted to the mouth as the actor started speaking. However, TD, but not autistic children then slowly shifted their attention back to the eyes.Conclusions: Rigorous analyses of how autistic children modulate their visual attention between key social features of the face over time may provide more accurate descriptions of their face scanning abilities.