Visual Scanning of Dynamic Faces in Relation to Varying Positive and Negative Affect

Background: The ability to derive socially relevant information from faces is fundamental to interpersonal communication and reciprocal social interaction. In structured viewing tasks, such as looking at still images of faces showing exemplar emotions, adults with autism exhibit increased fixation to atypical or nonfeature areas of the face (e.g., looking at the cheeks, chin, or hairline rather than at the eyes). And in face recognition tasks as well as when making judgments about facial emotions, individuals with autism show an over-reliance on information from the mouth region as well as increased fixation on the mouth area. Reduced looking at eyes and increased looking at the mouth have also been observed during natural viewing conditions (i.e., watching dynamic faces in scenes of social interaction). This observation was recently extended from adolescents and adults to 2-year-olds with autism. However, it is not known whether these children’s visual fixation patterns are impacted by varying facial affect.

Objectives: This study examines visual fixation patterns in toddlers with autism during viewing of dynamic faces displaying a range of naturally-occurring positive and negative affect.

Methods: Two-year-olds with autism spectrum disorders and control children matched on age-, verbal-, and nonverbal function, watched video scenes of female actors playing the role of caregiver and displaying a range of facial expressions. Dynamic facial expressions in the caregiver videos were quantitatively ranked by naïve external observers for degree of positive vs. negative affect. Then, using the ratings of affect as an analytic regressor, we examined the eye-tracking data in relation to varying degree of naturally-occurring facial affect.

Results: Preliminary results suggest that the emotional valence of dynamic faces alters visual fixation patterns in two-year-old, typically-developing children. In two-year-olds with autism, however, facial expressions have little impact on visual scanning. Across varying social affect, two-year-olds with autism look less at the eyes of others, while looking more at others’ mouths.

Conclusions: Differential attention to faces, particularly in conditions of changing affect, is critical for extracting information about the intentionality of others. Failure to do so suggests an altered path for learning about the surrounding world, with potentially profound impact on subsequent social development. Over the course of development, failing to reallocate visual resources in a manner that is contingent with changing facial affect is likely to exacerbate increasingly atypical neural specialization, altering the formation of the social mind and brain.